Orkney Sustainable Fisheries Ltd. No.21

Orkney Shellfish Research

Project Logbook and Observer Report

2013 - 2016

Matthew T. Coleman & Elisabete Rodrigues

18.05.2017

Coleman M T., Rodrigues E., (2017). Logbook and Observer Report: Orkney Shellfish Research Project.

Orkney Sustainable Fisheries Ltd. No. 21, Pp 25.

I

Executive summary

This report outlines the results of the logbook and observer programme undertaken as a component of the

Orkney Shellfish Research Project (OSRP) from 2013 – 2016. The logbook programme involved the

participation of Orkney creel fishers in submitting daily landing records relating to the number of creels

hauled per day and the amount in kilograms of each commercial species retained. Additional information

relating to undersize interaction and non-target species was also recorded. The OSRP observer

programme was undertaken by Orkney Sustainable Fisheries marine scientists. This involved

accompanying fishers on commercial fishing trip ranging from 1 – 2 days. During these trips detailed

information was recorded relating to catch composition, size frequency of undersize individuals and

detailed non-target species recording.

Logbook programme

A total of 8 vessels participated within the OSRP voluntary logbook programme, submitting daily effort

and landings information from 2013 -2016. These vessels represented 8% of registered fishing vessels

within Orkney.

Reported catch composition was dominated by brown crab which accounted for 80% of total landings

reported within the creel fishery. Over the same time period velvet crab accounted for 15%, European

lobster 4% and green crabs 1%. Catch-composition was seen to fluctuate temporally with fisheries

occurring within seasonal time frames. Landing per unit effort (LPUE) per100 creel estimates were

derived from submitted logbook information. Brown crab LPUE/100 creels ranged from 15.8 - 218

kg/100 creels with peaks documented in Q3 and Q4. In the case of velvet crab LPUE/100 creels ranged

from 3.7 – 34.7kg, with peaks documented in Q1 and Q4 identifying it as a winter fishery. European

lobster LPUE was highly seasonal with peaks in Q3 annually, LPUE/100 creels ranged from 0.7 – 9.5kg.

Undersize interaction was recorded within the logbook scheme as an arbitrary estimated percentage of

total catch. Brown crab dominated undersize interaction responsible for 48% of total reported discards

within the creel fishery. Seasonal trends in discarding were observed with the high brown crab discards

recorded in Q1 and Q2 coinciding with winter inshore fisheries of which it is not a major part. Velvet crab

accounted for 14% of total reported discards with species specific discard peaks occurring within Q1 and

Q2. European lobster accounted for 4% of total discards. Discards peaked within Q3 only coinciding with

the short annual fishery.

Information relating to non-target species was sporadic with varying levels recorded over the course of

the OSRP. A total of 14 species were recorded; 10 demersal fish species, 1 congridae and 2 crustaceans.

Of those species recorded Atlantic Cod displayed high levels of by-catch throughout the OSRP, with

Common Dogfish the second highest and peak annual interactions documented within August.

Observer programme

121 trips were conducted by OSF marine scientists over the course of the OSRP on board 16 different

commercial vessels. Overall boat participation and observe trip numbers increased each year.

II

Observed total catch composition (both landed and sub-legal individuals) was dominated by brown crab

which accounted for 74% of total observed catch composition, with velvet crab responsible for 21%,

European lobster 3% and Green crab 2%.

Retained catch composition was observed to be dominated by brown crab, accounting for 59% of total

landings, whilst velvet crab was responsible for 33% and European lobster 3%. Observed brown crab

LPUE remained stable throughout the observer programme. Seasonal patterns in European lobster LPUE

was observed, mirroring that of the logbook programme, with observed peak within July – September. In

the case of velvet crab observed peaks in LPUE occurred in late Oct – Dec coinciding with the winter

fishery.

Observed undersize interaction was seen to vary according to species. In the case of brown crab 67% of

all brown crab observed was discarded. Discard levels fluctuated with peaks observed within Q1 and Q4.

Discarded brown crab ranged from 53 – 212mm carapace width (CW) with the average discarded male

being 108.2 mm and female being 109 mm CW. 48% of velvet crab was discarded, with discard peaks

observed within October and November. Discarded individuals ranged from 50 – 90 mm CW, whilst the

average sizes of discarded males was 64.54 mm and 63.8 mm females. 45% of European lobsters were

discarded, with discard peaks occurring within August and September. Discarded individuals ranged from

55 – 140mm carapace length (CL), the average sizes of discarded males was 76.6mm and 86.2mm CL for

females.

A total of 42 different non-target species were recorded within the observer programme. Of those

recorded Common Dogfish was recorded as having peak annual interactions within August. Atlantic Cod

was also recorded as interacting within the fishery at low constant levels throughout the year. Of those

species recorded within the voluntary logbook programme all were observed by marine scientists during

observer trips.

Overall the logbook and observer programme provided valuable spatial and temporal information relating

to fishing activities, with the observer programme validating fisheries dependant data provided within the

logbook scheme and providing detailed creel by creel information. The OSRP observer programme has

provided valuable insight into the levels and types of species that interact within the creel fishery and is of

significant benefit in the progression toward sustainable management of the fishery.

Recommendations surrounding both projects include increasing fishers’ participation within the logbook

and observer programme, providing better spatial coverage across vessels sizes and further information

relating to stock health. Secondly OSF will implement a detailed non-target species sampling protocol,

providing further information relating to the size composition of non-target species.

III

Contents

Project Background ................................................................................................................................... 1

1. Logbook Report ................................................................................................................................ 3

1.1 Catch Composition and Logbook Landing per Unit Effort............................................................. 3

1.2 Undersize and Discard Catch Composition .................................................................................... 6

1.3. Non- Target Species ....................................................................................................................... 9

1.4 Summary ....................................................................................................................................... 11

2. Observer Report .............................................................................................................................. 12

2.1 Overview ....................................................................................................................................... 12

2.2 Cath per Unit effort ....................................................................................................................... 14

2.3 Landing Per Unit Effort ................................................................................................................ 16

2.4 Discard Per Unit Effort ................................................................................................................. 18

2.5 Non- target Species. ...................................................................................................................... 20

2.6 Summary ................................................................................................................................. 22

3. Conclusion ...................................................................................................................................... 22

References: .............................................................................................................................................. 23

Appendix ................................................................................................................................................... 1

List of Tables

Table 1 Vessel participation within OSRP logbook scheme and summary statistics of creel deployment

per year (2013- 2016) .................................................................................................................................... 3

Table 2 Reported landings and catch composition per year reported within logbook scheme (2013-2016) 3

Table 3 Average monthly brown crab landings (Kg) per 100 creels and associated prices at first sale (Jan

– Dec 2016) ................................................................................................................................................... 4

IV

Table 4. Average Monthly velvet crab landings (Kg) per 100 creels and associated prices at first sale (Jan

– Dec 2016) ................................................................................................................................................... 5

Table 5. Average monthly European lobster landings (Kg) per 100 creels and associated prices at first sale

(Jan – Dec 2016) ........................................................................................................................................... 5

Table 6.Monthly variation in green crab landings (Kg) per 100 creels and associated prices at first sale

(Jan – Dec 2016) ........................................................................................................................................... 6

Table 7. Total number Atlantic Cod (Gadus morhua) reported in the logbooks by year (2013-2016) ...... 10

Table 8. Total number of Common Dogfish (Scyliorhinus caniculus) reported in logbooks by year (2013-

2016) ........................................................................................................................................................... 10

Table 9 Total observer coverage achieved within the OSRP and coverage associated within each ICES

rectangle ...................................................................................................................................................... 14

Table 10 Monthly changes in brown crab catch per 100 creels (Jan – Dec 2016) ...................................... 14

Table 11 Monthly changes in European lobster catch per 100 creels (Jan – Dec 2016)............................ 15

Table 12 Monthly changes in velvet crab catch oer 100 creels (Jan – Dec 2016) ...................................... 15

Table 13 Monthly changes in green crab catch per 100 creels (Jan – Dec 2016) ....................................... 16

Table 14 Monthly changes in brown crab landing per 100 creels (Jan – Dec 2016) .................................. 16

Table 15 Monthly changes in European lobster landing per 100 creels (Jan – Dec 2016) ......................... 17

Table 16 Monthly changes in velvet crab landing per 100 creels (Jan – Dec 2016) .................................. 17

