Warmer seas bad news for threatened abalone and coastal economies

By Colin Ricketts - 26 May 2011 13:0:0 GMT
Warmer seas bad news for threatened abalone and coastal economies

Despite the efforts of fisheries authorities to protect them from overfishing, the northern abalone could be wiped out by poaching and increasing ocean acidity caused by climate change.

The northern abalone lives along the North American west coast from Baja California to Alaska and is prized as a delicacy. In order to protect the species from overfishing, British Columbia closed all commercial fisheries exploiting the species as far back as 1990, however, poachers continued to threaten the species' viability.

Now University of British Columbia (UBC) researchers are examining how climate change will affect this species, particularly as ocean acidity increases. UBC researchers tested the effects of increased levels of CO2 on northern abalone larvae finding that raising CO2 from 400 to 1,800 parts per million killed 40 per cent of larvae, decreased the size of larvae that did survive, and increased the rate of shell abnormalities.

''This is quite bad news, not only in terms of the endangered populations of abalone in the wild, but also the impact it might have on the prospects for aquaculture and coastal economics,'' says Christopher Harley, Associate Professor with the Department of Zoology and one of the authors of the study.

''And because the species is already thought to be limited by reproductive output and recruitment, these effects are likely to scale up to the population level, creating greater limits on population growth.''

Currently, CO2 levels in the open sea are around 380 parts per million. This is expected to rise and researchers have already reported much higher localised levels in areas and at times where and when northern abalone spawn.

The study, which is published in the latest issue of the Journal of Experimental Marine Biology and Ecology, may also point to problems for related species worldwide according to lead author Ryan Crim.

Abalone are commonly farmed, especially in Asia, while off the north American west coast only the red abalone remains as an economically viable food species.

The UBC team plan to expand their work to study other commonly farmed marine species, including oysters.