NITED STATES ARTMENT OF MMERCE BLiCATION

SEATTLE, WA

January 1973

NOAA TR NMFS SSRF-662

NOAA Technical Report NMFS SSRF·662 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service

Seasonal Distribution of Tunas and Billfishes in the Atlantic

JOHN P. WISE and CHARLES W. DAVIS

NOAA TECHNICAL REPORTS

National Marine Fisheries Service, Special Scientific Report--Fisheries Series

The major responsibiliti('s of the National Mar ine F isheri('s S!'rvicp ( N ;\IFS) ar!' to mon ito r a nd a s.'pss t he abundance and geographic distribution of fishery resources, to un ilprstanr! and pr!'riict f1uf·tuations in th r~ qua ntity and distribution of these resources, and to pstablish le\'pls for optimum usp of th(, rpSflu r rps. N.\lFS is a lso charged with the development and implem!'ntation of poliC'il's for managing natifHla J fishing g rflu nd lS , r!f'\,f, lop­ment and enforcement of domestic fishe>ries regulations, !iun'C'illal1(,p of foreign fishing off I nitrd Statf,s ('oastal waters, and the development and enforcement of international fis!H·ry agl'f'PIllf'nts and politlf',') , "''\1 FS al 0 as­sists the fishing industry through marke>ting service and ('('onomic anaJysi!i programs, and mortgag-r. insurance and vessel construction subsidi!'s. It coll!'cts, analyzps, and puhlishf's statistic, on various phases (If thp industry.

The Special Scientific Report-Fislwri(>s sl'ries was (>stuhlishNi in lD, I!J. 'I IH' sl'rips ('anips rpports on scipn­tific investigations that docwnent long-term continuing programs of N.\JFS, or nlr'nsi\,f' scir'ntifi(' rpports on studies of restricted scope. The l'eporb may dpal with appliN\ fishpry "roblr·llls. Thp srrirl'l is also uSNI as a m(>uium for the publication of bibliographies of a specializ ... d scipntific nature.

NOAA Technical Reports N:\IFS SSRF are availablr> frpp in limitr,r! numb(·!'!; tf) gow'rnmpntal agencipl;, buth Federal and State. They are also available in exchall'l'e for otiWl' sf'if'ntific and tr'chnical publications in th,· marine sciences. Individual copies may be ohtain(>d (unlpss "thr l'\\'isp notpd) from l\:OAA Puhlicationo; SpctlOn, Rockville, Md. 20852. Recent SSRF's are:

604. The flora and fauna of a basin in central Florida Bay. By J. Harold Hudson, Donald :\1. Allen, and T. J. Costello. l\Iay 1970, iii + 11 pp., 2 figs., 1 table.

605. Contributions to the life histories of seyeral penaeid shrimps (Pena(>idae) along the south Atlantic Coast of the United States. By William W. Anderson. l\Iay 1970, iii + 24 pp., i5 figs., 1~ tables.

606. Annotated references on the Pacific saury, C%l­abis sainI. By Steven E. Hughes. ,June 1970, iii + 12 pp.

607. Studies on continuous transmission frequpncy modulated sonar. Edited by Frank J. Hester. June 1970, iii + 26 pp. 1st paper, Sonar target classification experiments with a continuous­transmission ])oppler sonar, by Frank J. Hester, pp. 1-20, 14 figs., 4 tables; 2d paper, Acoustic target strength of several species of fish, by H. W. Volberg, pp. 21-26, 10 figs.

608. Preliminary designs of traveling screens to col­lect juvenile fi!:lh. July 1970, v + 15 pp, 1st paper, Traveling screens for collection of juvenile salmon (models I and II), by Daniel W. Bates and John G. Vanderwalker, pp. 1-5, 6 figs., 1 table; 2d paper, Design and operation of a canti­levered traveling fish screen (model V), by Dan­iel W. Bates, Ernest W. Murphey, and Earl F. Prentice, 10 figs., 1 table.

609. Annotated bibliography of zooplankton sampling devices. By Jack W. Jossi. July 1970, iii + 90 pp.

610. Limnological study of lower Columbia River, 1967-68. By Shirley 1\1. Clark and George R. Snyder. July 1970, iii + 14 pp., 15 figs., 11 tables.

611. Laboratory tests of an electrical barrier for con­trolling predation by northern squawfish. By Galen H. Maxfield, Robert H. Lander, and Charles D. Volz. July 1970, iii + 8 pp., 4 figs., 5 tables.

Gl~. Thp Tradr> Wind ZOJlP Ocpanography Pilot Study. Pa I't VI IT; Sr it , ',-I mf'tporological properties and hpat xchallgf' Ill'ucr'l'lses, July 19G;1 to Junf' 1!J(;r;. By Cunt"r R Seckel. June 197U, iv + 12~) pp., r. figs.. tabll's.

fi1J. Sr':l-Iottm" pliot"gruph.' and macrobr>nthos col­If'ctioll;; from the COlltilll'ntal :helf off :'lassa­('hu ,ptts. By Holand L. \\'igl ... y and Roger B. Tlwl'ollx. Augu.'t 1~'70, iii t 12 pp., 8 figs., 2 tablp;;,

1;11. A slf'<I-mount(>d suction. ampl ... r for henthic or­ganisms. By I )onald :'1. Allen and J. Harold Hudson. August 1D70, iii -r 5 pp., 5 figs., 1 table.

fi15. IJistrihution of fishing effort and catches of skip­jack tuna, /\rllSI1U'IJIIIIS pe/atHlS, in Hawaiian wat ... rs. by quart(>rs of the year, 1948-65. By Richard X. TJchida. .lunp 1970, iy + 37 pp., 6 figs" 22 tahlrs.

61!l. Effpct of quality of the. pa wning bed on growth and development of pink salmon embryos and aleYins. By Ralph A. \\'plls and \'\'illiam J. :'Ic­Xeil. August 1971), iii + 6 pp., 4 tables.

617. Fur seal illYestigations, 1968. By l'DIFS, :'Ia­rine :'Iammal Biological Laboratory. December 1970, iii + 69 pp., 68 tables.

618. Spawning areas and abundance of steel head trout and coho, sockeye, and chum salmon in the Columbia RiYer Basin - past and present. By Leonard A. Fulton. December 1970, iii + 37 pp., 6 figs., 11 maps, 9 tables.

619. :\Iacrozooplankton and small nekton in the coastal waters off Vancouyer I sland (Canada) and Washington, spring and fall of 1963. By Donald S. Day, January 1971, iii + 94 pp., 19 figs., 13 tables.

620. The Trade Wind Zone Oceanography P ilot Study. Part IX: The sea-level wind field and wind stress values, July 1963 t o J une 1965. By Gunter R. Seckel. J une 1970, iii + 66 pp., 5 figs .

Con tinued on inside back cover .

U.S. DEPARTMENT OF CO ERCE Peter G, Peterson, Secretary

NATIONAL OCEANIC AND AT OSPHERIC D I ISTR'TIO Robert M. White, Admmis rator

NATIO AL MARINE FISHERIES SERVICE Philip M. Roedel , Director

NOAA Technical Report NMFS SSRF-662

Seasonal Distribution of Tunas and Billfishes in the Atlantic

JOHN P. WISE and CHARLES W. DAVIS

E THE ,

The National ~!arint' Fish 'ril's S,·rvic.· (1\,\1 J •• ) dol's not appr IV', r 'c­ommend or ('IHlors,> any IJI-oPI"i. lCII-Y pr "Iuel or JlTI)prl!'Ulry m tprinl mentioned in this publicntion_ .. 'I) Tl·rf'r'>1\ ,> hall IH' nand'! to ... ',\IF. , or to this publication furni hl'lI by ." j IF', ill all~' ntiv.·rti illg or all' pro-motion which would indicalp or imply that. 'nl F_ nppro,-,·, r IIlmpnd or ('ndorsl's any propridnry pT' dud or propri" tir)' !lant"rinl m"nlion d herein, or which has a it "urpo ,> an inl. lit to cau , dirt ctl)' or indir 'clly the advertisPrl product to hl' \I I'd or purchn d \).-. au ,- of this '~lF

publication_

CONTENTS

Page Introduction .................................................. 1 Methods .. ... ..... . ....... ...... .............. ... ... ....... .. . 2 Interpretation of contours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7 Bluefin and southern bluefin tunas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10 Albacore ...................................................... 10 Bigeye tuna .......... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 Yellowfin tuna ... . ... . ..... ............ .. . . .................... 13 Swordfish ......... ...................... ..... ................. 16 White marlin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 16 Blue marlin ... .. ................... . ......... .. ............... 16 Black marlin . ..... .......................... .. .............. .. 16 Sailfish and spearfish ........................................... 20 Skipjack tuna ....................... . ..... . ............. .... .. 20 Literature cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 24

Figures

~. Pa~ 1. Divisions of the Atlantic Ocean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7 2. Catch per thousand hooks, 1956-68, various tunas and billfishes

in selected areas (s~e text) in the Atlantic Ocean . . . . . . . . . . . . . . . .. 7 3. Relative amounts of fishing by the Japanese longline fleet in

the Atlantic Ocean, 1956-68. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8 4. Distribution of catches of bluefin tunas (per 10,000 hooks) in

the four quarters of the year, 1956-68. . . . . . . . . . . . . . . . . . . . . . . . . .. 11 5. Distribution of catches of albacore (per 100 hooks) in the four

quarters of the year, 1956-68. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12 6. Distribution of catches of bigeye tuna (per 1,000 hooks) in the

four quarters of the year, 1956-68 .............................. 14 7. Distribution of catches of yellowfin tuna (per 100 hooks) in the

four quarters of the year, 1956-68. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15 8. Distribution of catches of swordfish (per 10,000 hooks) in the

four quarters of the year, 1956-68. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 17 9. Distribution of catches of white marlin (per 1,000 hooks) in the

four quarters of the year, 1956-68. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18 10. Distribution of catches of blue marlin (per 1,000 hooks) in the

four quarters of the year, 1956-68. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19 11. Distribution of catches of black marlin (per 10,000 hooks) in

the four quarters of the year, 1956-68 . ........ .. ................ 21 12. Distribution of catches of sailfish and spearfish (per 1,000 hooks)

in the four quarters of the year, 1956-68. . . . . . . . . . . . . . . . . . . . . . . . . 22 13. Distribution of catches of skipjack tuna (per 10,000 hooks)

in the four quarters of the year, 1956-68. . . . . . . . . . . . . . . . . . . . . . . .. 23

iii

Tables

No. Page 1. Number of observations, estimated total numbers of hooks, and

estimated numbers offish caught, Japanese Atlantic longlin fishery 1956-69 .................................................... 3

