Department of Primary Industries (NSW), Lord Howe Island Marine Park News, The Lord Howe Island Signal

Members of the Project Kingfish research team visited Lord Howe Island last December 2022 to kickstart research on the local kingfish population. Project Kingfish is a research program funded by the NSW Recreational Fishing Trust. The program aims to enable collaboration between scientists and expert anglers to improve understanding of the East Australia yellowtail kingfish stock.

Yellowtail kingfish (Seriola lalandi) are highly mobile marine predators that occur in coastal and offshore pelagic waters along the entire southern seaboard between Queensland and Western Australia, including Tasmania and offshore islands such as Lord Howe Island. Major knowledge gaps currently exist about the status of the ‘Eastern Australia’ biological population (which spans SA, VIC, TAS, NSW, QLD and NZ), the distribution and behaviour of reproductive individuals, the location of key spawning habitats and how the species recruits to the coast.

With help from recreational anglers, long term tag-and-release programs such as the NSW Game Fish Tagging Program have revealed a level of connectivity of kingfish between states across mainland Australia, as well as offshore sites such as Lord Howe Island and New Zealand. However, the frequency of such long-distance movements and the whereabouts of spawning-sized kingfish (>95 cm total length) between release and recapture remain a mystery. Using state-of-the-art satellite tracking technology and ocean microchemistry, Project Kingfish aims to fill these knowledge gaps.

With the assistance of Lord Howe’s very own expert anglers Scott Wilson and Grant Devine, the research team successfully deployed five satellite tags on large, sexually mature kingfish. These tags were programmed to remain attached to the fish for either 3 months (3 tags) or a full year (2 tags). During that time, each tag is programmed to gather information on the fish’s location, swimming depth and sea temperature. Following release at a programmed date, the tags are expected to surface and transmit the collected data to the research team via satellite.

Since the tags were deployed in December, two of the satellite tags successfully detached after 3 months and transmitted the data collected, allowing the team to reconstruct the most likely movement track of each fish and get a first peek at their behaviour. Both fish remained around Lord Howe Island after being released, with regular excursions off the Lord Howe shelf and beyond the boundaries of the NSW and Commonwealth marine parks. Unfortunately, one tag did not transmit sufficient data to gather insights into its behaviour. The remaining two tags have now been deployed for 9 months and are programmed to detach in December 2023. The team is crossing its fingers for successful data transmission to reveal what these two kingfish did over an entire year!

If you see or capture one of the satellite tagged kingfish, we kindly ask that you release the fish to help enhance our understanding of the Lord Howe kingfish population. Please contact the research team at project.kingfish@sims.org.au to report any catch or sighting of the tagged fish.

During the previous trip, the Project Kingfish team also received overwhelming donations from local anglers Scott Wilson, Grant Devine, Jack Shick and Alasdair Nicholson. A total of 90 kingfish heads or frames were donated, allowing the team to extract the following biological samples.

• Genetic samples from each fish frame or head donated.
• Ear bones (otoliths) from 64 heads, allowing the team to determine the sea temperature at birth for those fish.
• 30 gonads, providing insights into the sex ratio and state of maturity of each fish.
• 37 full stomachs, providing the first scientific insights into the diet of kingfish.

The research team welcomes additional donations of kingfish frames during their upcoming visit in December 2023 to collect further biological samples.

Congratulations to all anglers who have tagged kingfish as part of the 2023 Lord Howe Island Biggest Kingfish Prize so far. Grant Devine is currently in the lead with an 86 cm (fork length) kingfish. Make sure to register with the LHI Game Fishing Club and tag and release kingfish for your chance to win a share of over $3,000 worth of prizes! Winners will be announced in December during the Project Kingfish team’s next visit.

Tagging kingfish with conventional streamer tags is key to monitoring their long-term and broad-scale movement patterns, beyond the life of satellite tags. To date, a total of 310 kingfish have been tagged at Lord Howe Island since 1973, as part of the NSW Game Fish Tagging Program. Despite this tagging effort, none of these kingfish have been reported to be recaptured anywhere.

However, 3 kingfish tagged in coastal NSW, coastal Victoria and New Zealand were reported to have been recaptured at Lord Howe Island over the years. These reports provided crucial insights into the key role that Lord Howe Island may play in ensuring the connectivity of kingfish populations across the Tasman Sea.

If you happen to catch a tagged kingfish, please remember to report the recapture event to the NSW Game Fish Tagging Program, to provide further insights into kingfish connectivity across their range.

The team wishes to thank the Lord Howe Island community for their warm support of this research and looks forward to sharing more results in the coming months.

This article appeared in The Lord Howe Island Signal, 31 August 2023.