Spatial-temporal analysis of the billfish incidental catch by the venezuelan tuna purse-seine fishery in the eastern Pacific

Abstract

The Venezuelan eastern Pacific tuna purse-seine fishery was analyzed to determine the spatial and temporal distribution of billfish´s incidental catch. The Venezuelan National Observer Program data-base was used, including the incidental catch and fishing effort from 1995 to 2006. Effort was expressed in number of sets and catch in number of organisms. Billfishes represented only 0.4% of the total incidental catch, and were grouped in two families: Xiphidae (swordfish) and Isthiophoridae (marlins and sailfish). The mean incidental catch did not show a well defined annual distribution pattern, with the highest vales registered in 1998, 2000 and 2003, with significant statistical differences among years. The highest catches were observed in Zone 3, ranging from the central American coasts to 120° W, between 5 and 20° N. Significant statistical differences were found among zones. The highest percentage of billfish incidental catch was registered with marine mammal sets (55%), followed by school-sets (29%) and lastly log-sets (16%). With significant statistical differences among these three types of sets. Billfishes were mainly incidentally caught from 26.5 to 30.5 °C of sea surface temperature. Most billfishes caught incidentally were big (>150 cm) (88%).