2. Five-degree squares not fished by Japanese longlines, 1956-68, by quarter of the year .................................... ... , 4

3. Five-degree squares not fished and not filled, by quarter of the year.. 6 4. Distribution of percentages of fi hing effort for each quarter . . . . . . .. 9

IV

SEASONAL DISTRIBUTION OF TUNAS AN D BILLFISHES IN THE ATLAN TIC I

By

JOHN P. WISE and CHARLES W. DAVIS2

A BSTRACT

C harts of t he Atlantic Ocean for each quarter of the year-january-March, etc.­s how t he di stribu tion of 10 species and groups of species fished by the Japanee Atla nt ic longline fishery in the years 1956-68. These charts are based on detailed catch a nd fishin g effor t data published by the Japanese Government. Quarterly average catch per unit of effort was calculated for each 5 ° X 5° square, and contour lines "ere d raw n t h roug h eq ual levels of catch per unit of effort. The text explain the calcu­lat ion a nd contou ring processes in detail , and has a sect ion of remarks and e:>.planation for each of t he 10 species or groups.

INTRODUCTION

After World War II the Japanese longline fishery for tu nas and billfishes t>egan to ex­pand from the area of the home islands. By 1953 the fishery had reached about long 160 oW in the eastern Pacific; by 1956 the Pacific fishery extended at least to long 140 0W (Roths­child, 1966) , and the first commercial ven­tures had begun in the Atlantic. Subsequent expansion was rapid; in 1962 most of the world ocean between lat 25 °N and 25 °S was being fished by Japanese longliners. In 1969 the fishery had expanded so that most waters between lat 40 0N and 40 0S were being fished -the maximum north-south extension of the fishery reached from nearly the Arctic Circle to 55 °S (Fisheries Agency of Japan , 1971).

The Japanese Go,-ernment has collected detailed catch and effort data on this unique fishery for many years and has publi hed

I Contributi on ~o. :!1l. :\'ational r.Iarine Fisherie Service, outheast Fisheries Center. :'IIi ami Laboratory. Miami, FL 331-19.

~ ~ational Marine Fisheries Sen-ice, ~outhea t Fish­erie Center. J\Iiami Laboratory. J\Iiami. FL 331-1~1.

1

most of the available information. The puh­lished data for the Atlantic begin with thE' inception of the Atlantic fi, hery in 1 ~:)(;: worldwide coverage starts in 1%2. The,' l' data are of inestimabh.! \'alue from the point of view of understanding the fishery and HI '()

from the ecological standpoint by virtue (If the information they contain on the dL·tril,u­tion and abundance of the specie;; caught. Many studies have been based on t htl p cla ta -the earliest were those publi.-;hed by tIlt' Nankai Regional Fisheries Research Labora­tory on 1952 data (195-1) and on l~l,) data (1959). Both co\'ered only the PaCific, ~L did Howard and Ueyanagi's (1%:) atla: 1.11 th" distribution of billfishe:.

The data u ed here wer taken from lub­lications of the ~ankai Regional F i htrl' Research Laboratory ('hiohama. MyoJin. and Sakamoto. 1965 ) and uf the Re.· arch I)i\ 1 1011,

Fisheries Agency of Japan (Fl,'h'rip g IlC)

of Japan. 196.-. 1% '. 1%'1<1. 1~1 'Ill, 1~11' , 1 li • 19(0). hiohama et al. replJJ' ul 11 > I rH!-

line fishery in the Atlantic for h Fi heries Agency puulicatioll ery in the \\'nrld IlC 'all f r 1.11 _-

the data presented are the number of hooks set and the catch in numbers of 10 species or grou ps of species for each 5 ° X 5 ° square and each month. The data for 1969 became available as this report was in preparation (Fisheries Agency of Japan, 1971) and are summarized in Table 1 but not included in this analysis.

From 1956 through 1966 the values pub­lished are from the longliners from which logbooks were available. Conversion factors are provided to adjust these data to estimates for the whole Japanese fleet. The data from 1967 onward were adjusted before publica­tion. The factors used to adjust the data to values for the whole Atlantic fleet are:

1956 1.00 1957 1.15 1958 2.57 1959 1.97 1960 1.34 1961 1.29 1962 1 ~.)

.1-

1963 1.60 1964 1.52 (Longliners)

1.47 (Mothel'ships with longline boats) 1965 1.60 (Longliners)

1.27 (Mothel'ships with longline boats) 1966 1.54 (Longliners)

1.17 (Motherships with longline boats) 1967 1.21 (Longliners)

1.14 (Motherships with longline boats) 1968 1.61 (Longliners)

1.16 (Motherships with longline boats)

Factors for 1961 and 1962 have been changed slightly from those indicated in Shiohama et al. (1965) because of the deletion of some suspect data on the advice of Dr. Akira Suda of the Far Seas Fisheries Research Labora­tory of the Fisheries Agency of Japan. Shio­hama (1971) has recently published a table of corrections which agrees almost exactly with Suda's letter-our data are very slightly at variance with the later corrections.

Table 1 summarizes the Japanese Atlantic catch and fishing effort for the period studied.

Through 1965 the Japanese fleet accounted for 90% or more of all Atlantic longline catches. The percentage decreased rapidly in 1966 and following years as the Japanese reduced their effort and the Chinese (Taiwan) and South Koreans increased theirs . In 1969 the Japanese fleet only took about 30% of the

2

total Atlantic longline catch, but fishing oper­ations were widely enough distributed in time and space that the Japanese fleet could still be considered a good sampling device for de­riving indices of catch per unit of effort and abundance.

The tunas and bill fishes were originally identified in the data report.':! only by their Japanese and English common names. Be­ginning in 1967 the names for the Atlantic tunas and billfishes are given as follows :

./opall l'!W IWIIII' 56, 1I11.til· 1/(/111(' Ell yli~h I/O IIII'

Kuromaguro T 11/1111111.' I It Y 1/111/ s Bluefin tuna Minamimaguro T. 11/(1I"'lIyil Southern bluefin Binnag-a T . alO/lillYu Albacore Mebachi T. OUI'.",., Bigeye tuna Kihada T. (/1/)(1 ('(I /'I'.~ Yellowfin tuna 1ekaj iki Xlpili(ls yladil/.~ Swordfish

r'\ishimakaJlki Tl'lrapllll'IIS O/l)/(/IIS White marlin ~ishikurokajikl J1aklli I'll IlIl) I'II'a II.' Blue marlin Shirokajlkl .11. /IIdlcO Black marlin Nishibashokajiki l sliopilorlls alblcOIiS Sailfish Kuchinag'ufurai Tcll'Ilpllll'lls p.tlI1P{jcl'I Longbi II spearfish Katsuo Ell tilYIi III1S pc/a III is , kipjack tuna

METHODS

The area covered in this tudy is the At­lantic Ocean, exclu ive of the Mediterranean Sea, but including the Gulf of Mexico and Caribbean Sea, from lat 45 °N to 40 0 S, west of long 20 °E. Twelve of the 6,045 observa­tions in 1956-68, including some 72,000 hooks in 1965-68, occurred just north or south of this area and are not included in subsequent consideration. Two hundred fifty 5 ° X 5 ° squares all or part water are included. Two hundred thirty of these were fished at least once during the 13-year period. The 20 squares in which there was no fishing are in coastal areas or at the southern boundary.

The number of month-squares for which there are observations in a given year varies from 23 in 1956 to 1,053 in 1965. An average year has about 464 of a possible 2,760 (230 X 12) month-squares. When the data are grouped into quarters of the year, the range is from 19 quarter-squares in 1956 to 548 quarter-squares in 1965, with an average of about 264 of a possible 920 (230 x 4) quarter­squares. Since the mean density is 29% (264/ 920) for quarter-squares vs. 17% (464/2,760)

Table 1.--Number of observations*, estimated total numbers of hooks and estimated numbers of fish caught, Japanese Atlantic long1ine fishery, 1956-69.

oj< t:: t:: '0 til

t:: ..... t:: ..... t::..c: 0 M ..... M co til

..... oj< t:: ..c: ,... M ,... ..... oI.J oj< Q) ..... til co ,... co ..c:~ .!<: co t:: ,... ~ ..... El co El til"" ()

> ..... 0 Q) ~ ~ El ..... co co ,... til ~ () :>... 0 '0 Q) .!<: ~Q) ." Q) .!<: Q) t1I Q) M ,... oI.J Q) () Mo.. 0..

til 0 ::l .D bO M 0 ..... ::l t1I ..... til ..... .D 0 M M ..... ~ ~ !i M M t1I .!<:

Year 0 ~ !Xl < !Xl !Xl !Xl Cf.) Cf.)