Table 17 Monthly changes in green crab landing per 100 creels (Jan – Dec 2016) ................................... 17

Table 18 Monthly brown crab discards per 100 creels (Jan – Dec 2016) ................................................... 18

Table 19 Monthly European lobster discards per 100 creels (Jan – Dec 2016) .......................................... 19

Table 20 Monthly velvet crab discards per 100 creels (Jan – Dec 2016) ................................................... 19

Table 21. Monthly green crab discards per 100 creels (Jan – Dec 2016) ................................................... 20

Appendix

Appendix 1 Log transformed landing per unit effort per 100 creels reported within the logbook scheme

(2013 - 2016)................................................................................................................................................. 1

Appendix 2 Monthly total catch compositions per commercial important crustacean species reported by

the logbook fleet by year (2013 – 2016) ....................................................................................................... 2

Appendix 3 Monthly percentage undersize interaction rates of commercially important crustacean species

reported by the logbook fleet (2012 – 2016) ................................................................................................. 3

Appendix 4 Monthly discard rates of commercially important crustacean species (Jan – Dec 2016) ......... 4

Appendix 5 Total recorded interaction of non-target species reported by the logbook fleet (2014 -2016) .. 5

Appendix 6 Total number of non-target species recorded during observer trips (2014 -2016) .................... 6

V

Appendix 7 Average LPUE of commercial species recorded by Observers (2014 -2016) ........................... 8

Appendix 8 Average LPUE per year for Atlantic Cod, Common Dogfish and V-notch lobsters recorded

by the observer programme (2014 -2016) ..................................................................................................... 8

Appendix 9 Catch frequency of brown crab below minimum landing size (140mm carapace width) and

discarded during observer trips (2015 -2016) ............................................................................................... 9

Appendix 10 Catch frequency of velvet crabs below minimum landing size (2015 – 65mm CW; 2016 –

70mm CW) and discarded during observer trips (2015 – 2016) ................................................................ 10

Appendix 11 Catch frequency of European lobster below minimum landing size and discarded during

observer trips (2016) ................................................................................................................................... 11

Appendix 12 Catch frequency of green crabs below minimum landing size and discarder during observer

trips (2016) .................................................................................................................................................. 12

Glossary:

LPUE: Landing per unit effort (LPUE) refers to all species of commercial importance that are above

MLS and retained for profit. In this case LPUE refers to kilograms (Kg) landed per 100 creels.

CPUE: Catch per Unit Effort (CPUE) refers to total fishing interaction of commercial targeted species by

the creel fishery. This encompasses individuals both above and below minimum landing size, recently

moulted or individuals discarded due to unmarketability (black spot, missing limbs, etc.). In this case

CPUE refers to the number of individuals caught per creel 100 creels.

DPUE: Discard per unit effort (DPUE) refers to all commercial species that are below minimum landing

size and are restricted by additional regulatory measures and subsequently returned. Individuals that are

restricted by regulatory measures include, V-notch lobster; “White crab”, berried brown crab and berried

velvet crabs. LPUE in these cases refers to the number of individuals discarded per creel 100 creels.

1

Orkney Shellfish Research Project

Logbook and Observer Report

2013 -2016

Project Background

The Orkney shellfish research project (OSRP) has come to end of its four- year project (2013 – 2016).

The project encompasses a number of objectives that addressed the needs of two important sectors:

Inshore fisheries and marine renewables.

Specific objectives of the project relating to the fishing sector were:

• To assess the status of Orkney crustacean stocks in relation to sustainability criteria;

• To provide monitoring data and biological understanding to support the development and

implementation of a harvest strategy and management systems for sustainable fishing in the context of

marine spatial planning for renewable energy and other activities in Pentland Firth and Orkney waters;

• To satisfy shellfish consumers of Orkney’s commitment to sustainable fishing.

Objectives relating to the marine renewable energy industry:

• To determine key areas providing value to the Orkney creel fishery in terms of catch rates and the

magnitude, composition and quality of catches.

• To describe spatial patterns of space use by the Orkney creel fishery in terms of fishing effort,

navigation, relocation of gear during bad weather and seasonal and inter-annual patterns of variability.

• To determine locations of critical habitat for crustacean species targeted by the Orkney creel

fishery, particularly in terms of spawning areas and movement and migration patterns of brown crab.

This report outlines the results collected over the past 4 years specifically relating to the logbook scheme

and observe programme. These two programmes have provided a data set can now be used to monitor the

fishery, collecting important information on the spatial and temporal changes in fishing activity over time.

Additionally, the role of the OSRP observer programme has allowed the comparison and validation of the

use of fishery dependant data collected via the logbook scheme and its role in monitoring the fishery.

2

This report is broken into 2 main components:

1. Logbook Programme

2. Observer Programme

3

1. Logbook Report

A total of 8 vessels participated within the OSPR logbook scheme from 2013 -2016, representing 7% of

the registered inshore Orkney fleet of 107 vessels (Scottish Government, 2015). Over the course of this

time-period a total of 256,925 creels were hauled and redeployed by these 8 vessels (Table 1).

The average breakdown of creel deployment was seen to fluctuate between years, however this can be

directly related to the number of participating vessels within the logbook programme (Table 1).

Additionally, this variability can also be attributed to both the increase in boat size and the number

vessels. Large vessels are capable of working larger sets of gear and increasing the overall average

variability reported.

Table 1 Vessel participation within OSRP logbook scheme and summary statistics of creel deployment per year (2013- 2016)

Year Total No. Creels Boat

Participation

Average No.

Creels per Day

Average No. Creels

Per Month

2013 70,129 3 284 ± 40 7,013 ± 3,707

2014 103,270 4 278 ± 23 10,327 ± 5,348

2015 159,410 5 249 ± 19 13,284 ± 4,587

2016 256,925 8 270 ± 53 21,410 ± 14,012

2013 -16 589,734 8 274 ± 110 13,403 ± 9,699

1.1 Catch Composition and Logbook Landing per Unit Effort (LPUE)

Total observed landings composition reported by the logbook programme within the OSRP (2013 -2016)

demonstrated that brown crab comprised 80% of the total landings, velvet crabs 15%, European lobster

4% and green crabs 1% (Table 2).

Table 2 Reported landings and catch composition per year reported within logbook scheme (2013-2016)

Brown Crab

Brown crab was responsible for more than 50% of the landings compositions across all years (Table 2).

Within the brown crab fishery seasonal changes in LPUE and catch compositions were observed.

Total Catch Composition (%)/Reported Landings (Kg) Total

2013 2014 2015 2016 2013 -2014

Boat Participation 3 4 5 8 9

Brown Crab 40,295 (64) 55,899 (61) 112,726 (72) 351,584 (90.5) 560,504 (80)

Velvet Crab 18,719 (30) 30,540 (33 34,675 (22) 23,313 (6) 107,277 (15)

European Lobster 3,808 (6) 5,304 (6) 6,314 (4) 10,978 (3) 26,405 (4)

Green Crab * * 1,425 (1) 2,264 (0.5) 3,689 (1)

4

Increases in LPUE were observed within Q3 with the highest LPUE recorded within this time-period

(Appendix 1; Table 3). This can be linked to changes stock behaviour and resulting targeting behaviour of

the fishery. Over this time-period large seasonal migration events occur within the brown crab female

proportion of the stock (Coleman & Rodrigues, 2015), with females entering the inshore fishery in large

numbers to moult and subsequently mate (See Crab tagging Report). The onset of these large migration

events are exhibited within the size frequency recorded within market sampling (Rodrigues & Coleman,

2017) with females proportionally dominating catches. In comparison a reverse trend is observed with

males dominating catches within Q1 & 2, with skewed size frequencies linked to the limited spatial

overlap of the fishery in winter months and the primary habitat distribution of male brown crab, typically

occurring within the sublittoral zone of inshore waters.

