Reproductive traits of female of pink cusk-eel (Genypterus blacodes Schneider, 1801) in the fjords of the Chilean Patagonia

Abstract

Genypterus blacodes is a bento-demersal species endemic of the southern hemisphere distributed in Chile, Argentina, New Zealand and southern Australia. In the Chilean Patagonia (41°00′S and 57°00′S), information in relation to life history traits was assessed on the basis of individuals collected from open sea, whereas knowledge of basic biological attributes on this species in inner channels and fjords is very scarce. Therefore, the aim of this study is to evaluate the maturity aspects in female pink cusk-eel based on samples collected inside fjords and inner channels during research surveys conducted in spring. Histological and gonometric (a staging method based on gonadosomatic index) analysis of the gonads collected was performed to estimate the maturity ogive. In addition, batch fecundity was estimated using the gravimetric method and gonadosomatic index, hepatosomatic index and condition factor were computed. Results show that maturity ogives were different (P<0.05) between administrative areas of the Patagonia, in which individuals from the northern zone (41°00′S and 47°00′S) mature at smaller sizes in comparison with the southern zone (47°00′S and 57°00′S). These results confirmed previous latitudinal gradients in life history traits reported on this species. Likewise, estimated batch fecundity was comparable to previous estimates reported using individuals collected from open sea. The presence of skipped spawning and females with low fecundity confirms this species has low resilience to fishing exploitation. We discuss how habitat temperature and food availability are key factors in shaping the latitudinal variations of maturation rate for this species.