-------- ------------------Thousands---------------------------------

1956 23 131 0 1 0 12 0 0 1 0 0

1957 134 3,376 0 32 9 259 1 1 9 0 3

1958 132 8,001 0 100 15 746 1 1 10 0 4

1959 241 15,312 3 357 45 1,098 2 7 23 0 6

1960 307 20,727 7 452 71 1,159 3 11 27 0 12

1961 401 26,660 4 430 243 980 11 38 43 1 28

1962 440 54,920 54 1,102 367 991 20 113 112 3 68

1963 586 55,004 67 1,133 285 886 24 87 96 1 51

1964 806 84,998 63 2,134 344 879 31 163 84 0 118

1965 1,058 97,580 60 1,769 650 927 44 129 45 0 118

1966 757 53,79l 29 1,586 232 395 22 89 22 0 65

1967 609 31,154 5 688 181 366 16 43 11 0 59

1968 551 30,200 8 917 205 274 17 43 9 0 52

1969 588 29,676 32 390 264 242 58 27 13 0 26

Total 6,633 511,531 335 11,090 2,909 9,213 249 753 503 6 610

*An "observation" is a set of effort and catch data for a 5° square for a single month. A total of 24 observations in 1961 and 1962 have been eliminated and raising factors adjusted appropriately as stated in the text.

**Inc1udes southern b1uefin - previous to 1966 the published statistics do not separate the two species.

o Less than 500 fish.

for month-squares, the data were grouped into quarters for analysis.

The number of squares fished at least once in each quarter in the 13 years is:

3

January-March 176 squares April-June 193 July-September 203 October-December 200

Squares not fished are shown in Table 2.

0

0

0

0

0

0

0

1

2

3

1

1

0

0

8

Table 2.--Five degree squares not fished by Japanese longlines, 19S6-68, by quarter of the year. Each square is identified by the coordinates of its southeast corner.

Never fished* First q uarter"rl< Second quarter Third quarter Fourth quarter

not fished not

40 0N, - 700W 3SoN - - 7S oW. 40 0N

40 0N - OS Ow 3SoN - 700W. 3S oN

400N - 00° 3SoN ,., - 6SoW. 3SoN

3SoN - OSOW 3SoN - 600W. 3SoN

300N - 8SoW 3S()N - 4S <>w. 300N

300N - 100W 3SoN - 2S oW. 2SoN

300N - OS Ow 3SoN - lS oW. 2SoN

2SoN - 100W 3SoN - 100W. 20 0N

OSoN - 60 0W 300N - 800W. OSoN

OSoS - 50 0W 300N - 7SoW. OSoN

OSoS - 4SoW 2SoN - 80 0W. OSoN

2S Os - 4SoW 2SoN - 300W. 200S

400S - 60 0W 2SoN - 20 0W. 200S

400S - SSOW 20 0N - 80 0W. 200S

400S - 2SoW 20 0N - 7SoW. 2S Os

400S - lQoW 20 0N. - 4SoW. 2S Os

400S - OS Ow 20 0N - 300W. 2SoS

400S - 00° 200N - 2SoW. 2SoS

40 0S - lODE lSON - 900W. 2S Os

40 0S - lSoE lOoN - lQow. 2SoS

The mean catch per unit of effort taken as apparent abundance for a square for a quarter was computed as the arithmetic mean of the catch per unit of effort for each month in the quarter for each year-possibly 39 values had the square been fished in every month of the quarter in all of the 13 years . The method was selected over the a lternative of dividing

fished not fished not fished

--

-

-

-

----

-

---

-

-

-

-

-

-

-

4

lSoW 40 0N - 100W 40 0N - 6SoW

200W 3SoN - 7SoW 40 0N - 60 0W

lSoW 3SoN - 4SoW 400N - lSoW

lQoW 300N - 80 0 W 40 0N - 100W

lSoW 30 0 N - 7SoW 3SoN - 7SoW

80 0W 30 0 N - 30 0 W 3SoN - 70o~

lSoW 300N - lSoW 3SoN - lSoW

2S oW 2SoN - lSoW 3SoN - 100W

80 0W 20 0N - 2SoW 300N - 80 0W

7SoW 200N - lSoW 300N - 7SoW

OSoW lOoN - 100W 30 0N - 700W

3SoW OSoN - OS Ow 300N - 6SoW

200W OSoN - 00° 300N - SOow

lSoW OSoN - lODE 300N - lSow

400W 2SoS - 300W 2SoN - 80 0W

3SoW 2S Os - 2SoW 2S oN - 7SoW

200W 2SoS - 200W 2SoN - 6SoW

lSoW 300S - 300W 2SoN - 60 0W

100W 3SoS - SOOW 2SoN - SSOW

OSOW 40 0S - SOOW 2SoN - SOOW

total catch by total effort because we desired to weight each unit of time equally to elimi­nate the possible biasing effects of large vari­ations in fishing effort in different years. Over 70% of the fishing in the 13 years took place in the 5 years 1962-66 (Table 1).

Catch per unit of effort was estimated for most unfished squares, and they were "filled"

Table 2.--Continued.

Never fished* First quarter** Second quarter Third quarter Fourth quarter

not fished not fished not fished not fished

05°N - 100E 25 Os - 00° 400S - 45°W 25°N - 40,oW

00° - 50 0W 25 Os - 05°E 400S - 400W 25°N - 35°W

200S - 00° 300S - 45°W 400S - 35°W 200N - 75°W

25 Os - 00° 30°8 - 35°W 40°8 - 300W 20 0N - 50 0W

30°8 - 300W 30°8 - 300w 40°8 - 200W 20 0N - 400W

30°8 - 25°W 30°8 - 25°W 40°8 - l5°W l5°N - 95°W

30°8 - 00° 30 °8 - 20 0W 40°8 - 05°E l5°N - 900W

30°8 - 20 0E 35°8 - 50 0W 05°N - 100E

35 °8 - 35°W 35°8 . - 35°W 35°8 - 50 0W

35 °8 - 30 0W 35°8 - 300W 40°8 - 500W

35°8 - 25°W 35°8 - 25°W

35 °8 - 200W 35°8 - 200W

35°8 - 100W 40°8 - 35°W

35°8 - 05°W 40 °8 - 300W

35°8 - 00° 40°8 - 200W

40°8 - 45°W 40°8 - l5°W

40°8 - 200W 40°8 - 05°E

40°8 - l5°W

40°8 - 05°E

*These squares not included in listing by quarter. **No fishing north of 40 0N in this quarter.

since we felt that with certain limitations values in surrounding squares cou ld be taken as estimators. The four adjacent squares and the four squares at the corners of each un ­fished square were cons idered. An unfi shed square was filled if there were data in at least: two adjacent squares, one adjacent square and two opposing corner squares, or

5

four corner squares . Adjacent squares were assigned a weight of two, the corner squares a weight of one.

The catch per unit of effort of an unfished square was calculated by multiplying values in the adjoining squares by the appropriate weighting factors, summing the products, and dividing by the sum of the factors. The

Table 3.--Five-degree squares not fished and not filled, by quarter of the year. Each square is identified by the coordinates of its southeast corner.

First quarter** Second quarter Third quarter Fourth quarter Never filled* not filled not filled not filled not filled

40 0N - 05°W 35°N - 75°W 35°N - 100W 35°N - 75°W 40 0N - 700W

40 0N - 00° 35°N - 70"W 300N - 15°W 30 0 N - 85°W 40 0 N - 65°W

35°N - 05°W 35°N - 65°W 05°N - 80 0 W 30 0 N - 80 0W 40 0 N - 15°W

300N - 100W 35°N - 10"W 05°N - 75°W 25°N - 15°W 40 0N - 100W

300N - 05 Ow 300N - 85°W 25°S - 45°W 35°S - 50 0W 35°N - 75°W

25°N - 100W 300N - 80 0W 25 Os - 400W 400S - SOOW 35°N - 700W

05°S - 50 0W 35°S - 300W 300S - 300W 40 0S - 45 Ow 35°N - 15°W

40 0S - 60 0W 35°S - 25°W 300S - 25°W 400S - 400w 35°N - 100W

400S - 55°W 35°g - 05°W 35°S - 35°W 40 0S - 35°W 300N - 8SoW

40 0S - 05°W 35°S - 00° 35°S - 300W 400S - 300W 300N - 80 0W

400 s - 25°W 35°S - 25°W 400s - 25°W 300N - 75°W

40 Os 200W 35°S - 200W 40 0S - 200W 300N - 700W

40 0S - l5°W 40 0s - 35°W 40 0S - 15°W 25°N - 75°W

40 0S - lOoW 40 0 S - 300W 40 0S - 100W 15°N - 95°W

40 0S - 00° 40 0S - 25°W 40 0S - 00° 35°S - 50 0W

40"S - OSOE 40 0S - 200W 40 0S - 05°E 40 0S - 50 0 W

40 0S - looE 40 0S - 15°W 40 0S - lOGE

40 0s - 100W

40 0S - 00°

40"S - 05°E

40 0S - lOGE

*These squares not inc luded in listing by quarter. **No filling north of 40 0N in this quarter.

procedure was reapplied to a single square, lat 20 ° -25 0 S, long 15 0 -20 oW, in the secong. quarter only, which remained as a "hole"

in the data field after the filling process. Table 3 shows the squares which remained without observed or assigned values after filling.

6

Contouring was done by computer, assign­ing the catch-per-unit-of-effort value for each square to a point in the geometric center of the square. Although our charts (Figures 1 and 4-13) are a square projection, the "squares" are, of course, not square. One degree of longitude is approximately equal to 60.722 nautical miles x cosine latitude.

100" 80"

20"

40" 40"

100· 80" o· 20"

Figure 1. - Divi sions of the Atlanti c Ocean .

The program used for contouring could not effectively distinguish squares with no data from those with values of zero , and it contoured squares which are part water as if they were all water. For these reasons we edited the computer plots, terminating all contours at the coast and a half-square be­fore the edge of the data field .

