By Atuna.com
Purse seine fishing on tuna-dolphin associations was given the “green†go-ahead by ISSF scientists in their 2012 technical report.
According to the ISSF Scientific Advisory Committee, the “green†rating means the fishing tactic is safe to use because it is not expected to negatively impact the population of by-catch species.
The International Seafood Sustainability Foundation (ISSF) is a global coalition of tuna industry leaders, scientists and environmentalists. All ISSF participating tuna companies are certified “Dolphin Safe†by the Earth Island Institute, an organization that says fishing on tuna-dolphin associations results in a very high by-catch of dolphins and therefore should be avoided.
Dolphins only swim with yellowfin tuna in the Eastern Pacific Ocean (EPO). Twenty years ago, there was an enormous mortality of dolphins, but purse seine fishermen have since learned to set their nets on these associations with minimal harm to the dolphin species. The development of new catching techniques has made it possible to release the dolphins alive after a set, while retaining the tuna, says ISSF in its report.
It continues to mention that the Inter American Tropical Tuna Commission (IATTC) estimates the number of dolphins killed has declined by 98% since the late 1980s. The total mortality of dolphins in the fishery was reduced from about 132,000 in 1986 to less than 1,200 in 2010. However, some scientists believe there is an unknown level of mortality occurring after dolphins are released, due to stress.
According to the ISSF report the Agreement on the International Dolphin Conservation Program (AIDCP) aims to reduce the number of dolphins killed in the EPO fishery by establishing annual mortality limits for each stock. There is 100% observer coverage on all large purse seiners so the incidental deaths can be properly reported. Once the maximum limit has been reached, a vessel must stop setting on dolphin associations for the rest of the year. The 2011 dolphin mortalities were far from hitting the limit, reaching only 25% of what was allowed conclude ISSF scientists.
The ISSF scientists also rated purse seining on free schools as “green,†while purse seining on fish-aggregating devices (FADs) and pole-and-line fishing both received “yellow.†A “yellow†rating means harmful population effects on by-catch species are expected, but the scientists find that there are management measures or research programs in place to mitigate these effects, and that also adequate monitoring of by-catch is being implemented.
While the by-catch of non-target species is not a concern with pole-and-line fishing, the method does rely on the use of live baitfish to lure the tuna. There is currently a lack of data on the potential negative effects of fishing on these baitfish stocks, resulting in an orange rating.
Longlining was rated “orange†due to the high levels of by-catch associated with the fishing method, including sharks, sea turtles, sea birds, and other finfish.