Abstract
Acoustic surveys for assessing the biomass and distribution of the jumbo squid ( Dosidicus gigas ) and the lightfish ( Vinciguerria lucetia ) were carried out in the Humboldt Current System of Peru in 2007 and 2008. At the same time, 937 jumbo squid were caught and their stomach contents analyzed. The diet of the jumbo squid was dominated by mesopelagic fish. The first component of their fish diet was V. lucetia and the second component was the myctophid fish Diogenichthys laternatus . Acoustic biomass estimates of these species show that V. lucetia is an important component in aggregative structures in the Humboldt Current System of Peru and its distribution and movements are closely related to the migratory movements of the jumbo squid. The trophic relationship observed between D. gigas and V. lucetia promotes an increase in jumbo squid biomass and, has a positive trophic effect on the ocean ecosystem.
Highlights
The jumbo squid Dosidicus gigas is a voracious predator that attacks a great variety of prey, including fish, crustaceans and other invertebrates (Ehrhardt et al, 1986, Markaida and Sosa-Nishizaki, 2003, Markaida et al, 2008)
In Peru the jumbo squid fishery has been one of the most important fisheries since 1990 (Yamashiro et al, 1998, Markaida and Sosa-Nishizaki, 2003, RosasLuis et al, 2008, Keyl et al, 2008). This species feeds mainly at night, but there are reports of jumbo squid feeding during the day in the California Current System of Mexico (Markaida and Sosa-Nishizaki, 2003, Rosas-Luis et al, 2008), and in the Humboldt Current System of Peru (Alegre-Norza, personal observations, 2010), which shows that the species carries out both vertical (Gilly et al, 2006) and horizontal migrations (Markaida et al, 2005)
In 2007 fish and cephalopods (Teuthida) were the most important groups and we observed that D. gigas fed primarily on these two groups (Fish index of relative importance (IRI)=1841, Teuthida=1238)
Summary
The jumbo squid Dosidicus gigas (dOrbigny, 1835) is a voracious predator that attacks a great variety of prey, including fish, crustaceans and other invertebrates (Ehrhardt et al, 1986, Markaida and Sosa-Nishizaki, 2003, Markaida et al, 2008). It i s c o n sidered an important organism in the ecosystem due. This species feeds mainly at night, but there are reports of jumbo squid feeding during the day in the California Current System of Mexico (Markaida and Sosa-Nishizaki, 2003, Rosas-Luis et al, 2008), and in the Humboldt Current System of Peru (Alegre-Norza, personal observations, 2010), which shows that the species carries out both vertical (Gilly et al, 2006) and horizontal migrations (Markaida et al, 2005)
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