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

Researchers Jonathan Mitchell and Victoria Camilieri-Asch from The University of Western Australia recently completed the final report for the Lord Howe Island (LHI) Galapagos shark research project, which has been running since January 2018.

This research used acoustic listening stations around LHI waters to track Galapagos sharks fitted with internal acoustic tags to determine their movement patterns, as well as identifying where, when and how frequently these sharks interact with fishing vessels. These interactions can have negative impacts, not only for fishers because the sharks eat their bait and hooked fish, but also for the sharks because they often get caught, injured or killed in the process. By learning more about the movements of the Galapagos sharks and talking to fishers about their experiences, the project aimed to identify ways to reduce these mutually-negative interactions.

Main findings

• The tracking indicated that tagged Galapagos sharks were present in Lord Howe Island waters across the whole three-year study period, although they showed greater activity in spring and early summer months.
• Home range sizes varied from 1.6 km² – 1342.6 km² (496 km2 on average), and shark presence was higher at locations near shelf edges in the north-east and south-east parts of the LHI shelf and the northern edge of the Ball’s Pyramid shelf. Their presence in these areas was linked to prey availability, current patterns and the occurrence of fishing activity.
• Four sharks were also found to be highly resident at a site where fish were cleaned regularly in the past, suggesting that this availabilty of food may have led to them spending more time in this location, along with favourable environmental conditions.
• Only one tagged shark was found to move a long distance, from the West LHI shelf where it was detected by a listening station on 30/11/2019 to 20km offshore from Port Stephens on the NSW coast, where it was detected on 03/02/2021 by a listening station on a Fish Aggregating Device, a distance of 637 km! Reports of Galapagos sharks are rare in mainland Australian waters and this is potentially the first documented evidence of such a movement from LHI to the mainland.

Next steps

A list of recommendations has been produced from the project, which brings together information from the tracking research and discussions with the fishing community, to identify measures that can be used by fishers to reduce their chance of having negative interactions with Galapagos sharks. This will improve their fishing experience and the ability to coexist with the sharks, which are a key predator species that help to regulate the healthy food chain present in Lord Howe Island waters. These measures include;

• Avoiding 4 key areas (see map below) which the researchers identified as ‘hotspots’ where shark activity was found to overlap with fishing activity the most;
• Moving regularly between fishing spots and rotating the areas that get fished so that the sharks don’t get used to the presence of fishing vessels in the same area;
• Fishing in shallower (< 30m) or deeper (> 100m) waters can reduce interactions with sharks as the tracking research identified that the sharks spend most of their time in depths of 30 – 100m;
• Using different fishing gear, such as electric reels or handlines instead of rod and reel will help to retrieve fish to the boat more quickly;
• Switching from bait to jigs and lures reduces the chance of attracting sharks;
• Cleaning fish well away from the Island and whilst moving at speed will help to reduce the behaviour of sharks following boats;
• Diversifying the target species from kingfish to demersal fish such as redthroat emperor may result in less catch lost to sharks, because the Galapagos sharks have been reported to be less interested in eating these demersal fish when they are hooked and being retrieved to the boat.

Ultimately, the researchers seek to continue working with the LHI community to help manage the interactions between fishers and sharks. The final report, list of recommendations and a three page summary of the research findings are available online at: https://parksaustralia.gov.au/marine/management/resources/scientific-publications/galapagos-shark-movement-patterns-and-interactions-with-fishing-vessels-in-the-marine-parks-surrounding-howe-island/

The research has been funded by Parks Australia with in-kind support from NSW DPI & IMOS in response to long-standing community concerns about the issue. The researchers welcome any feedback on the report and can be contacted via: Jonathan.mitchell@uwa.edu.au or 0476 966 941.

Survey of Lord Howe Island residents

To investigate the perceptions of the LHI community towards Galapagos sharks, a survey is available online (see link below) and via the LHI Marine Park Office (UWA Human Ethics Permit no. RA/4/20/6218)

This survey seeks to learn more about when and where residents encounter sharks and during which types of activities, as well as how they perceive them. It will help to determine whether the sharks have a positive or negative effect on businesses on the Island and the health of the marine ecosystem.

This survey is limited to adult residents (18+), is fully anonymous and takes 10 minutes to complete.

If you are unable to complete the online survey, paper-based survey forms are available at the LHI Marine Park Office.

This research requires a minimum of 100 participants for the results to be useful in assessing the socio-economic and ecological aspects of these human-wildlife interactions so please complete the survey to help us better understand the situation and thus develop more appropriate mitigation strategies regarding these interactions.

The UWA researchers greatly value the input and time of the LHI community in learning more about how they interact with Galapagos sharks.

https://www.surveymonkey.com/r/LordHoweIslandGalapagosShark

This article appeared in The Lord Howe Island Signal, 30 October 2021.

Related story: Galapagos shark research project update