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Project Report No. 32

Canada. Fisheries Service. Industrial Development Service. PROJECT REPORT

Progress Reports Nos. 1 to 5 of ~the ,,/

American Eel (Anguilla rostrata) Studies in Canada

by

Vadim D. Vladykov, Ph.D., Professor of Biology,

Faculty of Pure and Applied Science, University of Ottawa,

Ottawa

for

I ndustrial Development Branch, Fisheries Service,

Department of Fisheries and Forestry, April 1970

Progress Reports Nos. 1 to 5 of the American Eel (Anguilla rostrata) Studies

in Canada

by

Vadim D. Vladykov, Ph.D.

This was a project carried out by Dr. Vladykov under contract to the Industrial Development Branch, Fisheries Service, Department of Fisheries and Forestry,

Ottawa, Canada.

.•

- 1 -

PROGRESS REPORT NO. 1 OF 'l'HE jJ'1l<~IUC./'i N iEL (ANGUILLA H.O~TH.A'l'A) S'l'UDI.ES IN CANADA

by

VADIM D. VLADYKOV

My initial work in regard to the eel studies in Canada

was devoted to the following three aspects.

TAGS AND TAGGING

In order to understand better the seasonal movement, rate of growth,

intensity of fisheries and many other ~spects of eel biology in freshwater

habi tat, an extensive t".gging programme was prepured.

TYPE OF TAGS

As the American eel in freshwater habitat usually hides under rocks

or buries itself in the mud, they Can be tagged successfully only with

specially designed tags. Some years ago, I (Vladykov, 1957) developed

such a type of tag.

This model I named "split ring and plate tag". Three sizes of

split rings, made of stainless steel piano wire, were manufactured:

J/8, 5/8 and 7/8 inch in diameter. They can be opened sideways by means

of specially designed pliers, one for each ring size. The plate or tag

proper is made of laminated vinylite of different colours and in two

sizes: about 1 x 1/4 of an inch and 9/16 x 3/16 of an inch. Four colours

are used. The numbers are stamped on one surface (face), prefixed by a

letter cor responding to the colour: B (blue), G (green), W (white) and

Y (yellow). On the under surface of the plate is printed "Cana.da".

2

'l'he split rings and tags are attached around the lower jaw of the eel.

To prevent accidental opening of the sp: it I'ings, the ends are welded

by using a portable electric welder.

After an extensive correspondence with two firms and several telephone

calls, eventu~lly on June 28, 1967 we agreed to terms as to the dimensions of

the vinylite plate and size of the number and letters.

A) The vinylite plates were ordered from the Stanley Manufacturing Co.

(230 Bartley Drive) Toronto. Our order consists of 20,000 large plates

and 12,000 small plates to the global amount of $1,706.40, tax not included.

b) Split rings of three sizes in a combined quantity of 9,000 and 6 pairs

of pliers were ordered from Accessories Manufacturers Ltd., (595 St. Remi

Street) Montreal, to the global amount of $1,542.50, tax not inc1udl'-d.

The above plates and rings have not been received as yet, but this

delay does not affect our studies. This year I plan to tag eels only

during the late summer and fall months.

ELVERS

The term elver applies to recently metamorphosed "glass eel". The

glass eel is intermediate between the early larval stage or leptocephalus

and elver proper.

Knowledge of the time when elvers first reach the estuaries of different

rivers, their abundance and the duration of their run is very important.

This year we limited our observations on elvers, close to the two

biological stations on the Atlantic coast: St. Andrews, N.B. and the

Bedford Institute of Oceanography, Dartmough, N. S. The proximity to the

research stations is extremely useful for our future studies.

3

Bedford Basin, N.S.

At the head of the Bedford Basin, is found the Sackville river.

This locality is not very far from the Bedford Institute of Oceanography.

Mr. S. Miles, graduate student of Dalhousie University, N. S. during

June 1967 collected about 10,000 elvers. They were so plentiful at a

certain date th~t he could c~tch several hundred by using an aquarium

dip net ~j.bout four inches in diameter.

St.Andrews, N.B.

Around the area of this Biological station are located three

brooks in which elvers are found in considerable numbers. These localities

are as follows: Birch Cove Pond (about 6 miles distant), Digdeguash river

(about 16 miles distant) and Bocabec river (about 13 miles distant) •

Mr. D. James with an assistant, used a hand seine, four feet in

length and provided with a wooden stick at either end, to catch elvers

in this area. During the period May 13, to June 6, 1967 he caught

about 2') ,000 elvers.

During his second collecting trip from July 21, to 25, 1967 he

obtained in the estuary (at the falls) of the Digdegu~ sh river 11,000

elvers.

""hite Lake Hatchery. Ontario

After severa.l unsuccessful attempts to locate a convenient pond

within a radius of 100 miles from Ottawa, I eventually decided oh

Pond No.1 at White Lake Hatchery, located on Highway No.7 about

100 miles from Ottawa.

4

On June 15th, I wrote to the Authoritips of the Ontario Department

of Lands and Forests, Maple, Ontario. At last, on June 29th, I received a

f~vourable answer to my request. However, this pond is at our disposal

only until the Spring of 1968. This pond is very rich in natural food.

On July 27th, D. James liberhted 10,000 elvers in Pond No.1. These

elvers were caught by him at Digdeguash river. The size of these elvers

varies from 2 1/2 to 3 inches. There are about 4,000 elvers per pound.

After spending the winter in the pond, we shall know about the rate

of growth of the elvers and the changes in their otoliths. The age

determination of an eel is made by their otoliths. There are successive

transparent (winter) and opaque (summer) layers. However, it is not

known as yet whether each transparent layer ("annulus") corresponds

to a single winter period or whether more than one annulus is fonned

each winter.

COMMERCIAL POSSIBILI'fr8S

Eel catches in Canada during recent years were given by Vladykov

(1966). The Province of Quebec yields about twice the eel catch of all

the other provinces put together.

From T~ble 1 it is evident that eel fisheries in the Maritime

Provinces are not extensively developed.

5

Table 1. Mean annual catches of the American eel (Anguilla rostrata)

in Canada per 5-year periods.

Five-year periods Province 1950-54 195.5-59 1960-64

1bs Ibs 1bs

Newfoundland 23600

Prince Edward Island 40800 43600 42000

New Brunswick 7)400 75200 147000

Nova Scotia 112200 113600 118600

Quebec 793600 981200 955000

Ontario 57400 100800 162200

Total 1077400 1314400 1454300

A recent survey of eel fisheries in the Maritime provinces by

ERles (1966) confirms this.

In my opinion in order to increase catches of eels, fishermen

should be assured that their catches will be sold and at reasonable

prices. To do so there should be organised one or several centres

could be kept alive until potential buyers come for them.

So far two of the larger European buyers in their reply to me

expressed their desire to buy both green (immature) and bronze (mature)

eels from Can~da. These buyers are as follows:

1. Fa. Joh. Kuijten Import and Export Spaarndam, Holland

2. Masala Pasquale Industria Allevamento Novellame San Vero Milis (Cagliari), Italy.

6

REFER.8NCES

Eales, J.G. 1966 (MS). A survey of eel fishing in the Maritime Provinces.

57 pp. OTTA't:A.

Vladykov, V. D. 1957. Fish tags and tagging in ~uebec waters Trans. Am.Fish

Soc. Vol. 86 (1956), pp. 345 - 49.

Vladykov, V. D. 1966. Remarks on the American eel (Anguilla rostrata

LeSueur). Sizes of elvers entering streams;

the relative abundance of adul t males and females.;

and present economic importance of eels in North

America. Verh. Internat. Verein. Limmol. Vol. 16,

pp. 1007 - 17.

July )1, 1967. Ottawa.

- 7 -

PROGRESS REPORT NO. 2

ELVERS OF THE AMERICAN EEL (ANGUILLA ROSTRATA)

IN THE MARITIME PROVINCES

by

VADIM D. VLADYKOV

INTRODUCTION

The American eel (Anguilla rostr~) like the European species,

A. anguilla, passes through several larval stages. The earliest

stages, known as preteptocephalus and leptoceEbalu~, are shaped like

willow leaves, are completely transparent, and have long, needle­

sharp larval teeth. They live in the open sea and actively feed on

plankton.

Later, the leptocephali gradually transform into gjass eels,

which have the cylindrical shape of an adult eel. The glass eels

lose their teeth and do not feed. In their early stage they are

completely transparent. After, they acquire dark pigmentation on

the top of the head and at the base of the caudal fin. In this

latter stage they approach the shore. Needler (1929) in the latter

half of May 1928 found many glass eels in the stomachs of haddock

at Ingonish, Cape Breton. Schmidt (1909) observed that leptocephali

of the European eel during their transformation into the glass eel

- 8 -

stage shrink in length on the average from 75 mm to 60 mm, and their

average weight decreases from 1.5 g to 0.15 q. Similar phenomena

take place in the American eel.

European authors (Gilsonj

1908; Strubberg, 1913) have established

several stages in the metamorphosis of the European eel. For the time

being, we apply, with some reservations, their definitions to the

Ameri can eel 1/.

MATERIAL

The present report is based on a study of over 7,000 elvers

collected in Nova Scotia and New Brunswick. This material can be

grouped into two sections, based on the dates of collections.

Early Collections, 1952-1960

Table 2 contains collecting data for this period. The main

collections were made at Ingonish Beach, Nova Scotia, in June 1955,

and in the Digdeguash River, New Brunswick, July - August 1955 and

on May 13, 1960. Altogether 820 specimens are available.

Elvers of early collections belong to either the VI Al or VI A2

stages; while those collected at later dates are either in the

VI A3 or VI B stages.

1/ We are working now to properly define the different stages of the

transformation of the American eel, particularly from the glass eel

to the elver stages. In France the elver is called "civellell•

- 9 -

In all t he co 11 ect ion s, i rrespec t i ve of 1 oca 11 ties., made between

May 13 and July 4, the lengths of the elvers varied between 50'mm

and 69 11m. On the other hand, in the collections made between July 12

and August 8, 1955 in the Digdeguash River, the size of the elvers

was from 50 mm to 89 mm (Table 5). The frequency in percentages of

different length-classes is given in Table 5 and Figure 1.

Collections made in 196]

Early this year collections of elvers were made in the

Sackville River, Nova Scotia, and in four New Brunswick streams

near the Biological Station at St. Andrews. Altogether 6,417 elvers

were available for the present study. Details of the different

samples are given in Tables 4 and 6 and Figure 2.

With the exception of samples taken in the Digdeguash River

between July 21-25, the collections contained elvers only in stages

VI Al to VI A3-

It is interesting to note that our material clearly shows that

elvers shrink on the average from 57.6 mm to 56.2 mm (about 2%)

during their transition from stage VI Al to VI A3, and to VI B.

This reduction in size is not as great as changes in their weight.

For instance, in stage VI At one hundred elvers weighed 17.6 g.

In stage VI B their weight only totaled 13.8 g, that is a loss of

about 21% (Table 7 and Figure 3).

- 10 -

VARIATIONS IN THE SIZE OF ELVERS

It is of considerable importance to be able to properly

ascertain the size of an elver in order to make correct analyses

among samples. There are two principle causes for length variations

among elvers.

Variations due to Stages of Development

Table I shows that the length (and weight) of an eel varies

according to its stage of development. In its earlier stages., from

a full grown leptocephalus to a glass eel, the fish decreases in

size. The same phenomenon is observed during the transition from

the glass eel to the elver stage. Moreover, the elve~ stage itself

can be subdivided into several phases, from the "early elver" (stage

VI At) to the "tate elver" (stages VI A3 and VI B).