Table 3 Average quarterly brown crab LPUE (Kg) per 100 creels and associated prices at first sale (Jan – Dec 2016)

Velvet Crab

Velvet crabs are an important component of the inshore fishery, being the second highest in its overall

landings contribution (15%: table 2) within the logbook scheme, but also in terms of value within the

inshore fishery as whole (440 tonnes/£1,231 million: Scottish Government, 2015). Total landings

contribution fluctuates between years, 2016 for instances were considerably lower (Appendix 2). This in

part can be attributed to the types of vessels participating within the logbook scheme in 2016. A number

of them primarily targeted brown crab, skewing the observed landings contribution. During this year

larger landings of brown crab were also reported than any other year (Appendix 1), indicating increased

effort towards targeting this species. In addition the reduced volume of velvet landings in 2016 can be

attributed to the changes in MLS, with an increase of 65mm to 70mm March 2016. This change in MLS

is exhibited in monthly landings compositions with velvets responsible for 50% in Nov/Dec 2015, and

25% in Jan/Feb 2016, after which their contribution drops dramatically to <5% in later months. It is

important however to interpret changes in LPUE and catch compositions within a temporal context.

Changes in velvet catch compositions will fluctuate due to the targeting behaviour of the fishery, with

Q1 Q2 Q3 Q4

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

LPUE

(Kg)/100

Creels

67.9 53.3 85.4 78.3 42.7 15.8 198.8 123.4 162.4 165.2 157.6 218

£/Kg £1.45 £1.40 £1.40 £1.39 £1.52 £1.49 £1.42 £1.38 £1.40 £1.42 £1.54 £1.60

£ value £98.39 £74.42 £119.63 £108.76 £65.10 £23.54 £282.89 £169.94 £227.27 £234.05 £242.76 £348.15

5

decreases in landings recorded post Q1 for a large proportion of vessels due to the changes in primary

target species, in this case being brown crab and subsequently lobster in Q3 (Table 4; Appendix 2).

Table 4. Average quarterly velvet crab landings (Kg) per 100 creels and associated prices at first sale (Jan – Dec 2016)

European Lobster

The Orkney European lobster fishery is heavily influenced by environmental conditions, specifically sea

bottom temperature (Lizárraga et al, 2015), resulting in a highly seasonal fishery. This seasonality is

mirrored within the annual catch composition and LPUE data collected by the logbook index fleet over

the course of the OSRP. Peaks in lobster landings and catches were typically seen in Q3, with gradual

increases observed pre Q3 and subsequent declines in Q4 (Table 5; Appendix1 & 2). This rise and fall in

catches are seen to follow seasonal and yearly changes in sea bottom temperature and sea- surface records

(Appendix 1), reaffirming the significant relationship highlighted between this species (Lizárraga et al,

2015) that doesn’t seem to occur within any other crustacean species within the inshore creel fishery.

Additional factors influencing catch compositions and the decline in lobster LPUE catch compositions

can be related to the seasonal movements of the fishery, with fishers excluded from ideal fishing grounds

in later months due to adverse winter weather. In comparison to previous years, little to no difference was

seen between overall yearly catch compositions (Appendix 1), this change being surprising due to the

introduction of increases MLS of 87 – 88mm (Scottish Government, 2016). However, the subsequent

increase to 90mm could result in a more detectable change in lobster landings in subsequent years.

Table 5. Average quarterly European lobster landings (Kg) per 100 creels and associated prices at first sale (Jan – Dec 2016)

Q1 Q2 Q3 Q4

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

LPUE

(Kg)/100

Creels

27.2 26.8 11.2 8.4 18.6 6.9 3.7 9.1 16 10.5 32.9 34.7

£/Kg £2.79 £3.23 £3.43 £3.76 £3.74 £3.26 £2.95 £2.72 £2.27 £2.16 £2.21 £4.06

£ value £76.00 £86.62 £38.46 £31.60 £69.57 £22.48 £10.90 £24.72 £36.31 £22.68 £72.85 £140.78

Q1 Q2 Q3 Q4

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

LPUE

(Kg)/100

Creels

1.7 1.8 2.7 1 2.8 1.6 3.2 9.5 6.7 6.3 3.3 0.7

£/Kg £17.4 £18.8 £15.77 £12.71 £11.81 £9.25 £9.94 £10.08 £11.50 £13.30 £17.16 £21.86

£ value £29.6 £33.8 £42.58 £12.71 £33.06 £14.80 £31.81 £95.75 £77.05 £83.77 £56.62 £15.30

6

Green Crab

Green crab represents the least commercially valuable species, undergoing highly seasonal levels of

exploitation. However even though this species has little commercial value, its makes up an important

component of the winter fishery and is the mainstay for a number of smaller inshore vessels that operate

as part of the Orkney fleet. The seasonal nature of the fishery is not clearly highlighted in 2016, with

peaks in LPUE occurring in both Q3 and Q4 and previous years (Table 6; Appendix 2). The low

economic value of this species is exemplified when comparing its 1st value sale against velvet crabs. In

the case of November 2016, similar weights of both species are landed, however the market value of the

velvets at the same weight is 225% greater. The low commercial value of this species results in the

fishery operating under a high-volume exploitation model. Further research into the green crab fishery is

recommended to investigate the implications of this fishery, with OSF building upon research undertaken

in 2015 investigating size at maturity of this species within Orkney (Duncan, 2015; Coleman &

Rodrigues, 2016).

Table 6. Average quarterly variation in green crab landings (Kg) per 100 creels and associated prices at first sale (Jan – Dec

2016)

1.2 Undersize and Discard Catch Composition

Discard catch compositions refers to the returning of individuals to the sea which are not retained within

the landed catch. Individuals can be discarded for a number of reasons, the most common being that an

individual is below the minimum landings size currently enforced for that specific species (lobsters &

velvet crabs; Scottish statuary instruments (2016), brown Crab; EC, 1998). In addition, the practise of

discarding can also be influenced by a number of other reasons, such as discarding of individuals due to

their reduced marketability. This includes larger sizes preferred by merchants, poor condition (missing

limbs, black spot, soft individuals) and egg-bearing females. In the case of lobsters, egg bearing females

can also be marked with a voluntary v-notch making the individual illegal to land.

Q1 Q2 Q3 Q4

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

LPUE

(Kg)/100

Creels

- 57.1 75 - 64 69.8 79.4 40 40 83.3 32.5 4

£/Kg £00.69 £00.69 £00.69 £00.69 £00.69 £00.69 £00.69 £00.69 £00.69 £00.69 £00.69 £00.69

£ value - £33.40 $51.75 - £44.16 £48.16 £54.78 £27.60 £27.60 £57.47 £22.42 £2.76

7

Overall the average percentage discarded per commercially exploited species varied between species

throughout the OSRP (Appendix 3&4).

Brown Crab

In the case of brown crab the average undersize discard rate reported within the OSRP was 47%, however

change in undersize interaction can fluctuate temporally. In the case of Q1 and Q2 an average undersize

interaction rate of 48% was reported (Appendix 3), however a large variability in the level of interaction

within these two quarters occurs (<95%). This variability can be attributed to the spatial extent of the

fishery at this time. Within Q1 and Q2 the extent of the fishery is predominantly restricted within

sheltered locations, typically targeting small intertidal species (velvet crab and green crab: Appendix 2).

The preferred habitat of both species overlaps with juvenile brown crab nursery areas (Heraghty, 2013)

resulting in high undersize interaction rates. Within the tail end of Q2 however declines in undersize

interactions is reported. This decline coincides with the movement of the fishery into more exposed

offshore areas with differing habitat types which the adult proportion of the stock inhabits. Continued low

levels of undersize brown crab interaction is reported from Q2 until the end of Q4 (2016: 26%). The

reported peaks within Q3 and Q4 can be linked to subsequent capture of undersize individuals as a by-

product of the lobster fishery, with peaks in undersize interaction matching peaks in lobster LPUE

(Appendix 1).

For the first time in 2016, slight changes in the logbook scheme enabled differentiation between

individuals discarded due to being undersize compared to those unmarketable1 and subsequently

discarded (Appendix 4). In 2016 the overall average discarded rate was reported at 27%, with levels of

discarding fluctuating within quarters. Within Q1 the average discarding rate was reported as 0.24%. This

low level of discarding behaviour can be linked to catches dominated by undersize individuals due to the

current spatial extent of the fishery which is mirrored within undersize reporting (See Succorfish Report:

Coleman & Rodrigues, 2017). Whilst low levels of discarding are potentially attributed to unmarketable

black spot individuals, the level of discarding is seen to increase in later quarters, with peaks in discarding

occurring in Q3/4. High levels of discarding within these months can be linked to key biological

processes occurring within the fishery, specifically moulting. During these months large volumes of the

stock becomes unmarketable with fishermen discarding large individuals greater than MLS due to them

being “white2”.