For the sake of clarity and simplicity the contours in Figures 4-13 are usually drawn at the levels of 2, 4, and 6, and the number of hooks is varied appropriately by orders of magnitude:

Fi sh per 100 hooks -

Fish per 1,000 hooks -

Fi sh per 10,000 hooks -

Albacore Yellowfin Bigeye White marlin Blue marlin Sailfish and spearfi sh Bluefin Swordfish Black marlin Skipjack

7

The level of 4 (per 100 or 1,000 or 10,000 hooks) is shown by a dashed line. In cases where the catch rates exceeded 6 (per 100, etc., hooks) in significant amounts, the fact is noted in the explanatory text for each species. Black marlin and skipjack are ,ex­ceptions-their apparent abundance is so low that contours are drawn only at the single level of 1 per 10,000 hooks, roughly equivalent to comparison of presence vs. ab­sence.

INTERPRETATION OF CONTOURS

The various species have shown differing apparent responses to exploitation, and these responses, of course, affect the mean abundance values. (Wise, 1968; Wise and Fox, 1969; Wise and LeGuen, 1969.) For this reason, in Figure 2, we show for each species the annual

BlUEF tN 100 ALBACO RE

'0) ~

~"]V ':: ~ £:)

z « '0 V)

::::l o I .2S ~

a:: w Q..

I U ';:{ U

BLUE MARL IN

~ SAILFI SH & SPEARFISH

1956 1960 1965

YEAR

W HITE MARLI N

08

04

04 SKIPJACK

02

1956 1960 1965

YEAR

Figure 2. - Catch per th ousand hooks, 1956-68 , variou s tunas and billfishes in selected areas (see text) in the Atlanti c Ocean.

catch per unit of effort only in the areas in which the catches of the species were great­est in 1956-68, dividing the Atlantic as shown in Figure 1. Catches were distributed as follows:

Bluefin

Albacore

Bigeye

Yellowfin

Swordfish

- 89o/c of the catch in NOW, GU!, and BAH

- 86% of the catch in NOW, BAH, BEN, and RIO

- 860/c of the catch in Gur, ev, GG, and BEN

60fc of the catch in G I , CV, and GG

- 81 Of( of the catch in GUI, V. GG. BAH, and BE

Whit marlin

Blue marlin

- 72'1, of the catch in NOW, GUI, BAH, and RIO

- 72'7< oflh 'catch in NOW, GUI, CG, and BAH

Black marlin - n'lr ofth'caL('hin(,V,GG, and BAlI

Sailfishandspcarfish- 76'1r ofthccatchlnG I, CG, BAH, and RIO

Catch rates of skipjack are 'alculated for the whol ocean.

Examination of Figure 2 makes it clear that th contour levels shown for the variou.' pecies can r ft ct only relative overall abun­

dane and ar not n cessarily repres ntativ of anyone year or , hort s ries of year .

Figure 3. - Relative amounts of fishing by the Japanese longline fleet in the Atlantic Ocean, 1956-68. Darkest portion includes 75% of the effort; intermediate shading plus darkest portion includes 95% of the effort; all shaded areas include 99 % of the effort.

8

Most, if not all, previous studies based on the Japanese longline data-e.g., Koto (1969); Mather, Jones, and Beardsley (1972); Saka­moto (1967)-have tacitly assumed that all observations are of equal value in delimiting distribution and abundance of the species taken by the fishery. The assumption probably is not correct because of the grossly unequal amounts of fishing in different parts of the Atlantic. For example, there were a total of some 7 million hooks fished in 1956-68 in each of the two most heavily fished 5 0 x 5 0 squares, vs. a total of only about a thousand hooks fished in the most lightly fished square in the course of the 13 years, a difference of nearly four orders of magnitude.

For this reason, we show the relative amounts of fishing in Figure 3. The shaded areas include 99% of the fishing effort in each quarter during 1956-68. Within the shaded area the darkest portion includes squares which total cumulatively 75% of the effort;

the intermediate shading plus the darkest portion includes 95% of the effort. Table 4 shows the range of the percentages. The total fishing effort was approximately equal in each of the four quarters-first quarter 120.5 million hooks, second quarter 131.6 mill,ion hooks, third quarter 120.7 million hooks, fourth quarter 109.0 million hooks.

Thus, all of the squares outside of the shaded areas in any quarter taken together include no more than 1% of the fishing effort for that quarter, and no one unshaded square in­cludes more than about 0.05% of the fishing for that quarter-at the maximum about 5,000 hooks total in 13 years (131.6 million hooks x 0.05% /13). Most of the squares out­side the shaded area include less than 0.05% of the fishing; the average is less than 0.02% , or less than 2,000 hooks t9tal in 13 years.

A recent publication by Shiohama (1971) shows graphically the distribution of Japanese longline fishing effort for each year in the 1956-68 period.

Table 4.--Distribution of percentages of fishing effort for each quarter.

First guarter Second guarter Third quarter Fourth quarter

Effort Range Number Range Number Range Number Range Number level of % of of % of of % of of % of

squares squares squares squares

75% 5 0894- 34 5 0075- 48 5 0169- 44 4 0070- 55

0.924 0 0766 0.814 0.584

95% 5.894 78 5.075- 88 5.169- 101 4 0070- 109

00176 0 0225 0.163 0.208

99% 5 0894- 115 5.075- 124 5.169- 141 4 0070- 144

0 0055 0 0046 0.049 0 0048

100% 176 193 203 200

Note: The number of squares shown for each effort level is cumu1ative--i.e., in the

first quarter 95% of the fishing is included in the 34 squares which include

75% of the fishing, plus 44 others, or 78 squares.

9

The shaded regions include the areas in which we have reasonable confidence in the contours, with confidence increasing as the amount of fishing included increases. Contour lines outside of the shaded areas are related to very small amounts of fishing and should be interpreted with caution, especially where there are isolated peaks of high apparent abundance.

In evaluating the amount of confidence to be placed in the contour lines, however, we feel that giving consideration only to the amount of fishing is oversimplification. When a concentration repeats in more than one quarter, or when it appears to be coherent with one or more others appearing in other quarters, it can often be given more credence than that based simply on the amount of fishing. The ideal, of course, would be to have the fishing uniformly distributed over the ocean. An alternative would be to apply an objective statistical procedure to reject catch­per-unit-of-effort values derived from amount of fishing below a critical value. The first is impossible and the second probably not practical, so a certain amount of ubjectivity must remain in the interpretation of the con­tours.

BLUEFIN AND SOUTHERN BLUEFI N TUNAS

The published Japanese statistics did not separate the bluefin and the southern bluefin previous to 1966. In the period 1966-68 about 30% of the total catch of both species was southern bluefin, but less than 100 southern bluefin were caught north of lat 20 0S. About 75% of the catch south of lat 20 0S was report­ed as southern bluefin. We shall generally consider concentrations north of lat 20 0S as bluefin and concentrations south of 20 0S as southern bluefin.

Figure 4 shows the distribution of catches of bluefin for the four quarters of the year. The most consistent features are a concentra­tion of bluefin off the easternmost part of South America all year round and another, probably of bluefin and southern bluefin (Tal­bot and Penrith, 1963), on or near the African coast south of lat 20 0S, in every quarter but

10

the first. There is a concentration in the first quarter just north of lat 20 S; it appears probable that this is related to the African coastal group.

There is a concentration around ('uba and Puerto Rico in the first quarter, extending into the northern Gulf of Mexico and along the east coast of North Ameri'a in the .'econd quart r. It is off the northeastern United

tat s and Newfoundland in the third quarter and ext nds southward in open water from

ova cotia and Newfoundland in the fourth quo rt r. Thi: pattern is consistent with a migration pattern outlined by Riva' (195::». Th migration hypothesis for northwe.'t At­lantic bluefin \\'a.' unsupport d by any direct evidence for many years, but recently long­lin r8 off New England and ~ova cotia caught t\\O bluefin tagged in th Bahama' (F . .J. Math r, III, p rsonal communication).

In the first through third quarter there are "spots" of bluefin ext nding ea tward from the concentration' mentioned above, and in the fourth quarter there i' a large concentration centered on long :30 W in the North Atlantic. These di'tribution may be related to the irregular tran atlantic migra­tion of bluefin discu ed by :Mather (1969).

Although there are relatiYely important fi herie for bluefin on th European coa t, in the Mediterranean. and on the northwe t coast of Africa. nearly all of the large con­centration in Figure .! occur we t of long 20 W.

The apparent abundance of bluefin during the 1956-68 period increased from very low levels in the early years to a peak in 1962-66, then returned to lov.' level (Figure 2). A similar cycle may be seen in the purse- eine catches off Nev.' England (Wise, Beardsley, and Mather, 1971). While great changes in catch-per-unit-of-effort value with time make any absolute values questionable, average catches per unit of effort in the concentrations shown run over 50 per 10,000 hooks in the first quarter and over 100 per 10,000 hooks in the second quarter.

ALBACORE

The most obvious feature in the distribution of albacore for the four quarters of the year,

.... ....

100" __ r---r ·- r

~l ~ , 'r;::;;y' C l " .. ~ / .

~~/

20"

./r

J

.. , ~ ((it (~ ~

20"

40

--1 20

~

~

~

-< 0

~

d!§J ( 1 ..... 20

J.A.N-MA

. 0

o·

JUl-SEP

" ,A,-::::"

4(]

«f T T T T

\,.';'::9 ';:)

4 1 fJ

.7

.. ,

N

20' T T f

<../

4'

, 0 \j

0 '

o fVT

;

J',f ...... ~~ ~ .