During this entire transitory period until the earty VI B stage,

the elver does not feed and so shrinks in size. It loses its "baby

fat" and its flesh becomes coarse and unsuitable for human consumption.

In the Maritime Provinces elvers taken in fresh-water streams

during May and June vary in length from 50 mm to 69 mm. For our

study purposes these fish belong to two length-classes, namely,

50-59 mm and 60-69 mm. The interrelationship between these

- 11 -

classes in different samples is most interesting. Among early'elvers

from 59 to 64%, or approximately 60%, belong to the 50-59 mm class

and 34 to 42%, or around 40%, to the 60-69 mm class.

In collections made late in June the interrelationship between

the length-classes changes. Class 50-59 mm occurs in 79 to 85 % of

the samples, but class 60-69 mm, only from 16 to 28%. In other words,

the relative abundance of class 50-59 mm among elvers of the same run

increases with their stay in the stream. More details are given it .

Table 6.

There are other cases. On June 5, 1967, a sample of elvers

was taken in Chamcook Creek (Table 6). The two length-classes,

namely, 50-59 mm and 60-69 mm, occurred in nearly equal proportions.

There is no explanation readily available. It could be that this

sample contained elvers from several runs.

When samples are collected during consecutive months from the

same stream, and even in different years, the changes in the inter-

relationship between the lenght-classes are striking. Collections

of elvers from the Digdeguash River illustrate this:

3;

Date Occurrence of length-classes in % W

............. 50-59 mm 60-69 mm 70-79 mm 80-89 mm

Q

May 13, 1~0 78.7 21.3

June 4, 1955 90.7 9.3

July 12-Aug. 8, 1955 18.7 41.5 27.3 12.5

- 12 -

There is a noticeable difference in the length composition

of the third sample. This may be explained by the fact that fish

in the 70-79 mm and 80-89 mm classes are no longer elvers, but are

newly transformed eels that have begun to feed and grow.

Variations according to Geo~phicaL Region

The author's recent study (Vtadykov, 1966) of elvers, obtained

from various geographical regions, clearly showed that a pronounced

difference exists between the average lengths of the fish.

For the present report we selected only three localities (Table 8);

a) southerly; b) intermediate; and c) northerly. These localities

are as follows:

a) The Patuxent River, flowing into Chesapeake Bay, Maryland,

where collections of elvers were made on April 20, 1960

by the late Dr. R.J. ~ansueti;

b) Turnvil1e Creek, near Ocean City, Maryland, where collections

were made on April 14, 1960 by Mr. E.M. Barry; and

c) The Sackville River, N.S., where collections were made during

May 15-25, 1967.

The average lengths of elvers from the three above localities

varied from south to north as follows: 52.9 mm, 55.7 mm and 58.6 mm.

From Table 8 it is also evident that elvers of the American eel

from the above three localities were represented by three length­

classes: 40-49 mm, 50-59 mm and 60-69 mm. However, their frequencies

- 13 -

are not the same in different regions. The class 50-59 mm is always

present, although its occurrence varies somewhat with 10ca1ity~ 86.9%

in the south, 91.5% in the intermediate locality and 62.2% in the north.

Much more interesting are the occurrences of 40-49 mm and 60-69 mm classes.

The abundance of the 40-49 mm class decrease~rom south to north:

11.7% in the Patuxent River, 0.5% in Turnvi11e Creek, and it is completely

absent in the Sackvi11e River. The reverse situation exists for the

class 60-69 mm. Its predominance increases from south to north, res­

pectively being: 1.4%, 8.0% and 37.8% (Table 8).

On the basis of the above observations it may be definitely

stated that the size of elvers of the American eel along the Atlantic

shore increases from south to north.

In the same fashion the weight of A. rostrate elvers varies

according to the locality: those fro~ the Chesapeake Bay weighed

an average of 104 milligrams each and those from Nova Scotia, 169

milligrams. In other words, there are 4,441 elvers to a pound

~0.454 kg) from Chesapeake Bay and 2,691 from Nova Scotia (Vladykov,

1966).

The elvers of A. anguilla are not only longer than the American

elvers, but their average weight in milligrams is greater, being from

170 to 369. Frost (195~ and Deeldnr (1952) calculated that there

are 1,400 European elvers to the English pound.

- 14 -

IMPORTANCE OF THE STUDY OF ELVERS

Detailed knowledge of the biology of elvers of the American

eel is extremely valuable. In general, there are three important

aspects of this study.

Elvers in Streams

According to our present knowledge, elvers of the American

eel are easily collected in a great many North American streams

emptying into the Atlantic Ocean. Practically every river or brook

in the Maritime Provinces receives at one time or another a considerable

influx of young elvers o We presume (although at the present time

there is no definite proof}) that many elvers, instead of entering

freshwater, remain in the sea. Therefore, our observations are

limited to elvers found in either freshwater streams or brackish

estuaries.

The following aspects of elver biOlogy should be considered

in this connection:

1) Time of first arrival (or first run) of elvers into Maritime

streams emptying into the Atlantic and Gulf of St. Lawrence.

2) Seasonal variation from year to year in the time of arrival

of the first run and the total duration of all runs in

the same stream; also variation in the abundance of elvers

from month to month and from year to year.

3) Factors influencing the elver migrations, such as tide,

floods, temperature, wind, light, etc.

- 15 -

4) Details of the transition fro~ the glass eel stage to the

actively feeding young eel stage.

5} Variation in the growth rate of elvers in different streams,

their density and its possibl~ influence on the sex of the

adult eels.

6} What is the relationship between the number of elvers in

the river system and the quantity of adult eels available

for commercial exploitation?

7) Interrelation between elvers and other fishes found in the

same stream. Do elvers actively prey upon young Salmonid

fishes, or do the elvers constitute a valuable diet for

the latter?

Elvers for Transpl~ntation

In many European countries, it is customary to fish for

A. anguilla elvers or to buy them from special agencies for

transplantation purposes. Elvers or newly transformed eels are

liberated in lakes in which they feed and grow for several years.

The adult eels during their descent from these lakes to the sea are

captured for commercial purposes. This is a lucrative fishery that

involves very little capital investment.

Among European countries where elvers are available in large

numbers (for transplantation) are the Netherlands (Deelder, 1952)

and Northern Ireland (Frost, 1950; Lowe, 1951).

- 16 -

It was noticed by people who buy elvers for transplantation

that those from certain areas produce predominantly large eels

(females), whereas elvers from other areas produce mainly small

eels (males). Unfortunately, these observations are not supported

by critical scientific studies.

In this connection should be mentioned interesting observations

by Bellini (1907). His experiments showed that the larger elvers

yielded predominantly female eels, while the smaller elvers became

mainly male eels.

Our study (Vladykov, 1966) showed that the size of elvers of

the American eel, vary with the geographical region. Those popula­

ting the Maritime Provinces are much larger(57-58 mm), than those

found in southern waters, such as Chesapeake Bay or Florida, where

the average size of elvers is 52-53 mm. It is of importance to note

that in the Maritime Provinces, female eels which are considerably

larger than males, are much more abundant than in southern waters.

Tms situation is comparable with results obtained by Bellini (1907).

Elvers of intermediate size (55-56 mm) are found along the coast of

the Middle Atlantic (New Jersey; Ocean City, Maryland).

Near Ocean City, Maryland, in Turnville Creek, the Maryland

Fishery Division collected elvers for the Pennsylvania Fish Com­

mission. Thanks to Messrs. E.M. Barry and G.S. Rogers of the

Maryland Game & Inland Fish Commission, we were able to obtain the

interesting information that is summarized on the next page o

- 17 -

Number of elvers collected in Turnvil1e Creek, Maryland, during 1958-1960

Date Number of Number of elvers days fished captured

. -April 18-23, 1958 4 590,000

Apri 1 10-16, 1959 2 1,000,000

Apri 1 14-25, 1960 4 4,850,000

From the above data it is apparent that elvers of the American

eel are as abundant as those of the European eel. Unfortunately,

published information such as that by Jeffries (1960) gives the

opposite impression. His paper is based on findings of only six

elvers taken off Rhode Island during January - March.

Elvers for Human Consumption

In many southern European countries such as France, Spain,

Portugal, the early elvers (stage VI Al ) that are still rich in

IIbaby fat II are fished conmercia1ly and considered a gourmet dish.

The elvers are usually fried in olive oil.

Elvers are also taken in great quantities and used as food in

south-western Great Britain. "They are either fried in cakes or

stewed, and are accounted very delicious ll (Schmidt, 1906; 197-204).

- 18 -

In Canada and the United States, elvers are not eaten as yet.

Nevertheless, in Ottawa, in some grocery stores, a canned Portugese

delicacy called "Engyias" is available. It is "fried baby eels with

spices".

In conclusion, we feel that the great abundance of American eel

elvers in the Maritime Provinces could be exploited for a number of

commercial purposes.

ACKNOWLEDGEMENTS

The preparation of this report was made possible with the help

of several persons in the United States and Canada whose names

appeared in Tables 2 and 3 and in the text. The author is indebted

to his assistants, Messrs. P. Burns and D. James, who measured the

elvers and prepared the tables, and to Miss H. March, who drew the

graphs.

REFERENCES

Betlini, A. 1907. Experiences sur 1 'elevage de 1 'Anguilla en stabulation

~ Comacchio. Bull. Soc. Centre Aquic. P8ch~ !2, 186-225.

Deelder, C.l. 1952. On the migration of the elver (Anguilla vulgaris

TurtJ at sea. J. du Conseil, ~ 187-218.

E 1950 The eel fisheries of the River Bann, Northern Frost, W. • •

Ireland, and observations on the age of the silver eels. ~ du Conseil,

!i (3): 359-383.

- 19 -

Gilson, G. 1908. L·anguille. Sa reproduction, ses migrations et son

inter8t economique en Belgique. ~. Soc. roy. Zoot. et Malacol. de Betg.,.

~ 7-58.

Jeffries, H.P. 1960. Winter occurrences of AnguilJa rostrata elvers in

New England and middle Atlantic estuaries. Limnot. a~eano9r. i (3):

338-340.

Lowe, R. H. 1951. Factors influencing the runs of elvers in the

River Bann, Northern Ireland. J. du Conseil, lL (3): 299-315

Needler, A.W.H. 1929. Unpigmented elvers (Anguilla rostrata Le Sueur')

in haddock stomachs at Ingonish, Cape Breton. Copeia, !1lJ 41-42

Schmidt, J. 1906. Contributions to the life-history of the eel

(Anguilla vulgaris Flem.). Con. perm. inter. expl. mer. Rape. & Proc.

Verb., V: 135-265.

Schmidt, J. 1909. On the distribution of the fresh-water eels

(Anguilla) throughout the world. I. Atlantic Ocean and adjacent regions.

A biogeographical investigation. Medd. Komme Hav. Fisk., 1 (7): 45pp

Strubberg, A.C. 1913. The metamorphosis of elvers as influenced by

outward conditions. Medd Komm. Hav. Fisk., ~ (3): llpp

VTadykov, V.D. 1966. Remarks on the American eel (Anguilla rostrata

Le Sueur). Sizes of elvers entering streams; the relative abundance

of adult males and females; and present economic importance of eels

in North America • . Verh. Internat. Verein. Limnot., ~ 1007-1017.

