Squid as a resource shared by fish and humans on the Falkland Islands’ shelf

Abstract

Nektonic squids are the dominant group in the Falklands Islands’ fishery representing >75% of the total annual catch. Among these squids, the benthopelagic Loligo gahi is an important link between zooplankton and fish in the shelf food web. It is preyed upon by diverse and numerous demersal and benthopelagic fishes, penguins and marine mammals, and is harvested by fishermen. Pelagic squids, Illex argentinus, Onykia ingens, and Gonatus antarcticus though seasonally very abundant, are scarce in fish diet because of the absence of specialised pelagic predators. This ecological niche is shared between humans (targeting Illex) and penguins (targeting Onykia and Gonatus). Martialia hyadesi though was abundant in some years in the past, it has now virtually disappeared from the shelf ecosystem. The biomass produced by L. gahi remains in the Falkland waters, whereas that of pelagic squid is transported out of the shelf either to the northern Patagonian slope ( I. argentinus) or to deeper waters around the islands ( O. ingens and G. antarcticus). Generally squids occupy the ecological niche of epipelagic fish on the Falkland shelf and slope.