Biology, population structure and fishery of jumbo flying squid (Dosidicus gigas) in Peru

Abstract

Jumbo flying squid (Dosidicus gigas) is found in high abundance along the whole Peruvian coast from 10 to more than 500 nautical miles from the coast. It performs diel vertical migrations from 0 to more than 650 m of depth, with regular inshore-offshore ontogenetic migrations and less regular latitudinal migrations of several hundred nautical miles. It is a very aggressive predator, having a wide food spectrum with predominance, in the last 14 years, of cephalopods (42.33%, by weight) and the mesopelagic fishes Vinciguerria lucetia (13.05%) and Myctophidae (12.38%). Observed differences in their size at sexual maturity, growth and distribution areas suggests that there are at least three phenotypic groups or population subunits off Peru. Their size frequency distribution in catches by both artisanal and industrial fleets in Peruvian waters has been highly variable, with a significant shift to much larger sizes that started in 2000 and became evident in 2001. Since then, squids caught in Peruvian waters have generally been much larger than those caught in the adjacent high seas. The Peruvian squid fishery developed rapidly during the early 1990s with increased catches by a licensed foreign industrial jigger fleet and a rapidly expanding local artisanal fishery that gradually phased out the industrial fishery. Total Peruvian catches of jumbo flying squid peaked at 556 thousand tons in 2014, all taken by local artisanal fleets. The stock or stocks of jumbo flying squid in Peruvian waters are considered to be underexploited or moderately exploited, and the assessments are based on biomass estimates from acoustic surveys combined with surplus production modelling. The suitability of these and other stock assessment methods is discussed giving particular attention to the observed population structure, the presence of three phenotypic groups or possible stock subunits, as well as other characteristics of jumbo flying squid off Peru and what they may imply for the assessment and management of this fishery.