February 21, 2018 — CORVALLIS, Ore. – Savvy Northwest anglers have long known that when patches of warm Pacific Ocean water drift closer to shore each summer, it’s time to chase after the feisty and tasty albacore tuna.
Now a new study confirms that tuna are more likely to be found in regions of the California Current System with certain oceanographic conditions – and that commercial fishermen who work those areas more frequently bring in up to three times the revenue of other tuna anglers.
Results of the study, which was supported by the National Science Foundation and led by Oregon State University, were published today in the journal Frontiers in Marine Science.
These oceanographic conditions are more complex than simply being warmer temperatures, said James Watson, an OSU marine ecologist and lead author on the study. Their technical name is Lagrangian Coherent Structures, though scientists often refer to them as “the skeletons of the sea.”
“Essentially they are physical ocean fronts where surface waters converge,” Watson said. “If you toss two tennis balls in the water and they converge quickly, it is considered a Lagrangian Coherent Structure, or LCS.”
“What we’ve found is that the stronger the convergence, the more likely it is to attract certain things, beginning with the aggregation of phytoplankton, which in turn attracts larger organisms like tuna – and, ultimately, tuna fishermen.”
The researchers sought to discover whether anglers were utilizing these LCSs and if so, whether it had an economic impact. They compiled data from a vessel monitoring system on the location of more than 1,000 fishing vessels every hour in the U.S. California Current Large Marine Ecosystem for a four-year period – a total of more than 340,000 trips. They then collected fisheries catch and price data.