David B. Rudders William D. DuPaul Jeanna Hudson Jessica Bergeron Virginia Institute of Marine Science

Transcription

1 David B. Rudders William D. DuPaul Jeanna Hudson Jessica Bergeron Virginia Institute of Marine Science Sea Scallop Plan Development Team Woods Hole, MA August 19-20, 2013

2 The 2013 Campaign Georges Bank

3 The 2013 Campaign Mid-Atlantic

4 Primary Project Objectives Assess the abundance and distribution of scallops in selected areas. Nantucket Lightship Closed Area NE Georges Bank Mid-Atlantic Bight (S. of Hudson Canyon) HCCA, DMV, ETCA, Open area Estimate exploitable biomass Biomass of scallops available for capture with 4 inch ring commercial dredge.

5 Secondary Project Objectives Gear performance Estimate size selectivity and relative performance of 4.0 ring turtle CFTDD. Scallop Biology & Product Quality Spatially and temporally explicit shell height:meat weight relationships. Assess metrics associated with product quality. (especially in the NEG) Examine the incidence and pathology of the shell disease observed in the MAB. Finfish Bycatch By utilizing a commercial dredge we can get a snapshot of finfish bycatch rates and species assemblages in the surveyed areas.

6 Survey Design Stations: Systematic design (grid) with random start point Constrained by depth (offshore), NMFS strata and prior survey information. 15 minute tow time kt. tow speed 3:1 scope

7 Sampling Gear Coonamessett Farm Turtle Deflector Dredge 15 ft. or 14 ft. width 4 inch rings No liner 10 inch twine top NMFS Sea Scallop Survey Dredge 8 ft. width 2 inch rings 1.5 inch liner 3.5 inch twine top No chains in the areas surveyed

8 Sampling Protocol Standard sampling protocol Sample scallops for length frequency (sub-sample depending upon total volume) Sample finfish for length frequency Volumetric measure of trash Samples for SH:MW Assessment of product quality parameters and MAB shell disease.

9 Analytical Framework Area swept per tow Navigational info Tilt sensor Catch weight per tow Length frequencies Length-weight relationship (for this analysis regional SARC 50). Selectivity (Yochum and DuPaul, 2008) Efficiency (constant) Values from SARC % - 65%Commercial Dredge 38%- 44% NMFS Survey Dredge Sub-Area (constant) MAB open 9,442 km^2 HCCA - 4,201 km^2 (<50 fathoms) DMV - 4,462 km^2 (<50 fathoms) ETCA - 4,527 km^2 (<50 fathoms) NLCA - 2,362 km^2 HAPC km^2 GSNE km^2 CA2-515 km^2 TotalBiomass = j CatchWtperTowinSubarea AreaSweptperTow Efficiency j SubArea j

10 SH:MW Relationship For each survey, ~250 SH:MW samples were taken. (25 Average depth was calculated for each tow from tilt sensor A GLMM was used to fit model (Gamma distribution, log link, random effect at the station level) with SAS PROC GLIMMIX. For all of the VIMS estimates (except NEG), depth was significant factor with respect to calculated meat weights.

11 SH:MW Results NLCA & NEG Northeast Georges Subareas were not different and appear to be consistent with SARC50. Nantucket Lightship Closed Area Significantly heavier meats relative to the depth weighted SARC GB relationship. For Georges Bank, NLCA meats tend to be heavier than the average which is represented in the SARC curve.

12 SH:MW Results MAB MAB Closed Areas Significantly different relationships observed relative to the depth weighted SARC relationship. Likely a function of average depths for each of subarea, possible seasonal causes? Given the length frequency of the population, there is a relative minimal impact on exploitable biomass

13 Length Frequency- HCCA & ETCA Hudson Canyon and Elephant Trunk Closed Areas dominated by incoming year class at 70-75mm Modest numbers of adult animals sampled roughly 31,562 scallops (HCCA) and 59,901 scallops (ETCA).

14 Length Frequency DMV and Open MAB Areas DelMarVa Closed Area Bimodal distribution dominated by 2 incoming year classes of modest abundance. Few adult animals present. sampled roughly 19,420 animals. MAB Open Areas Broad distribution of size classes observed (both recruits and pre-recruits) Adult abundance was fairly low and very patchy. Spatially broad area from S. of DMV to N. of Hudson Canyon sampled roughly 24,000 animals.

15 Length Frequency HAPC and GSNE HAPC Length Frequency distribution dominated by adult year classes with high abundance. Some evidence of modest incoming year classes Sampled roughly 56,273 animals. GSNE Broad distribution of size classes observed (both recruits and pre-recruits) Adult abundance was widespread spatially and moderate in scale. Sampled roughly 29,531 animals.

16 Length Frequency NLCA Nantucket Lightship Closed Area Length frequency distribution dominated by incoming year classes of high abundance. Modest adult animals present. sampled roughly 120,000 animals.

17 Scallop Distribution-MAB Mid Atlantic Bight Pre-recruits (left) were observed in the same areas where they were first observed last year. Abundance was generally high although these animals were ~75mm. Recruit abundance was generally low.

18 Scallop Distribution-DMV Georges Bank (NLCA and NEG) Pre recruits with very high abundance was observed in the SE corner of the NLCA access area (~25mm) as well as in GSNE/HAPC subarea. NEG abundance was in the expected areas, however GSNE had a broad population structure and high abundance.

