New Zealand’s big blue backyard is home to over 68 species of shark. Most species are not observed often as they prefer deeper waters. One of the more frequently encountered species is the school shark (Galeorhinus galeus, also known as greyboy, Tope and tupere). School sharks can be found throughout New Zealand, from the Three Kings Islands to the Campbell Islands, from coastal waters to out to the continental shelf and slope. They only occasionally venture near surface waters, spending most of their time near the seafloor.
School sharks are a smaller species, born around 30 cm long and can grow to up to 1.8-1.9 m. They can be distinguished from other common coastal species, such as bronze whalers (Carcharhinus brachyurus), spiny dogfish (Squalus acanthias) and rig/spotted smoothhound (Mustelus lenticulatus), by their pointed, translucent snout, greyish upper body, distinctively shaped tail, and lack of dorsal spines. Young school sharks also have black colouration on the tips of their dorsal fins and the upper lobe of their tail.
Despite school sharks being one of the most commonly encountered species, surprisingly little is known about their biology. Massey University PhD student Alex Burton is trying to change that. As part of his research, Alex is examining various aspects of school shark biology and ecology, such as their reproduction, movement and habitat use. Such information is crucial to aid in the conservation efforts and management of this species in New Zealand and around the world.
To track the movement and habitat use of school sharks in New Zealand waters, school sharks have been fitted with dart tags and satellite tags, with the help of the Tindale Marine Research Charitable Trust (TMRCT). Dart tags are small, green, elastomer tags with unique ID numbers so that a fish/shark can be identified if it is recaptured. Thousands of these tags are being deployed by fishers onto dozens of species around the country, as part of the TMRCT tagging programme.
Satellite ‘mini-PAT’ tags, on the other hand, have been attached to 25 adult school sharks. These tags collect detailed information on the shark’s movement and habitat use over a year, after which they pop-off and transmit the data to Alex via satellite. If tags can be recovered, more in-depth data can be obtained from the on-board archive and, subsequently, allow for better insight into the movement and habitat use of the shark the tag was attached to. The tag can then be refurbished and used again.
Thanks to the efforts of New Zealanders, many recaptures have been reported and even some mini-PAT tags have been recovered and returned to Alex. This includes one tag that detached near Kapiti Island in August 2021 that was found washed up on Pitt Island nine months later in May 2022. Data that has been recovered from miniPAT tags is being analysed to plot the movement tracks of the sharks. One such track includes one individual’s movement from the Kaipara Harbour to the Snares Islands. For an animation of this journey, see this video: youtu.be/EBrMrhddvCo.
If you capture any fish with a TMRCT dart tag or a school shark with a miniPAT satellite tag, please record details relating to the capture (e.g., tag no., where, when, length) and report them to the TMRCT via tindaleresearch. org.nz/fish-tag-recoveryform. If possible, please also re-release the individual (especially if it has a satellite tag attached) so that valuable data can continue to be collected.
If a school shark with a satellite tag, is unable to be released or dies before release, or you observe a tag floating in the water or on the beach, please collect the tag, record capture/encounter details, and contact Alex (a.burton@ massey.ac.nz) or the Tindale Marine Research Charitable Trust (tindaleresearch@ xtra.co.nz) ASAP for further instructions.
For details on how and what to report when you capture a school shark, or you’d like more information on the school shark research project or the TMRCT tagging program, contact Alex or the TMRCT. Alternatively, visit the School Sharks New Zealand & International and TMRCT Facebook pages or the TMRCT website (tindaleresearch.org.nz).
