October 11, 2019 — The following is an excerpt from a story originally published by Sustainable Fisheries UW:
Over the last week there have been multiple news stories saying that we are harvesting tunas at unprecedented and unstainable rates—some stories have implied that tunas are on track for extinction. This is simply not true. Most of the time, catches are not a reliable indicator of abundance.
The news articles were based on a recent paper that showed that global catches have increased more than 1,000% over the past 60 years. That statistic sounds large and scary, but it is the poor understanding of how fisheries develop that is scariest.
Fisheries develop, just like other products and industries
The increase in tuna catches reflects the classic behavior of any developing fishery. Throughout history, catches increase until they level out or until they start declining because of two potential reasons: 1. abundance of populations goes down and therefore with the same fishing effort catches go down, or 2. fisheries management is put in place to reduce fishing effort and therefore catch goes down. In the case of industrial tuna fisheries, it is not surprising that tuna’s catches increased since 1950, because this is when these fisheries started.
Global catches of large commercial tuna species from 1950 to 2017. SKJ = skipjack tuna, BFT = bluefin tuna, BET = bigeye tuna, ALB= albacore tuna. PBF= pacific bluefin tuna, SBF = southern bluefin tuna. Updated from: Pons et al. 2017. Effects of biological, economic and management factors on tuna and billfish stock status.
Moreover, recent catches are not increasing very fast. In 2017, total tuna catches were only 18% higher than in 2000. Most of this increase was generated by an increase in skipjack tuna catches, the most productive of all the major tuna species. Further, skipjack are fished at sustainable levels in all Oceans (see figure below). Are we driving skipjack tuna to extinction or even overfishing them? Definitely not.