Sentp.mhpT'~ lQh7

- 20 -

Table 1. Later stages of transformation of the European eel

(A. angui!! a )

Designation Stages Characters

Glass eel v Dark pigmentation on the top of the head

and at the base of the caudal fin; body

transparent, without dark pigmentation;

toothless, non-feeding but containing some

fat; shorter than a leptocephalus stage

but longer than stage VI.

Elver VI A Dark pigmentation appears over the back

and flanks, but not on the sides below the

lateral line; adult teeth appear; length

shorter than in stage V; a little fat still

present; non-feeding stage.

Elver VI B Dark pigmentation allover the fish except

belly; the length shrinks to its shortest;

"baby fat" completely lost; teeth on jaws

visible; early in this stage elvers do not

feed, but at the end begin to take food and

grow again.

- 21 -

Table 2. Number of elvers collected during the years 1952-1960

Locality

Sackville River, N. S.

1ngonish Beach, N. S.

Ingoni sh Beach, N. S.

Birch Cove Creek, N. B.

Bocabec River, N.B.

Digdeguash River, N.B.

Digdeguash River, N.B.

Digdeguash River N. B.

Total

;

Date

May 25, 1953

June " 1955

May 10-12, 1960

April 24, 1952

June 19, 1952

May 13,1960

Jul y 4, 1955

July 12-Aug. 8, 1953

1952-1960

Number of elvers

75

262

90

122

54

176

820

t; =

Collector

J.p. Cuerrier

J. P. Cuerd er

J. Po Cuerri er

L.R. Day

L.R. Day

L.R. Day

L.R. Day

L.R. Day

-:: Indicates small saflllles that have been excluded from further consideration.

- 22 -

Table 3. Number of elvers collected during 1967

Locality Date

Sackvil1e River, May 15-25 N. S.

Chamcook Creek, May 14 .. June 5 N.9.

Birch Cove Creek, May 15-July 16 N.B.

Bocabec River, May 30- J.lne 4 N.B.

Digdeguash River, May 14-Jul y 25 N.B.

-~--

Total May 14-Jul y 25

Number of elvers

566

1,503

1,838

939

1,571

6,417

S"

D.

D.

D.

D.

Collector

Miles & D. James

James & H.. McSheffrey·

James & H. McSheffrey

James & M. Wood

James & M. \>,bod

- 23 -

Table 4. List of localities in the Mar"it;me Provinces designated

by the Roman numerals (1 - VI) on Figures 1 and 2

Roman numerals Locality Years of collection

I Sackvil1e River, N.S. 1953 and 1967

II Ingonish Beach, N.S, 1955

III Bocabec River, N.B. 1952 and 1967

IV Digdeguash River, N.I3. 1955, 1960 and 1967

V Birch Cove Creek, N. B. 1967

VI Chamcook Creek" N. B. 1967

- 24 -

Table 5. Occurrence in percentages of different length-classes (mm)

among elvers from the Maritime Provi~ces, 1952-1960

Locali ty Date of Length-classes ~mm)

collection 50-9 60-9 70-9 % % %

Sackvi 11 e Ri ver May 25, 1953 78.7 21. 3

Ingonish Beach June I, 1955 62.6 37.4

Bocabec River June 19, 1952 83.3 16.7

Digdeguash River May 13, 1960 78.7 21.3

Digdeguash River July 4, 1955 90.7 9.3

Digdeguash River July 12-Aug. 8" 18.7 41.5 27.3 1955

80-9 %

=

12.5

- 25 -

Table 6. Occurrence in percentages of different length-classes (mm)

among elvers from Maritime Provinces, 1967

length-c1 asses (mm) Locali ty Date of

c011ecHon 50-9 60 .. 9 % %

Sackville River May 15-17 61.0 39.0

Sackvi lIe River May 25 64.0 36.0

Bocabec River May 30 58.5 41.5

Bocabec River June 4 74.0 26.0

Birch Cove Creek May 15 64.0 36.0

Birch Cove Creek May 28 63.5 36.5

Birch Cove Creek June 4 68.7 31. 3

Digdeguash River May 14 66.7 33.3

Digdeguash River May 28 80.5 19.5

Digdeguash River June 3 81.0 19.0

Digdeguash River July 21-25 84.5 15.5

Chamcook Creek May 14 66.0 34.0

Chamcook Creek June 1 72.0 28.0

Chamcook Creek June 5 49.0 51.0

- 26 -

. Table 7. Variation in the length (mm) of individual elvers an~

the weight (g) per 100 fish in different stages from

Stage

VI Al

VI A2

VI A3

VI B

the Digdeguash River, N.B. collected in June and July

1967. Earlier stages, VI At - VI A3, were taken on

June 3, and the late stage, VI B, on July 21-25

Total length (mm) Weight (g) per

Range Mean 100 elvers =

51-65 57.6 17.6

49-68 57.0 17.2

50-65 56.2 16.8

46-65 56.2 13.8

- 27 -

Table B. Geographical variation in the average length (mm) and

frequency of length-classes (mm) of elvers of the

American eel along the Atlantic coast

Locali ty Patuxent River, Turnvi 11 e Creek, Sackvi t le River, Maryland Maryland Nova Scotia

--Date of Co 11 ecti on Apd 1 20, 1960 Apr; 1 14, 1960 May 15-25, 1967

Number of elvers 213 201 200

Average length

of elvers (mm) 52.9 5507 58.6

Frequency (%) of Length-Classes

40-49 mm 11.7 0.5 0

50-59 mm 86.9 91.5 62.2

60-69 mm 1.4 B.o 37.B

- 28-

LOCALITIE S

100 I II " lIT TIL A ,--A--, I ,.---A---, A

I

~ 80 COLLECTION DATES:

Z .-Ilt 81- 2 nd

en §-3rd UTI- 4 th &II

u Z &II j

0 IaJ

I A: I IL

~ en en en en en en en en en en I I I I , I I I I I

0 0 0 0 0 0 0 0 0 0 10 CD 10 CD 10 CD ." CD ~ CD

LENGTH C LASSES (mm)

Ire 1. rrequencies in percentages of different length-classes (mm) among elvers

from the Maritime Provinces, 1952-1960. Details of localities and

collection dates are given in Tables 4 and 5.

Figure 2. Frequencies in percentages of different length-classes (mm) among elvers from the. Maritime Provinces, 1967.

Details of localities and collection dates are given in Tables 4 and 6.

- 30 -

18

17 58

- mm 16 E ~

E 0-

--- ~ 9 ---.. • •

% 57 15 .t-.... % CD CD Z -1&1 &IJ

..J • 56 13

3lIAI JZIA 2 1lIA3 JITB

STAGES

Figure 3. Variation in the length (mm) of individual elvers and the weight (g)

per 100 fish in different stages, from the Digdeguash River, N.B. collected

in June and July 1967. For further details see Table 7.

- 31 -

100

• 40- 49 mm CLASS

[:J .. 50-59 CLASS •• mm ..

*- § 60-69 mm CLASS

Z 60 -U)

40 LLI -(,)

Z &&I 20 :l 0 &&I 0= 0 LL . . .

a: a: a:: 0 .... &&.I &&.I

Z ..J ..J L&.I ..J ..J X :;; :;; :::> z lr::: f- a: 0 ~ ~ cr

~ en

LOCALITIES

Figure 4. Frequencies in percentages of different length-classes (mm)

among el~~rs from three different localities from South to

North.

- 32 -

PROGRESS REPORT NO. 3

AGE DETERMINATION AND AGE OF THE

AMERICAN EEL (ANGUILLA ROSTRATA )

FROM

NEW BRUNSWICK WATERS

I NTRODUCT! ON

In order to properly utilize local populations of the American

eel, as with any other fish species, a knowledge of their sizes,

sex, and age composition is essential.

This report deals only with methods of age determination,

variation in age with size and locality of the fish. Other infor­

mation pertaining to size and sex will be presented in future reports.

METHODS OF AGE DETERMINATION

Very little information is available on the age of the

Amer i can ee I .

Seal es

An attempt by Smith and Saunders (1955) to determine the age

of eels from certain New Brunswick waters was based on a study of

scales. Unfortunately, the scales of both species, AnguilLa anguilla

and A. rostrata.are not formed at a definite age, and moreover scales

from the same fish may possess different numbers of winter marks (an­

nuli). European authors such as Hornyold (1937) and Frost (1945)

concluded that the "readingll of scales for age determination of eels

• __ ..t.... __ ...J .a..L _ _ _.J ~ 1_. _... _ • , ... I

- 33 -

The otoliths of eels, as with other fish species, are composed

principally of calcium carbonate and found in the inner ear of the

fish. There are three on each side: the lapillus, the astericus,

and the sagitta. This last, the largest, is the only one that is

used to determine the age.

Even the sagittae of eels are small. For instance, those from

American eels 822-965 mm in length are only 4.0-4.5 mm long and

2.3-2.5 mm wide. Nevertheless eel otoliths are rather thick and

their growth zones are not readily visible, especially in larger

fish. Therefore, it was necessary to make the otoliths more

transparent by grinding and polishing them on a fine carborundum

stone. Even this preparation did not always give satisfactory

results.

The growth zones of the otoliths consist of alternate bands

of predominantly organic matter and inorganic matter. To make

them more visible, the otoliths are heated over a Bunsen flame,

that carbonizes the organic substances more than the inorganic

ones. This results in a greater distinction between the zones.

- 34 -

Christenson (1964) successfully used the method of heating

otoliths with a variety of species of fishes, including the

European eel (Ansuilla anguilla). Christenson's technique consisting

of heating, breaking and counting the number of zones along the

broken edges of the otoliths was tried with the American eel, but

it did not give satisfactory results. Therefore, Mr. D. James,

my assistant, was obliged to find a new technique for determining

the age of the American eel. Preliminary information on this

new method was recently published (James and Vladykov, 1967).

Due to the fact that this new technique has been further

improved, it is desirable to describe it in more detail.

- 35 -

Method of Preparing Eel Otoliths for Age Determination

In order to obtain the otoliths, the eel's head is split longi­

tudinallyon the dorsal surface along a line midway between the

eyes. The two halves of the brain are removed together with the

inner ear sacs of the fish. The largest otoliths (sagittae) are

then cleaned between the fingers and placed for a short time in

ethyl alcohol (70%). For prolonged storage otoliths are kept dry.

To make the growth zones and nucleus of the otoliths more

visible the otoliths are carefully ground. Before grinding, the

otolith is mounted on a black paraffin wax block, with the dorsal,

convex surface exposed. The otolith is ground under a binocular

microscope (25 X), with a steel "bur" 1/ rotated by a small por­

table dentist drill. To obtain the best results, grinding usually

takes from 5 to 20 minutes. During grinding the otolith is kept

continuously moist with ethyl alcohol (70 - 80%), which clarifies

the otolith's layers and cools the paraffin block •

. 1/ Dentists use burs of various shapes and sizes made either from

steel or ~ungsten carbide. We found that the smallest (No 1/4)

steel bur of regular pattern, round plain cut, was the most satis­

factory for our purpose. These burs could be used for about 3

otoliths before they became too dull for grinding purposes. The

price for this type of bur is 80 cents per dozen.