~ 40"

-; 1 J 20

20 r

1

'"I. .• ,1 vl

20

o

100" 110"

~ . ,-

~ •• I"~

I I

~~ (:'_1, '- f) ~~~, ~ /~

.. , 2rf

~

~ ~

0 ..-

2~l

-:z: .;' ~\\~; ( ~~. ~~-; G" I

"\ APR-JUN

~ I .r:, ('" .01

rl~LLl f 1

100 ' 10 Ih 4(] 20"

100 \1(1 ' bO' 4(]' 20 ~ r T T ~ T T T ~ S T T " T - or or r T

C-:l ,-40" __ ,r- I•u,\

I '. I 1 , 1 , \ I

~ ~ \ ,- , I-

, '~ "'-a

4' 20'

OCT-DEC cJ

/.2 ,

10'

.. ,

-4 2<7

~

-i

o

.... 2~

'O-~ It\ ~ '. \ ~ ~ ~~~

- HO

o 20"'

20'

20"'

..... t-:l

4Cf'

2(/'

4(/'

4Cf'

2(/'

(/'

2(/'

4Cf'

JUl-SEP

I 2

('

.. 2

~ '---~::<02\5a\ " ,~

" I( :,. I." I ,... I , 6.6'

' ... ;! \ ' I \1 \ ~ ,---....

,. \

2(/'

"2

. ~ \

~~) ,~-~ ",', (} /M' l \ ,'---- " 'X , \.6 -" ·6 6 \ )

(/'

20"

4Cf'

20° 2if

0° (/'

2(/'

4Cf'

20°

4Cf'

20° 2(/'

0° if

20"

4Cf'

10(/'

