Factors affecting estimates of size at age and growth in grey triggerfish Balistes capriscus
 from the northern Gulf of Mexico

Few data exist to evaluate the performance or assess the potential impacts of hook regulations on catchability or selectivity of recreational fisheries in the northern Gulf of Mexico. The purpose of this study was to test the effects of hook type (circle vs. J hook) and hook size (1/0, 4/0, and 7/0) on catch composition, traumatic hooking, species-specific catches, and size-selectivity of red snapper, Lutjanus campechanus, and grey triggerfish, Balistes capriscus. Selectivity was estimated by conditioning size distributions from hook-specific catches against in situ size distributions observed with a remotely operated vehicle. Deep hooking (hook set in gills or beyond) was low in all hook treatments for red snapper (<10%) and grey triggerfish (<6%), but was generally higher with J hooks, especially for other fishes caught with the largest J hook (34%). Hook type did not significantly affect catches, but catches decreased significantly with increasing hook size in all groups except red snapper. Selectivity curves were dome-shaped for both focus species in all hook treatments and selection peaks were similar among treatments for red snapper. Peak selectivity was 78.1 mm larger for J hooks than circle hooks for grey triggerfish. Overall, study results indicate that the circle hook regulation may have reduced traumatic hooking mortality by up to 50%, and that catchability is similar between hook types for both red snapper and grey triggerfish when controlling for hook size. Strong dome-shaped selection estimated for nearly all selectivity curves suggest logistic size-selectivity assumptions in assessment models are likely inappropriate for recreational sectors targeting red snapper or grey triggerfish.

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Seasonal and spatial variation in the abundance and size distribution of fishes associated with a petroleum platform in the northern Gulf of Mexico

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f97-005 ◽

1997 ◽

Vol 54 (5) ◽

pp. 1166-1176 ◽

Cited By ~ 2

Author(s):

D R Stanley ◽

C A Wilson

Keyword(s):

Coral Reef ◽

Gulf Of Mexico ◽

Species Composition ◽

Target Strength ◽

Lutjanus Campechanus ◽

Point Count ◽

Northern Gulf Of Mexico ◽

Current Vector ◽

Dual Beam ◽

Balistes Capriscus

Stationary dual-beam hydroacoustics and visual point count surveys were used in tandem to measure the density, target strength, and species composition of fishes associated with a petroleum platform in the northern Gulf of Mexico. Fish densities ranged from 0 to 10.5 fish · m-3 during monthly sampling trips from January 1991 to May 1992. Density and target strength were spatially and temporally variable. Target strengths varied significantly with side of the platform, month, and east and north current vectors. Density varied significantly with platform side, month, east current vector, and depth. Density and target strength did not change over 24 h periods or with water temperature. Fish densities were highest adjacent to the platform and decreased significantly beyond 16 m. Approximately 1990 - 28<|>100 fish were associated with the platform depending on the month. A total of 19 species were observed at the platform, with Chaetodipterus faber, Caranx fusus, Seriola dumerili, Balistes capriscus,Lutjanus campechanus, andArchosargus probatocephalus constituting 97% of observed fishes. Based on our results, we conclude that the fishes associated with a petroleum platform conform with the open nonequilibrium hypothesis proposed for fishes in coral reef habitats.

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