- 36 -

The thinned otolith is removed from the paraffin block and

heated for I - 2 minutes on a porcelain plate over a Bunsen flame

until it becomes dark brown. Then the otolith is placed on a

glass microscope slide and cooled for a short time to prevent its

shattering when placed in creosote. Only a chemically pure creosote

should be used. The examination of the ground otolith is done in

reflected light against a black background under a binocular micro­

scope at approximately 25 X magnification. During this examination

the otolith is kept submerged in creosote on a glass microscope

depression slide. After the study the otolith is again stored dry.

Heating and immersion of the otolith in creosote make the pre­

viously opaque and transparent zones distinct yellow and dark brown

bands respectively.

Otoliths from elvers or small eels, less than 200 mm, are thin

and transparent. Since they do not require grinding they are

mounted in ·"permount ll mounting medium 2/ on depression slides

for storage and subsequent study.

2/ IIPermount" is a solution of synth~tic resin material

made and sold by Fisher Scientific Company.

- 37 -

Growth Zones on the Otoliths

The nucleus consisting of tightly packed zones is found in the

middle of an eel otolith (Figure 1). These are the sea rings or

zones representing that part of the otolith laid down in the

leptocephalus stage and during the life of the "glass eel" (or

"early elver"), until H reaches the coast. The alternating

broad and narrow zones which surround the nucleus, represent, on

the other hand, the successive stages of the life of the eel in

fresh water.

The eel otolith, when seen by reflected light against a dark

background, shows alternating light and dark concentric zones;

the former are whitish and opaque and were laid down in the

summer (summer growth), the 1 atter are darker and comparati vel y

trans 1 ucent and represented the wi .nter growth. The i nterpreta­

tion of such zones as annual and thus as records of the age of

the European eel has been justified by the experiments of Ehren­

baum and Marukawa (1913), 3/ who took glass eels and kept them

in aquaria from I to 5 years.

3/ We are conducting a comparable experiment with the American eel.

On July 27, 1967, about 10,000 eivers from a New Brunsl.'Jick stream

were transplanted to a pond at the White Lake Hatchery, Ontario

Department of Lands and Forest. Periodical samples of these elvers

were taken regularly, and their otoliths were studi ,~d. During the

spring and summer of 1968 the otoliths from our young eels shall

show us what type and how many "winter zones" have been formed.

- 38 -

They found that the zoning on the otoliths of such eels, with few

exceptions, registered the number of summers and winters of capti­

vi ty.

The experience gained from European authors can be applied

with some reservation to the American eel as well. Therefore, the

IIreading" of otoliths for age determination is based on two sets

of rings or zones:

a) those, composing the nucleus, formed during

the larval period in the sea, 4/ and

b) those formed in fresh water.

Around the nucleus, on the otolith of a young eel, which

entered a brook in the spring as an elver the year before, is

formed a rather wide white opaque zone, the first zone having

been recorded in fresh water and laid in the first summer there,

then followed by a rather narrow dark translucent zone which had

4/ It is presumed that many elvers of the American eel captured

on their entrance into the river in the spring are one year old.

However, I have some leptocephali of the American eel, which,

no doubt, spent 2 years in the sea.

- 39 -

been formed during the first winter in fresh water. This eel had

spent a year in fresh water.

The subsequent alternating opaque and translucent zones mark

the summers and winters of the successive years in the freshwater

life of the eel. In normal conditions only one opaque (summer)

zone and one translucent (winter) zone are formed during a

single year. However, there are cases where between normal

opaque and translucent zones have been laid down one or more

secondary translucent rings. The reason for this abnormal

formation of new zones is unknown at the present.

The winter zone indicates completion of the yearly growth;

hence it can be called the annulus, or the yearly mark. Further

examples illustrate how the "reading" of eel otoliths can be

applied to age determination. For instance, otoliths with 2

summer and 2 winter zones laid down in addition to the nucleus

are found in eels which have spent 2 complete years in fresh

water. In the case of an eel which has passed 3 winters and

4 sUl11llers in fresh water, the fourth winter mark has not been

laid down as yet.

It is of importance to note, that on eel otoliths, which were

heated, the opaque (summer) zones remained practically unstained,

while the translucent (winter) zones became dark brown.

- 40 -

LENGTH AND AGE RELATIONSHIP

In 1965 we started to collect samples of eels from different

Canadian provinces for age determination. Many hundreds of eels

have been preserved frozen awaiting otolith removal.

The two preceeding chapters of the present report not only

explained the technique of removing and preparing otoliths for

age determination but also gave some idea that age determination

of eels is a time consuming study. In almost every case, even

in otoliths with distinct growth zones, repeated observations

were required. Moreover, a sketch of each otolith and its zones

are made. To measure, weigh and register the fish and to remove

the otolith in preparation for its study requires at least one

hour per fish.

- 41 -

The present report contains some information about eels

from New Brunswick waters collected during 1967 (Table I). . 5/

The total number of fish studied is 205, of which only 148

eels (Table II) possessed otoliths of high quality in rela-

tion to the clear distinction of the growth zones.

we followed the lead of Jensen (1965) and subdivided the

otoliths into three categories according to the degree of

distinction between summer (opaque) and winter (translucent)

zones.

Category of Otoliths

Vladykov (present report)

Jensen (1965)

A o

B

c 2

Quality

Good

Fair

Poor

Explanation

The zones are plainly visible with a generally good definition between translucent and opaque zones.

The zones are visible but not well defined.

The zones are vaguely marked.

5/ It is of importance to note that all eels used for age

determination in the present report were females.

- 42 -

Eel specimens discussed in the present report range from late

elvers (60~69.mmf/ to an adult of 760 mm in length.

Elvers

Glass eels at the time of their arrival to freshwater streams

are still unpigmented, except for a dark spot at the base of the

caudal fin. They are actually "earlyU elvers ,,,hose otoliths

consist only of the nucleus (Figure 1) with no zones acquired

in fresh water. It is very difficult to state definitely the

age of these early elvers.

The late elvers, which are completely pigmented, start to

feed and grow in fresh water. The length of these elvers

varies from 60-69 mm. Table III shows that the majority of

these elvers have spent only part of a summer in fresh water

and hence no winter zone (annulUS) is present on their otoliths.

6/ More information on the sizes of elvers from New Brunswick

were given in Progress Report No.2.

- 43 -

Small Eels

Elvers from the end of the first summer in fresh water

through the first winter gradually become young eels. The

smallest length class (70-79 mm) is characterized by the

presence of only one annulus on their otoliths. The next

class (80-89 mm) comprises fish with one, two and three

annuli acquired in fresh water. In this class as in the

following class (90-99 mm) which consists of fish with two

and three annuli~fish with two annuli predominate.

Small eels of the three length-classes (100-159 mm)

are fish predominantly with three and four annuli on their

otoliths. The next two classes (160-199 mm) are fish with

five and six annuli. The upper groups (200-349 mm) of

small eels showed from six to nine annuli (Table III).

- 44 -

Large Eels

Although the total number of eels which could be considered

as "large" is HmHed (only 54 fish) nevertheless, preliminary

data showed interesting features (Table IV).

The smallest length-class (350-399 mm) consists of eels with

6-14 annuli. The next group (400-549 mm) are predominantly fish

with 9 and 10 annuli. The group (550-699 mm) display a conside­

rable range in the number of annuli, mainly from 9 to 17. How­

ever, the most common number of annuli is from 11 to 15.

The two largest eels, one 711 and the other 750 mm showed

respectively 14 and 18 annuli on their otoliths (Table IV). In

other words the last fish spent co~plete 18 years and a few

months in fresh water. Up to the present this eel was the

oldest one examined from New Brunswick waters.

In future reports we plan to give information on the age

of much larger American eels from Quebec and Ontario waters.

- 45 -

General Remarks

The age determination of 148 eels from the New Brunswick waters

has been considered in the present report. The relationship between

the number of otolith annuli and the lengths of eels are given in

Table V. Excluding ~he elvers (61-66 mm) which spent a few months

in fresh water and did not acquire a single annulus, the remaining

eels showed from 1 to 18 annuli.

The eels with I to 11 annuli showed a progressive increase in

their average size from 75 to 533 mm. The exception is evident for

the group with seven annuli because it was represented by a single

fish.

Among older eels with the number of annuli ranging from 12 to

16, the progressive increase in their lengths with age is not clearly

shown (Table V) no doubt because of the small number of eels available

for the present study.

If we compare our observations on the age-length relationship

among American eels with those made on the European eel (Frost,

1945) we find that they are quite similar.

It is rather surprising to find that both,A. anguilla and A. rostrata,

are slow growing fish. For instance eels about 600 mm or 24 inches in

length are fish 15 to 16 years of age.

ACKNOWLEDGMENTS

In the preparation of this report the following assistants

were particularly helpful: Miss H. March prepared the figure,;

Mr. P. Burns made calculations, and Mr. D. James prepared the

otoliths and determined the age of the eels.

December 14, 1967

- 46

------} ----- "

Itntn

Figure I. A semi-schematic drawing of the right otolith

(sagitta) of a female American eel (Anguilla

rostrata),435 mm long, weighing 150 g, taken

on August 25, 1967, in Kouchibouguac Bay, New

Brunswick.

The otolith, examined by reflected light, shows

10 summer zones as white and 9(1-lX) winter

zones (annuli) as cross-lines in the drawing.

All these zones were formed in fresh water,

while the nucleus (n) was formed in the sea.

- 47 -

REFERENCES

Christensen, J.M. 1964. Burning of otoliths, a technique

for age determination of soles and other fish,J. du Conseil

29 (1): 73-81.

Ehrenbaum, E. und H. Marukawa. 1913. Ueber Altersbestimmung

und Wachstum beim Aal. Z. Fisch. ~: 89-127.

. -.-~

Frost, W. E. 1945. The age and growth of eels (Anguilla anguilla)

from the Windermere catchment area. Part I. J. Anim. Ecology,

~ (1): 26-36. Part II. Ibidem, l!! (2): 106-124.

Hornyold, A. c. 1937. La frequence des ecailles avec le

nombre maximum de zones sur quatre regions du corps de

l l anguille. Rive Bi01. Firenze, ~ (2): 201-212.

James, D. T. and V. D. Vladykov. 1967. A method of prepadng

eel otoliths for age determination.Anna1es de 1 ' ACFAS, 33: 69.

Jensen, A. C. 1965. A standard terminology and notation for

otolith readers. ICNAF Res. Bull.) 2: 5-7.

Smith, M. W. and J. W. Saunders. 1955. The American eel

in certain fresh waters of the Maritime Provinces of Canada.

J. Fish, Res. Bd. Canada, 1! (2): 238-269.

- 48 -

Table I. Collection data for eels from New Brunswick, 1967, used for age determination.

locality

hamcook Creek

irch Cove Creek

ocabec River

'i gdeguash Creek

~ichibucto River

it. lou; s Ri ver

~uchibouguac Bay

:ocagne

.aie du Vi" River

TOTAL

Date

Hay 14

Hay 15 - September 26

May 30

May 13 - July 25

June 4 - August 23

August 25

August 25

August 23-24

October 1

May 14 - October 1

Number of spedmens

3

77

29

20

22

10

36

6

2

205

Range (1Ml)

67-68

61-236

144-468

62-151

311-678

329-711

407-692 , 609-687

671-760

61-760

- 49 -

Table II. Number of eels from different localities in New Brunswick,

collected from May 13 to October 1, 1967.

