The overall population of tuna and mackerel has declined 60 percent in the world’s oceans since 1954, according to a study by a multinational group of researchers.
The research was reported in the Proceedings of the National Academy of Sciences. In all, 26 populations of fish were studied. They included 17 tuna populations, five mackerel populations and four populations of Spanish mackerel.
“The steepest declines are exhibited by two distinct groups: the largest, longest lived, highest value temperate tunas and the smaller, short-lived mackerels, both with most of their populations being overexploited,” said a summary. The remaining populations, mostly tropical tunas, have been fished
down to approximately maximum sustainable yield levels, preventing further expansion of catches in these fisheries, the report said.
The population of cold water tuna, including the red tuna of the Atlantic, have decreased 80 percent over the last 50 years, said the report. About 12.5 percent of the tuna population is caught each year, it estimated.
To guarantee higher catches, stabilize profits, and reduce impacts on marine ecosystems requires the rebuilding of overexploited populations and stricter management measures to reduce overcapacity and regulate threatening trade, the study said.
The lead author was Maria José Juan-Jordá of the Universidad de A Coruña, Spain.