Doryteuthis pealeii, Longfin inshore squid.

Abstract

The longfin inshore squid (formerly Loligo pealeii) has been a premier biomedical model organism in neuroscience for many decades, and since the 1800s has been the subject of a valuable commercial fishery. This loliginid squid species is widely distributed in the western North Atlantic Ocean from Newfoundland to Venezuela and tolerates a wide range of temperatures from 9-30\textdegreeC. It is most abundant along the northeast coast of the US, where squids migrate inshore during the spring and summer, and offshore to canyons on the continental slope during winter. The current fishery has a large offshore winter component and a relatively smaller inshore component that targets animals as they migrate to spawn. Growth is exponential throughout the life cycle: average adult size is 14 – 17 cm dorsal mantle length and the life span in the temperate range is estimated to be 9-12 months. Longfin squid play a vital role in the coastal food web of the western North Atlantic by serving as a link between higher and lower tropic levels. Extremely high consumption rates make longfin squid major predators and competitors of juvenile fishes, crustaceans, other squid species and conspecifics. In addition, numerous commercially and ecologically important finfishes, elasmobranchs, and marine mammals forage on longfin squid, and demonstrate shifts in predation that are dependent on predator and prey behavior, and seasonal availability in coastal waters. Predators that target adult squids and exhibit high predatory demand compete directly with the summer and winter commercial fishery for squid biomass. The biology of reproduction has been worked out in considerable detail. Squids in the northern ranges spawn inshore during spring and summer; those in the southern ranges throughout the year. The mating system is complex and flexible, and DNA fingerprinting combined with lab and field behavioral studies show that multiple paternity in egg capsules is widespread and common. A powerful contact pheromone that initiates extreme aggression in males has recently been discovered in the outer tunic of egg capsules. Overall, the life history of D. pealeii is characterized by very fast growth, predation on a wide variety of crustaceans and fishes, high daily mobility, substantial migrations, flexible reproductive tactics, and a short life span.