Number of fish Number of fi sh

Length-Class Quality of otoliths Total

Length-Class Quality of otoliths (mm) A B C (mm) A B C

Sr all Eels Lc rge Eel

60-69 10 13 - 23 350-99 7 2 1

70-79 14 3 - 17 400-49 8 2 -80-89 9 1 - 10 450-99 8 1 1

90-99 10 - - 10 500-49 10 - -100-19 9 I - 10 550-79 8 1 I

120-39 8 2 - 10 600-49 6 3 1

140-59 7 3 ... 10 650-99 5 3 2

160-79 5 3 2 10 711 1 - -180-99 5 3 - 8 760 1 ... -200-49 10 2 - 12

250-99 4 1 - 5 Sub Total 54 12 6

300-49 3 4 1 8 % 75.0 16.7 8.3

Sub Total 94 36 133 Grand Total 148 48 9

% 70.7 27.1 2.2 . 100.0 % 72.2 23.4 4.4

Tot.

10

10

10

10

10

10

10

1

1

72

100

205

100

length-Class (mm)

60-69

70-79

80-89

90-99

00-19

20-39

40-59

60-79

80-99

00-49

50-99

100-349

TOTAL

- 50 -

Table III. Percentage frequency and range of the number of otolith annuli, according to the length of eels from New Brunswick, 1967.

Small Eels

Number Number of annuli

of sped mens 0 I II III IV V VI I VII'

10 90.0 10.0 - - - - - -14 - 100.0 - - - - - -9 - 33.3 55.6 11. 1 - - - -

to - - 80.0 20 - - - -9 - - 33.3 55.6 11.1 - - -8 - - - 62.5 37.5 - - -7 - - - 14.3 71.4 14.3 - -5 - - - - - 60.0 40.0 -5 - - - - - 20.0 80.0 -

10 - - - - - 20.0 70.0 -4 - - - - - - 50.0 -3 - - - - - - 33.3 33.3

94

VIII IX

- -- -- -- -- - -

- --- -

- -- -

10.0 -25.0 25.0

33.3 -

-

Length-Class (mm)

350-99

400-49

450-99

500-49

.550-99

600-49

650-99

711

760

TOTAL

- 51 -

Table IV. Percentage frequency and range of the number of otolith annuli according to the length of eels from New Brunswick, 1967.

Large Eels

Number Number of annul i of speci mens . VI VII VIII IX X XI XII XIII XIV XV XVI XVII

7 14.3 - .. 57.1 14. - - - 1/ •• 3 - - .. 8 .. - - 62.5 37. ! - - - - .. - -8 - - .. 50.0 12. ~ 37.5 - .. .. - .. -

10 - - .. 40.0 50.( - - - .. 10.0 .. -8 .. - - 37.5 .. - 12. I 25.0 - I 12.5 .. 12.5

6 - .. - .. 16. 7 .. 33.3 - 33.3 .. 16.7 .. 5 - .. - 20.0 .. 20.0 - .. 20.0 20.0 20.0 -1 - .. - - - .. - .. 100.0 - - -1 .. . .. - .. - - - - - .. - ..

-

54

XVII

---..

-..

.. -

100. (

Number

- 52 -

Table V. Relationship between the number of otolith annuli and the length of eels from New Brunswick, 1967.

Number Length (nm)

of annul i of speci mens Average

0 9 63.7

I 18 74.9

II 16 94.0

III 14 114.0

IV 9 138.4

V 7 181. 7

VI 17 227.5

VII 1 343.0

VIII 3 275.7

IX 22 470.2

X 11 492.0

XI 4 532.5

XII 3 618.0

XIII 3 514.3

XIV 4 648.0

XV 3 599.0

XVI 3 627.3

XVII - -XVIII 1 760.0

TOTAL 148

Range

61-66

66-87

82-112

84-155

118-157

158-212

168-365

343

221-317

288-657

366-633

472-687

584-640

391-593

605-711

510-692

567-678

-760

- 53 -

PROGRESS REPORT NO. 4

LENGTHS OF AMERICAN EEL (ANGUILLA ROSTRATA) IN

COMMERCIAL CATCHES OF EASTERN CANADIAN PROVINCES

INTRODUCTION

There is very little information available on sizes of the

American eel taken commercially in different Canadian Provinces.

In future reports, after studies of representative samples from

all the Maritime Provinces, detailed information on the weight

and lengths of eels taken there will be given.

The present paper is only a preliminary guideline to lengths

of eels taken commercially in different provinces. Even this in­

complete information could be useful to government agencies or

buyers of eels. It will be clearly shown that there is a very

distinct difference between the sizes of eels caught in various

provinces.

In this report, the length of eels refers to the total length

which is measured in a straight line from the tip of the lower jaw

to the posterior end of the middle caudal ray (Vladykov, 1966).

The samples of eels were usually obtained from commercial

fishermen, whose methods of fishing vary according to region.

In the Maritime Provinces and in Lake Ontario, eels are taken

with hoopnets.

In the Ottawa River, near Ottawa, small quantities of eels

are taken commercially or used for personal consumption. They

are usually taken on nightlines. In the same river, during the

summer months, great concentrations of eels are foulld below hydro­

electric dams, such as Chats Falls and Carillon. According to

- 54 -

our present knOWledge, these eels in attempting to ascend the

river have difficulty in passing these dams. In order to obtain

information on the sizes of these eels, two samples were collected

below Chats Falls with a small mesh seine (Table VIII).

In Quebec, in the estuary of the St. lawrence River, the

common method of fishing consists of building tidal weirs locally

known as IIp€ches ll • A description of typical "p€chesll is given

by Vladykov (1958).

The present report is based on the examination of 3,326 eels

from five provinces (Table I). Unfortunately, we were unable to

secure a representative sample from Prince Edward Island • . To gain a comprehensive picture of sizes of eels taken com-

mercially, fish smalter than 200 mm in length, which are occa-

sionally taken in hoopnets, were excluded from the present study.

The only exceptions were the small eels (100-199 mm) in samples

obtained immediately below the Chats Falls Hydro Electric Dam

on the Ottawa River. This was done purposely to show the minimum

size of eels ascending the Ottawa River and being retained and

concentrated below the Hydro Electric station.

- 55 -

LENGTH VARIATION ACCORDING TO PROVINCE

The size of eels is not governed by provincial boundaries

but rather by geographical locations of the watersheds and their

types. On the other hand, fishermen and hence their gear are

governed by local traditions and provincial regulations.

The method of fishing and mesh size of the gear used in

various provinces are somewhat different. It is quite probable

that the size of eels in our samples could be affected by the

mesh size,method of fishing, and by differences in fishing

seasons. However, at the present time at least, we must con­

sider that the size of eels in our samples does correspond to

that of the respective populations from which they were drawn.

In other words, we could say that our samples from the Maritime

Provinces, from the St. Lawrence River in Quebec and from Lake

Ontario are random samples, whereas those from the Ottawa River

tend to be biased.

To better express the local differences of eel populations

from different watersheds the samples from different provinces

should be treated separately.

- 56 -

Maritime Provinces

Of the four Maritime Provinces unfortunately, we have no

samples from Prince Edward Island. Our sample from Nova Scotia

is rather small (Tables II and V). Samples from the other two

provinces are substantial.

Nova Scotia. From this province, only 36 eels were

available to us. Nevertheless, the two length-classes, 400-99 mm

and 500-99 mm are predominant and their frequency corresponds

closely with those from the other two Maritime Provinces (Table V).

Newfoundland. - From this island province, we have 172 eels

collected during the summer of 1960 from four rivers, from the

Little Codroy to the Salmon, along the southern coast.

The two length-cl asses, 400-99 mm and 500-99 mm represent

nearly 74 % of the total number of eels in the samples. It is

of interest to note that one large eel, 930 mm in length and

with a weight of 2,350 g (5.2 Ibs), was taken in the estuary

of the Little Codroy River on June 17, 1960. In the other

Maritime Provinces (Table V), the largest eels captured were

less than 800 mm in length.

New Brunswick. - Our largest sampJes came from this

province. Early collections, consisting of 163 adult eels, were

obtained during the summer of 1960 from the St. John and Digdeguash

- 57 -

Rivers,along the Bay of Fundy shore. Later collections of 680

specimens were obtained during August - September 1967 in five

different rivers, from the Miramichi southward to the Cocagne,

along the coast of the Gulf of St. Lawrence (Table II). Alto­

gether, 843 eels have been studied from New Brunswick waters.

The two length-classes, 400-99 mm and 500-99 mm represent

72% of the fish in these samples (Table V). The most striking

feature with the New Brunswick samples is a scarcity of large

eels. Only seven fish (0.8%) were in the length-class 700-99 mm,

whereas the occurrence of this class exceeded ~~ in Newfoundland

and 8% in Nova Scotia.

Ontario

From this inland province we have samples from three

different areas: South Bay, Lake Ontario, the Ottawa River,

near the city of Ottawa,and below the Chats Falls Hydro Electric

dam. Altogether, 659 eels were available (Table III).

Lake Ontario. - A regular eel fishery with hoopnets exists

along the north shore of Lake Ontario in Prince Edward County,

Ontario, particularly in South and Smith's Bays. Our samples

were obtained during May and June of 1965 and 1966 (Table VI)

from South Bay.

- 58 -

The three most numerous length-classes, 600-99 mm, 700-99 mm

and 800-99 mm, represented 88% of the sample in 1965 and 84% in

1966. The close similarity between these two samples is noticeable

also in the length-class of 900-99 mm which is effectively 10% for

each year. In both years even larger eels were present, although

in small numbers. For instance, in 1965 one eel measuring 1,000 mm

and weighing 2,211 g was taken, and in 1966 the following three

large eels were captured: 1,017 mm (2,640 g), 1,032 mm (3,040 g),

and 1,047 mm (3,021 g). Thus their weight varied from 5 to 7 pounds.

On the other hand, in the Lake Ontario fishery the length­

class 500-99 mm was very poorly represented: 1.1% and 4.2% in

1965 and 1966 respectively. This same class in the Maritime

fishery was the second most predominant, comprising 25% of the

total catch (Table V).

Ottawa River. - Only a small commercial fishery for eels

exists in this river, near Ottawa. The usual method of fishing

is with baited nightlines. This gear is not very selective (even

small eels have relatively large mouths), thus eels of a great

range of sizes are taken (Table VII). This range extends from

the length-class 200-99 mm to the class 900-99 mm. The most

common sizes were from 400-99 mm to 700-99 mm.

- 59 -

This method of fishing, particularly with the small number

of eels available for our studies, does not give a clear picture.

It can be said only that there is a variety of sizes available

ranging from 242 mm to 940 mm.

Chats Falls. - A high Hydro Electric dam across the Ottawa

River prevents the direct ascent of eels through the gates. How­

ever, there is a remote possibility that eels can by-pass this

obstruction.

To learn about the length-classes of eels found below Chats

Falls we collected two samples. One was obtained between June 22

and August 24, 1965, when many eels were caught with a small mesh

seine. We retained only 75 eels, including the smallest (104 mm)

and the largest (510 mm) ones.

During the 1966 season, we collected between July 8 and

August 25 with the same seine as in the previous year. From

the specimens collected we retained only 152 fish, ranging in

length from 123 mm to 514 mm (Table VIII).

The most surprising feature is the occurrence below Chats

Falls, at such a great distance from the sea, of many small (104-

123 mm) eels. However, these seemingly young fish spent at least

two and often three years in fresh water. Thus, they are in ro­

ality stunted specimens. More information will be available when

Mr. D. James completes the determination of th~ ago of eels from

these samples.

