Mexico closes down bluefin tuna fishing for rest of 2014

By JIM MATTHEWS www.OutdoorNewsService.com Mexican officials announced early this past week that it was closing down the commercial and sportfishing season for bluefin tuna for the remainder of 2014, and the news immediately caused an uproar within the sportfishing community in Southern California just as the second season in a row of phenomenal bluefin fishing for the San Diego-based sportfishing fleet was kicking into high gear. While Mexican officials have not explained why they closed the season for both sport and commercial fishing, it has been speculated that the move was made after a new assessment of the Pacific bluefin population was made by the Pew Chartiable Trusts and released in April this year. (You can read the report at this direct link: http://isc.ac.affrc.go.jp/pdf/Stock_assessment/PBF_2014_Exec_Summary_4-28-2014_gtd.pdf.) The press releases about the April report were released July 11 and were widely published in mainstream media, and it was almost immediately after that Mexico announced its closures. And why not? Here’s the opening paragraph of the press release: “Pacific bluefin tuna are in trouble. After decades of overfishing, the population hovers at just 4 percent of its original size, and the unsustainably high catch of juveniles -- the smallest fish -- threatens the species’ continued existence.” I have a problem with the press release and the report itself. I don’t doubt the Pacific bluefin tuna has been fished to the point that its current stock is somewhat below “its original size,” but I was unable to find any scientific data to support the four-percent number. That appears to be some estimate based someone’s guess of what the original population size might have been based on someone else’s estimate of what historical commercial catches were earlier in this century. In other words, the four percent number is pulled out of high elevation air. This is a scare tactic and nothing more. But the data in the report is rock solid. It is based on commercial catch rates reliably reported since 1952 by most countries that commercially fish bluefin. But the interpretation of this data, in my mind, is about as sketchy as the four-percent number. For example, the catch rate in 1952 is not much different than the catch rate data for 2012, the last year of data analyzed and compared to previous years. The catch rate has been lower several years in between, often with the catch rate skyrocketing after the low catch period. If you look at all the graphs of the catch rates during the past 60 years, it appears the population of bluefin has been fairly stable, with population peaks and valleys, but no steady, long-term overall decline. The concern is that the majority of the spawning adults are reaching the end of their productive years and that the catch rate on juvenile fish is so high few fish are reaching spawning age. All analysis is based only on the commercial catch. There has been no attempt correlate or analyze any other variables that might affect the catch rate, why more juveniles are being landed, or the bluefin’s overall population. Pew suggests that fewer than 40,000 adult bluefin weighing more than 44 pounds remain in the Pacific, and that the catch rate of juveniles threatens the species very existence. Pew wants a 44-pound minimum size placed bluefin catches, assuring that the juvenile fish are protected and allowed to reach adult, spawning-age size. The ironic part of this report – and again, I want to emphasize that it only used catch data through 2012 – is that the catch of bluefin tuna the past two years has skyrocketed for the San Diego sport fleet. Many of these fish were right at or above the 44-pound minimum size suggest by PEW, which would suggest that recruitment of juvenile fish into the older age class has been exceptional in recent years. The fleet has also been seeing, hooking, and mostly losing large numbers of bigger bluefin from 80 to 120 pounds. Catch data can definitely point to long-term trends in populations, but using only catch-rate data can paint a skewed picture of the bluefin population, especially when management decisions are made two to three years behind current data. By not looking at other factors impacting the population or fishing success, and by making recommendations without the most current data allows you to make changes that may not apply to today’s bluefin population. The San Diego sportfleet’s catches and observations suggest this is indeed the case for bluefin tuna. The last point I want to make is simply that sport-caught fish represent a very small percentage of the bluefin tuna catch and that closing down the sport-fleet, which has been targeting bluefin at or near the 44-pound minimum suggested size limit by the scientists, is senseless. Why gore an ox that is currently meeting the management suggestions? Mexico needs to reopen the sportfishing season for bluefin. END

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