Family Alepisauridae

Common names:  lancetfishes

Distribution:  Worldwide primarily in the mesopelagic zone but also sometimes caught on longlines in the epipelagic and to depths of 1800 meters.

General description and features:  These fishes are some of the largest midwater predators growing to lengths of up to 6 ft.  They have a large mouth with bladelike backward curving teeth that can be used to bisect larger prey.  Their large dorsal sail may function to increase the body plane area for rapid and abrupt turning during prey pursuit in a fashion that has been demonstrated for sailfishes (Family Istiophoridae). 

Feeding:  Voracious predators, these fishes eat a variety of mesopelagic fishes, cephalopods, crustaceans, salps, and jellyfish.  Cannabalism on their young is not uncommon.

Reproduction and life history:  The members of this family are synchronous hermaphrodites, possessing both male and female sex organs at the same time.  This strategy for reproduction is very effective in the deep sea where population densities are low and the chance of finding a mate are low.  By being hermaphrotidic, the fish need only find a member of its own species (instead of a member of its own species and of the opposite sex) thus doubling its chance of finding a mate.

This is a photo of an Alepisaurus ferox which washed up alive on the beach in front of MBARI in the spring of 2002.  Tonatiuh Trejo, a graduate student at Moss Landing Marine Laboratory, and I are holding up the specimen after we dissected it for various tissues and stomach contents.  Several strandings of this species occurred this year in Monterey Bay, and strandings are usual in the spring (Bond, 1996).