- 60 -

Quebec

The most important eel fishery in Canada is found in this

province. Some information on the method of fishing, annual

catches, and the sizes of eels taken is given by Vladykov (1955,

1958 and 1966).

Table IX contains information regarding the length compo-

sition of a large sample of eels taken in tidal weirs in the

St. Lawrence River near Quebec, during 1944, as well as similar

data on less valuable, smaller samples from the same province,

taken between 1953 and 1960.

Considering the large sample from 1944 as being more typical

of the Quebec fishery, the smaller one can be excluded from

further discussion.

The striking feature of the Quebec samples is the unusually

large size of the eels. Although in Lake Ontario large eels are

found (Table VI), they are not as abundant as in Quebec. The

following table illustrates this point:

Length-Class % of occurrence

(mm)

800-99

900-99

1,000-99

1,100-99

Lake Ontario

29

10

St. Lawrence River Que. 43

45

8

0.4

"

- 61 -

It should be added that large eels weighing 5-8 pounds are

taken regularly in Quebec. The largest specimen was taken in

Quebec near Ile d'Orleans during the autumn of 1943, when, ac­

cording to the fisherman, it weighed 13 pounds and 5 ounces.

When we received this female eel, which had been kept in cold

storage for one year, it weighed 11.5 pounds and measured 50

inches (1,275 mm) in length.

As it was mentioned earlier (Vladykov, 1955), the average

length of eels taken in the Quebec fishery is 36 inches, and

their average weight is close to 3.5 pounds.

General Observations

In order to obtain a clearer view of the differences in

eel lengths from different provinces, Figure 1 is added. In

the Maritime Provinces, more specifically in New Brunswick,

the dominant length-class is 400-99 mm.

In Lake Ontario, the three dominant classes are: 600-99 mm,

700-99 mm and 800-99 mm. In the St. Lawrence River, in the vi­

cinity of Quebec City, the dominant length-classes of about the

same strength are: 800-99 mm and 900-99 mm.

- 62 -

SEX RATIO AMONG EELS FROM DIFFERENT PROVINCES

Although the method of collecting adult eels for our studies

was not uniform throughout the different areas, certain conclusions

can be drawn about the relative abundance of sexes among eels from

different provinces.

In Ontario, no male eels were observed in any of our samples.

The same holds true for Nova Scotia. In other provinces males

were present, but their frequency varies with the region.

In Quebec, from the many thousands of eels examined, so far

only three males were observed: one, 255 mm long, was taken at

Barachois on November 17, 1956; and two others were caught, one

(400 mm) on August 15, 1967 in Riviere Petits Escoumins, Cote Nord,

and the last one (402 mm) in Petite Riviere Blanche, Comte de

Matane, on September 20, 1967.

The males are particularly abundant in Newfoundland and

in some parts of New Brunswick. Table X contains information

on the sizes of these males.

Up to the present, no male American eel examined by us

exceeded 450 mm in length. To be on the safe side, we can

consider all eels 600 mm or more in length to be female.

- 63 -

ACKNOWLEDGEMENTS

The preparation of the present report was made possible

with the help of several persons, too numerous to be mentioned

individually. Our thanks goes to government employees, both

federal and provincial, and to many fisherman from different

provinces. The author is indebted to his assistants, Messrs.

P. Burns and D. James, who measured the eels and prepared the

tables, and to Miss H. March, who drew the graph.

REFERENCES

1. Vladykov, V.D. 1955. Eel, fishes of Quebec. Album No.6:

1-12. Dept. of Fisheries, Quebec.

2. Vladykov, V.D. 1958. Deux peches caracteristiques du

Fleuve St-Laurent. Actualites Marines, Departement des

Pecheries, Quebec. Vol. 2(1): 6-12.

3. Vladykov, V.D. 1966. Remarks on the American eel (Anguilla

rostrata Le Sueur). Sizes of elvers entering streams;

the relative abundance of adult males and females; and

present economic importance of eels in North America.

Verh. Internat. Verein. Limnol., ~: 1007-1017.

March 15, 1968

50

4 0

30

10

0') en I

o o. ",

- 64 -

-MARITIMES

• •

0 .x._ en en en en I I

0 0 0 0 10

,.. LEN G T H - C LAS S· E S

FIG URE

e- -e

-QUEBEC

o L.ONTARIO

o

( mm )

- 65 -

Table I. Number of eels studied for the present report •.

Collection Area

Mad time Provinces

Quebec, St. Lawrence River

Lake Ontad 0

Ottawa Ri ver, near Ottawa

Ottawa River, Chats Falls

Total

Number of

Specimens

1,053

1,614

323

107

229

3,326

Collecting Method

Hoopnets

Ti dal wei rs (IIPSches ll )

Hoopnets

Nightline (baited hooks)

Sma 11 Mesh Sei ne

- 66 -

Table II. Collecting details on eels from the Maritime Provinces, 1960-1967.

Date

June-Sept. 1960

Aug.-Sept. 1960

Aug.-Oct. 1960

Aug. -Sept. 1967

Total

Locality

Newfoundland

4 rivers (Little Codroy-Salmon), along southern shores

Nova Scoti a

7 different rivers

New Brunswick

St. John & Digdeguash Rivers, along Bay of Fundy shore

5 rivers (Miramichi-Cocogne), along the Gulf of St. Lawrence

Number of eels

174

36

163

680

1,053

- 67 -

Table III. Collecting details on eels from Ontario, 1959-1966

May-June 1965-1966

April-Oct. 1959-1960

June-Aug. 1965-1966

Total

Locali ty

Lake Ontario

Ottawa River near Ottawa

Ottawa River

Chats Falls

Number of eels

323

107

229

659

Table IV. Collecting details on eels from Quebec, 1944-1960

Date

Aug.-Oct. 1944

Ju1 y-Oct. 1953-1960

Total

Locality

St. Lawrence River near Quebec City

St. Lawrence River near Quebec City

Number of eels

1,487

127

1,614

Province

- 68 -

Table V. Number of eels of different length-classes (mm) taken with hoopnets in the Maritime Provinces during 1960 and 1967.

Newfoundland Nova Scotia New Brunswick Total

Length-class Specimens collected

Specimens coll ected

Specimens collected

Specimens collected

(mm) Nunber % Number % NuiTlber % Nun6er %

200-99 2 1.15 22 2.61 24 Z.28

300-99 23 13.22 3 8.33 155 18.39 181 17.19

400-99 79 45.41 12 33.33 398 47.21 489 46.44

500-99 49 28.16 12 33.33 211 25.03 272 25.83

600-99 14 8.04 6 16.68 50 5.93 70 6.65

700-99 6 3.44 3 8.33 7 0.83 16 1.52

800-99

900-99 1 0.58 0.09

Total 174 100.0 36 100.0 843 100.0 1,053 100.0

Year

Length-class

(mm)

500-99

600-99

700-99

800-99

900-99

1000-99

Total

- 69 -

Table VI. Number of eels of different length-classes (mm) caught with hoopnets in South Bay, Lake Ontario, during the fishing seasons (May-June) of 1965 and 1966.

1965 1966 Total

Specimens collected Specimens collected Specimens collected

Number % Nunber % Nunber %

2 1.12 6 4.17 8 2.48

50 27.93 35 24.31 85 26.31

56 31.29 45 31.25 101 31.27

52 29.05 41 28.47 93 28.79

18 10.06 .14 9.72 32 9.91

0.55 3 2.08 4 1.24

179 100.0 144 100.0 323 100.0

- 70 -

Table VII. Number of eels of different length-classes (mm) caught with nightlines in the Ottawa River, near Ottawa, during the summers of 1959 and 1960.

Specimens collected

Len~th-C1aSS Number % mm)

200-99 0.93

300-99 2 1.87

400-99 17 15.89

500-99 30 28.04

600-99 29 27.10

700-99 19 17.76

800-99 8 7.48

900-99 0.93

Total 107 100.0 :

Year

Length-ctass

(11'111 )

100-49

150-99

200-99

300-99

400-99

500-99

Total

- 71 -

Table VIII. Number of eels of different length-classes (mm)

caught with small mesh seine in the Ottawa. River

below Chats Falk Hydro Electr;c Dam, during the

summers of 1965 and 1966.

N.B. Samples were selected and not taken at random.

g

1965 1966 Total

Sped mens collected Sped mens cot tected Spedmens collectet

Number % Number % Number %

26 34.67 31 20.t3 57 24.89

20 26.66 35 22.73 55 24.02

6 8.00 25 16.23 31 13.54

13 17.33 25 16.23 38 16.59

8 10.67 36 23.38 1f4 19.21

2 2.67 2 1. 30 4 1.75

75 tOO.O 154 100.0 229 100.0

Year

Length-class

(mm)

500-99

600-99

700-99

800-99

900-99

1000-99

1100-99

Total

- 72 -

Table IX. Number of eels of different length-classes (mm). caught with tidal weirs in Quebec, 1944-1960.

1944 1953-1960 Total

Specimens collected Specimens collected Specimens collected

Number % Number % Number %

--0.07 0.79 2 0.12

3 0.20 27 21.26 30 1.86

52 3.50 57 44.88 109 6.75

642 43.17 28 22.05 670 41.51

668 44.92 14 11.02 682 42.26

115 7.73 115 7.13

6 0.41 6 0.37

1,487 100.00 127 100.00 1,614 100.00

- 73 -

Table X. Number (N) and lengths (mm) of male eels from

Newfoundland and New Brunswick, 1960.

Length-ct ass Newfoundland New Brunswick Total

{mm} N Mean length N Mean length N Mean length {mm} {mm} (mm)

200-49 3 229.7 3 229.7

250-99 6 271.8 5 281.0 11 276.0

300-49 3 343.3 3 322.0 6 332.7

350-99 357.0 357.0

Total 12 9 21

- 74 -

PROGRESS REPORT NO. 5

EEL TAGGING IN NEW BRUNSWICK WATERS.

I. LENGTH AND COLOURATION OF TAGGED EELS

INlRODUCTION .

Due to the active interest on the part of the New Brunswick

Government, the eel fishery in that province has developed to a considerable

level. For instance, during the 1967 season, about 200,000 pounds of

eels were taken from the New Brunswick waters. There is a definite

possibility of increasing the yield to a much higher level, by modifying

fishing gear in use at present and extending fishery operations to

several rivers of the Bay of Fundy and the Gulf of St. Lawrence coasts.

The principle fishing method for eels in New Brunswtk waters

is the use of hoopnets made of nylon netting. This stationary method

can only be effective if the eels are swimming up or down stream, whether

on daily or seasonal movements, or most particularly during their final

migration to the sea for reproductive purposes.

To understand properly the direction and extent of daily or

seasonal movements of eels the tagging of these fish is essential.

Furthermore, by the recapture of tagged fish, the efficiency of present

fishing methods can be ascertained. The rate of growth and changes

in colouration, which relate to sexual maturation of the eels, may also

be learned properly by tagging methods.

While waiting for returns on recaptured eels, a subject which

will be dealt with in Part II of the present study, this report will

describe the size and colouration of tagged eels at the time of their

liberation. CORRECTION

Throughout the present report, including tables and Figure 1, the tagging locality mentioned as the St. Louis de Kent River, should correctly be called the Kouchibouguacis River.

- 75 -

TAGGING

As the American eel in freshwater habitat usually hides under

rocks or buries itself in the mud, it can be tagged successfully only

with specially designed tags. Some years ago, the author (Vladykov, 1956)

developed such a type of tags.

