Mako shark research report

Victorian Gamefishing: Knowledge, movement, and best practice for catching and releasing shortfin mako sharks (Isurus oxyrinchus)

Access to the full report can be found here.

Targeting sharks has also become more popular to Victorian anglers, with the shortfin mako shark being highly prized due to its fighting ability and culinary qualities. Although considerable information about the population dynamics of mako sharks is available globally, targeted research is necessary to supplement existing information locally, close knowledge gaps identified during research extension activities, and test new innovative assessment tools.

This research project funded by Victorian Government’s Recreational Fishing Grants Program investigated movement characteristics of shortfin mako sharks; developed innovative molecular techniques to detect near shore movements of shortfin mako sharks; and provided support to an existing federally funded project developing ‘best practice principles’ for the capture and release of sharks and rays.

Satellite tags were attached to the dorsal fins of five shortfin mako sharks caught and released off the coast of Victoria during 2021 and 2022.  Results indicated that shortfin mako sharks display highly migratory movement patterns that are individually unique. These results were consistent with those from other tagging studies. A common feature was their association with the continental shelf break where the shelf transitions sharply to the slope. All five sharks were observed to have a strong association with this inflection point and although some time was spent within the shallower (<100 m) waters of Bass Strait and the Great Australian Bight, most was on or near the continental slope. The reason for this is likely to be prey availability.

Using environmental DNA techniques, we were able to validate the presence of shortfin mako shark from seawater samples and use species-specific assays to identify the presence of shortfin mako shark over different spatial and temporal scales. Results indicated that peak presence off the Victorian coast occurred during Autumn, but this was somewhat dependent on location and periodicity of sampling. Testing of monthly samples from inside the large embayment of Port Phillip indicated that while occasional detections do occur near the entrance to the embayment, shortfin mako shark do not frequently enter and stay within this embayment for long periods.

Lastly, this research contributed to a larger FRDC project aiming to create ‘best-practice’ capture, handling, and release guidelines for recreational fishing of sharks and rays. A survey of over 1000 recreational anglers was conducted to assess current community attitudes and behaviours towards fishing for sharks and rays, with the survey subsequently informing an education campaign. An online platform called ‘Shark Mates’ was established in 2020 (https://sharkmates.com.au/) to help Victoria’s recreational fishers take better care of sharks and rays when out fishing.

Ongoing spatially resolved management based upon sustainable fishing principles in conjunction with advocating for the importance of applying ‘best practice’ for the capture (and release) of sharks and rays will ensure that the underpinning research from this project will benefit the recreational fishing community into the future.

Access to the full report can be found HERE.