~2 I \----~ .) 22 •

~~~ .. 2

~ ~2 ~~

APR-JUN -) 2 I .6 , 6

(/! j\, o

,0(/' 80" 60" 4Cf' 20°

~ ' ,-' " I " ( r. 2'0 ',2

2 " \ 6 J\. ~ r'2~'----,' \:!)

o ~ ). 1..../ • 2

; C2 " 2

--:::-----2 ~ .,- .... " , '-\ ,. '-, \ ,.

\ " \ I , I

'--OCT-DEC ,-, , ___ '---......... ' .. J

/' ,\ ...... ,.6,\ ,.--

Figure 5. - Distribution of catches of albacore (per 100 hooks) in the four quarters of the year, 1956-68.

20°

20°

0°

20"

0"

as shown in Figure 5, is the separated northern and southern distribution of the species, with very low catch rates between about lat 15 °N and 5 0S.

Beardsley (1969) and Koto (1969) both studied distribution of albacore in the At­lantic on the basis of longline catch and effort. Their analyses were based on shorter series of data than we have used-Beardsley used 9 years, 1957-65, while Koto used 5 years, 1961-65. Both agreed on generally east-west seasonal migrations within both the northern and the southern groups of albacore, with the group of small fish located off extreme south­west Africa interchanging with Indian Ocean populations.

Highest average catch rates occur off south­west Africa-up to 10 fish per 100 hooks in the first and third quarters and up to 17 fish per 100 hooks in the second quarter. In other areas, highest average catch rates almost never are above 7 per 100 hooks.

The almost complete absence of albacore from the Gulf of Mexico, although not ap­parent in Figure 5, is of some ecological interest. Almost 11 million albacore were caught in the Atlantic by longliners during 1956-68, but only 0.02% were caught in the Gulf of Mexico (GM in Figure 1). The two poorest areas for albacore outside of the Gulf of Mexico, the CV and GG areas -of Figure 1, yielded 2.4 and 3.1 fish per 1,0('0 hooks (total catch divided by the total effort for the 13 years), but the same figure for the Gulf of Mexico (GM) was only 0.5 per 1,000 hooks.

Also not shown on Figure 5 is the large shallow concentration of albacore in the Bay of Biscay from about June to October or November of each year. While the longliners fish little or none east of long 20 oW, north of lat 20 0N (Figure 3), catches of more than 30.000 metric tons of albacore (roughly half of the total Atlantic catch) are taken annual­ly by French and Spanish fishermen with live bait and by trolling.

BIGEYE TUNA

The distribution of bigeye is shown for the four quarters of the year in Figure 6. Two large concentrations are evident off the coast of west Africa, separated at or near the

13

equator, changing their shapes and bound­aries with the seasons. The northern con­centration is not defined at its northern edge in any quarter except the third, and may ex­tend all of the way across the Atlantic at about lat 35°-400N in every quarter exc-ept the second.

These distributions are different in many respects from those outlined by Sakamoto (1967)-the differences may be due to the fact that Sakamoto used data only for 3 years, 1962-64.

The apparently anomalous minor concentra­tion of bigeye along the east coast of southern Mexico and Central America in all four quarters may be due to misidentification by the fishermen of large blackfin tuna (T. at­la n tic'Us ) .

Average catches inside the contour of 6 fish per 1,000 hooks reach over 30 fish per 1,000 hooks in some cases along the southern African coast in the last two quarters, and near this level in the northern concentration in the first two quarters.

YELLOWFIN TUNA

Concentrations of yellowfin tuna are almost entirely confined to tropical waters between lat 20 0N and 10 0S, except for low or small concentrations in the northwest Atlantic in the third and fourth quarters and some con­centrations in the Gulf of Mexico in all four quarters (Figure 7).

Wise and Le Guen (1969), among others, have hypothesized that there may be eastern and western populations of yellowfin in the tropical Atlantic. There is some evidence in Figure 7 of such a division, but the dividing line could be placed at about long 70 0W, con­siderably farther west than suggested by Wise and Le Guen.

The catch per unit of effort of yellowfin has dropped markedly and steadily from 9 or 10 fish per 100 hooks in the first three years of the fishery to less than 2 fish per 100 hooks in 1964-68 (Figure 2) so that absolute values must be interpreted with considerable caution. The highest average value is nearly 19 fish per 100 hooks in the western Gulf of Mexico in the first quarter and nearly 12 fish per 100 hooks occur on the north coast of South

100" 80" 40"

40"

0 1

d

20° .6

20

:"')6V~~ --i 0 \:- " \ /) }', I

\ ~-~ \ t _________ " _, j

\"~~"'~:----J J20

c 1 ~~ ~j I, , ~-,

40'

-L.L .L L 1 . - I -l.--L-1. J......J~ 0 40"

0°

20" JAN-MAR

1 ........ " --40"

100" 80" 6(f'

2,,1

I '~ ~\ \, ....

.. "~ . .'-=-=~- 1 _~~ co ' /'_ ' , ,....-2") • '- ,,'

"-~~ '~\--_.-"- .-,, .---,---,

) ''0. ~ '-c;r.:-'-' (

> ",' 0 -. 6 V ~ ' ... I

40"

i 2O"

1 o 0"

1

20"~ "': 20 O';\6~ 1 " _/

(~ ~ .e. ~ , APR-JUN

f-,

4a ,

L ~ 1 1 100' 1<1' 00

/ -' \

- 4rr

J..J...LJ...L...Ll L---L-o ~' 20' 0' 20

...... 100" 80" 6(f' 40" 20" ct' 20 ' 10(7' 10 ' 1>0 40 20 0 20 ~ , ~ ~ ~ r ~ ~ ~ ~ r ~ T r 1) r T r ~,~ '["""'0 T

",.-- c.

40"~ f.~,,~-~.6 / -', '\.. C/ g'\''-.:;M)14a 40'f ~.-~. .'-...,.~ "'; ''1. _40 ",:~ .... _ 6.,)' '" . )L ... ) , ,---' "~.' 1 /' -'-.... -1 J " _ \ , ... ~ m ... ' __ ' _, ,

'-2 1 _ _ ,.--,., ' __ ', /~ _ -.." 1'-. / 1 \, , 6',1

.2 ,'... ~ . 1. , .... , 1 '.::::>-" ~ 2ifl.:: '--- h1 :::~ , ~, ,./,( .., 20 ' 20 '~ ~1) G, .--.' -20

,/ J ~ C1 " " " C\ - t -- ----__ ' -,-, \ ---",_, ___ ; '1 ,/ ;"T if ' ( \ " 0 ' 0. 1 , , /'1 ,-, • ~ _ 0

r- __ f') 1'-"/ t- L - \ t.' \ O~, r-'-...... I '\. I I

"J [ 1 ("'- ~. ( .. ~ "-', • .... -- " , --.......... '2 \ " '\ '_ .. ~ i r-"" I .&

I I , ... 1 ' 20" 1- IV; '_', -i20' 2a'~ , \ - 2(1'

JUl-SEP --:,~(.li '.' 'i • 1 > OCT-DEC ,,----. \ -. '~ 1 ._L-·6 (\ ' __ ;, 1 ~ ! .~"'_ ~~; , .. ' 6-1 ~ / <:" • 6, ' ? ,,,

1/ I I ."..-.......... ",<6 4O"1-.../' j 4<1 40 , I C'" ... 4(1'

I ,

.....L ...L L . .-.I....-.!. J ..l .1. _ --4.... 1 ..L J. _.1. 1 ... 1 -1 1 l ~.~..1&. l .... .... J.. 1 .L .1. L 1 .L. J.. .L .1. .1. .1... .1.. L '1 100° 110" 6(f' 40" 20" 0 ' 20" 100 ' 1<1 00' ~' 1(1' 0 ' 1(1'

Fig-ul't' G, ni ~l rtiJuliul1 of l'llll'hl'~ uf "il<l'Yl~ tUlia lpvl' I,UOO houks) III litl' full I' q\WI'tl'I''; llf tlh' Yl';!I'. I~l;"l;-li~ ,

f-' 01

4(f'

2ft'

a'

2a'

4a'

4(f'

2a'

a'

2a'

4(f'

20°

20° 20°

("~ 0° 0° 0°

JAN-MAR APR-JUN

2~;

.. 2 '\

20° 20°1 2a'

4a' 4a' 4a'

4a' 2ft'

4(f' 20°

;::;> .. 2

,----, ' ~ .6 , ,_,,1 __ 2 - ~-;/

20°

4a' r! ~ ~vj1 400 / Q ",N . V 1

.. 2 . I -~--'1 ~ / ~ ( ~

a'~~ \ _

~ ~2"'---"'~ 1

"~~ :00

20°

0° 0°

20' 2a' .. 2 l 200'

.. 2 OCT-DEC

4a' 400

2ft' 4a'

Figure 7. - Distri bution of catches of yellowfin tuna (per 100 hooks) in the four quarters of the year, 1956-68.

America in th second quarter-in all other cases the contour of 6 fish P'l' 100 hooks does not enclose \alues of much abo\'l' G.

SWORDFISH

The plots of sworcltish apparent abundantt' shown in Figure for the four quarters ap­pear on cursor~' xaminatinn to be am, n,; tht' most complex of all the species and Rrollp.· of species. In fact. they are among- the .'im­plest. since th y demon:trat' litt!t> diffen'ncl' in distribution with refer nte t() Illngitudl" l<1titude. land masse ... open OCean an'n., Ill'

e,' n with eason. In the fir't, third, and fOUI'th quarter', th northern limit (If di ·trihution at the lowe. t le\'el :hown, ~ ti .. h IWI' lO,()III)

hooks. extends beyond the limit· of tlw fi hpry, The highe.t <lv'rag' catl'h per unit Ill'

effort is about :27 ft.'h per In,non hook.·, at til • northern limit in th fourth quarter-in other quarters it runs aboll t 1:2-1 ~l Ii: h }ll'r III ,I 11)(

hooks. eithe~' at the nOlihern limit (r 11 a1' lat 10 ~ T on the coast of we .. t Afnca.

The catch-per-unit-of-effort t1!--'1.11' '. riven are for swordfish caught incidental t I daytinw longline fi heries primarily for (lth '}' . p l'i : -commercial longline fish ries for sWlmlfi.·h operate primarily at night, .·inc> catches an' considerably higher than they are in daylight hours. Thi fact. together with th increa:e in apparent abundanc of ."wunlfish thl'llug-h the 1956-63 period (Figure :2) mean. that the values in Figure mu t be interpret d with considerable caution.

WHITE MARLIN

Figure 9 shows catch rate' for white marlin for the four quarter of the year. The major concentrations of white marlin occur in th western Atlantic. There i a concentration along the east coa t of South America in each quarter except the second and another which appears to move along the north coa t of outh America, through the Caribbean, and into the northern Gulf of Mexico. starting in the fir t quarter. Mather et al. (1972). after tudying 65 tag returns, mostly from the commercial fishery, state that these shifts may be attrib­uted to seasonal migration. They hypothesize that there are probably no major migrations

16

of whitE' marlin IWt\\'('(,1l Uw two WI', t 'I'll At­lanti(' cOllct'ntratiol1s and tha th,,), may b Sl'pHl'at(' poplilat ion .

\'('ragc' catc'h ratl'S rl'((('h ~W Of' nHIl'I' whit!' madill pl'l' l.OOD hook, in till' (,ulf of Mf'xir'o and ('arihl)('an in tIll' . ('('IlIIII '1l1art 'I' and fwady that rak off P(l t('rll :outh m'ricH in thp first and fourth qUart!'I',.

Fig-un· ~ ,how, that thl' ('atl'h I'll • of vhitp ma r Ii 11 t!' ncll'd 0 i Ill'!' a. I' d It ri II ~ till' 1 ~!,jr, -I; period, with ratp' (If ab III I ft. h pel' l,IJI)I)

hook: or IJI'lo\\' in 1 ~J"",(;-(;fl and ,'atp r'f} rally o\!'r ~ n.h pl'r 1.IIIH) hook in IUi1-!), dp­JlI'oat'hill~ ~: fi h pl'r 1,IH)() hook in

BLU E M AR LI N

!'igurp \1) .i1( \\. ('at II ratt> C I' hhlp madill