Type of Tags

This type was named "Split-Ring and Plate Tag". Two sizes of

split-rings, made of stainless steel piano wire, were manufactured:

5/8 and 7/8 inch in diameter. They can be opened sideways by means

of specially designed pliers, one for each ring size. The plate or

tag proper is made of laminated vinylite of different colours, about

1 x 1/4 of an inch. Four colours are used. The numbers are stamped

on one surface, prefixed by a letter corresponding to the colour:

G (green), 0 (orange), W (white), and Y (yellow). On the undersurface

of the plate is printed "Canada". These split rings and tags are attached

around the lower jaw bone of the fish (Figure 4). Eels, taken commercially

in the New Brunswick waters, are small or medium size fish (Table IX),

therefore 5/8 inch split-rings were used to tag them. To prevent

accidental opening of the split-rings, the ends are welded by using a

portable electric welder.

- 76 -

There are several models of such welders, among which the

"Uni tek" model ; s parti cularl y sui table, as its el ectrodes are connected

to the welder by cables which permit free movement while soldering of

the rings on the fish (Figures 1, 3 and 5).

Length of Tagged Eels

All eels previous to tagging were anesthetized in a water

solution (1 :3,000) of tricaine methanesulfonate (MS-222) for a

duration of about 10-20 minutes. As soon as the eels stopped active

movements, their total length was measured in a straight line, from

the tip of the lower jaw to the posterier end of the middle caudal

ray, to the neares t mi l1imeter, on a speci a 1 lime as uri ng board"

(Figure 2-3). Details are given on Table III.

Colour of Tagged Eels

During tagging, the tag number, length of the fish and its

colouration were noted. The most imporatant colours of eels fell

into two catagories: a) half-grown, immature fish, predominantly

of yellow or green colouration; and b) adult, maturing fish, pre­

dominantly of bronze colour. For further details see Table I.

- 77 -

Condition of Tagged Eels

While eels were being measured, observations on their state

of health was made. Only healthy, vigorous eels were used for tagging.

However, on some fish, particularly from the Big Tracadie River,

healed "la~rey marks", made by the sucking disc of the sea lamprey

(Petromyzon marinus), were present. But a much larger number of eels

carried healed spear marks. No doubt, these eels had escaped when

they were speared during the past winter. Goldman (1967:25) correctly

remarked, that: "these injured eels are practically worthless on

an export market featuring wholly smoked eels as the gash mars their

appearance."

- 78 -

LENGTH OF TAGGED EELS

Nearly 3,000 (2,893 to be exact) eels were tagged and liberated

by us in N~~ Brunswick waters during the fall fishing season of 1967 and

the spring season of 1968 (Table I). All eels, except those from the -Bocabec

River, were caught in hoopnets with stretched mesh of 1 inch. Bocabec

River fish, for demonstration purposes, were collected with an electric

shocker.

Practically all tagged eels came from rivers, emptying into

the Gulf of St. Lawrence. These rivers can be considered under two

different sections: the Miramichi Estuary (Figure 1, localities 2-4)

and individual rivers (Figure 1, localities 1, 5 and 6). Small samples

from the Shediac River and Bocabec River are excluded from detailed

discussion.

Miramichi Estuary

Two samples of eels from this general area were tagged in

October, 1967 and one sample from the Black River during May, 1968.

Miramichi River - A sample of 200 eels were tagged and liberated

in this river, in the vicinity of Newcastle (Figure 1). The average

length of these fish was 487.3 mm. These eels and those from the Black

River, taken in the spring of 1968, were somewhat larger than the eels

from the Baie du Vin River (Table III).

- 79 -

Baie du Vin River - A sample of 251 eels, tagged on October 2,

1967, represents on the average (451.6 mm) the smallest fish of all

the rivers of the Gulf of St. Lawrence.

Black River - During May 24-27, 1968, 1,315 eels were tagged

and released in this river. Their average size was 476.3 mm (Table II).

The average length of the three samples of tagged eels from the

Miramichi Estuary, was equal to 474 rrm(Table III). Grouping tagged

eels into 100 rrm length-classes reveals that in all three Miramichi

samples, irrespective of locality or season, the length-class 400-99

mm is the most important and represents 55.6% of the total number of

eels in the samples. The 500-99 mm class is next in importance, and

represents 25.3%. The 300-99 mm class is equal to 13.1%.

Individual Rivers

Eels from two different and widely separated rivers of the

Gulf of St. Lawrence were tagged during the spring of 1968.

Big Tracadie River - On May 28, 1968, 377 eels were tagged and

liberated in this river. Their average size was 561.5 mm (Table II).

St. Louis de Kent River - During the pertod of May 29-June 1,

1968, 736 eels were tagged from this river (Table III). The majority

of fiSh (64]) wi th an average length of 544.6 mm were 1 iberated in St.

Louis de Kent River, while a sample of smaller fish (477.4 mm) was

released in the Shediac River (Table 11). The a11-over average length

of St. Louis de Kent eels was equal to 536.5 mm (Table III).

- 80 -

By combining the samples from the above two rivers, their average

size is 544.6 mm. Among length-classes, the 500-99 mm was predominant,

being equal to 55.7%. The two neighbouring classes, 400-99 mm and 600-99 mm,

were nearly equally represented, being 18.1% and 19.~~, respectively. Two

eels frOm the ,St. Louis de Kent River, fell into the 800-99 mm class. Such

large eels were observed by us for the first time in New Brunswick waters

(V1adykov»: 1ge8~.

The length of eels from the Miramichi Estuary, taken in spring

and during the fall months does not differ greatly. All these fish,

as it was mentioned-already, are decidedly smaller than those from either

Big Tracadie River, or the St. Louis de Kent. It appears that variation

in length does not depend on the season, but rather on the type of

'rivers inhabited by the eels.

Table III, based on the study of 2,879 fish, presents clear

evidence that the average length of eels, commercially taken in New

Brunswick, is 20 inches (or 500 mm) and their weight is about 3/4 of

a pound. In other terms, eels from New Brunswick waters are much

smaller than eels taken in Quebec, where the average length is equal

to 3 1/2 feet (or ~OO mm) and their weight is 3 1/2 pounds, or 1.6 kg ',

(V1adykov, 1955).

- 81 -

COLOURATION OF TAGGEO EELS

Among fishermen from the Maritime Provinces, there exists an

opinion that several kinds of eels are found because some of the fish

are yellow, others are green, and some dark with a metallic shine. The

eel buyers, especially those from Europe, are looking for "silver-eels"

which are so important on the European market. Although the silver

eel phase in North American waters does not exist (Vladykov, 1955),

there is, however, the bronze eel phase, which is comparable to its

European counterpart by its rich content of fat. Both silver eels

of Europe and bronze eels of North America are equally suitable for

smoking purposes.

Because in Europe silver eels are taken principally during

the fall season, the European buyers are wary of buying American

eels taken during spring months. The object of the present report

is to find out if American eels (Anguilla rostrata) taken in New

Brunswick during fall months are different from those taken in spring.

Phases of Colouration

Among American eels, half-grown and adult specimens which

are fished commercially, there are found several colour phases.

-- 82 -

Yellow Eels or Green Eels - Immature eels, due to length differences

between sexes (males are always small, less than 2 feet in length), vary

considerably in size and are predominantly of yellow or green ~ints. The

younger fish acquire, first of all, a yellow colour, and later on become

green. In some specimens, a combination of both yellow and green are found.

Bronze Eels - In the process of maturation, the colouration of

an eel changes considerably: from yellow or green tint, they gradually

display bronze colouration. The American eel, in advanced stage of

maturity, displays a bronze shine over the sides and back. In addition,

along the lateral line, dark pigment develops, thus giving the appearance

of a black line. The pectoral and caudal fins become black also. The

diameter of the eye enlarges considerably. Furthermore, these bronze

eels stop feeding. Eels under such conditions are referred to in our

TablesIV-VIII under gro~p IIBII. Such eels are taken in New Brunswick

in rather small numbers during the fall or spring season and they

represent 0.7 to 6.2% of total catches.

Ee'ls, in early maturity, display a combination of yellow or

green and bronze tints. These eels feed voraciously, as we observed

during the spring and fall seasons in New Brunswick. Since bronze eels

are particularly valuable for smoking purposes, they command higher

prices. Unfortunately, there is no information about differences in the

fatness of flesh existing between bronze and bronze-green (or bronze-

yellow) eels. we are planning in the future to fill this gap in our

knOWledge.

- 83 -

Table IX, where eels of different degrees of "bronzenes~" are

combined under the title of "Bronze Eels", clearly shows that there is

no practical difference between eels taken during the spring or fall

seasons, in New Brunswick waters. The fish of the Baie du Vin River

represent an exception as only 10% of the eels there are bronze.

In general, in New Brunswick waters, bronze eels, irrespective

of the season, represent about 1/3 of the fish (29.5%) against 70.5%

of immature or yellow eels (Table IX). In our opinion, there shocld

be no discrimination among buyers.between spring and fall eels.

ACKNOWLEDGEMENTS

During the tagging operations, the author was helped by several

persons. During the 1967 season, Messrs. P. Burns and D. James were

involved, while during 1968, the tagging team consisted of Messrs. O.

Doiron and D. James. In addition, eel fishermen were most helpful in

bringing fish from nets or holding trunks to the tagging table and

carrying tagged eels back to the water. Several other fishermen, too

numerous to mention individually, were kind enough to give us permission

to use their electricity for our spot welder.

In the tedious work of arranging nearly 3,000 eels according

to their length-classes and colour-phases the author was helped by

his assistants, N. Khan, D. James and Miss. H. March. Typing was done

by Mr s • R. Se 1 wood.

Photographs of·eel tagging operations were expertly taken

by Mr. W. McMullon, of Fisheries Research Board Biological Station

at St. Andrews, New Brunswick~

- 84 -

REFERENCES

Goldman, J.W. 1967. (MS) Report on New Brunswick

experimental eel project. 27 pp.,5 tables, 8 figures.

Vladykov, V.D. 1955. Eel, fishes of Quebec. Album No.6:

1-12. Dept. of Fisheries, ~ebec

June 20, 1968

1956. Fish tags and tagging in Quebec waters

Trans. ~. Fish. ~., ~: 345-349

1968. (MS) Lengths of American eel (Anguilla rostrata)

in commercial catches of Eastern Canadian Province.

Prog. Rep. No.4, 12 pp., 10 tables, 1 figure, Ottawa.

Table I. Characteristic colouration of half-grown and adult American eels (Anguilla rostrata).

I.

II.

Half-grown, imnature fish:

Adult, maturing fi sh:

Symbol

Y

G

Y-G (G-Y)

B

B-G (B-Y)

G-B (Y-B)

Definition

predominantly yellow in colour over flanks and sides of the belly; this colour phase, irrespective of the size of fish, characterizes an immature eel; it gradually changes into green tint.

predominantly green or olive colour over flanks and sides of the belly; it succeeds the yellow phase.

combination of yellow and green tints.

Remarks: on Tables IV - VIII colour phases Y, G, Y-G (or G-Y) are included into Total Y & G.

Fishermen usually call both yellOW and green phases ye I 1 ow-ee 1 •

any American eel in advance stage of maturity, previous to under­taking seaward reproduction migration, acquires a metallic shine with bronze or purple reflections, which are particularly pronounced on back and sides.

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although the bronze colour is predominant, green and yellow tints are still clearly visable.

mixture of green and bronze or yellow and bronze, but the bronze colour is subordinate to either of the green or yellow.

