Sea Grant's bycatch project began 

 earlier this year when Marine Advisory 

 Service agent Jim Bahen began to in- 

 terview fishermen up and down the 

 North Carolina coast. He questioned 

 them about possible designs for 

 bycatch-reducing trawls. 



When federal fisheries officials began 

 design work on turtle excluder devices 

 (TEDs) a couple of years ago, local 

 fishermen complained that they were 

 left out of the process. "We didn't want 

 that mistake repeated with FSDs," 

 Bahen says. 



Several good ideas were garnered 

 from the fishermen. Shortly, three new 

 trawl designs incorporating these ideas 

 were in the works. Assisting was Steve 

 Parrish of S&S Net Shop in Holden's 

 Beach. Parrish is the designer of the 

 Parrish "soft" TED. 



After a few kinks were worked out of 

 the original FSD designs, scale models 

 were constructed and transported to 

 the David Taylor Naval Research Center 

 in Bethesda, Md. The nets were 

 lowered into a large tank of circulating 

 water and dye tests were done to 

 determine water flow dynamics. 



Using the results from the flume tank 

 tests, Bahen and Parrish made im- 

 provements in the net designs and full- 

 scale models were constructed. 



In June, FSD designs were installed 

 in standard shrimp trawls and were 



towed off the coast of St. Simons 

 Island, Ga., aboard the Georgia 

 Bulldog, Georgia Sea Grant's research 

 vessel. The Bulldog is a fully-rigged 

 72-foot shrimp trawler. 



"We wanted to fish these nets out in 

 the field, right among the fleet," Bahen 

 says. "We felt there was no better way 

 to see if bycatch could be reduced 

 than by actually catching shrimp with 

 our nets." 



The key to these experiments, Bahen 

 says, was towing the FSD-equipped 

 nets alongside a standard shrimp trawl 

 that had not been modified for bycatcn 

 reduction or TED use. 



"We knew if we compared the 

 biomass of the FSD nets with the non- 

 FSD nets, we could come up with a 

 good idea of how the test nets were 

 working," he says. 



Three designs were tested. 



In one design, a large-square mesh 

 was sewn in an extension that also in- 

 cluded a funnel-shaped accelerator. 



Another used the same design, but 

 diamond-shaped holes were cut in the 

 extension near the accelerator funnel. 



The third was a Parrish TED 

 redesigned to include escape panels 

 for finfish. 



"One thing we discovered in our 

 tests at the David Taylor Research 

 Center was that the accelerator, which 

 was sewn into an extension in the net 



just before the tailbag, increased water 

 flow to the tailbag while creating 

 calmer water around the outside of the 

 funnel," Bahen says. 



The resulting flow dynamics proved 

 that the weaker and slower-swimming 

 shrimp could be forced into the tailbag 

 by water flowing through the accelera- 

 tor while the stronger swimming crea- 

 tures such as finfish could seek the 

 area of quiet or calmer water. 



"So, we located the larger mesh and 

 the diamond-shaped holes in the por- 

 tion of the net where we felt the fish 

 would congregate, in the dead-water 

 section," Bahen says. 



Those innovations proved favorable in 

 the field tests, says Roger Rulifson, an 

 East Carolina University fish biologist. 



The nets (the FSDs and the standard 

 trawls) were tested in 90-minute trawls 



ESCAPE PANEL OF 

 4" SQUARE MESH POLY 



%" GALV. HOOP 1 



DEFLECTOR OD 

 ' SQUARE ME81 



MODIFIED PARRISH TED- 



W/ SQUARE MESH ESCAPE PAEl 



FLOATS 



UNC Sea Grant's 

 Experimental 

 FSD Designs 



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