tw( major ('OI1C 'n ration., b Atlantic. 'lit> appal' 'nt If Africa in tllP fir. t ljlldr l'r litt!' fl:hing-.J On' f thl: ('(lIle ·ntration. lie f he >a:ternm part of .' uth Amll'ica in th> til'. t and . cond qu. rt '\'.. \\ i 11 .t 'U~g" '. tion ( r i. exi t ne > in the fourth quart'r. Th' 0 her lie. in th rulf of :'II 'xicn and 'arihb~an, centered around l uila. in th : clint! and third qual' er:. Mather et a!. (l~17:2) ha\'e hypothe:iz d n the ba 'is of :pawning information that the e two widely ,'eparated cflncentration: repr ,'en :eparat population. althuug-h Ceyanagi et a!. (1. 70) b lie\' there 1 .. mixing in equatorial area.'.

Highe .. t i.l\'erage catch rat: in both con­centration. reach oyer 1:3 fi'h per 1.000 hook~ in the. econd quarter.

BLACK MARLIN

Black marlin had not been reported in the Atlantic until the fil"t tati 'tical report on the Japanese longline fi hery ( hiohama et al .. 1965). Its exi tence in the Atlantic till has not been confirmed by examination of speci­mens by a qualified ichthyologist. Nonethele s.

~ 0 1 1 T , ,

" .? N 0

\O}(

1 1-

0 ,..

~ ",

L .L

\\

C))O" \ :.--". , .......... ~ ... j

;. <.J-; ';,'e\

\

z ::J ...,

I oc a.. <{

t 1-..1 1 1 .L

0 0 ,..

0 0 ,.. T T T T T

1 .&.. .L .1. 1 J..

o 0 ,..

L

0 . b . ,

o

-i~

-i

.... 0

~

~

-i

1~

-i

~

o

o .

~

0-

~ r-

o

J..

T

S ,"'

(;;.-

ok .. ~ ~ 0

~ ~ b T T T , T T

(/

1-.. ')' ,

... ' . ' .. } : ,,' ,.' , . , ,U·

, ... ' r-__ _ • c....> .' ,... .. Ui. , ....

~ ; E.-:-::-':'~:' ... -u ,... , . , ' ,

:\( < :), .. , ., (..>

.. . , . , \ , .L

b

,-. , , ~

,"

to

u o I ... ~

r .. o

,. .. ':) \.;.:-....-.

100" 10" 6d' 4(f' 20° 0" 20°

4(f' ~/ oy 40" 40" c2

J -----------200k '---fI ~~~6'\\

0 20° --120°

0°1- / '-----. .' 2 0°

~~ ( )~ --I 0°

~ 20"1- ", J!, 20° 20°

APR-JUN"! --120°' '0 .. :-l \ 2 JAN-MAR &" o •• '

c2

...... 2

I~t, Ii ,r:, • I". JI r~t · I (,£ , --140"

I I I t I I , I I I I I I , I , I , 80" 6d' 4(f' 2(j' 80" 6d' 4(f' 2(j' 0° 20° 100° 0° 20° 100°

I I

f-' 100" 80" 6d' 4(f' 20° 0" 20°

I 00

J I

'jt~ .. , i i I

'~ .. .~~ At ~ 'j ' -:'\ /~~ 40° C2

D 2 ~~ .-/.'~ c2

20"k: ~N: ~. --1 20° ,.~~. --1 20°

0 2 r--2 •

0 2

0"1- / ~2 r-... \ -I 0° 0° ---- --I 0°

G ~ ,,--2 --

20"1- ,-/ V 20° 20" \ ) /(-.~\ ~ J 20J JUL - SEP OCT-DEC

c2

40" 4(f' 40° ~40"

Figure 9. - Distri bution of catches of white marl in (per 1,000 hooks) in the four quarters of the year, 1956-68.

100" 80" 6d 4(/' 20" rt' 20° 100" 80" 6C' 4(/' 20° 0° 20°

4(/'

c2

2rt' ~2 ! ---1 20°1 brt'L \ "(i~6r;::...--.. -hoo

00~ ( ~ \ j 0°1 1 0l ( ~~ ( ~ 0°

,~~ /I\~O ., \ T1 I'~r APR-JUN ) /" ~., ~ ~" "'t I, I I ,L , I, I, I, ,l'" .~I '/ \.j ...

100° 8rt' 6C' 4(/' 20" 0° 2rt' 100° art' 6C' W 2rf' oc L--

I--' C!) 100" 80" 6d W 20° rt' 20° 100" 8rt' 1>00 ~rt' 20° 0 20

--v--r-rJ W~ / / 0 ,,;.\ -1~0"1 14rf'~ /' ~/ ~'\.s., 40 02 ~ v.

--- \...... -<

'~k~~.x--·' ,"'"I I'~~ '-..Iil$9 '. ., ( 1 ~

" ~ ( ~ :-\ i~1 It ( "-) , !;' ,. ~ JUl - SEP / ., \ 1'"1 I'~r OCT-DEC ) // \j ., \ ~ " 4rt'1- I (' JWI I~O"I- I /' ·; 40"

.L .L~ ~L. _ .L 1 1 ......J~ .L .L .L .L .L -!-.L I", I -'-~-'---'- LJ..........,. -,--"-1. LL....L --'-- -'- l-'------L .L 1.---'-.L .L 1 L .L L .:. J

100· 10' 60 ' 40" 2rf' 0 ' 2rf' 100° 8(1"' tn' 40 ' N ' 0 ' 20

Fi~'lr(' \II 111"ll'lbutlOll (If l'nt<.hl's of ],'Ul~ madill (1"'1' I,llI)\) hooks) III th" four quarter;; of thl' ),l'<lI'. 111:i(,-liS

the Japanese longline fishermen, many of whom would be expected to recognize the species, have reported catches consistently in everyone of the 13 years studied. Ueyanagi et al. (1970) believe that the black marlin in the Atlantic are strays from the Indian Ocean.

Figure 11 shows the distribution of th catches at a level of 1 fish per 10,000 hooks or higher for each quarter of the year. atche are extremely low outside of the areas ou t­lined, but can be quite high within them-up to 186 per 1,000 hooks in the fir t quarter­although most of the rates are less than 10 per 10,000 hooks.

Little can be aid of the general distribu­tion of the species. A concentration appears in the Gulf of Guinea, off Africa, in th fir t and second quarters, and concentrations appear along the coast of South Am rica in the first and third quarters, related p rhaps to a South Atlantic concentration in th fourth quarter.

The fact that the concentration appear off­shore and distant from population centers may explain why the specie has not b en recorded in the sport fishery.

SAILFISH AND SPEARFISH

The status of the spearfishes in the Atlantic is not entirely clear; Tetmptlll'uS pfill(gel'i, the longbill spearfish, occurs in the open Atlantic, and T. belolle occurs only in the Mediterranean. In addition there may be one other species of spearfish in the Atlantic, whose status is presently unclear. The tati­tics published by the Fisheries Agency of Japan combine sailfish and spearfishes in a category almost certainly equivalent to that reported by Shiohama et al. (1965) as "other marlins."

Ueyanagi et al. (1970) suggest that the sailfish lives close to land, while the longbill spearfish is found offshore. We assume that all concentrations in Figure 12 at or above the level of 6 fish per 1,000 hooks are sailfish, except for the two in the second and fourth quarters in the central North Atlantic. S. Hayasi and S. U eyanagi suggest (personal communication) that all of the open sea con­centrations shown in Figure 12 may reflect

20

the distribution of sp arfish rath I' than sail­fish.

oncentrations of sailfish occur along th east coast of 'outh America in all four quarters, extending in th s cond and third quart rs along the north coast of .'outh Am rica. In the second quarter th) concentrations reach into the aribbean and the southern Gulf of M xico. Another 'oncentration may b> seen on the w st coast of Africa from about lat :) N to about 10 in >very quart r exc 'pt th third.

Most cone ntrations of sailfish do not go much above 6 n:h per 1,000 hook -excep­tions o· 'ur only in the s ond quart r in th east rn 'aribb an with over :~:- p r 1,000 hook: and on the north coast of ,'outh America \\'ith OV'r 15 per 1.000 hooks. The concentra­tion in the central J. Torth Atlantic in thi .. quart r. probably spearfish, ris . to ju .. t ov I'

14 per 1.000 hook'. Figure 2 demon:trate' that there ha been

a st ady increa. in catch per unit of effort of sailfish and 'pearfi .. h during 1956-6 . although the 'ombination of mol' than ne :peci in the 'tati'tic.' makes interpr tation of the phenomenon difficult.

SKIPJACK TUNA

Longline catche' of kipjack have b en \'ery low-Table 1 how that in certain year none were reported by the Japane e longliner. There i a trong ugge tion in the data that thi repre ent a lack of reporting rather than a lack of catch-compare the data in Table 1 for 1959 with tho e for 1962. There i prece­dent, however, for con idering longline catche of skipjack at least a an indication of distri­bution (Miyake, 196 ).

Figure 13 how the di tribution of the catches at a level of 1 fish per 10,000 hooks or higher for each quarter of the year . Average catches inside the contours are 10 fish per 10,000 hooks or Ie ,except for one instance on the north coast of South America in the fourth quarter when the catch reached nearly 40 per 10,000. In general, catches outside of the contours shown are very low.

Probably the major value of Figure 13 is the indication that skipjack are very widely distributed in the Atlantic,

l'.:> ~

4(f'

0°

2rf'

4rf'

40°

20°

0°

2rf'

4rf'

4(f' 20°

40"

«I «I

20° 20° 20°

)J 0°

20'

7 0° \) ~ 0°

\ ~ ,~ ~J

2rf' « 1

4rf' ---1 4rf'

I I I I 2rf' I ° I --'---'~ o 20<

40°

100° I r 80° I I I 60°

40° ~ ' I 20°

40°

Q

20°

0°

20'

0°

-~" ~ --} /

' \ ~ 0°

o ( l~

20°

2rf' OCT-DEC

4(f' 40° 4rf'

100° 2rf' 0°

Figure 11. - Distribution of catches of black marlin (per 10,000 hooks) in the four quarters of the year, 1956-68.

4(f' 20" 0" 20° 100" 80" 60" 4(f'

I I

"'~" '] ~ 1 '1'#£"1

] 0(=, ~~ 40" 40"

.2

0 2

~2 ( j 2001 1200~~... fi/ /)/ ~200

.,6 ...... J ;r2

Oo~ / ~\ '---J:\ 20 0° ~ ( ~(, • \J i ~ 0° -- 2

) /.~, .' \ I

~ Y ( 20" ~

, :,: 20 ' I --j 20°' 20" -

''''';

' ( ~A-PR~JUN ~ .2 JAN-MAR \

.2

40"~ 1 , ,Jr:, Jl rt . , I l,r:, ...J 40"

I I I I I I I I , I , , I 100° 80" 60" 4(f' 20" 0° 80" 60" 4(f' 20" 0° 20· 20° 100°

t\:) 100" 80" 60" 4(f' 20° 0° 20° 100" 80" 60" 40° 20° O· 20· t\:)

[ 1 I I '~'ll' 'I' UP7 ' I ] [ 1 I I '3X"'i 'I ' U~/ ' I J

40"~ /' / Q ,,1>\ -140°1 I.~" ~/~\):~'" ~\.

(2 --'l ~2

23 ( l 2001

~ () ~ J ~

r t ~ " · " 02 ~ 'i J ~O ~ ", 2

20"~ / 20° 20" -...........::. - , --j 20°' JUl-SEP OCT-DEC ~

40"~ 0 2

,-/ ~40"1

140" t I , I l,r:, --j40"

I , I I I I I I 0° 20" I 100° 80" 60" 4(f' 20" 0° 20"

Figure 12. - Distribution of catches of sailfi sh and spearfish (per 1,000 hooks) in the four quarters of the year, 1956-68.

4(f' 20' r!' 20' I I

"'~~~L ['''' 1 }lAO "~~~L 4r!'~ _I 40'

.. , I

-1 20·1 120. l ~ [) ~~ . ( j 20' a ~

~./" '----

0 O( l: if~ (

~~ --I o'

j I , () ( APR-JUN ";

.. , 2o" f.- / .. , Q

20' I --1 20" JAN-MAR r \

\ '-

4°l, ,( ,r ... I .,. I", I", ITr!'1 rOl, , 1 , I l, [ , J 4r!'

, I , I I I I , I I 100' 8r!' bO° 4r!' 20" O' 20'

t\:) 100" 8rf' bO" 4(f' 20' rr 20° 100" 8r!' bO° 40° 20 0" 20 W I I I ' , I)/J i I I 'I' DU7 " 1 I [ 1 1 1 '::::::YJ[ ' 1 1 ' 1 1 ' U?)

4r!'f.- ,{ LJ v 'VI ,..1~-1 14O°r- / 2' /0'- ~ . / a \.. N j 40

/--~.~_v _

0 ( + 00\ \200~ ~= · D .. , (

200k '-..JI O~ · ~ 20'

] '-----' ~') '~

o°f.- { '----- 01 ~ 0°1 I oo~ ( ~ ~ o~

/ ~ .. , ~ \ +01 12r!' ~ OCT-DEC "; 2r!' f.- / / .' ~ --1 20"

.. , \) t

4r!'~ , , ( (, 4r!'1 14r!'~ 1 , , Il,[, -l 4r!'

I ••• """"J , I , , 1

100' 000 bO" 4r!' 2rf'

Figure 13. - Distribution of catches of skipjack tuna (per 10,000 hooks) in the four quarters of the year, 1956-68.

LITERATUR E CITED

BEARDSLEY, G. L., Jr. 1969. Proposed migrations of albacore, Th wl1l11S

aiaillnga, in the Atlantic Ocean. Trans. Am. Fish. Soc. 98:589-598.

FISHERIES AGE~CY OF JAPAN. 1965. Annual report of effort and catch statistics

by area on Japanese tuna longline fishery, 1962. Fish. Agency Jap., Res. Div., 183 p.

1966. Annual report of effort and catch statistics by area on Japanese tuna longline fishery, 1963. Fish. Agency Jap., Res. Div., 322 p.

