Posted by admin | 09.08.2011 | Conservation, Marine Science

Reeling in the Deep

Life in the deep sea is difficult. Light rarely penetrates, making photosynthesis virtually obsolete. The temperature is cold, sometimes a few degrees above freezing. The pressure limits species’ body plans. Life is scarce, so food and mates are hard to come by. Therefore, it shouldn’t be surprising that life proceeds slowly at depth.

What is surprising is that despite the slow production, human exploitation of deep sea fishers has been occurring at an increasingly rapid rate. When coastal fisheries became over exploited in the 1970s, fishermen began searching further from shore for catch. They use trawls to scour deep sea habitats for commercial fish and in the meantime do tremendous damage to the habitat through destructive practices, overfishing, and bycatch.

The species residing at depth are long lived and therefore take a long time to reach maturity – orange roughy can live to be 125 and some deep sea corals are over 4,000 years old. This is why an international group of marine scientists are calling for an end to commercial fishing in the deep sea. Since these populations are unable to repopulate successfully due to fishing pressure, these fisheries are not sustainable. Orange roughy provide the best example.  Fishing began in New Zealand and once those stocks were depleted fleets moved on to Australia, Namibia, southwestern Indian Ocean, Chile, and then Ireland – all in 20 to 30 years.

Management of these fisheries is exceptionally difficult as they reside in the “high seas” an area beyond the control of any single government. Some of the marine scientists think that deep sea trawler subsidies should be redirected to make it disadvantageous to fish the high seas – trawlers receive $162 million year from governments to support their industry. Regardless of the measures used, the one certainty is that the delicate deep sea habitats will not be able to withstand this assault much longer.