1 Unmarketable in this case can be attributed to individuals that cannot be sold due to damage, black spot infection

or moult condition 2 White – White crab refers to an individuals that has recently moulted, causing shell condition to be thin and white

in appearance. During this moult stage individuals are not landed due to the limited commercial value.

8

Velvet Crab

Velvet crab undersize interaction rate averaged 14% within the OSRP. Discards rates were seen to

fluctuate throughout the course of the project (39%: 2013; 20%: 2014; 14%: 2015; 5%: 2016).This

gradual decline can be attributed to the types of vessel which participated within the logbook programme.

In 2016 the participation within the project doubled, however uptake was by those vessels predominantly

targeting the brown crab/lobster fishery, compared to those in 2014/2015 with a more equal spread of

participants. Though levels of undersize interaction are low overall, indications of a seasonal trend were

observed across all years (Appendix 3), with slightly higher levels of undersize interaction reported

within Q1 and subsequent increases in Q4. This increase can be linked to changes in the spatial extent of

the fishery in Q2/4, with the expansion of the fishery into summer offshore brown crab grounds and

exposed lobster grounds, resulting in declines in velvet landings (Appendix 2). Observed increases in Q4

of undersized can be linked to the retraction of the fishery, with the movement of gear into sheltered

inshore areas used by the winter fishery (See Succorfish Report: Coleman & Rodrigues, 2017).

As with brown crab, the discarding of velvets in 2016 due to non-marketability was recorded separately to

that of undersized individuals (Appendix 4). The separation of the two discarding behaviours provides

greater insight into both the behaviour of the fishery and the biological process underpinning these

behaviours. Peaks within discarding behaviour follow clear seasonal trends, differing from the undersize

interaction behaviour, with a peak in discarding occurring in August. This peak within the fishery can be

linked to the primary moulting period (Hearn, 2004). Similar trends are exhibited in earlier years,

especially 2015 where an overall high level of percentage discarding was recorded within Q3, with this

summarily linked to moulting and the resulting non-marketability of the catch.

European Lobster

European lobster undersize interaction was recorded at an overall average of 16% for the OSRP, with

fluctuation recorded within years (39%: 2013, 23%:2014; 13%: 2015; 8%: 2016). Seasonality within the

varying levels of undersize interaction was also recorded, with interaction levels following the seasonal

nature of the fishery and peaks recorded within Q3 and Q4 (Appendix 3). This interaction cycle mirrors

that of the commercial fishery (Appendix 1), indicating that the undersize proportion of the stock follows

and is influenced by the same environmental variables. Subsequent further investigation into the nature of

undersize interaction is explored later within the report, with further insight into the size distribution of

undersize individuals reported (See section: Observed Report: Undersize Interaction).

Average discarding rates in lobsters was 4% (Appendix 4). This low level of discarding combined with

low levels of undersize discarding behaviour potentially indicates that recruitment into the fishery is

9

highly size related, with individuals typically >80mm before first capture (Appendix 11). The reason why

lobsters could be released or classed as unmarketable could result from the discarding of v-notched

individuals, however this is uncertain. Other reasons for discarding of lobsters could be the occurrence of

multiple lobsters in creels, resulting in low levels of in-creel lobster mortality. Such interaction events

sometimes result in severe maiming of individuals e.g. the loss of both claws making them commercially

unmarketable.

Green Crab

In the case of green crabs, low levels of undersize interaction were reported at <1%, with this low level a

result of their low commercial value and subsequent limited targeting (Appendix 3). In regards to

discarding, similar low levels of discarding were reported (1%), however slight seasonality is

demonstrated within this fishery with a peak observed in June (Appendix 4). The reasons behind this

apparent spike are purely speculative, however peaks in discarding in this time-period could be attributed

to moulting. As a sublittoral species found in shallow inshore water at typically < 20m, this means

moulting will occur far earlier in the year, potentially occurring within July due to seasonal fluctuations in

SST (Lyons, et al 2012).

1.3. Non- Target Species

Non-target species refers to all species that are not targeted commercially by the creel fishery. The

description of species as non-target, as opposed to discard, is due to the subsequent retention of particular

species on-board due to their use as bait within the fishery.

In the case of the logbook scheme, varying levels of non-target species interaction was recorded

throughout the course of the OSRP. During this a total of 14 species were recorded with 10 demersal fish

species, 1 congridae, 1 elasmobranch and 2 crustacean species (Appendix 5).

Of these 14 species, Atlantic Cod (Gadus morhua) displayed the highest level of interaction of any

recorded non-target species (n=3,703), with continued interaction reported throughout the OSRP (Table

7; Appendix 5). Initially limited amounts of reporting occurred in 2012/14 (Table 7), but greater reporting

of this species was documented in 15/16 (Table 7). It is important to interpret this species as having high

interaction rates within the fishery having been potentially under-reported in 2103/14 period of the OSRP.

Of those individuals caught, they ranged from 235 – 536mm total length (TL). Sex specific information

was not collected as gonad dissections were not carried out (OSF). Atlantic cod also presents the only

species that is currently listed as vulnerable under IUCN red list (Sobel, 1996), with significant

conservation measures in place, including reduced total allowable catch (TAC), and the implementation

of a Scottish cod recovery zone.

10

Table 7. Total number Atlantic Cod (Gadus morhua) reported in the logbooks by year (2013-2016)

Atlantic Cod (Gadus morhua) No. Caught No./100 creels

2013 65 0.09 ± 0.1

2014 160 0.002 ± 0.002

2015 912 0.57 ± 0.56

2016 2,566 1 ± 1.02

Common Dogfish (Scyliorhinus caniculus) was the second most highly reported non-target species

reported within the logbook scheme (n =1,844: Appendix 5). Similar to Atlantic cod, reduced reporting

of common dogfish occurred within 2013 and 2015 (Table 8; Appendix 5), however interaction events

were recorded more frequently in 2014/2016. In relation to identifying trends within interaction rates, the

appearance of peaks can be identified within Q3 across all years (Appendix 8). These peaks could be

attributed to changes in fishing patterns and the targeting behaviours of fishers, with the peak coinciding

with the brown crab fishery (OSF, 2016). Of those individuals caught, they ranged from 373mm –

783mm TL with no data collected on the sex of the individuals. Based on the known reproductive biology

of the species and the limited size frequency recorded, it indicates that individuals are caught prior to

becoming sexually mature (Henderson & Casey, 2001). This identifies the potential for increased

mortality due to the opportunistic removal of the species as bait. It is therefore recommended that the

interaction rates of this species continue to be monitored as part of OSF’s ongoing work, and further

regional research be conducted on this non-target species.

Table 8. Total number of Common Dogfish (Scyliorhinus caniculus) reported in logbooks by year (2013-2016)

Common Dogfish No. Caught No./100 creels

2013 95 0.13 ± 0.27

2014 414 0.004 ± 0.005

2015 233 0.14 ± 0.13

2016 1102 0.4 ± 0.5

Similar to Atlantic Cod and Common Dogfish, demersal species dominate reported non-target species

within the logbook scheme, due to their financial benefit in relation bait usage. This is further highlighted

by the other species which are recorded in high numbers being bait species: Ling molva molva (n=513)

and Wrasse sp.(n-= 1403), whilst species with no bait value or limited interaction are not recorded.

11

In comparison to previous years, high numbers of curled octopus were reported in 2016 (Appendix 5),

with this species historically only recorded within the observer programme. The subsequent reporting of

this species highlights potential substantial increases in population numbers, with fishermen remarking on

the loss of catch due to octopus predation (person.comm). Reason behind the increases in abundance

could be attributed to natural occurring predator prey cycles, with increases in prey abundance resulting in

increased predator survival and overall predator density within the ecosystem. Coincidently this increase

in octopus corresponds to fishermen’s comments relating to substantial increases in juvenile brown crab

within inshore waters over previous years. Furthermore the subsequent decline in large predatory fish

within inshore waters could have contributed to increased abundance, with increases in cephalopod

abundance documented worldwide linked to decreases in large predatory fish biomass (Doubleday et al,

2016)

1.4 Summary

In Summary, the logbook programmes provide valuable insight into the spatial and temporal fishing

pattern of the Orkney inshore fleet. The necessity of detailed fisheries dependant data has become of

increased importance, with OSF looking to build upon the data collected throughout the course of the next

OSRP. A number of additional avenues of research have been highlighted, including further research into

the interaction of non-target species and the production of a standardised LPUE time series

12

2. Observer Report

2.1 Overview

The OSF observer programme involved the participation of fishermen and marine scientists. Through

observer trips OSF collected trip-specific information, providing a snapshot of fishing activity within both

a spatial and temporal context. Information collected included; effort, retained catch, interaction with non-

target species and commercial species discards.

