NZMRF
Figure 3: The global distribution of southern bluefin tuna catch for two time periods. The size of the circle increases with higher catch. The only known spawning area is in the Indian Ocean, southeast of Java, Indonesia (red star).
Challenges for anglers There will be considerable interest in the southern bluefin tuna fishery off the east coast of the North Island next winter. Anglers will be looking forward to the challenge of finding and fishing schools of large tuna, and social media will quickly spread the word.
However, there is no guarantee that the fishery in 2018 will the same as it was this year. The fish may be a lot further offshore, the weather conditions could be worse and some less experienced people may try their luck. Boat owners are responsible, so they need to be prepared to ensure the safety of the crew, as well as quickly provide assistance if boats around them get into trouble. Another challenge is to release more of the catch. Satellite tagging in Australia has proven good survival of southern bluefin of all sizes. Longer fight times did not increase mortality, but deep hooking did. Release all fish alongside the boat. If the hook can be seen, removing it with a de-hooker on a pole is best. Fish as a team and share any fish you keep. Yes, they are good eating, but how long will it take your family to eat 50kg of sashimi or steaks, and how many months will it spend in the freezer?
We have a remarkable opportunity to access high quality fresh tuna from a stock that is still recovering from a very low level. Treat each fish with the respect it deserves and look after the fish you keep. It is best practice to land them on a cool, soft surface. Dispatch the fish quickly by spiking the brain, iki jime style. This is better for the welfare of the fish and also stops the fish moving (which can cause the flesh to heat up and reduce its quality). Bleed the tuna by making a deep cut behind the pectoral fin on both sides to reduce the amount of blood retained in the flesh. The more blood that is released, the milder the resulting flavour. Poorly-bled bluefin tuna are often too rich in taste for most people. The IGFA now allows spiked and bled tuna to be weighed within its rules. Chill your fish quickly with salt ice and protect it from the sun. NZSFC and LegaSea will be developing some recommendations about voluntary recreational limits on southern bluefin tuna landed catch, and hope to discuss these aspects with clubs in the near future. 19  www.nzsportfishing.co.nz