David B. Rudders
Sally Roman
Jeanna Hudson
Virginia Institute of Marine Science
Sea Scallop Plan Development Team
Falmouth, MA
August 25-26, 2015
Preliminary – PDT use only.
2015 VIMS-Industry Cooperative Surveys The 2015 Campaign – Mid-Atlantic Bight
2015 VIMS-Industry Cooperative Surveys Primary Project Objectives
• Assess the abundance and
distribution of scallops in the Mid-
Atlantic Bight. • Mid-Atlantic Bight (Block Island to
VA/NC)
– 2015 SAMS Area
– 2015 SAMS Extended Area
• Estimate exploitable biomass.
• Biomass of scallops available for
capture with 4 inch ring commercial
dredge.
• Calibrate a number of similarly
classed vessels.
• Horsepower, LOA, berths
2015 VIMS-Industry Cooperative Surveys 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.
• Examine the incidence and pathology of
the shell disease observed in the MAB.
• Investigate newly observed parasite in
scallop meats
• Finfish Bycatch
• By utilizing a commercial dredge we can
get a snapshot of finfish bycatch rates
and species assemblages in the
surveyed areas.
• Additional Sample Requests
• Whelks, scallop shell and starfish
2015 VIMS-Industry Cooperative Surveys What’ s new
• Sampling design – Stratified random design
– NMFS shellfish strata plus
– Allocation
– Area, prior year catch
data (biomass, number)
• Vessels • 2 of 3 vessels were new to the survey
• Carolina Capes II (new), K.A.T.E. II
(new), Celtic (veteran).
• Data acquisition system • Electronic boards (1mm res.)
• Custom front end to Access DB
• Integrated with Marel scale
• Personnel • Sally Roman as lead
• All other protocols remained the
same (see scallop survey peer
review materials for details)
2015 VIMS-Industry Cooperative Surveys Analytical Framework
j
j
j
SubAreaEfficiency
erTowAreaSweptp
eaTowinSubarCatchWtper
ssTotalBioma
• Area swept per tow • Navigational info
• Tilt sensor
• Catch weight per tow (stratified means
and variances) • Length frequencies
• Length-weight relationship (for this analysis regional
SARC 59).
• Selectivity (Yochum and DuPaul, 2008)
• Efficiency (constant)
• Values from SARC 2014 – 65%Commercial Dredge
– 40% NMFS Survey Dredge
• Sub-Area (constant) • Dependant upon the spatial extent of the survey
domain
• 2015 NMFS SAMS
• 2015 SAMS VIMS extended
2015 VIMS-Industry Cooperative Surveys SAMS Region/Zone
• The projection model
(SAMS) examines the
resource on a variety of
spatial scales. • region, zone
• The VIMS survey
included some areas
outside of the NMFS area
specification.
• Biomass estimates will
be presented in the
context of the NMFS
specification as well as
the VIMS expanded area
2015 VIMS-Industry Cooperative Surveys SH:MW Relationship
~5000 SH:MW samples were taken from all stations that had scallops. (~10-15/station). Sampling extended for nematode
surveillance.
The objective is to construct a model
to predict meat weight based on a suite of potential covariates (i.e. shell height, depth, SAMS area, sex, disease…).
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.
2014 VIMS-Industry Cooperative Surveys SH:MW Results
•MAB SAMS Areas
•Significantly different relationships between areas.
•Likely a function of average depths for each of subarea, as well as the temporal spread of the
sampling
Meat weight anomalies (MAB)
SARC 59
2015 VIMS-Industry Cooperative Surveys SH:MW Results – Comparisons with SARC59
•These results highlight the spatial and temporal variability in the SH:MW relationship.
•Overall, the SARC 59 estimates for the MAB are in agreement with the observed SHMW
from the VIMS 2015 survey.
•Biomass of an area is a dynamic process that has significant spatial and temporal
components that warrant consideration in the specification process.
