Global fishing feet grows as catch falls

Harvest measured by CPUE is declining

A new analysis of global fishing data by researchers in Australia and Tasmania concludes that the global fishing fleet doubled in size from 1950 to 2015, but that for the effort expended the harvest fell over 80 percent.

The study by researchers from Commonwealth Scientific and Industrial Research Organisation and the University of Tasmania, published in the journal Proceedings of the National Academy of Sciences, says the global fishing fleet grew from 1.7 million vessels over that 65-year period to 3.7 million vessels. CSIRO is Australia’s national science agency. The study was also reported at Eurek Alert, the online journal of the American Association for the Advancement of Science.

Meanwhile despite improved technology and ship engines, modern fishing vessels take only one fifth of the catch per unit of effort than that achieved by the fleet in the 1950s, their researchers said.

“What we have seen over the last 65 years is more and more fishing vessels chasing fewer fish,” said Yanick Rousseau, a doctoral student at the University of Tasmania who led the study. “Since 1950 a dramatic increase in the size of the fishing fleet in Asia has more than off-setting small declines in North America and Western Europe.  Most of the increase in vessel numbers has been in motorized fishing boats, a change from the unpowered artisanal fishing vessels that once characterized Asian and African fishing fleets. But despite its advanced technology and increased numbers, the modern motorized fleet is having to work much harder to catch fewer fish.”

Rousseau noted that fisheries scientists use the measure of catch per unit of effort, or CPUE to assess fisheries management and the health of fish stocks.

“In recent years a sharp drop in CPUE in Southeast Asia, Latin America and the Southern Mediterranean indicates their fisheries expanded at a much faster rate than fish stocks could support,” he said.

Researchers found that in developed countries like Australia more effective fisheries management and a sharp drop in the size of the fishing fleet over the last decade has led to recent stabilization of CPUE. Still on current worldwide trends “we can expect to see a further one-million vessels on the water by mid-century and the average engine power of the global fleet continues to increase,” he said.  “These changes will further challenge the sustainable use of fisheries resources in coming years.”