Size structure, length-body mass relationship, and relative condition factor of the crocodile shark, Pseudocarcharias kamoharai, in the Southeastern Pacific Ocean, Ecuador

Abstract

The crocodile shark, Pseudocarcharias kamoharai, is a species of ecological and economic importance in the marine ecosystems of Ecuador. Although it is a fishery resource for local consumption, biological and ecological information and appropriate fishery management are needed to allow its sustainable use. This research aimed to analyze the population’s size and total body mass structures, determine the length-body mass relationship, and the relative condition factor of the crocodile shark in the Ecuadorian Pacific Ocean. Samples were collected from June 2012 to May 2013 and from June 2017 to May 2018 in Santa Rosa, Ecuador. The size of females (n=202) ranged from 50 to 117 cm total length, while males (n=206) ranged from 72.5 to 110 cm TL. The total body mass for females was between 700 and 7 100 g and from 2 000 to 5 000 g for males. Significant differences were observed between sizes (Mann Whitney test, W= 55 018.50; p < 0.05) and body mass for females and males (W= 56 338.50; p < 0.05). Length-body mass relationship parameters for the combined sexes were a=0.015, b=2.70, R2=0.79; for females: a=0.045, b=2.48, R2=0.80; and for males a=0.098, b=2.28, R2=0.66. In all cases, length-body mass relationship patterns were hypoallometric. The relative condition factor for combined sex ranged between Kr=0.81 and 1.34 (Kr= 0.84–1.34 for females and Kr= 0.81–1.30 for males), demonstrating that this species had a healthy nutritional condition. This study investigates the fishery biology of the species in this region of the Pacific Ocean for a future management plan.