CAMBRIDGE, U.K.--In a good year, squid fishers haul up to 300,000 tons of squid out of the South Atlantic ocean, one of the world's largest squid fisheries. But this year is shaping up to be the poorest year since record keeping began in 1987. That's dismal news for squid fishers and calamari aficionados--but no surprise to a team of scientists who predicted the dearth of squid off the Falkland Islands using information about ocean currents and temperatures 8 months ago.
The larvae of the Argentinean flying squid hatch near the River Plate estuary, off the coast of Argentina, every year in July. After maturing, the squid swim several hundred kilometers south to cooler, plankton-rich waters near the Falkland Islands, where international fishing vessels normally catch them in great numbers between February and June. Those that elude capture attempt to return to their breeding grounds, where they spawn and die.
The fact that the population goes from larvae to fully grown adults in only a few months makes sampling and predictions based on the previous year's catch difficult. So Paul Rodhouse and Claire Waluda, marine biologists at the British Antarctic Survey here, developed a model based on ocean currents and temperatures in the nursery region, and they discovered two factors known to strongly affect the final population size. Last July, temperatures were 1.5° Celsius warmer than average, driving a shift in currents that swept larvae into the open ocean. Using their model, the duo predicted a catch of 73,000 tons this year, near the bottom of an annual catch that fluctuates wildly between 60,000 and 290,000 tons a year. The reality was even bleaker: With only a few weeks to go this season, the haul has barely reached 10,000 tons--a severe economic loss considering that the squid fetches $3000 per ton.
Although overfishing is not to blame for this year's appalling catch, the model's success may help fishery managers cope with future disastrous years, for example, by suggesting in advance how many vessels should be licensed, says Rodhouse. This type of model could work for other fisheries--such as a squid fishery off the coast of South Africa--that are susceptible to the vagaries of currents, says Jean-Paul Robin, an expert on cephalopod fisheries at the University of Caen, France.