SAMS Region Avg_Depth VIMS Est. @120mm SARC Est. @120mm % Difference
DMV 64.37 29.60 31.50 -6.42
ET 56.20 31.77 29.66 6.65
HC 59.64 32.53 31.75 2.40
HCnr 51.97 31.15 33.40 -7.22
HCsr 54.85 30.47 32.75 -7.47
LI 53.16 31.44 33.46 -6.41
VA 62.58 23.13 29.67 -28.28
2015 VIMS-Industry Cooperative Surveys Length Frequency- SAMS Region
2015 VIMS-Industry Cooperative Surveys Length Frequency- SAMS Zone
2015 VIMS-Industry Cooperative Surveys Scallop Distribution-MAB
2015 VIMS-Industry Cooperative Surveys Total Biomass
SAMS Region Total Biomass (mt) SE Biomass_est Density (scal/m^2) Avg MW (g) Total #
DMV 8,719 1,090.47 0.335 10.86 959,100,951
DMV expanded 11,458 2,174.98 0.282 9.68 1,393,034,040
ET 29,997 3,337.15 1.196 6.91 5,825,998,460
ET expanded 30,079 3,399.06 1.156 6.89 5,823,702,868
HC 20,136 2,682.61 0.533 5.79 4,441,144,376
HCnr 12,364 2,051.37 0.244 8.11 1,397,823,435
HCsr 4,239 648.62 0.154 9.84 512,547,623
LI 9,733 1,381.97 0.106 10.56 937,812,376
Virginia 150 30.65 0.051 2.96 70,221,890
SAMS Zone Total Biomass (mt) SE Biomass_est Density (scal/m^2) Avg MW (g) Total #
DMV 8,719 1,090.47 0.335 10.86 959,100,951
DMV expanded 11,458 2,174.98 0.282 9.68 1,393,034,040
ET_NW 11,098 1,671.91 1.291 6.67 2,315,480,122
ET_NM expanded 11,134 1,709.30 1.271 6.67 2,384,306,693
ET_SE 18,495 1,990.40 1.168 7.08 2,745,262,745
ET_SE expanded 18,664 2,143.45 1.114 7.06 3,021,373,345
ETin 106 28.02 0.006 32.17 4,258,608
HCS 17,257 1,824.00 0.808 5.65 3,513,328,962
HCSin 2,803 1,090.07 0.091 8.23 302,025,730
HCSoff 9 1.92 0.005 3.13 3,002,557
HCnr 16,848 2,394.67 0.244 8.11 1,397,823,435
HCsr 4,239 648.62 0.154 9.84 512,547,623
BI 1,074 189.85 0.091 15.85 69,354,272
LI 8,662 1,169.01 0.108 10.17 867,302,330
Virginia 150 30.65 0.051 2.96 70,221,890
2015 VIMS-Industry Cooperative Surveys Exploitable Biomass Survey
SAMS Region Exp Biomass (mt) SE Biomass_est Density (scal/m^2) Avg MW (g) Total #
DMV 4,450 627.87 0.073 25.28 208,622,805
DMV expanded 5,592 1,210.76 0.053 24.70 260,296,737
ET 13,733 2,256.15 0.156 24.31 759,660,613
ET expanded 13,683 2,292.93 0.150 24.30 757,402,996
HC 6,414 1,007.65 0.042 22.74 346,562,207
HCnr 2,946 246.71 0.022 21.99 126,730,833
HCsr 1,332 161.77 0.021 21.51 70,954,584
LI 3,737 431.34 0.017 25.27 146,285,240
Virginia 4 0.97 0.001 6.59 921,238
SAMS Zone Exp Biomass (mt) SE Biomass_est Density (scal/m^2) Avg MW (g) Total #
DMV 4,450 627.87 0.073 25.28 208,622,805
DMV expanded 5,592 1,210.76 0.053 24.70 260,296,737
ET_NW 3,984 1,088.19 0.150 24.51 269,304,104
ET_NM expanded 3,993 1,112.62 0.148 24.51 277,304,932
