Deepwater fish face extinction

It's not just cod that are being driven to extinction by overfishing, now experts believe that a number of deepwater species are facing the same threat.

Experts believe that the decline in catches of popular food fish, such as cod, and the introduction of tighter quotas to limit the amount of fish landed has led to trawlers going offshore to catch other species in deep waters.

New research published by Canadian fisheries scientists working at the Memorial University in Newfoundland has provided evidence to suggest that five Atlantic species found in deepwater may be approaching extinction due to overfishing.

Their paper, which was published in the journal Nature this week says that the current fishing methods used are unsustainable and that several species could become extinct unless changes are made to fishing patterns.

"There is a real danger that slow -growing, deepwater species will take centuries to recover from current fishing, if they can at all"The scientists wrote: "Our results indicate that urgent action is needed for the sustainable management of deep-sea fisheries.

"There is a real danger that slow -growing, deepwater species will take centuries to recover from current fishing, if they can at all."

Population doubling timeThe study focused on five deep water fish species found in the North Atlantic Continental Slope: the Roundnose grenadier (Coryphaenoides rupestris); the Onion eye grenadier (Macrourus berglax); the Blue hake (Macruronus novaezelandiae); the Spiny eel and the Spiny tail skate.

Many of the species at risk are members of the Macrouridae family, such as the Roundnose grenadier, Coryphaenoides rupestris, which reaches around 1m/39" in length and can live for over 50 years.

Like other fishes found in deep water, most macrourids have a low mean population doubling time, and this species does not spawn until it is between five and 15 years old. The fear is that many deep water fishes are being captured before they have had an opportunity to reproduce, which is leading to a decline in the population sizes.

All of the most at risk species are large fishes, reaching around 1m/39" in length, all mature late and all have a low mean population doubling time, which the experts believe puts them at immediate risk of extinction.

For more information see the paper: Devine JA, Baker KD, Haedrich RL. (2006) - Fisheries: Deep-sea fishes qualify as endangered. Nature. 2006 Jan 5;439(7072):29.