FISHERY-DEPENDENT EVALUATION OF A SPAWNING AGGREGATION OF TIGER GROUPER (MYCTEROPERCA TIGRIS) AT VIEQUES ISLAND, PUERTO RICO

摘要

Fishery-dependent monitoring of the tiger grouper, Mycteroperca tigris (Valenciennes, 1833) spawning aggregation at Vieques Island, Puerto Rico was conducted from 1995 to 1999 with very limited fishing in 1999. The aggregation formed at the "El Seco" site 2 d after the full moon in February and March and rarely in January or April. Hook and line fishing with live baits at the site was 4-7 d per aggregation period and an average of seven boats handlined per aggregation period. Spearfish-ing effort was limited and declined to zero by the end of the study. Predation losses of hooked fish to sharks were quantified and on average 33% of captured fish were lost to predation. Documented landings from the fishery declined about 60% from almost 5000 kg in 1995 to about 2000 kg in 1998. A total of over 6700 fish was estimated to have been landed in 4 yrs. Fleet catch-per-unit-effort (CPUE) data, as a proxy for abundance, demonstrated a strong declining trend from 1996 to 1998. In the 4 yrs of catch sampling, the mean size of males was significantly greater than that of females. The modal value of the size distribution (sexes combined) increased from 510 mm SL (standard length) in 1995 to 550 mm SL in 1998. The sex ratio (M: F) of samples from the aggregation were all male-biased and increased from 3.7:1 in 1995 to 12:1 in 1998. Continued fishing at the levels of fishing effort observed is not considered sustainable. A seasonal closure of the El Seco site should be considered as a management option.