Posted by David Itano
27 June 2012
David Itano is a fisheries research associate with the Pelagic Fisheries Research Program at the University of Hawaii and is currently serving as a principal investigator during the western and central Pacific Ocean cruise of the ISSF #BycatchProject. He is currently onboard the Cape Finisterre, a 1500 GRT tuna purse seine tuna fishing vessel operating in the western Pacific.
We are now on the second and final leg of our cruise, operating in the area of the northern Tokelau and southern Phoenix Islands (Kiribati) EEZs. By the way, we are grateful to have received research permits to conduct this cruise from the Solomon Islands, Kiribati, Tuvalu, Tokelau and the Cook Islands. These countries recognized the importance of this research and their support is greatly appreciated by ISSF and Tri Marine.
Since leaving Pago Pago eight days ago we have made nine sets, catching over 550 tons of tuna and have made careful diving observations of the release panel during every set. We have not lost any tuna out of the release panel. However, after the first couple sets, another line was installed that allows the panel to be raised up and closed by a crewman in a workboat/towboat of the type used by WCPO purse seiners to tow FADs and logs. What have we learned in so far? Basically, the following: 1) tuna or non-target species will not try to “sneak” out the edges of the panel; 2) with a little practice, the panel can be quickly released and then raised back up; 3) tuna generally remain deeper in the net and will not approach the escape panel in small to medium size sets; 4) sharks and bycatch species can be effectively released from the panel if conditions are favorable; 5) there is no relationship between the number of sharks and bycatch species on a FAD to the size of the associated tuna school; 6) the sharks and bycatch will not always end up in a favorable position to be released; and 6) each set is different and we need to do more trials under different conditions (current speed/direction, skiff pulling speeds, water clarity, set sizes, species mixes).
So far we feel the jury is still out on how effective this release panel may prove to be, but we feel it is definitely worth pursuing. shows the release panel location between the large red floats and the workboat about to release the line that opens the panel. When it is working most efficiently the net is virtually pulled out from under the non-target species that tend to mill in circles at or near the surface of the “pocket”. In this respect, the concept is similar to the “backdown” procedure developed by Captain Harold Medina to catch large yellowfin tuna while safely releasing dolphin. This concept was then tested, refined and promoted through scientific observation, training and collaboration between the IATTC, NMFS and the US tuna industry.
This example reminds us that nothing works perfectly the first time out and that the most effective and practical solutions to fishery issues are those that have been developed when fishermen and scientists team up to address a common goal. Right now we feel that this cruise, with highly experienced fisheries scientists in the net is the best chance we have to observe and document the reaction of tuna, sharks and other fish to the “release panel” concept. We will continue to test, observe and document the operation of the panel under different conditions during the remainder of the cruise.