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Tender Vessels Can Increase Purse-Seiner Performance In 50%, Says Report

A report entitled Analysis of Auxiliary Vessels Activities in the Atlantic Ocean and Their Effect Over the Performance on Cold Storage Tuna Boats concluded that auxiliary vessels, better known as tender boats, can increase fishing efficiency of tuna purse-seiners by 50%.

The document has many researchers as authors and it was published among the collective volume of scientific papers of the International Commission for the Conservation of Atlantic Tunas (ICCAT) in 2001.

According to the report, a tuna vessel without any tender boats spends over 70% of its time searching for fish schools, while vessels with auxiliary boats invest less than 50% of their time in such activity.

While most of the tender boats act as searching for Fishing Aggregating Devices (FADs) and ride in a similar route to tuna seiners and longliners, anchored vessels – another category of tender boats – are stationary, serving as FADs themselves.

“(…) when we compared the time invested by tuna boats with and without tender vessels, we could observe that the ones working with tender vessels spend more time placing, modifying and collecting their own objects (FADs). This information makes sense if we assume that, in general, tuna boats in association with tender vessels will have a larger number of objects (FADs) than boats without them”, the report states.

This basically means that technology is a constant stimulator for boat owners to catch more. Nowadays, devices such as sonar, helicopters and tender boats increase exponentially tuna fishing efficiency.

The report concludes that skipjack and bigeye were the two species more affected by the use of tender boats. This was no surprise considering a larger usage of FADs in their capturing.

The Inter-American Tropical Tuna Commission (IATTC) is the only tuna RFMO to have forbidden tender vessels related to tuna fishing in the Easter Pacific Ocean since 1999. Even though it’s considered one of the many methods that increase tuna boats’ efficiency by the Commission, the decision was not made based on any scientific study.