Artisanal Shark Fishery at "Tres Marias" Islands and Isabel Island in the Central Mexican Pacific

Abstract

There is a lack of basic biological information on the shark species caught in the region around the Tres Marias Islands and Isabel Island in the Central Mexican Pacific. Intensive monitoring was undertaken from October 1995 to March 1996 of shark landings by the artisanal fleet at La Cruz de Huanacaxtle, Nayarit, that fished south of Tres Marias Islands and, from November 2000 to February 2001, of landings by another fleet that fished around Isabel Island and close to the Tres Marias. Smooth hammerhead Sphyrna zygaena (35%), silky shark Carcharhinus falciformis (27%) and blue shark Prionace glauca (25%) were the most important species of 2 004 sharks observed at La Cruz de Huanacaxtle. At Isabel Island, the most important species of 7 464 sharks sampled were S. lewini (49%) and Pacific sharpnose shark Rhizoprionodon longurio (45%). This paper describes the shark species caught at these islands, the catch per unit effort of the principal species throughout the fishing season, their length frequency distributions and percent mature, and gear selectivity issues.