Figure 1 Orkney stock assessment area, comprising of four ICES rectangles.

121 trips were conducted throughout the course of 2013 – 2016 across a total of 16 vessels of differing

sizes (vessel total length>10m & <10m) within the Orkney stock assessment area (Figure 1). Vessels

targeted a combination of brown crab, European lobster, velvet crab and green crab, with the primary

target species of each trip depending on a combination of environmental and market value factors. These

13

16 vessels represented 15% of the total licenced creel fishing vessels within Orkney, (107 Vessels:

Scottish Government, 2015). A total of 30,036 creels were observed across 1,150 ropes over the project

time-period (Table 9).

Boat participation remained steady within the later years of the project (2015/2016), with large

improvements made from the first two years. This increase in participation can be attributed to greater

outreach activities being undertaken within the project along with an increase in manpower within 2015-

2016. Overall vessel coverage mirrored a similar trend to that of vessel participation with both 2015 and

2016, demonstrating high spatial coverage, with the exception of reduced coverage in ICES rectangle

46E7 in 2016. The reduced coverage within these areas can be attributed to fewer fishermen participating

within the observer component of the OSRP, however coverage within this area is supplemented by

vessels’ participation within the logbook and succorfish aspect of the OSRP.

Typically vessel data is separated in accordance to vessel size, however in this case vessel size was seen

not to play an important part in the number creels deployed per trip, with vessels at both <10m and >10m

deploying a similar number of creels per trip (2016: <10m – 275 creels per trip; >10m – 280 creels per

trip). Therefore, all observer trips regardless of vessel size have been amalgamated. Additional further

analysis into the key influencing variables of the inshore creel fishery will be explored.

Overall temporal changes in creel deployment per trips are seen not to differ considerably from 2014 -

2016. Average creel numbers per rope is seen to be consistent, with variability between years reducing

with increased sampling effort. Consequently, a similar trend is observed within the average number of

creels per trip, with variability reducing over time. Whilst variation in creels per trip reduces, the

observed variation in the number of creels per rope and trip can be attributed to a combination of factors.

These variables include grounds on which the fishery operates or biological characteristics of the stocks.

In situations where fishing grounds are less productive increased effort (CPUE) would be required to

extract similar returns to that of a more productive region. Temporal and spatial fluctuations in stock

density also cause variation in returns and can result in increased effort to extract similar returns over

varying time frames or reduced effort due to scarcity.

14

Table 9 Total observer coverage achieved within the OSRP (2013-2016) and coverage associated within each ICES rectangle

2013 2014 2015 2016 2013 -2016

No. Vessels Sampled 1 6 16 15 16

ICES 46E6 - 4 17 9 30

ICES 46E7 - - 3 - 3

ICES 47E6 - - 7 5 12

ICES 47E7 - 2 5 13 20

ICES 46E6/47E6 2 - 23 20 45

ICES 46E7/ 47E7 - - 3 0 3

ICES 47E6 / 47E7 - - 2 6 8

Total No. Creels Observed - 1,646 15,204 13,186 30,036

Avg. No. Creels Per Rope - 27 ± 15 29 ± 8 28 ± 9 28 ± 9

Avg. No. Creels Per Trip - 274 ± 179 253 ± 105 280 ± 102 265 ± 108

2.2 Observed Catch Composition & Cath per Unit effort

Brown Crab

Brown crab made up 74% of total catch compositions observed during OSRP observer trips. Total

observed catch composition remained constant over the OSRP observe programmes with similar levels

observed between years (77% 2015; 82% 2014). Variability in the CPUE fluctuates through the course of

the sampling period with variation in CPUE linked to a combination of environmental and fisher driven

variables. Observed CPUE remained constant throughout the OSRP observer programme with its peak in

May (Table 10), highlighting the constant interaction of brown crab within the inshore fishery year round,

irrespective of changes in primary target species.

Table 10 Monthly changes in observed brown crab catch per 100 creels (Mar – Dec) throughout the OSRP

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught 5,252 2,017 7,910 20,925 24,109 26,805 11,890 15,431 16,919 2,235

CPUE/100

Creels 548 974 604 385 403 411 426 410 658 573

15

European Lobster

European lobster made up 3% of the total catch composition observed during OSRP observer trips, with

total catch contribution remaining stable fluctuating by 1% annually since 2013 (2% - 2015; 2% - 2014).

CPUE was observed to fluctuate throughout the observer programme, with these fluctuations known to be

heavily attributed to changes in environmental conditions dictating the nature of the lobster fishery,

especially water temperature (Lizárraga et al, 2015). This is evident with the peak interaction within the

fishery occurring in August, mirroring the peak in sea bottom temperature (OSF – Sea Bottom

Temperature Project (unpublished))

Table 11 Monthly changes in European lobster catch per 100 creels (Mar – Dec) throughout the OSRP

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught 49 5 121 184 420 1,847 631 797 57 67

CPUE/100

Creels 5 2 9 3 7 28 23 21 2 17

Velvet crab

Velvet crab made up 21% of total observed catch composition during OSRP observer trips. With little

variability between years (21%; 2015, 24%: 2014). Peak observed interaction is observed in October and

November, with a gradual increase in CPUE seen in the previous quarter. This variability in CPUE data

collected can be attributed to the vessel on which observer trips were conducted, with some trips

conducted on vessels targeting solely brown crab and lobster in Aug/Sept and Dec. This trend is visible in

previous years (Appendix2) as is the trend also observed with changes in velvet catches recorded in the

logbook scheme (Appendix 1& 2)..

Table 12 Monthly changes in velvet crab catch per 100 creels (Mar – Dec) throughout the OSRP

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught 959 NA 207 1309 5439 5988 6515 2789 3764 -

CPUE/100

Creels 95 NA 1,226 345 408 95 18 34 326 -

Green Crab

Green crab made up only 2% of the catch composition during OSRP observer trips. The low percentage

can be attributed to it being predominantly a winter fishery, with a small number of <10m vessel targeting

16

this fishery all year round. However, in the cases in which it is targeted the species is removed in large

numbers due to its low commercial value and the subsequent high volume needed to make it financially

viable

Table 13 Monthly changes in green crab catch per 100 creels (Mar – Dec) throughout the OSRP

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught - - - - 2458 - - - 10 -

CPUE/100

Creels - - - - 3072.5 - - - 21.7 -

2.3 Observed Landings Composition & Landing Per Unit Effort

Brown Crab

Brown crab comprised 59% of the total observed landings composition during OSRP observer trips. In

the case of those caught only 33% were retained. LPUE fluctuated through the course of the observer

period, with peaks in LPUE occurring within March and November. Subsequent decreases in LPUE in

September/October can be associated with both the targeting behaviour of the fishery and the subsequent

movement of gear into more sheltered areas in time for the winter fishery. The subsequent movement of

gear to sheltered winter grounds results in increased interaction with the male proportion of the brown

crab stock, causing an observed spike in the landings. In comparison to previous years, overall LPUE has

remained constant in comparison to 2015 (62%),

Table 14 Monthly changes in brown crab landing per 100 creels (Mar – Dec) throughout the OSRP

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught 2,403 775 1,028 8,239 8,111 9,596 4,142 3,509 5,333 160

CPUE/100

Creels 251 374 79 151 135 147 149 93 207 41

European Lobster

European lobster composed 3% of the total observed landings composition during OSRP observer trips.

However of those caught only 55% of those were retained. LPUE for lobster is seen to follow a highly

seasonal pattern with the peak fishery occurring in August and a second peak occurring in December. The

high seasonal nature of the lobster fishery is well documented within the logbook programme (Appendix1

&2) and is known to coincide with the increase in sea bottom temperature (Lizárraga et al, 2015). As a

17

result the fisheries length can vary annually from June – September due water temperature. The secondary

peak in December illustrated here however should be interpreted cautiously, as these estimates are based

on one observer trip and are therefore not representative.

