REDUCING THE BYCATCH IN A COMMERCIAL TROTLINE FISHERY 



Lawrence W McEachron,' Jeff F Doerzbacher,- Gary C Matlock,^ 

 Albert W. Green,^ and Gary E, Saul- 



ABSTRACT 



Reducing the bycatch of red drum, Sciaenops ocellatus, and spotted seatrout, Cynoscion nebulosus, in 

 the Texas commercial trotline fishery is desirable. Hook placement within the water column was 

 examined as a means of accomplishing this objective. The commercial trotline fishery was simulated 

 in the Laguna Madre during February 1985 through January 1986. Requiring placement of trotline 

 hooks on bottom will reduce bycatch of red drum, spotted seatrout, and other nonmarketable fishes 

 and improve operational efficiency of commercial fishermen without significantly reducing catch of 

 black drum, Pogonias cromis, a target commercial species. Other than crab and shrimp being more 

 effective baits than oleander leaves, no other generalization could be made concerning baits and 

 seasons. 



Longlines catch species unwanted or legally non- 

 retainable by fishermen and have been regulated 

 to reduce the bycatch of nontargeted species 

 (South Atlantic Fishery Management Council 

 1985). Trotlines (Figs. 1, 2) are a specialized long- 

 line used in shallow (<4 m) Texas estuaries to 

 catch fish (Simmons and Breuer 1962; Breuer 

 1973, 1974, 1975; Matlock 1980). Red drum, 

 Sciaenops ocellatus, and spotted seatrout, 

 Cynoscion nebulosus, were the primary targets 

 until 1981 when their sale was prohibited be- 

 cause of overfishing (Matlock et al. 1979; Anony- 

 mous 1979, 1981, 1983). The effort has since been 

 redirected toward black drum, Pogonias cromis. 

 Regulations requiring the use of circle hooks and 

 placement of the mainline under water were en- 

 acted to reduce the bycatch of red drum and spot- 

 ted seatrout. However, a bycatch still occurs. This 

 study was conducted to determine if the bycatch 

 could be further reduced by additional regulation 

 of where in the water column hooks are fished and 

 bait types. 



MATERIALS AND METHODS 



The catch on trotlines with hooks placed on the 

 bottom or in the top of the water column was 

 compared by simulating commercial fishing tech- 

 niques in the Laguna Madre, TX (Fig. 3). Bottom 

 trotlines were set with the mainline on the bot- 

 tom. Top trotlines had the mainline floated with 



iTexas Parks and Wildlife Department, P.O. Box 1717, Rock- 

 port, TX 78382. 



2Texas Parks and Wildlife Department, 4200 Smith School 

 Road, Austin, TX 78744. 



the hooks suspended in water >0.6 m deep to 

 insure hooks fished in the water column. Texas 

 Parks and Wildlife Department (TPWD) trotlines 

 were set in the same area as commercial trotlines. 

 Commercial fishermen were contacted by tele- 

 phone within 24 hours prior to TPWD sets to de- 

 termine areas of commercial activity. All TPWD 

 trotlines were at least 15 m apart. 



Trotlines with 100 hooks each were built ac- 

 cording to commercial fishermen specifications 

 (McEachron et al. 1985). The mainline (182.9 m 

 long) consisted of #36 nylon twine, knotted twice 

 every 1.8 m for swivel (1/0 black brass barrel) 

 placement (Figs. 1, 2). Hooks (#8 Mustad 

 39960ST) were attached by a 610-686 mm long 

 staging (56.7 kg test monofiliament) to the swivel 

 at 1.8 m intervals. Stakes (51 cm x 76 mm) and/or 

 anchors were placed on each end to stretch the 

 mainline. Floats (3.8 L) were attached to the 

 mainline every 15 hooks for navigation identifi- 

 cation. 



Eighteen trotlines were set overnight each 

 month in both the upper and lower Laguna Madre 

 during 1 February 1985 through 31 January 

 1986. Six (3 top; 3 bottom) were set during each of 

 two monthly sampling periods (first and last 15 

 days of the month). Another six sets were made in 

 either the first or last half of each month; the 

 period was randomly selected each month. Each 

 trotline was baited completely with one of three 

 bait types — cut portions of blue crab, Callinectes 

 sapidus; dead shrimp, Penaeus sp.; or oleander, 

 Nerium sp. leaves — so that all bait types were 

 used on both top and bottom trotlines during 

 every period. These baits represented the most 



Manuscript accepted October 1987. 

 FISHERY BULLETIN; VOL. 86. NO 1, 1987. 



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