ET_SE 9,444 1,307.53 0.165 24.17 387,458,491
ET_SE expanded 9,451 1,403.68 0.157 24.16 424,464,792
ETin 92 27.24 0.004 45.06 2,654,279
HCS 5,311 745.51 0.061 22.44 265,824,728
HCSin 1,022 128.13 0.011 26.13 36,531,195
HCSoff 0 0.06 0.000 5.29 36,176
HCnr 4,014 288.00 0.022 21.99 126,730,833
HCsr 1,332 161.77 0.021 21.51 70,954,584
BI 572 89.13 0.028 27.29 21,302,876
LI 3,167 294.60 0.016 24.95 125,854,054
Virginia 4 0.97 0.001 6.59 921,238
2015 VIMS-Industry Cooperative Surveys Exploitable Biomass - Commercial
SAMS Region Exp Biomass (mt) SE Biomass_est Density (scal/m^2) Avg MW (g) Total #
DMV 5,595 983.69 0.0821 28.76 234,785,407
DMV expanded 6,295 1,557.29 0.0552 24.70 272,692,874
ET 22,053 5,978.06 0.2007 26.92 977,904,453
ET expanded 21,933 6,069.93 0.1935 26.92 974,825,012
HC 7,424 1,788.97 0.0398 28.00 332,112,170
HCnr 2,583 285.45 0.0137 33.14 78,779,879
HCsr 1,244 226.84 0.0150 29.30 49,768,056
LI 3,603 516.52 0.0116 34.71 102,380,450
Virginia 8 6.16 0.0002 19.92 301,580
SAMS Zone Exp Biomass (mt) SE Biomass_est Density (scal/m^2) Avg MW (g) Total #
DMV 5,595 983.69 0.0821 28.76 234,785,407
DMV expanded 6,295 1,557.29 0.0552 28.47 272,692,874
ET_NW 6,464 2,138.00 0.1547 27.29 277,607,146
ET_NM expanded 6,495 2,182.76 0.1524 27.29 285,929,612
ET_SE 14,824 3,866.60 0.2395 26.75 562,799,671
ET_SE expanded 14,816 4,150.81 0.2272 26.75 616,129,665
ETin 120 45.35 0.0058 37.34 4,194,187
HCS 6,096 1,319.00 0.0595 27.34 258,938,174
HCSin 1,265 190.45 0.0097 35.98 32,351,401
HCSoff 10 3.25 0.0008 20.32 502,870
HCnr 3,520 333.22 0.0137 33.14 78,779,879
HCsr 1,244 226.84 0.0150 29.30 49,768,056
BI 307 87.58 0.0122 34.69 9,308,653
LI 3,296 404.18 0.0116 34.71 93,123,966
Virginia 8 6.16 0.0002 19.92 301,580
2015 VIMS-Industry Cooperative Surveys Summary
• The good
• Biomass in the MAB closed areas appear to be strong
• Very high levels of recruitment (2 year old animals, 40-50
mm).
• Causes of concern
• Adult biomass in the MAB open areas was low and lack of
strong 3 year old animals to fill in for the 2016 FY
• Spatial co-occurrence of the highest areas of seed and
adult scallops (esp. in the ET_SE).
• Emergence of a nematode parasite observed in the scallop
meats.
Acknowledgements
• The owners, captains and crews;
• F/V Carolina Capes II
• F/V K.A.T.E II
• F/V Celtic
• Sarah Borsetti, Daniel Smith, Lee
Rollins, Crystal Vaughn, Nick
Cardoso
• Support from NMFS NEFSC: Dvora
Hart, Russ Brown, Vic Nordahl.
• Scientific staff that participated on
the cruises.
• Funding through Sea Scallop RSA
program.
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