Antarctic toothfish Dissostichus mawsoni

Dissostichus mawsoni is found throughout Antarctica from 20-1,600 meters depth [1,2]. D. mawsoni have been collected up to 1.75 meters long, and up to eighty kilograms in weight [1,2]. D. mawsoni is usually found near the bottom [2].

Dissostichus mawsoni is an opportunistic feeder, eating zooplankton and other pelagic invertebrates as juveniles, and shifting to various mid- to deep-water fish and squid by their third year [1]. The species of fish and crustaceans found in D. mawsoni stomachs in McMurdo Sound indicates that they feed deep and in the open sea, and close under the sea ice [1]. Predators of D. mawsoni include Weddell seals, sperm whales, and orcas [1,2,4].

Dissostichus mawsoni has no swim bladder, and relies on reduced calcification of its skeleton, and lipid production in adipose tissue cells, to maintain neutral buoyancy [2].

Dissostichus mawsoni is sexually mature at eight years of age and one meter in length [2]. A well-regulated and enforced commercial fishing for Antarctic toothfish would factor in their slow growth and long lifespan. Such fish cannot be harvested in great quantities, or it will be pushed towards extinction.

Dissostichus mawsoni is related to the Patagonian toothfish, or Chilean sea bass. Large, unreported catches from illegal fishing of Patagonian toothfish, or Chilean sea bass, has made effective fisheries management difficult, and it is being overfished in some areas [3]. Overfishing of long-lived fish pushes them towards extinction. A fate similar to that of the Patagonian toothfish, or Chilean sea bass, may await the Antarctic toothfish. Effective fisheries management in the remote waters of Antarctica is nearly impossible.

Dissostichus mawsoni is named after Douglas Mawson, the leader of early Australian Antarctic exploration.

1: History and Atlas of the Fishes of the Antarctic Ocean. RG Miller. Carson City, Nev. : Foresta Institute for Ocean and Mountain Studies, 1993; 2: Fishes of the Southern Ocean. O Gon & PC Heemstra, eds. Grahamstown, South Africa : JLB Smith Institute of Ichthyology, 1990; 3: Fact Sheet, Joint U.S. Department of Commerce/U.S. Department of State. Washington, DC. March 26, 2002; 4: Norbert Wu, personal communication, 2001

Text ©Peter Brueggeman. Photographs ©Paul Cziko (photographer with fish wrangler Kevin Hoefling) & Rob Robbins. Photographs may not be used in any form without the express written permission of Paul Cziko & Rob Robbins.