Hi everybody! Last month I returned from my last trip at-sea here in southern Brazil, on board a pelagic longliner. The cruise was amazing, and in addition to the success in obtaining data on our mitigation measure research, I experienced incredible and magic moments.
The fishing area was the continental slope in the southernmost part of Brazil, just adjacent to Uruguayan waters, between 300-100 m deep. The target fish species for the trip were tunas. We conducted eight longline sets (four with tori lines and four without) during which were deployed a total of 6,180 hooks (between 500 and 1,210 hooks per set).
Fortunately there were no seabirds caught during this trip, even during a daylight set without the tori line! My impression was that it was due, in part, to the low seabird abundance - less than 20 birds per set - and to the fact that the other tree sets without a tori line were performed at night. This minimizes the chances of bycatch.
However, another detail may also have contributed to the low seabird bycatch: the way the bait was hooked. On this vessel the crew prepare the hooks depending on the bait. This includes attaching bait to the hook by inserting the barb through:
Therefore, instead of taking the entire hook with the bait, the birds were able to remove the baits from the hooks without becoming snared themselves.
During this daylight set without the tori line I watched several seabirds taking baited hooks, hoping none was captured, and to my great relief, all the birds managed to steel the bait without becoming hooked.
Below: Observing the daylight set from the aft-deck
Despite this interesting observation, the way bait is hooked should not be interpreted as a mitigation measure. It’s important to clarify that the mitigation measures must keep the seabirds away from the baited hooks in the first place!
During this cruise I also collected more data comparing sink rate of baited hooks under different configuration of fishing lines, and the presence or absence of battery-powered fishing lights.
All of this was carried out in some extreme weather that we have become used to experiencing during our fishing trips. One day the weather was so good I was able to jump in and snorkel around the vessel (don’t try this at home!). To my surprise a pod of common dolphins appeared, swimming with me around the vessel. Three days later we were facing a storm with 100 km/h winds and 8-9 m waves (Beaufort 10).
Below: A storm rages at-sea in Brazil
Three days later the storm had subsided and the sun returned with the sea like a mirror. For me, snorkelling in the deep blue among 50 common dolphins was one of the most exciting experiences I've had aboard, highlighted only by the beauty of a powerful storm in the south west Atlantic!
Below: Dolphins accompanying the fishing vessel