Illex argentinus, a species of shortfin squid that forms the second largest squid fishery on the planet. The squid are found tens to hundreds of kilometers offshore from roughly Rio de Janeiro to Tierra del Fuego (22 to 54 degrees South latitude). They live 80 to 600 meters (250 to 2,000 feet) below the surface.
They reproduce via internal fertilization and lay egg cases full of thousands of eggs on the sea floor. During mating, a female may lay as many as 750 thousand eggs. Like many squids, Argentine shortfin squid have a very fast life cycle and only live for about one year. During that time, they grow from tiny (one millimeter) juveniles to their maximum size, reproduce once, and die. The eggs develop at varying rates so that all individuals do not hatch at the same time.
This species, throughout their short lifetime, individuals eat a variety of prey of different sizes, actively feeds on shrimp, crabs,other squids, and small bony fishes. In turn, Illex are consumed by larger finfish, whales, seals, sea birds, penguins...and humans.
Illex Squid live along the underwater edge of the continental shelf, the nutrient-rich Malvinas Current, and the boundaries of the exclusive economic zones of Argentina and the Falkland Islands.
As known, the Argentine squid is the target of an extremely large fishery, throughout its range. In some recent years, as many as one million metric tonnes (2.2 billion pounds) of this species have been captured in a single fishing season. It is the second largest (by weight) squid fishery in the world.
The fishery is fueled by abundant nutrients and plankton carried on the Malvinas Current. Spun off of the Circumpolar Current of the Southern Ocean, the Malvinas flows north and east along the South American coast. The waters are enriched by iron and other nutrients from Antarctica and Patagonia, and they are made even richer by the interaction of ocean currents along the shelfbreak front, where the continental shelf slopes down to the deep ocean abyssal plain.
Fishers use large, bright lights to bring the species closer to the surface at night and capture them with large nets or individually using hand lines and jigs. There are so many fishers participating in this fishery on any given night during the fishing season that the lights from the aggregation of boats can be seen from outer space. Catch levels have varied significantly in recent years, with some years being much lower than the million tonne maximums, but populations seem to consistently bounce back (likely a result of the very fast life cycle and high number of eggs produced by each female).
In a recent analysis of Illex Argentinus, scientists determined it to be of least concern.