1. Effects of By-Catch Reduction Devices (BRDs) on Commercial Crab Catch Will Bennett University of Mary Washington Mentors: Romuald Lipcius, Rochelle Seitz, and Danielle McCulloch August 4, 2010

2. Introduction Blue crab industry – $25 Million+ in 2008 Terrapin mortality – Other species Pot types BRDs Rook et al. 2010 Opposition- Fishing Industry Watermen Claims – Catch increase in peeler pots – Catch decrease in standard pots

3. Objectives Determine if BRD usage has any impact on commercial crab catch Determine scientifically if the BRD claims of the watermen have any ground Make a policy recommendation to the VMRC about BRD usage in commercial crabbing

4. Expected Results Hypotheses- – BRD usage will decrease crab catch in standard crab pots – BRD usage will increase crab catch in peeler crab pots – BRD usage will decrease bycatch in both peeler and standard crab pots – Crabs caught in BRD pots will have lesser widths than those in non BRD pots

5. Methods Three rivers Upriver/Downriver location Peeler Pots – 20 per location Standard Pots – 4 Per location Up Rapp. Down Rapp. Up York Down York Up James Down James

6. Statistics Statistical method – AIC statistics Ranks the models given by best fit to the data – Use 3 models to test the response variables, crab catch and total bycatch number, against BRD usage, river, and upriver/downriver location Model 1 (BRD) – y = β 0 +β 1 X 1 +ξ Model 2 (Location + River) – y = β 0 +β 2 X 2 +β 3 X 3 +β 4 X 4 +ξ Model 3 (BRD + Location + River) – y = β 0 +β 1 X 1 +β 2 X 2 +β 3 X 3 +β 4 X 4 +ξ BRD = β 1, Upriver/downriver= β 2, River= β 3 and β 4,

7. Legal Crab Catch ~0.5 per pot more without BRD Little confidence with SE ~1 per pot more without BRD Strong confidence

8. Crab Catch AIC Tables Model- Stan. AICModel Weight αβ 1 BRDβ 2 Loc- upper β 3 R v Jβ 4 Y v J BRD741.66<0.0053.55±0.31-0.60±0.44Na NaNa Loc + River 708.560.523.10±0.43Na-2.84±0.441.75±0.571.41±.57 BRD + Loc + River 708.710.483.38±0.47-0.54±0.39-2.84±0.431.73±0.571.42±.57 Model- Peel. AICModel Weight αβ 1 BRDβ 2 Loc- upper β 3 R v Jβ 4 Y v J BRD2342.98<0.0052.38±0.130.92±0.18Na Loc + River 2291.96<0.0053.03±0.18Na-1.34±0.181.17±0.220.05±0.21 BRD + Loc + River 2262.040.992.57±0.190.93±0.16-1.36±0.171.15±0.210.03±0.20

9. Bycatch The primary bycatch species were Croaker, Oystertoad, Flounder, Perch, Spot, Hogchoker, Catfish, and Eel Only four Terrapins were caught in this study All in non-BRD pots

10. Bycatch AIC Tables Model Stan. AICModel Weight αβ 1 BRDβ 2 Loc- upper β 3 R v Jβ 4 Y v J BRD315.30.030.29±0.07-0.09±0.1Na NaNa Loc + River 309.460.590.09±0.11Na-0.12±0.110.08±0.150.4±0.15 BRD + Loc + River 310.330.380.15±0.12-0.11±0.1-0.12±0.110.08±0.150.4±0.15 Model Peel. AICModel Weight αβ 1 BRDβ 2 Loc- upper β 3 R v Jβ 4 Y v J BRD1585.23<0.0050.46±0.060.56±0.09Na Loc + River 1571.13<0.0050.89±0.09Na-0.39±0.090.46±0.11-0.31±0.1 BRD + Loc + River 1529.31.00.61±0.10.56±0.08-0.4±0.090.45±0.11-0.31±0.1

11. Width Minimal difference in crab carapace width when using a BRD Standard Pot

12. Statistics – Crab Catch Standard Pots – Location + River Peeler Pots – BRD + Location + River

13. Statistics - Bycatch Standard Pots – Location + River Peeler Pots – BRD + Location + River

14. Results Effects on crab catch – Not confident that BRDs affect standard pot crab catch – BRDs negatively affect peeler pot catch Consistent effects on bycatch – BRDs decrease bycatch in both peeler and standard crab pots AIC - River and location to explain bycatch and crab catch in standard pots fit the data better than the same two with BRD included

15. Policy Discussion Slightly fewer crabs with BRDs Less bycatch All 4 terrapins caught in non BRD pots Judgment Call economically and ethically

16. Acknowledgments Grant - Drs. Linda C. Schaffner and Rochelle D. Seitz NSF OCE 0552612 Blue Crab Disaster Relief Funds from NOAA Thanks to Romuald Lipcius, Rochelle Seitz, Danielle McCulloch, Allison Colden, Gina Ralph, Mike Seebo, Alison Smith, Seth Theurkeuf, Emily Kimminau, Liz Gomez, Cassie Bradley, Gabby Saluta, Cassie Glaspie, Andrew 107 lab group, my fellow REU interns, and all the watermen who participated in this study