Table 15 Monthly changes in European lobster landing per 100 creels (Mar – Dec) throughout the OSRP

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught 33 3 74 122 294 1,029 289 322 35 53

CPUE/100

Creels

3 1 6 2 5 16 10 9 1 14

Velvet Crab

Velvet crab account for 33% of the observed LPUE from 2016, in comparison with observations made in

2015 (36% LPUE) and remaining an important component of the Orkney inshore fishery. Retention rates

were high with 52% of observed individuals retained. Peaks in LPUE occurred in the final quarter of the

year (Oct – Dec: Appendix 1). Additionally, a secondary peak is observed in May. This peak is mirrored

in a decline in brown crab LPUE and also recorded within the catch compositions of the logbook fleet

(Appendix 2).

Table 16 Monthly changes in velvet crab landing per 100 creels (Mar – Dec) throughout the OSRP

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught 617 - 1434 3219 2819 429 875 6335 9213 -

CPUE/100

Creels

64 - 110 59 47 7 31 168 358 -

Green Crab

Green crab represented 2% of the total LPUE. This low percentage is anticipated due to green crab being

target predominantly in Q3 and subsequently in Q1 of the following year due to necessity. However, a

number of smaller inshore vessels do target this fishery year round. In this instance, green crabs are

landed in large quantities, due to their low commercial value resulting in a high volume fishery.

Table 17 Monthly changes in green crab landing per 100 creels (Jan – Dec 2016)

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught - - - - 679 - - - 10 -

CPUE/100

Creels - - - - 848.8 - - - 7 -

18

2.4 Observed Discard Composition& Discard Per Unit Effort (DPUE)

Brown Crab

Brown crab accounted for 83% of those species discarded during OSRP observer trips, indicating high

levels of undersize interaction within the fishery, with similar values observed across years (84% 2014;

84% 2015; 82% 2016). Overall 67% of observed brown crab was discarded whilst DPUE varied between

months, with the highest discards observed in Q1 and Q4. High discards level during these time periods

can be attributed to the movement of fishing gear into more sheltered inshore areas used during the winter

fishery, with these areas being important juvenile undersize brown crab nursery grounds (Heraghty, 2013;

Bakonyi, 2016). The discarding behaviour observed is similar to that of the logbook fleet over the same

time period. Continued analysis on the size distribution of discarded crab provides an insight into the

population structure of brown crab within the inshore fishery. The results of 2016 highlight the continued

possibility of identifying recruitment cohorts into the fishery, with a post recruitment cohort identified at

86-92mm (Appendix 9), similar to the cohort identified in 2015. Of those individuals sampled as discards,

size frequency ranged from 23 – 212mm CW. The discarding of individuals greater than 140mm CW can

be attributed to unmarketability including, white or black spot crabs. The average size of females less than

140mm was 108.2mm with males at 109.7mm CW and where average size was calculated on individuals

less than 140mm to provide insight into true undersize interaction, reducing bias caused by discarding due

to the unmarketability of larger crabs. In comparison to 2015 (Appendix 9) less brown crabs >80mm

were encountered in 2016 reducing the ability to detect recruitment cohorts. This lack of individuals

>80mm can be attributed to less observed trips conducted on vessels targeting velvet crabs over the

course of the year, thereby reducing the opportunity to sample this proportion of the population due the

high degree of habitat overlap between the two species.

Table 18 Monthly brown crab discards per 100 creels (Mar – Dec) throughout the OSRP

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught 2,849 1,242 6,882 12,686 15,998 17,209 7,748 11,922 11,586 2,075

CPUE/100

Creels 297 600 526 233 267 264 278 317 451 532

European Lobster

European lobster made up only 2% of those species discarded during OSRP observer trips. Of those

observed 45% were discarded, with discard peaks observed within August. This coincides with peak

19

LPUE, indicating that there is a general increase in stock movement during this time-period. Those

individuals discarded ranged from 55 - 140mm CL (Appendix 11) with the average discarded female

being 86.2mm CL and male 79.65mm CL, the inclusion of individuals <89mm being attributed to v-

notched females. This size distribution indicates that discards are dominated by individuals ranging from

74-88mm, accounting for 80% of discards whilst individuals >70mm are far less common. The reduced

interaction of these smaller individuals within commercial creels makes recruitment inference difficult, as

undersize individuals are underrepresented within the catch. The reasons behind this could be the

increased risk of predation removing smaller lobsters from the creels and fundamental differences in their

behaviours. Another reason could be the habitat preferences of undersize and juvenile lobsters which

could favour areas out-with the range of the where the typical fishery occurs.

Table 19 Monthly European lobster discards per 100 creels (Mar – Dec) throughout the OSRP

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught 16 2 47 62 126 818 342 475 22 14

CPUE/100

Creels 2 1 4 1 2 13 12 13 1 4

Velvet Crab

Velvet crab was responsible for 12% of total discards observed during OSRP observer trips. 48% Of

those observed that were discarded, females dominated the discard composition with an approximate

female to male ratio of 29:21, with an average size of females being 63.8mm CW, and males 64.54mm

CW (Appendix 10). In 2016 discards are dominated by individuals at 65mm and this can be attributed to

the increase in MLS of 65 to 70mm which came into force in March 2016. This has shifted the discarding

behaviour of the fishery, whereas in 2015 velvet discards were limited to those <65mm.

Table 20 Monthly velvet crab discards per 100 creels (Mar – Dec) throughout the OSRP

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught 294 - 1103 1303 2346 664 1364 2751 3285 -

CPUE/100

Creels

31 - 84 24 39 10 49 73 128 -

Green Crab

Green crab comprised 13% of the total discards and this high percentage can be attributed to the low

commercial value and subsequent automatic discarding by fishers. Additionally, even within the fishery

targeting the species, high levels of discarding occurs. This can be due to the sheer volume of individuals

20

caught, enabling fishers to be highly selective. Additionally, the peak in the contribution to discards can

be attributed to the enforcement of a MLS in 2015, prior to when no MLS existed for this species and

resulting in greater recording of the species interaction as both a target and discarded species. Of those

species discarded, individuals range from 58 -78mm CW (Appendix 13), with the average female size

being discarded at 63.2mm CW and males 65.2mm CW.

Table 21. Monthly green crab discards per 100 creels (Mar – Dec) throughout the OSRP

Mar Apr May Jun July Aug Sept Oct Nov Dec

No. Caught - - - - 1,779 - - - 21 -

CPUE/100

Creels - - - - 2,223.8 - - - 14.7 -

2.5 Non- target Species.

A total of 42 non-target species were observed at varying levels throughout the course of the OSRP

observer programme which included; 7 crustacean species, 7 invertebrate species, 1 elasmobranch, 25

demersal fish species and 1 congridae specie (Appendix 6). Of those species caught, the level of observed

interaction varied considerably between years. Peak interaction events of certain species were heavily

influenced by environmental conditions relating to target species and subsequent fishing behaviour

associated with that fishery. Of those species recorded by scientific observers all of those recorded within

the index logbook fleet were also observed. In comparison to the index logbook fleet, a far greater

number of species were subsequently recorded, with similar trends observed in previous year (Coleman &

Rodrigues, 2016). The reasons behind the greater number of species recorded through the observer

programme can in part be attributed to the lack of recording of species with little monetary worth to the

fishermen, with those species recorded within the logbook providing fiscal worth as a bait species.

Subsequently lesser valued invertebrate species are discarded without thought, hence the lack of their

recording. In addition, the precision of recording undertaken by the observers is far greater than that of

the logbook fleet, with the observer programmer recording bycatch as close to species level as possible.

This level of precision increases the number of species recorded, for example, wrasse are recorded under

the blanket term ‘Wrasse sp.’ within the logbook programme, however they are recorded as 4 different

species within the observer programme.

