July 16, 2017
By Dr. Corey Green, Fisheries Scientist, Fisheries Victoria
Recreational anglers are taking advantage of exceptional opportunities to target gamefish along Victoria’s coastline. Landing southern bluefin tuna, albacore and swordfish in small boats is no longer a rare occurrence. Similarly, yellowtail kingfish have once again become a popular target species over summer and offer an alternative to snapper, whiting, calamari and flathead.
Victoria’s yellowtail kingfish have made a resurgence since their demise in size and numbers during the early 1990s. Since around 2010, targeting yellowtail kingfish increased in Victoria and a wide size-range of fish were reportedly taken.
Targeting kingfish at the Rip in Port Philip Bay
Research required to effectively manage such a popular species has been applied to fish caught off New South Wales (NSW) and South Australia (SA), however in Victoria, basic population characteristics are largely unknown. Information such as spatial and temporal stock, spawning age and growth data are basic knowledge requirements used to assess the status of fish populations like kingfish. This information helps us understand the productivity of the fishery and improve our management strategies.
Funded by Victorian recreational fishing licence fees, the objectives of this two-year project are to:
- Determine whether yellowtail kingfish caught in Victorian waters are from a single or multiple stocks;
- Define population characteristics (age and growth, size structure, spawning characteristics) of Victorian yellowtail kingfish;
- Determine the future potential of this fishery using historical recreational catch information;
- Trial the use of satellite tags as one method to understand movement characteristics (spatial, depth, temperature preference); and
- Trial otolith chemistry analyses as a method to investigate yellowtail kingfish temperature preference.
Dr. Corey Green from Fisheries Victoria dissecting a kingfish head to remove the otoliths
The success of this research project is largely due the involvement of recreational anglers and the charter boat industry. Scientific clerks (Scott Gray and Tara Hicks) have actively liaised with both groups to obtain catch statistics and collect more than 450 kingfish frames. All frames have been dissected, otoliths (earbones) removed for ageing and reproductive conditions assigned.
Researchers from NSW and Tasmania have collaborated with Fisheries Victoria to define the genetic stock structure. Initial results reveal they are likely a single stock, which is indicative of a species that move large distances and whose eggs are larvae, distributed widely by oceanic currents. It is well known that kingfish are fast growing, so it will be interesting to analyse growth information, compared with fish from other states, and determine their size at maturity.
During May 2017, a ‘rat’ kingfish (about 65 centimetres long) was satellite-tagged off Julia Percy Island (near Port Fairy). The tag is set to be automatically released from the fish at the end of June and may indicate whether kingfish move from Victorian waters during winter. It will also show depth and water temperature preferences during its time at liberty.
Full results will be provided at the end of 2017. For more information contact Dr Corey Green, the study’s lead fisheries scientist on T: (03) 5258 0275 or E: [email protected]