19 Recruitment GB Large recruitment (2012 YC) event observed in SE corner of NL access area (right). Not a traditional recruiting area. How far east-east does the settlement extend? Recruitment was also observed in modest amounts in the GSNE subarea MAB Areas Large recruitment event(s) with multiple year classes that were observed in 2012 (left) have persisted ~70-75 mm was the mode, but smaller animals observed in some tows. Historical scale? Should start to enter the fishery in 2015.

20 Scallop Density Average Total Density (scallops/m^2) Average Density of Exploitable Scallops (scallops/m^2) Gear Efficiency SE SE MAB MAB open Commercial 65% MAB open Survey 44% HCCA Commercial 65% HCCA Survey 44% ETCA Commercial 65% ETCA Survey 44% DMV Commercial 65% DMV Survey 44% Georges Bank CA2 Commercial CA2 Survey GSNE Commercial GSNE Survey HAPC Commercial HAPC Survey NLCA Commercial NLCA Survey

21 Estimated Total Number Gear Efficiency Estimated Total Estimated Total Exploitable MAB MAB open Commercial 65% 134,142,612 MAB open Survey 44% 417,149, ,044,734 HCCA Commercial 65% 72,520,565 HCCA Survey 44% 769,423, ,937,215 ETCA Commercial 65% 119,495,945 ETCA Survey 44% 1,642,435, ,013,308 DMV Commercial 65% 20,172,462 DMV Survey 44% 622,762,907 77,883,068 Georges Bank CA2 Commercial 60% 9,931,791 CA2 Survey 38% 16,976,504 14,871,563 GSNE Commercial 60% 55,247,464 GSNE Survey 38% 160,774,964 83,242,168 HAPC Commercial 60% 136,397,398 HAPC Survey 38% 256,265, ,828,210 NLCA Commercial 60% 76,358,393 NLCA Survey 38% 1,063,148,663 65,784,455

22 Mean Scallop Weight Mean Meat Weight (g) Total Scallops Mean Meat Weight (g) Exploitable Scallops Gear MAB MAB open Commercial MAB open Survey HCCA Commercial HCCA Survey ETCA Commercial ETCA Survey DMV Commercial DMV Survey Georges Bank CA2 Commercial CA2 Survey GSNE Commercial GSNE Survey HAPC Commercial HAPC Survey NLCA Commercial NLCA Survey

23 Total Biomass Biomass (mt) Lower Bound 95% CI Upper Bound 95%CI Gear Efficiency Samples 95% CI MAB MAB open Survey 44% 138 6, , , HCCA Survey 44% 64 7, , , , ETCA Survey 44% 68 14, , , , DMV Survey 44% 65 4, , , , Georges Bank CA2 Survey 38% , GSNE Survey 38% 46 4, , , , HAPC Survey 38% 29 8, , , , NLCA Survey 38% 99 3, , ,941.32

24 Exploitable Biomass Biomass (mt) Lower Bound 95% CI Upper Bound 95%CI Gear Efficiency Samples 95% CI MAB MAB open Commercial 65% 138 5, , , MAB open Survey 44% 138 4, , , HCCA Commercial 65% 64 1, , , HCCA Survey 44% 64 3, , , ETCA Commercial 65% 68 3, , , ETCA Survey 44% 68 3, , , DMV Commercial 65% , DMV Survey 44% 65 1, , Georges Bank CA2 Commercial 60% CA2 Survey 38% , GSNE Commercial 60% 46 2, , , GSNE Survey 38% 46 3, , , HAPC Commercial 60% 29 5, , , , HAPC Survey 38% 29 6, , , , NLCA Commercial 60% 99 3, , , , NLCA Survey 38% 99 2, , ,960.22

25 Product Quality - NEG Product Quality was assessed on the NEG Cruise. Qualitative assessment with 4 categories (0-3). 10 commercial sized animals (>~100mm)/station at random stations where SH:MW samples were taken. Given an overall marketability score as well as individual texture and color scores. Addl info: SH, sex, tow level info.

26 Product Quality - NEG Generally, categories 3 and 2 would be acceptable to the marketplace and all areas were observed to have high levels of marketable meats (>80%). HAPC in 2012 had ~55% marketability. Color was generally very good (no grey meats) and the marketability issues were related to texture.

27 Summary Nantucket Lightship Closed Area - Recruited scallop abundance was widespread and density was modest and reduced from High recruitment in the SE portion of the area. Should be able to support limited effort in NEG- Exploitable biomass in HAPC was reduced from Product quality was better and effective biomass might be higher in GSNE contained ~6 million lbs. as well as a broad age distribution. Scallop resource in CA2 was limited, Mid Atlantic Bight- Recruited scallop abundance was widespread and density was relatively low. Large recruitment event(s) observed in 2012 were still present and the scale was determined with higher confidence as a function of increasing size. Some effort in 2014 may be possible, but protection of incoming year class(es) is also a consideration and these animals should enter the fishery starting in 2015.

28 Acknowledgements The owners, captains and crews; F/V Carolina Boy (MAB Leg 1) F/V Kathy Ann (MAB Leg2) F/V Celtic (NEG) F/V Concordia (NLCA) Support from NMFS NEFSC: Dvora Hart, Russ Brown, Vic Nordahl. Scientific staff that participated on the cruises Funding through Sea Scallop RSA program.