Renaud et al.: Shrimp loss by TEDs in U.S. coastal waters 



131 



a tow separate to facilitate data collection on deck. 

 The conditions under which the data were collected 

 were assumed to be representative of commercial 

 fishing conditions. 



Gear tuning and control tows 



The fishing efficiency of all nets used in this study was 

 standardized by NMFS or Sea Grant gear specialists 

 during the initial trip of a participating vessel. Prior 

 to installation of TEDs, control tows were made using 

 standard nets. Lazy line, tickler chain, and float ad- 

 justments were made to each net until approximately 

 equal amounts of shrimp were caught by every net. 



A Georgia TED 



FRONT 



Super Shooter TED 

 FRONT 



SIDE 



Vessel captains were instructed by gear specialists 

 on the proper installation of TEDs. Once TEDs were 

 installed, the gear specialist modified the rigging for 

 the proper operation of the TED. This procedure usu- 

 ally required 2-3 d. The captain then was responsible 

 for later gear tuning. Differences in the tuning ability 

 of captains may contribute to variations in the catch 

 data. All Super Shooter TEDs were constructed with 

 accelerator funnels (Fig. 2), i.e., mesh in the shape of a 

 funnel sewn into the net directly in front of the TED. 

 Funnels accelerate water flow through the TED and 

 into the cod end of the net. Georgia TEDs were tested 

 with and without funnels. 



Data collection 



C. TED with accelerator funnel installed in shrimp trawl 



TED GRID ACCELERATOR FUNNEL 



Figure 2 



Schematics of Georgia and Super Shooter TEDs and accelerator funnel. 



Every phase of the operation was ex- 

 plained to vessel captains by NMFS 

 personnel to insure that all data could 

 be collected. Aside from sampling the 

 catch and working up the data, ob- 

 servers did not interfere with normal 

 fishing activity. The primary require- 

 ment of the study was that catches 

 from each net be kept separate from 

 all others so the shrimp from each 

 trawl could be weighed and recorded. 

 If necessary, the back deck of the ves- 

 sel was partitioned with wooden beams 

 to prevent catches from mixing. Cap- 

 tains of the vessels were requested to 

 examine the data collected by the 

 NMFS observer and to sign the data 

 sheets to verify their accuracy. 



Shrimp catch on observer vessel A 



random sample weighing 50-70 lb 

 was shoveled from the contents of 

 each trawl into standard-sized plastic 

 shrimp baskets. Thus, a quad-rigged 

 vessel produced four samples per tow 

 and a twin-rigged vessel two samples 

 per tow. Shrimp were separated from 

 each sample and total weight (to the 

 nearest lb) of brown, pink, and white 

 shrimp (Penaeus sp. ) combined was re- 

 corded for every net of each tow. No 

 analysis by species was possible or pro- 

 posed by this study. If the shrimper 

 discarded small shrimp, observers were 

 instructed to include only the size-range 

 of shrimp retained by the shrimpers 

 for their weights. Catch was recorded 

 as heads-on or heads-off. Heads-off 

 weight = (0.63 heads-on weight). 



