Diet and parasites of the jumbo squid Dosidicus gigas in the Humboldt Current System

Abstract

The habitat and diet can vary through host ontogeny, and, therefore, affect its parasitic fauna. We examined the relationship between diet and endoparasites of 124 Dosidicus gigas from coastal (73) and oceanic areas (51) of central Chile. The numerical descriptors and composition of 82 stomach contents and 120 infracommunities of parasites were evaluated. A total 24 prey items were identified in stomach contents. The infracommunities were composed of 1544 individuals belonging to six parasitic taxa. Host mantle length best explained the variation of the infracommunity descriptors, while the change of host diet was explained by the fishing zone factor. From 77 jumbo squids in which stomach contents and parasites were analyzed together, no significant association was found between the prey and parasites. D. gigas does not increase its trophic niche breadth through ontogeny, because the largest squids primarily feed on fish. The infracommunity descriptors showed an increase in relation to squid length. The feeding strategy of D. gigas may explain the absence of correlation between the diet and parasites. We recommended the application of stable isotopes, to avoid the problem of different incoming rates of parasites and prey, to study the association between the diet and parasites.

Keywords:

• infracommunities
• feeding
• Cephalopoda
• Pacific Ocean

Acknowledgements

We are grateful to John Field, Friedemann Keyl and Chingis Nigmatullin for their valuable comments on the manuscript. We are also grateful for the suggestions and recommendations of an anonymous referee.