Evaluation of 1463-m trammel and 4-square gill nets for estimating finfish abundance in Texas bays.

A 1463-m trammel net was compared with a 366-m trammel net and evaluated as a fish population sampling device in the nearshore habitat of Texas estuaries. Four separate 2.32-ha squares were delimited by monofilament nylon gill nets, each of a different size stretched mesh (7.6, 10.2, 12.7 and 15.2 cm); these nets were evaluated as fish population sampling devices in the open-water habitats of Texas estuaries. Neither the 1463-m trammel net nor the 4-square gill nets were acceptable for estimating adult finfish populations because of the lack of personnel, time, finance and number of available sampling sites required as well as possible equipment damage, adverse weather effects and sample size constraints. The 1463-m trammel net mean catches of black drum, Atlantic stingray, sea catfish and of 15 fish species combined were significantly different in each bay system. Galveston Bay system yielded the largest catches of black drum and sea catfish; San Antonio Bay system yielded the largest catches of Atlantic stingray. The mean catches of the remaining 12 individual species were not significantly different in each bay system. The greatest numbers of red drum, black drum, southern flounder and sea catfish were caught with 4-square gill nets in the Corpus Christi Bay system. Only lower Laguna Madre exceeded Corpus Christi Bay in catches of spotted seatrout. Generally, 4-square gill net catches of each species varied widely between bays. The mean catch rates of fish in the 1463-m and 366-m trammel nets were statistically similar, but the number of species caught with the long net was about twice that caught with the short net. The personnel, time, finance, net damage and sampling site constraints involved in the use of the long net did not apply to the short net. Tagged-fish recovery rates for all species with both gear types were generally low (<20%), perhaps because of lack of fish movement or of different behavioural responses by tagged and untagged fish.