Remarks: on Tables III - VIII colour phases B, B-G (or B-Y), and G-B (or V-B) are included into Total !.

Fishermen call "bronze eel" either black-eel, or (under influence of the European buyers) silver-eel.

"abl e II. Details of eel tagging in various New Brunswick rivers.

Date of Ori gin Release Fishermen Nunber Length of Fi sh (nm) ag Sedes Tagging of Fi sh locality of Fi sh Range Average

1967 Season

'. I. 200-399 October 1 Miramichi R. Miramichi R. M. Cormier 200 343-760 487.3 / .

I: 200-399 October 2 Baie du Vin R. Bafe du Vi n R. B. Jenki ns 200J 294-670 451.6 : 900-950 II II II II 51

1968 Season

) : 1-1319 May 24-27 Black R. Black R. F. MacRae 1315 301-794 476.3

():)

1320-1599 May 28 Big Tracadie R. Big Tracadie R. G. Savoie 280J 0\

I: 399-712 561.5 , : 3-99 II II .. II 97

1 (;O-74j' May 29 c~ 31 St. louis de Kent R. St. louis de Kent R. A. Richard 647 330-819 544.6

109-197 June 1 .. Shedfac R • II 89 301-8Lf4 477.4

,: 101-108 Ma Shed; ac R. St. loui s de Kent R. C. LeBlanc 8 401-581 497.5

19~.199 400-403 Jun~

, Bocabec R. St. Croix R. Estuary D. James 6 291-395 343.0 J

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Table III. Length frequencies of eels tagged in various New Brunswick rivers, 1967-1968

Tagging Date of Locality Tagging

200-99 300-99 400-99 500-99 600-99 700-99 800-99 Total Range Average

N % N % N % N % N % N % N % N % (nm) (nm)

Hiramichi R. October 1, 1967 - - 21 10.5 104 52.0 63 31.5 6 3.0 6 3.0 - - 200 100.0 343-760 487.3

Bafe du Vin R. October 2, 1967 2 0.8 71 28.3 111 44.2 52 20.7 15 6.0 - - - - 251 100.0 294-670 451.6

Two Rivers October 1967 2 0.4 92 20.4 215 47.7 115 25.5 21 4.7 6 1.3 - - 451 100.0 294-760 467.4

Black R. Hay 24-27, 1968 - - 139 10.5 766 58.3 332 25.2 64 4.9 14 1. I - - 1315 100.0 301-794 476.3 - I

Hi rami chi Estuary 1967-1968 2 0.1 231 13. I 981 55.6 447 25.3 85 4.8 20 1.1 - - 1766 100.0 294-794 474.0 00 --.J

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81 g Tracad1 e R. Hay 28, 1968 - - 7 1.9 40 10.7 241 63.9 82 21.7 7 1.8 - - 377 100.0 399-712 $61.5

St. Louis de .. Hay 29-June 1, Kent R. 1968 - - 43 5.8 161 21.9 379 51.5 133 18.2 18 2.4 2 0.2 736 100.0 301-844 536.5

Two Rivers Hay-June 1968 - - 50 4.5 201 18.1 620 55.7 215 19.3 25 2.2 2 0.2 1113 100.0 301-844 544.9

Grand Total 1967-1968 2 0.1 281 9.7 1182 41.0 1067 37. I 300 10.4 45 1.6 2 0.1 2879 100.0 . 294-844 501.4

Table I\f~ , · Number of eels fn various colour groups and length classes, based on taggfng, October 1, 1967, in the Hiramichi River, New Brunswfck.

Number and percentage of eels in various colour sroues

B 8-G G-B Total 8 Y G Y-G Total Y" G Grand Total

length-Class N % N % N % N % N % N % N % N % N % . (1\111)

300-99 - - 1 0.5 8 4.0 9 4.5 2 1.0 8 4.0 2 1.0 12 6.0 21 10.5

400-99 2 1.0 14 7.0 31 15.5 47 23.5 21 10.5 36 18.0 - - 57 28.5 104 52.0

500-99 3 1.5 6 3.0 18 9.0 27 13.5 15 7.5 20 10.0 1 0.5 36 18.0 63 31.5

600-99 - - 2 1.0 2 1.0 4 2.0 - - 2 1.0 - - 2 1.0 6 3.0 _.-

700-99 1 0.5 1 0.5 2 1.0 4 2.0 - - - - 2 1.0 2 1.0 6 3.0

Grand T.,~ al 6 3.0 24 12.0 61 30.5 91 45.5 38 19.0 66 33.0 5 2.5 109 54.5 200 100.0 --

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Table v~;

Length-Class (mm)

200-99

300-99

400-99 -

500-99

600-99

Grand Total

~r of eels in various colour groups and length classes, based on tagging, October 2, 1967, in the Hiramichi Estuary (Baie du Vin River), New Brunswick.

Number and percentage of eels in various colour groups

B B-G G-B Total 8 Y G Y-G Total Y" G

N % N % N % N % N % N % N % N %

- - - - - - - - - - 2 0.8 - - 2 0.8

1 0.4 - - 1. 0.4 2 0.8 31 12.4 38 15.1 - - 69 27.5

- - - - 7 2.8 7 2.8 53 21.1 51 20.3 - - 104 41.4

2 0.8 2 0.8 10 4.0 14 5.6 17 6.8 21 8.4 - - 38 15.1 -

2 0.8 - - -. - 2 0.8 9 3.6 4 1.6 - - 13 5.2

5 2.0 2 0.8 18 7.2 25 10.0 110 43.9 116 46.2 - - 226 90.0

Grand Total

N %

2 0.8

71 28.3

111 44.2

52 20.7

15 6.0

251 100.0

Table VI. Number of eels in various colour groups and length classes, based on tagging, Kay 24-27, 1968, in the H;ram;chi Estuary (Bl ack Ri ver), New Brunswf ck.

Number and percentage of eels in various colour groups

B B-G G-B Total B Y G Y-G Total Y 6- G

Length-Cl ass N % N % N % N % N % N % N % N % (nm)

300-99 1 0.1 13 1.0 5 0.4 19 1.5 62 4.6 14 1.1 44 3.3 120 9.0

400-99 27 2.1 161 12.2 26 2.0 214 16.3 217 16.5 113 8.6 222 16.9 552 42.0

500-99 45 3.4 106 8.1 14 1.0 165 12.5 68 5.2 31 2.3 68 5.2 167 12.7

600-99 8 0.6 22 1.7 1 0.1 31 2.4 26 2.0 3 0.2 4 0.3 33 2.5

700-99 - - 2 0.2 - - 2 0.2 9 0.7 - - 3 0.2 12 0.9 -

Grarnl Total 81 6.2 304 23.2 46 3.5 431 32.9 382 29.0 161 12.2 341 25.9 884 67.1

Grand Total

N %

139 10.5

766 58.3

332 25.2

64 4.9

14 ' 1.1

1315 100.0

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Table VII. Number of eels in various colour groups and length classes, based on tagging, Hay 28, 1968, in the Estuary of the Big Tracadfe River, New Brunswick.

Number and percentage of eels in various colour groups

B B-G G-B Total B Y G Y-G Total Y" G

Length-Class N % N % N % N % N % N % N % N % (11111)

300-99 - - - - - - - - 7 1.9 - - - - 7 1.9

400-99 - - 3 0.8 4 1. 1 7 1.9 15 4.0 3 0.8 15 4.0 33 8.8

500-99 2 0.5 35 9.3 27 7.2 64 17.0 70 18.6 12 3.2 95 25.1 177 46.9 ---

600-99 2 0.5 10 2.7 11 2.9 23 6.1 13 3.4 4 1.1 42 11.1 59 15.6

700-99 - - - - - - - - 2 0.5 - - 5 1.3 7 1.8

Grand Total 4 1.0 48 12.8 42 11.2 94 25.0 107 28.4 19 5.1 157 41.5 283 75.0

Grand Total

N %

7 1.9

40 10.7

241 63.9

82 21.7

7 1.8

377 100.,0

Table VIII. Number of eels in various colour groups and length classes, based on tagging, Hay 29 & 31, and June 1, 1968, in the Kouchfbouguac Bay (St. Louis de Kent River), New Brunswick.

Number and percentage of eels in various colour groups

B B-G G-B Total B Y G Y-G Total Y " G

Length-Class N % N % N % N % N % N % N % N % (nrn)

300-99 - - - - 3 0.4 3 0.4 33 4.4 - - 7 1.0 40 5.4

400-99 - - 4 0.5 14 1.9 18 2.4 82 11.2 24 3.3 37 5.0 143 19.5

500-99 2 0.3 37 5.0 91 12.4 130 17.7 114 15.5 37 5.0 98 13.3 249 33.8

600-99 2 0.3 18 2.5 30 4.1 50 6.9 43 5.8 8 1 .1 32 4.4 83 11.3

-

700-99 1 0.1 4 0.6 1 0.1 6 0.8 8 1.1 - - 4 0.5 12 1.6

800-99 - - 1 0.1 - - 1 0.1 1 0.1 - - - - 1 0.1 ""

I Grand Totai I 5 0.7 64 8.7 139 18.9 208 28.3 281 38.1 69 9.4 178 24.2 528 71.7

Grand Total

N %

43 5.8

161 21.9

I

379 51.5 ~ I

133 18.2

18 2.4

2 0.2

736 100.0

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Table IX. Number of bronze and yellow eels in commercial catches of New Brunswick, 1967-1968.

Locali ty Date Bronze Eel s Yellow Eels Tota 1 Number N % N % of Fi sh

Miramichi R. October 1, 1967 91 45.5 109 54.5 200

Baie du Vin R. October 2, 1967 25 10.0 226 90.0 251

Two Rivers October, 1967 116 25.7 335 74.3 451

Black R. May 24-27, 1968 431 32.9 884 67.1 1315

Hiramichi Estuary 1967 &- 1968 547 31.0 1219 69.0 1766

Big TracadiE: n. May 28, 1968 94 25.0 283 75.0 377

St. Louis de Kent R. Hay 29-June 1, 208 28.3 528 71.7 736 1968

Two Rivers Hay 28-June 1, 302 27.1 811 72.9 1113 1968 -

Grand Total 849 29.5 2030 70.5 2879

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BATHURST

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Figure 1. Eel tagging localities in New Brunswick,. 1967-1968: 1- estuary of the Big Tracadie River; 2- Miramichi River, in the vicinity of Newcastle; 3- Black River in the Miramichi Estuary; 4- Baie du Vin River in the Miiamichi Estuary; 5- estuary of the St. Louh de Kent River of thE: Kouchibouguac Bay; 6- estuary of the Shediac River.

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Figure 2. Tagging of eels along seashore of New Brunswick. Field equipment includes a portable IIUnitek" electrical spot welder for soldering stainless steel rings; a measuring board to determine the length of eels, and portable table used to keep tagging records. To protect the records from the rain a golf umbrella is used.

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Figure 3. Details of measuring eels. On left, plstic dishes containing tags attached to rings and strung by hundreds on rubber tubing. The Unitek spot welder has the tweezer handpiece with electrodes connected to the welder by cables which permit free movement in soldering of rings on eels.

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Figure 4. Stainless ring with tag on special pliers is passed around the lower jaw of the eel.

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Figure 5. Soldering of ring on tagged eels with copper electrodes on the tweezer handpiece of Unitek spot welder.

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