Fishery and morphometric relationships of the banded guitarfish, Zapteryx exasperata (Elasmobranchii, Rhinobatidae), from the Gulf of California, Mexico

Abstract

The banded guitarfish (Zapteryx exasperata) is a commercially-important species in the Northwest artisanal ray fishery of Mexico. However, very little information about its fisheries characteristics and catch abundance is available. Seasonal sampling was conducted between 1998─2000 and 2004─2005 in five fishery camps in the Gulf of California. Z. exasperata is a secondary resource in ground fisheries, and is caught using gill nets with mesh sizes between 15─20 cm from small fiberglass boats called “pangas,” fishing between 4─54 m depth. Catches were composed of individuals between 41.3─90 cm TL with an average weight of 2.18  1.13 kg. The sex ratio of the catches was 1:1. Females reached larger sizes and weights than males; therefore, the morphometric relationships were different between sexes. CPUE reached its highest values during spring (3.4 ind/trip), and was lowest during summer. CPUE was also higher in fishing sites with depths between 100─200 m (5.5 ind/trip). Z. exasperata fishery characteristics are similar to those reported for elasmobranchs in other regions of Mexico. In particular, the seasonality of the catches was similar to that reported for other ray species in the Gulf of California, with a peak during spring and summer.