Steve Hall biopsy sampling a ‘Short Sunfish’ or ‘Southern Sunfish’ (Mola ramsayi) caught and released
They’re big, they’re heavy, and they’re not the prettiest fish in the sea, but don’t tell that to the ocean sunfish. These large, enigmatic and little studied fish have been the focus of a 12 month biopsy sampling program headed by Prof Neil Loneragan and PhD candidate Marianne Nyegaard at Perth’s Murdoch University.
For the last 12 months, our Tuna and Billfish Longline Fisheries Observers have journeyed all the way from northern Queensland to southern New South Wales, taking tissue samples from sunfish. They catch the fish with a line and then use a 3m long pole mounted with biopsy heads, then once the sample has been taken the fish are released alive. It’s not an easy feat considering the size of some of these fish – average adult weight can reach in excess of 1,000kg!
“Their thick skin is tough and leathery, with a several centimeters of connective tissue underneath” Ms Nyegaard said “judging by how many sunfish swim around with healed-up propeller scars and shark-bite-sized bits missing, the shallow biopsies pose little threat to their overall health”.
The study has been focusing on genetic population connectivity between Indonesian and Australian sunfish and look at the relationship between sunfish caught on the east and west coasts of Australia.
“The observers have been absolutely fantastic and their hard work has really paid off” Ms Nyegaard said.
“The support and patience of the longline skippers and crew have been a crucial aspect to the success of the project, and I am very thankful for their cooperation. On a management level, the project would not have gone ahead had it not been for the support of Mike Yates, Observer Program Manager, and Steve Hall, Observer Program Regional Coordinator. They tirelessly coordinated the sampling, sent countless emails discussing logistics and progress, and shared the sunfish enthusiasm with me. These guys took the ball and ran with it, and it has been an absolute pleasure working with them”.
Ms Nyegaard has just completed the first stage of the genetic analysis, and is excited about the preliminary results that have enabled the better identification of sunfish species interacting with Australian Fisheries.
Ocean sunfish are caught as by-catch in the longline fishery for Tuna and Billfish across Australia and New Zealand, and are released alive. They can grow to impressive sizes, with one individual found off New South Wales in 1907 measuring 3.1m. The sunfish caught in the longline fishery are, however, typically much smaller.
The biopsy sampling project was actively supported by the AFMA Observer Program, as sunfish are one of seven bycatch species listed as potentially being ‘at risk’ in AFMA fisheries because there is so little known about them.
For more information please contact Mike Yates, Observer Program Manager, on 02 6225 5332 or mike.yates@afma.gov.au.