COMPARISONS OF CATCHES OF FISHES IN GILL NETS IN 



RELATION TO WEBBING MATERIAL, TIME OF DAY, AND 



WATER DEPTH IN ST. ANDREW BAY, FLORIDA 



Paul J. Pristas and Lee Trent 1 



ABSTRACT 



Monofilament and multifilament gill nets were fished simultaneously in shallow- (0.7-1.1 m), mid- 

 (2.2-2.6 m), and deep- (5.2-5.6 m) water zones for 40 days between 19 September and 29 December 1972, 

 in lower St. Andrew Bay, Fla. Each net was 33.3 m long, had stretched mesh of 9.5 cm, extended from 

 water surface to bottom, and was anchored in position. Nets were checked at sunrise and sunset. 

 Fifty-two species of fishes and one hybrid from 30 families were caught. The 12 most abundant species 

 composed 92^ of the total number (4,066) caught. Catch comparisons between 1 ) webbing materials, 2) 

 times of day, and 3) water depths were made from data on catches of the 12 most abundant species. 

 Catches in monofilament webbing were greater than those in multifilament webbing for 8 of the 12 

 species. Greater catches were made at night for all 12 species. Catches of eight species were highest in 

 the deep-water zone, but catches of the remaining four species were highest in the shallow-water zone. 

 Monofilament nets were damaged least, and percent damage decreased as depth zones increased. 



The National Marine Fisheries Service (NMFS) 

 began collecting a variety of fishes from coastal 

 and offshore waters throughout the United States 

 in 1972 for heavy-metal analyses. Each coastal 

 laboratory of NMFS was responsible for the fish 

 collections in their respective geographic area, 

 and we at the Panama City Laboratory were to 

 collect relatively large numbers of about 15 

 species. We decided that set gill nets would be our 

 most effective sampling gear but could find no 

 published information on their effectiveness in 

 Gulf of Mexico estuaries in relation to various 

 efficiency factors such as twine size, mesh size, and 

 location and time of day to set the nets. 



The literature did reveal that gill nets are 

 among the most important types of fishing gear 

 used in Florida. Over 34.6 million pounds of 

 finfish, valued at over $4.7 million to the 

 fishermen, were caught with gill and trammel 

 nets on the west coast of Florida in 1971 (National 

 Marine Fisheries Service 1974). Set gill nets, the 

 type used in this study, are not commercially used 

 to any extent in Florida estuaries except for spot- 

 ted seatrout, Cynoscion nebulosus, and even in 

 this fishery the nets are left in the water for only 

 about 2 h (Siebenaler 1955). Information about the 

 efficiency of set gill nets in the gulf was limited to 



'Southeast Fisheries Center Panama City Laboratory, Na- 

 tional Marine Fisheries Service, NOAA, P.O. Box 4218, Panama 

 City, FL 32401. 



comparisons of catches of king mackerel, 

 Scomberomorus cavalla, and Spanish mackerel, S. 

 maculatus, between monofilament and multi- 

 filament gill nets (Mihara et al. 1971). 



We decided to capture the fishes needed for the 

 heavy-metal survey in such a way that informa- 

 tion could be generated on the efficiency of gill nets 

 in our area. The objectives of this study were: 1) to 

 compare gill net catches in an estuarine system in 

 relation to webbing materials, times of day, and 

 depth zones; and 2) to estimate net damage in 

 relation to webbing materials and depth zones. 



STUDY AREA AND METHODS 



The St. Andrew Bay system, located between 

 long. 85°23' and 85°53'W and lat. 30°00' and 

 30°20'N along the northwest Florida coast, covers 

 about 280 km 2 (McNulty et al. 1972). Physical, 

 hydrological, and sedimentological characteris- 

 tics of the bay system have been presented by 

 Hopkins (1966), Ichiye and Jones (1961), and 

 Waller (1961). Tidal fluctuations in the bay aver- 

 age about 0.4 m (National Ocean Survey 1971). 



The study area was located 0.6 km northwest of 

 the western entrance into St. Andrew Bay. Depths 

 at the net locations at mean low tide were 0.7-1.1 

 m (shallow), 2.2-2.6 m (mid), and 5.2-5.6 m (deep). 

 During the study, surface temperatures and 

 salinities ranged from 11.4° to 27.0°C and 25.3 to 

 34.6%o, respectively (determined with a 



Manuscript accepted August 1976. 

 FISHERY BULLETIN: VOL. 75, NO. 1, 1977. 



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