Of the species observed a number were repeatedly caught with varying levels of interaction occurring

within different temporal scales and the reasons behind their repeated interaction attributed to a number of

environmental and fisher related variables. Of the crustacean species encountered, velvet crab, green crab

and common hermit crabs had the highest interaction rates of all crustacean species (Appendix 6). In the

21

case of velvet crabs, high levels of discards can be attributed to targeting behaviour of the fishery with

velvets a common bycatch of the lobster fishery due to similar habitat preferences and subsequent fishery

overlap. This is further highlighted by the large number of velvets recorded in July and August coinciding

with the peak lobster fishery (Section Observer: European Lobster LPUE). Additionally, the recording of

velvets as purely discards can be attributed to limited targeting of the species in general over this time-

frame due to key biological process making them unmarketable, in this case moulting. During the

moulting period large proportions of the fishery becomes unmarketable making it uneconomic. This

targeting behaviour is mirrored within the logbook scheme, with the highest discard rates of non-

undersized individuals occurring in August (See section: Logbook – Discards (Appendix 4).

Of the demersal species that exhibited high interaction rates with the inshore fishery, the Common

Dogfish (Scyliorhinus caniculus) demonstrates a sustained level of interaction with the inshore fishery,

with a slight peak exhibited in August (Appendix 8). This peak however should be interpreted cautiously

due to potential sampling bias causing a peak within the monthly break-down. However, this species was

frequently observed throughout the course of the OSRP (Appendix 6& 8) and under varying levels of

observer effort, indicating high levels of interaction within the fishery. Under current conservation advice

Common Dogfish are listed as a ‘least concern’ under IUCN classification (Ellis, 2009). Continued

monitoring of this species however should be undertaken due to its slow growth rates and low

reproductive output, making them vulnerable to excessive removal. For the first time in 2016, OSF

trialled a detailed discard collection (DDC) protocol over two observed trips which involved the

collecting of size-frequency and sex information where possible on discard species, predominantly

demersal fish. Of the data collected common dogfish ranged from 373mm – 783mm TL. No data was

collected on the sex of the individuals. Due to these factors, it is recommended that this species

interaction with the fishery continue to be monitored.

The interaction of Atlantic Cod (Gadus morhua) continues to be observed within the fishery. The

observations made are similar to those made in previous years (Coleman & Rodrigues, 2016; Coleman &

Rydzkowski, 2015) and similar to records in the logbook scheme. From the data collected via DDC,

Atlantic Cod ranged from 235 – 536 but sex specific information was not collected as gonad dissections

were not carried out. Additionally, two colour morphs are seen to interact within the fishery, “typical” and

“red” cod. Red cod are typically individuals of the species which inhabit close inshore waters and feed on

prey items within the kelp forest, ingesting red pigmentation, resulting in this colour morph. There is

however no differentiation between the two colour morphs in relation to stock identity. Due to

international conservation efforts surrounding Atlantic and North Sea cod, the interaction of this species

22

will continue to be monitored within the fishery. OSF will be looking at trialling DDC again in 2017 with

the aim of collecting more information on the size and sex structure of this species.

V-notched lobsters are seen to interact within the fishery at low levels following similar behaviours and

interaction cycles as that of the commercial fishery, with peak interaction between August and October

(Appendix 8). Varying levels of interaction are seen over the course of the years with the density of the v-

notched lobster being heavily dependent on the behaviour and voluntary v-notching of fishers (Appendix

5 & 6). Overall v-notched lobsters accounted for ±1.5% of total lobster observed in 2016. This is a

substantial drop compared to 2015, with v-notch lobster accounting for ±4% of total lobsters observed.

Overall however observed interaction rates forecast that approximately 1v-notched lobster is caught for

every 150 creels.

2.6 Summary

In summary, the observer program provides valuable detailed insight into the activities of the inshore

Orkney fleet. Data gathered throughout the course of the OSRP observer programme provides the basis

for future research regarding both target species and non-target species. A number of research avenues

have been highlighted, primarily relating to the interaction rates of non-target species and the process of

collecting more detailed information relating to their catch composition and baseline biological

characteristics. Future OSF work will look to build upon the outcomes of the work presented in its

ongoing research.

3. Conclusion

The OSRP logbook and observer programme has provided essential baseline information that can be used

towards progressing the fishery towards sustainable management. The use of and value of the baseline

data cannot be underestimated with the time-series data sets collected within the project being some of the

most detailed within Scotland. In regards to the logbook programme, OSF will be using the information

collected to produce a LPUE time-series of the fishery. This information will be used to monitor the

health of the fishery, detect declines within stock biomass and changes in overall fishing effort.

OSF will continue to expand the logbook programme, either through the use of its own programme or in

partnership with the new Marine Scotland logbook format. OSF will provide greater overall coverage

across differing vessel types and sizes and provide the opportunity to monitor the fishery by ICES

rectangle or smaller. OSF will continue to assess and monitor the interaction rates of non-target species

within the new 4-year project incorporating non-target species sampling as a primary component of its

research.

23

References:

Bakonya, L. (2016). Mapping the Habitat of Juvenile Edible Crabs (Cancer pagurus L.) in the Intertidal

areas of Mainland Orkney. MSc Thesis. Heriot-Watt University.

Coleman, M. and Rodrigues, E. (2016). Orkney Shellfish Project End of Year Report: January –

December 2015. Orkney Sustainable Fisheries Ltd., p.86.

Coleman, M. and Rydzkowski, K. (2015). Orkney Shellfish Research Project - End of Year Report 2014.

Orkney Sustainable Fisheries Ltd., p.38.

Duncan, C. (2015) Size of Maturity and Population Dynamcis of Green Crasb (Carcinus maenas) in

Mainland Orkney, Scotland. Unpublished MSc Thesis. Heriot- Watt University.

Ellis, J., Mancusi, C., Serena, F., Haka, F., Guallart, J., Ungaro, N., Coelho, R., Schembri, T. &

MacKenzie, K. 2009. Scyliorhinus canicula. The IUCN Red List of Threatened Species 2009:

e.T161399A5415204. http://dx.doi.org/10.2305/IUCN.UK.2009-2.RLTS.T161399A5415204.en.

European Commission (EC) (1998), “For the Conservation of Fishery Resources through Technical

Measures for the protection of Juvenile Marine Organisms”. Council Regulation (EC) No.850/98.

Hearn, A. (2004). Reproductive biology of the velvet swimming crab, Necora puber (Brachyura:

Portunidae), in the Orkney Islands, UK. Sarsia, 89(5), pp.318-325.

Henderson, A. and Casey, A. (2001). Reproduction and growth in the lesser-spotted dogfish Scyliohinus

canicula (Elasmobranchii: Scyliorhinidae) from the west coast of Ireland. Cahiers de Biologie

Marine, [online] 42, pp.397-405. Available at: http://www.vliz.be/imisdocs/publications/289183.pdf.

Heraghty, N. (2013). Investigating the abundance, distribution and habitat use of juvenile Cancer pagurus

(L.) of the intertidal zone around Anglesey and Llŷn Peninsula, North Wales (UK).. MSc Thesis.

Bangor University: Fisheries & Conservation report No. 29, Pp.75.

Lizárraga-Cubedo, H., Tuck, I., Bailey, N., Pierce, G., Zuur, A. and Bova, D. (2015). Scottish lobster

fisheries and environmental variability. ICES Journal of Marine Science: Journal du Conseil, 72(suppl 1),

pp.i211-i224.

Scottish Government (2015). “Scottish Sea Fisheries Statistics 2014”, Marine Scotland.

http://www.gov.scot/Resource/0048/00484499.pdf

Scottish statutory instruments (2016). “The Orkney Islands (Landing of Crabs and Lobsters) Order 2016”.

Sea Fisheries, Conservation of Sea Fish 2016 No. 50

Sobel, J. 1996. Gadus morhua. The IUCN Red List of Threatened Species 1996: e.T8784A12931575.

http://dx.doi.org/10.2305/IUCN.UK.1996.RLTS.T8784A12931575.en.

24

Zoë A. Doubleday, , Thomas A.A. Prowse, Alexander Arkhipkin, Graham J. Pierce, Jayson Semmens,

Michael Steer, Stephen C. Leporati, Sílvia Lourenço, Antoni Quetglas, Warwick Sauer, Bronwyn M.

Gillanders. 2016. Global proliferation of cephalopods. Current Biology, 26,10. DOI:

http://dx.doi.org/10.1016/j.cub.2016.04.002.

