Slow Mo

Try again next year. The long-promised recovery of two heavily-exploited Antarctic fish may take several more decades than many scientists hoped. A new survey suggests that marbled and humped rockcod numbers remain in the dregs despite a fishing ban enacted in 1990.

Rockcod fishing in the chilly waters just north of Antarctica hit full swing in the 1960s and 1970s after a crackdown on commercial whale and seal hunting. Rockcod, both marbled (Notothenia rossii) and humped (Gobionotothen gibberifrons), became in-demand food items. In one season, fisherman dragged up an estimated 400,000 tons of marbled rockcod, which often lurk near the bottom of icy fjords in the vicinity of South Georgia in the southern Atlantic. Soon after, their numbers plummeted to less than 5% of 1969 population sizes. An international convention closed rockcod fishing in South Georgia in 1985 and in the nearby South Shetland Islands in 1990.

To see how well the moratoria were working, Enrique Marschoff of the Instituto Antárctico Argentino in Buenos Aires and colleagues analyzed the contents of nets pulled up between 1983 and 2010 off Potter Cove, a small bay on King George Island in the South Shetland chain. The results show fishing’s full toll on the ecosystem. Both species hit lows in the mid- to late1980s, they report. Since then, marbled rockcod began to slowly regain a foothold. Humped rockcod, on the other hand, haven’t crept back, but they also haven’t dropped off further.

Both species, however, have a long way to go, the researchers conclude. It could take an extra 20 years for the fish to experience a full renaissance. And the rockcod’s fate, they argue, provides a good reminder to scientists that it’s important not to hesitate when it comes to the Antarctic: “Close attention using scientific monitoring, as well as basic life history research, is required to exercise effective management.” Daniel Strain | March 6, 2012

Source: Marschoff ER et al. (2012) Slow recovery of previously depleted demersal fish at the South Shetland Islands, 1983-2010. Fisheries Research. DOI: 10.1016/j.fishres.2012.02.017

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