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AGE, GROWTH, AND MORTALITY OF GRAY TRIGGERFISH, BALISTES CAPRISCUS, FROM THE NORTHEASTERN GULF OF MEXICO

1984; National Oceanic and Atmospheric Administration; Issue: 3 Linguagem: Inglês

1937-4518

Allyn G. Johnson, Carl H. Saloman,

Marine Bivalve and Aquaculture Studies

Age, growth, and mortality of gray triggerfish, Balistes capriscus, from the northeastern Gulf of Mexico were estimated from sections of the first dorsal spine of 1,746 fish. The oldest female was estimated to be 12 years old and the oldest male was 13 years old. The von Bertalanffy growth equa­ tions, using weighted means, were as follows: males, It = 491.9 (l - e - 0.382(1 - 0.227)) and females, It = 437.5 (1 - e- 0.383(t- 0.150)), where I = fork length in millimeters and t = age in years. The mean annual mortality rate as determined by four methods of analyses (based on number of fish at age) ranged from 0.32 to 0.53. The weight-length relationships of gray triggerfish were males, W = 6.71505 x 10- 6 L3.187, and females, W = 1.3939 x 10- 5 L3.065, where W = weight in grams and L = fork length in millimeters. Exploitation of fish from the northeastern Gulf of Mexico by recreational and commercial fisher­ men has created a demand for underutilized fish resources. One of the abundant fish resources that is being subjected to exploitation is the gray triggerfish, Batistes capriscus. A dramatic in­ crease in demand for this species can be seen in the commercial landings on the west coast of Florida: 7.8 t in 1967 and 26.7 t in 1977 (Anon­ ymous 1967, 1977). This species is known to occur in the western and eastern Atlantic. In the western Atlantic, its range is from Nova Scotia to Argentina, includ­ ing the Gulf of Mexico (Briggs 1958; Moore 1967). In the Gulf of Mexico, the gray triggerfish is a primary reef fish inhabiting the area between 12 and 42 m in depth (Smith 1976), except for its first year of life when it is planktonic and associ­ ated with Sargassum (Dooley 1972). The harvest of the gray triggerfish in the northeastern Gulf of Mexico and its utilization of reef habitats has created a need to know more about the biology of this species, especially age, growth, and mortality. Age and growth of gray triggerfish, using the first dorsal spine, has been reported only for the southwestern coast of Africa (Anonymous 1980; Caveriviere et al. 1981). This paper reports the results of our investigation on age, growth, and mortality, using the first dorsal