1967a. Annual report of effort and catch statistics by area on Japanese tuna longline fishery, 1964. Fish. Agency Jap., Res. Div., 379 p.

1967b. Annual report of effort and catch statistics by area on Japanese tuna longline fishery, 1965. Fish. Agency Jap., R es. Div., 375 p.

1968. Annual report of effort and cat ch statistics by area on Japanese tuna longline fishery, 1966. Fish. Agency Jap., Res. Di v., 299 p.

1969. Annual report of effort and catch statistics by area on Japanese tuna longline fishery, 1967. Fish. Agency Jap., Res. Div., 293 p.

1970. Annual report of effort and catch statistics by area on Japanese tuna longline fishery, 1968. Fish. Agency Jap., Res. Div. , 283 p.

1971. Annual report of effort and catch statistics by area on Japanese tuna longline fishery, 1969. Fish. Agency Jap., Res. Div. , 299 p.

HOWARD, J. K., and S. UEYANAGI. 1965. Distribution and relative abundance of bill­

fishes (Istiophoridae) of the Pacific Ocean. Stud. Trop. OceanogJ.'. (Miami) 2, 134 p., 38 maps in Atlas.

KOTO, T. 1969. Studies on the albacore-XIV. Distri bu tion

and movement of the albacore in the Indi an and the Atlantic Oceans based on the catch stati tics of Japanese tuna long-line fishery. [In Japane e, English ' summary.] Bull. Far Seas Fish. Res. Lab. (Shimizu) 1: 115-129.

MATHER, F. J., III. 1969. Long distance

lins. Underwater MATHER, F. J., III. A. LEY, JR.

migrations of tunas and mar­at. 6(1):6-14. . JONES, and G. L. BEARDS-

197~. '}Iigration and distribution of white marlin and blue marlin in the Atlanti c Ocean. Fi sh. Bull.. U.S. 70:~83-298.

;\IIYAKE, ;\1. P. 1116 . Distribution of skipjack in the Pacific Ocean,

ha ' ed on records of incidental catches by the .Japane e longline tuna fishery. [In Engli sh and :pani h.] Bull. Inter-Am. Trop. Tuna Comm. l~: fiO!l-608.

• ·A . ' KAI REGIO:-':AL FISHERIES RESEAR H LAB­ORATORY (editor).

U):i-l Ayerage year fi hing condition of tuna long­lin· fisheries, 1\)52 .• 'ippon Katsuo-Maguro Gyogyo Kumiai Rengokai, Tokyo (not paged).

24

1959. Average ye;r's fishing condition of tuna long­line fisheries, 1958 ed. [In Japanese with E nglish figure and table captions .] Nippon Katsuo-Maguro Gyogyo Kumiai Rengokai, Tokyo, 414 p. + 72 maps.

RIVAS , L. R. 1955. A comparison between giant bluefin tuna

(Th llnlWS thynnlls) from the Straits of Florida and the Gulf of Maine, with reference to migra­tion and population identity. Proc. Gulf Caribb. Fish. lnst., 7th Ann. Sess. , p. 133-150.

ROTHSCHILD, B. J. 1966. Major changes in the temporal-spatial dis­

tribution of catch and effort in the Japanese longline fleet. I n T. A. Manar (editor), Proceed­ings, Governor's Conference on Central Pacific Fi shery Resources, State of Hawaii, p. 91-126.

SAKAMOTO, H. 1967. Distribution of bigeye tuna in the Atlantic

Ocean. Rep. Nankai Reg. Fish. Res. Lab., 25: 67-73.

SHIOHAMA, T. 1971. Studies on measuring changes in the char­

acters of the fishing effort of the tuna longline fishery - I. Concentrations of the fishing effort to particular areas and species in the Japanese Atlantic Fishery. Bull. Far Seas Fish. Res. Lab. (Shi mizu ) 5: 107-130.

SHIOHAMA, T., M. MYOJIN, and H. SAKAMOTO. 1965. The catch statistic data for the Japanese

tuna long-line fishery in the Atlantic Ocean and some simple considerations on it. Rep. Nankai Reg. Fish. Res. Lab. 21, 131 p.

TALBOT, F. H. , and M. J . PENRlTH. 1963. Synopsis of biological data on species of the

genus Tlwn1l11S (Sensu lato) (South Africa). FAO (Food Agric. Organ. U .N. ) Fish. Rep. 6: 608-646.

UEYANAGI, S., S. KlKAWA, M. UTO, and Y. NISHIKAWA.

1970. Distribution, spawning, and relative abun­dance of billfishes in the Atlantic Ocean. Bull. Far Seas Fish. Res. Lab. (Shimizu) 3:15-42.

WISE, J . P . 1968. The Japanese Atlantic longline fishery , 1964,

and the status of the yellowfin tuna stocks. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish . 568, 5 p.

WISE , J. P., and W. W. FOX, JR. 1969. The Japanese Atlantic longline fishery, 1965,

and t he statu s of the yellowfin tuna and albacore stocks . U.S. Fish. Wildl. Serv., Spec. Sci. Rep. Fish. 582, 7 p.

WISE , J . P., and J. C. LE GUEN. 1969. The Japanese Atlantic longline fishery, 1956-

1963. Proceedings of the Symposium on the Oceanography and Fisheries Resources of the Tropical Atlantic - Review Papers and Con­tributions, UNESCO, Paris , p. 317-347.

WISE, J. P., G. L. BEARDSLEY, JR., and F. J . MATHER, III.

197 1. United States research report to the first regular meeting of the I CAT Council, 1970. Int. Comm. Conserv. Atl. Tunas, Rep. Bienn. Period 1970-71,2: 117-120.

-tt GPO 796-3 4 7

621. Predation by sculpins on fall chinook salmon, Oncor'hynchl1s tshawytscha, fry of hatchery or­igin. By Benjamin G. Patten. February 1971, iii + 14 pp., 6 figs., 9 tables.

622. Number and lengths, by season, of fishes caught with an otter trawl near Woods Hole, Massa­chusetts, September 1961 to December 1962. By F. E. Lux and F. E. Nichy. February 1971, iii + 15 pp., 3 figs., 19 tables.

623. Apparent abundance, distribution, and migra­tions of albacore, Thllllnl1s alallmga, on the North Pacific longline grounds. By Brian J. Rothschild and :\1arian Y. Y. Yong. September 1970, v + 37 pp., 19 figs., 5 tables.

624. Influence of mechanical processing on the quality and yield of bay scallop meats. By N. B. Webb and F. B. Thomas. April 1971, iii + 11 pp., 9 figs., 3 tables.

625. Distribution of salmon and related oceanographic features in the North Pacific Ocean, spring 1968. By Robert R. French, Richard G. Bakkala, Ma­sanao Osako, and Jun Ito. March 1971, iii + 22 pp., 19 figs., 3 tables.

626. Commercial fishery and biology of the fresh­water shrimp, l\iacrobrachilllll, in the Lower St. Paul River, Liberia, 1952-53. By George C. Mil­ler. February 1971, iii + 13 pp., 8 figs., 7 tables.

627. Calico scallops of the Southeastern United States, 1959-69. By Robert Cummins, Jr. June 1971, iii + 22 pp., 23 figs., 3 tables.

628. Fur Seal Investigations, 1969. By NMFS, Ma­rine 1Iammal Biological Laboratory. August 1971, 82 pp., 20 figs., 44 tables, 23 apppndix A tables, 10 appendix B tables.

629. Analysis of the operations of seven Hawaiian skipjack tuna fishing vessels, June-August 1967. By Richard N. Uchida and Ray F. Sumida. March 1971, v + 25 pp., 14 figs., 21 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - 35 cents.

630. Blue crab meat. 1. Preservation by freezing. July 1971, iii + 13 pp., 5 figs., 2 tables. II. Effect of chemical treatments on acceptability. By Jurgen H. Strasser, Jean S. Lennon, and Fred­erick J. King. July 1971, iii + 12 pp., 1 fig., 9 tables.

631. Occurrence of thiaminase in some common aquat­ic animals of the United States and Canada. By R. A. Greig and R. H. Gnaedinger. July 1971, iii + 7 pp., 2 tables.

632. An annotated bibliography of attempts to rear the larvae of marine fishes in the laboratory. By Robert C. May. August 1971, iii + 24 pp., 1 ap­pendix I table, 1 appendix II table. For sale by the Superintendent of Documents, U.S. Govern­ment Printing Office, Washington, D.C. 20402 -35 cents.

633. Blueing of processed crab meat. II. Identification of some factors involved in the blue discoloration of canned crab meat Callinectes sapidll-S. By Melvin E. Waters. May 1971, iii + 7 pp., 1 fig., 3 tables,

634. Age composition, weight, length, and sex of hell ring, Clupea pallasii, used for reduction in Ala ka, 1929-66. By Gerald M. Reid. July 197] iii + 25 pp., 4 figs., 18 tables.

635. A bibliography of the blackfin tuna Th~mnu, atlanticus (Lesson). By Grant L. Be~rdsley am David C. Simmons. August 1971, 10 pp. Fo) sale by the Superintendent of Documents U.S Government Printing Office, Washington,' D.C 20402 - 25 cents.

636. Oil pollution on Wake Island from the tankel R. C. Stoner. By Reginald M. Gooding. Ma) 1971, iii + 12 pp., 8 figs., 2 tables. For sale b~ the Superintendent of Documents, U.S. Govern, ment Printing Office, Washington, D.C. 20402 ' Price 25 cents.

637. Occurrence of larval, juvenile, and mature crabs in the vicinity of Beaufort Inlet, North Carolina. By DO!':!lie L, Dudley and Mayo H. Judy. August 1971, III + 10 pp., 1 fig., 5 tables. For sale by the Superintendent of Documents, U.S. Govern­ment Printing Office, Washington, D.C. 20402 -Price 25 cents.

638. Length-weight relations of haddock from com­mercial landings in New England, 1931-55. By Bradford E. Brown and Richard C. Hennemuth. August. 1971, v + 13 pp., 16 fig., 6 tables, 10 appendIX A tables. For sale by the Superintend­ent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price 25 cents.

639. A hydrographic survey Of the Galveston Bay system, Texas 1963-66. By E. J. Pullen, W. L. Trent, and G. B. Adams. October 1971, v + 13 pp., 15 figs., 12 tables. For sale by the Super­intendent of Documents, U.S. Government Print­ing Office, Washington, D.C. 20402 - Price 30 cents.

640. Annotated bibliography on the fishing industry and biology of the blue crab, Callinectes sapidlls. By Marlin E. Tagatz and Ann Bowman Hall. August 1971, 94 pp. For sale by the Superinten­dent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.00.

641. Use of threadfin shad, D01'osoma petenense as live bait during experimental pole-and-line fish­ing for skipjack tuna, Katsuwonus pelamis in ~awaii. By Robert T. B. Iversen. August 1971, III + 10 pp., 3 figs., 7 tables. For sale by the Superintendent of Documents U.S. Government Printing Office, Washington, D.C. 20402 - Price 25 cents.

642. Atlantic menhaden B1'evoortia ty?'annus resource and fishery-analysis of decline. By Kenneth A. Henry. August 1971, v + 32 pp., 40 figs., 5 appendix figs., 3 tables, 2 appendix tables. For sale by the Superintendent of Documents, U.S. Governmen~ Printing Office, Washington, D.C. 20402 - Pl'lce 45 cents.

646. Dissolved nitrogen concentrations in the Colum­bia and Snake Rivers in 1970 and their effect on chinook salmon and steelhead trout. By Wesley J. Ebel. August 1971, iii + 7 pp., 2 figs., 6 tables. For sale by the Superintendent of Doc­uments, U.S. Government Printing Office, Wash­ington, D.C. 20402 - Price 20 cents.