1

Appendix

Appendix 1 Log transformed landing per unit effort per 100 creels reported within the logbook scheme (2013 - 2016)

2

Appendix 2 Monthly total catch compositions per commercial important crustacean species reported by the logbook fleet by

year (2013 – 2016)

3

Appendix 3 Monthly percentage undersize interaction rates of commercially important crustacean species reported by the logbook fleet (2012 – 2016)

4

Appendix 4 Monthly discard rates of commercially important crustacean species (Jan – Dec 2016)

5

Appendix 5 Total recorded interaction of non-target species reported by the logbook fleet (2014 -2016)

Total No. Caught (CPUE/100 Creels)

2014 2015 2016

Common Dogfish

Scyliorhinus caniculus 414 (0.004 ± 0.005) 233 (0.14 ± 0.13) 1102 (0.4 ± 0.5)

Wrasse

Labridae sp. 195 (0.002 ± 0.002) 109 (0.06 ± 0.07) 1099 (0.4 ± 0.2)

Atlantic Cod

Gadus morhua 160 (0.002 ± 0.002) 912 (0.57 ± 0.56) 2566 (1 ± 1.02)

Haddock

Melanogrammus aeglefinus - 1 (<0.0006± 0.001) 21 (0.008 ± 0.008)

Conger Eel

Conger conger 152 (0.001 ± 0.002) 95 (0.06 ± 0.06) 225 (0.09 ± 0.07)

3 Brd Rockling

Gaidropsarus mediterraneus 14 (<0.001 ± <0.001) 2 (0.001 ± 0.004) 219 (0.08 ± 0.05)

Wolf Fish

Anarhichas lupus - - 1 (0.0003 ± 0.002)

Curled Octopus

Eledone cirrhosa 17 (0.02 ± 0.05) 3 (0.001 ± 0.003) 304 (0.11 ± 0.11)

Sea Scorpion

Taurulus bubalis - 28 (0.01 ± 0.03) 123 (0.04 ± 0.04)

Comper

Serranus cabrilla 43 (0.04 ± 0.07) 98 (0.03 ± 0.2) 52 (0.02 ± 0.1)

Monkfish

Lophius piscatorius - 1(0.0003 ± 0.001) -

Ling

Molva molva - 111 (0.04 ± 0.09) 402 (0.1 ± 0.1)

Saithe

Pollachius virens - - 1 (0.0003 ± 0.001)

V-Notch

Hommarus Gammarus 38 (0.04 ± 0.04) - 1 (0.0003 ± 0.002)

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Appendix 6 Total number of non-target species recorded during observer trips (2014 -2016)

Total No. Caught (CPUE/100 Creels)

Species 2014 2015 2016

Velvet Crab Necora puber

1403 (91.04 ± 2.03) 859 (5.64 ± 0.04) 3288 (24.94 ±18.46)

Green Crab Carcinus meanas

- 1970 ( 12.95 ± 0.11) 515 (3.91 ± 6.56)

Harbour Crab Liocarcinys depurator

- 538 (3.53 ± 0.03) 38 (0.29 ± 0.02)

Common Hermit Crab Pagrus bernhardus

1 (0.06 ± <0.001) 55 (0.36 ± 0.01) 1804 (13.68 ± 0.55)

Majidae Sp. 11 (0.71 ± 0.006) 115 (0.75 ± 0.01) 71 ( 0.5 ± 0.01)

Squat Lobster Munida rugosa

- 6 (0.03 ± 0.08) 3 (0.03 ± 0.06)

Nephrop - 7 (0.04 ± 0.06) -

V-Notch European

Lobster Homarus gammarus

21 (1.36 ± 0.012) 66 (0.43 ± 0.5) 31 (0.33 ± 0.25)

Common Star Fish Asteria rubens

4 (0.25 ± 0.002) 165 (1.08 ± 0.9) 140 (1.35 ± 1.06)

Sun Star Crossasteer papposus

3 (0.19 ± 0.002) 100 (0.65 ± 0.9) 49 (0.52 ± 0.44)

Cushion Starfish Asteria gibbosa

- 6 (0.03 ± 0.06) 14 (0.15 ± 0.1)

Seven Armed Starfish Luidia ciliaris

- 1 (0.006 ± 0.05) 1 (0.01 ± 0.008)

Whelk Buccinum undatum

24 (1.55 ± 0.01) 294 (1.93 ± 1.37) 629 (6.73 ± 5.26)

Sea Urchin Echinus esculentis

13 (0.84 ± 0.002) 151 (0.99 ± 0.79) 175 (1.87 ± 3.12)

Curled Octopus Eledone cirrhosa

2 ( 0.1 ± 0.2) 60 (0.3 ± 0.77) 63 (0.6 ± 0.58)

Sea Scorpion Taurulus bubalus

12 (0.77 ± 1.07) 155 (1.01 ± 0.11) 104 (1.14 ± 0.58)

Comber - - 7 (0.07 ± 0.16)

Tad Pole fish Raniceps raninus

- - 2 (0.02 ± 0.03)

Common Dogfish Scyliorhinus caniculus

127 (8.24 ± 5.15) 539 (3.54 ± 3.77) 317 (3.39 ± 2.4)

Ballen Wrasse Crenilabrus melops

19 (1.2 ± 1.86) 206 (1.35 ± 0.9) 142 (1.52 ± 0.8)

Goldsinny Wrasse Ctenolabrus rupestris

1 (0.06 ± 0.2) 8 (0.05 ± 0.14) 5 (0.04 ± 0.05)

Cuckoo Wrasee Labrus mixtus

- 11 (0.07 ± 0.04) 26 (0.19 ± 0.2)

7

Rock Cook - - 1 (0.007 ± 0.008)

Butterfish Pholis gunnellus

1 (0.06 ± 0.07) 7 (0.04 ± 0.05) 29 (0.2 ± 0.25)

Atlantic Cod Gadus morhua

25 (1.6 ± 1.3) 417 (2.74 ± 1.17) 364 (2.76 ± 3.8)

Pouting Trisopterus luscus

- - 1 (0.007 ± 0.014)

Poor Cod Trisopterus minutus

- 3 (0.02 ± 0.05) 5 (0.03 ± 0.06)

Haddock Melanogrammus aeglefinus

- 6 (0.39 ± 0.04) 7 (0.05 ± 0.05)

Pollack Pollachius SP.

- 24 (0.15 ± 0.25) 7 (0.05 ± 0.05)

Coley Pollachius virens

- 1 (0.006 ± 0.012) 43 (0.32 ± 0.24)

Blue Whiting Trisopterus minutus

- - 5 (0.037 ± 0.03)

Red Gurnard Chelidonichthys cuculus

- - 1 (0.007 ± 0.008)

Conger Eel Conger conger

40 (2.5 ± 6.1) 65 (0.4 ± 0.27) 57 (0.43 ± 0.8)

Three Bearded Rockling Gaidropsarus vulgaris

34 (2.2 ± 1.9) 102 (0.67 ± 0.4) 79 (0.59 ± 0.5)

Ling Molva molva

7 (0.45 ± 0.66) 48 (0.3 ± 0.15) 38 (0.28 ± 0.68)

Tusk Brosome brosome

- 4 (0.02 ± 0.02) 10 (0.07 ± 0.07)

Dab Limanda limanda

- 499 (3.3 ± 3.4) 56 (0.42 ± 0.75)

Flounder Platichthys flesus

1 (0.06 ± 0.2) 1 (0.006 ± 0.008) 1 (0.007 ± 0.008)

European Plaice Pleuronectes platessa

- 86 (0.56 ± 0.76) 3 (0.02 ± 0.02)

Topknot Zeugopterus punctatus

- 3 (0.01 ± 0.05) 3 (0.22 ± 0.04)

Lemon Sole Microstomus kitt

- - 1 (0.007 ± 0.15)

Flatfish sp. - 9 (0.06 ± 0.06) 8 (0.06 ± 0.069)

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Appendix 7 Average LPUE of commercial species recorded by Observers (2014 -2016)

Appendix 8 Average LPUE per year for Atlantic Cod, Common Dogfish and V-notch lobsters recorded by the observer programme

(2014 -2016)

9

Appendix 9 Catch frequency of brown crab below minimum landing size (140mm carapace width) and discarded during observer trips (2015 -2016)

10

Appendix 10 Catch frequency of velvet crabs below minimum landing size (2015 – 65mm CW; 2016 – 70mm CW) and discarded during observer

trips (2015 – 2016)

11

Appendix 11 Catch frequency of European lobster below minimum landing size and discarded during observer trips (2016)

12

Appendix 12 Catch frequency of green crabs below minimum landing size and discarder during observer trips (2016)