New Zealand is a host to a variety of shark species from well-known species such as the great white – Carcharodon carcharias and whale sharks – Rhincodon typus to deep-sea species like the smalltooth sandtiger – Odontaspis fero and goblin shark – Mitsukurina owstoni sharks. This article is about a school shark tagging program.
Some species are encountered more than others, one such species is the school shark – Galeorhinus galeus which is one of New Zealand’s most commonly encountered inshore shark species. Known by many names e.g., Tope, Tupere, Grey boy, and sand shark, school shark’s can be mistaken for other shark species such as bronze whalers – Carcharhinus brachyurus. More school shark or tope photographs.
Ranging in size from 30cm to just under 2m, school sharks can be distinguished from other shark species by their long, pointed, translucent snout, body colouration (greyish above, white below), and notched tail (the notch is generally longer than the rest of the tail’s upper lobe). Juvenile school sharks also have black colouration on the tips of their dorsal fins and the tip of their tail.
Despite predominantly inhabiting the continental shelf and coastal areas around New Zealand’s main islands, school sharks can be found as far north as the Three Kings Islands, as far south as the Campbell Islands, and up to 400 nautical miles off northern New Zealand towards the Kermadec Islands. This species typically inhabits the seafloor and can reach depths greater than 600m. Although, they can inhabit different areas of the water column and have been observed to make regular vertical migrations between the ocean’s depths and near-surface waters.
Encounters with school sharks are more common in coastal waters during summer when this species comes inshore to breed and feed. Over winter, juvenile school sharks will remain in coastal waters, whereas larger individuals will generally migrate to offshore habitats. This is where school sharks are more likely to be captured in pelagic environments.
Like other shark species, school sharks have complex movements, which are dependent on the habitat preferences of the individual. Movements may consist of short migrations between nearby habitats or sometimes may require large-scale migrations to reach or even return to their preferred habitat.
From movement data, New Zealand school sharks have been observed to move between New Zealand’s main islands and even undertake trans-Tasman migrations up to 4940km long. Australian school sharks have also been observed to also make trans-Tasman migrations to New Zealand.
Unfortunately, like other shark species, school sharks are vulnerable to overfishing and habitat degradation due to being high-level predators, slow-growing, long-lived, and reliant on particular habitats (i.e., nurseries). As a result of these threats, many school shark populations worldwide have been overexploited, with some subsequently collapsing and still being classified as overfished. This has led the International Union for Conservation of Nature (IUCN), in 2020, to re-classify school sharks, globally, as critically endangered and the Convention on the Conservation of Migratory Species of Wild Animals (CMS) to add school sharks to CMS Appendix II.
Luckily, in New Zealand, school sharks are still relatively abundant in our inshore waters. However, we know little about which inshore habitats are important to school sharks, and how and when they use them. Such information is key to help improve the management of this species.
The Kaipara Harbour, located in northern New Zealand, is the largest harbour in the southern hemisphere. The harbour’s large size and a broad variety of habitats make it important to many species such as Snapper – Pagrus auratus and the spotted smoothhound (rig) – Mustelus lenticulatus.
During the summer, juvenile and mature, and pregnant female school sharks are observed in the Kaipara Harbour in high abundance. This suggests that this harbour may contain important school shark habitats, including a potential nursery for newborn sharks. Although, this is yet to be confirmed.
Within New Zealand, school sharks from various regions have been observed to migrate to areas along the upper west coast of the North Island, with some being recaptured just outside the Kaipara Harbour. This suggests that the Kaipara Harbour may be important to school sharks from around New Zealand.
In the face of increasing human impacts in the region and the knowledge gaps that remain about how school sharks use different habitats, the importance of the Kaipara Harbour to New Zealand school sharks requires urgent assessment. This is where the research conducted by PhD student Alex Burton comes in.
Alex’s research aims to document the spatial and seasonal abundance, demographic structure, movements, heavy metal accumulation, growth, and diet of school sharks in the Kaipara Harbour in order to aid with this assessment. This information will be critical to efforts to conserve and protect this species in New Zealand waters.
For the movement section of his research, Alex is focusing on identifying school shark movement patterns to establish the origins of school sharks found in the Kaipara Harbour, what areas of the harbour different life stages use, and where school sharks are migrating too, once they leave the harbour.
To do this, he is using two types of tags. The first is mini–Pop-up Archival Transmitting (mini-PAT) or satellite tags, which collect and transmit data on the movements of sharks over the course of one year via satellite. The second is plastic ‘spaghetti’ tags, which have been and are currently being used to tag and track the movements and growth of various fish, shark, and ray species around New Zealand as part of tagging programs such as the Tindale Marine Research Charitable Trust’s (TMRCT) inshore tagging program.
To track the movement of spaghetti-tagged individuals, Alex is relying on the public and fishers to report recaptures of tagged school sharks through the TMRCT inshore tagging program.
If you catch a fish that has been tagged, please take note of the following and report it to the TMRCT:
Tag number, Date captured, Capture location, Capture depth, Overall length, and Sex.
If possible, please also re-release the fish as it will allow for its movement to be tracked further. If you also find a spaghetti or satellite tag floating freely in the water or on the beach, please collect them and report them.
Furthermore, you can start tagging fish yourself by signing up to the program via the website here: Tagger Registration Form
If you tag school sharks in the Kaipara Harbour, Alex will replace the tags that are deployed onto school sharks. Another way to help is by talking to other people about getting involved. The more the merrier!
By becoming a citizen scientist and getting involved with Alex’s project and the TMRCT tagging program, you will be contributing to the conservation and kaitiakitanga (guardianship) of this species in New Zealand.
If you would like to contact Alex about his project, you can contact him on 0224005009 or via email: firstname.lastname@example.org
For more information on the TMRCT inshore tagging program, visit Tindale Marine Research Charitable Trust or email email@example.com
Thank you to you all for creating awareness about our project and keeping an eye out for tagged sharks thus far, I really appreciate it!
Since the last update, the school shark research project has evolved and I thought it would be a good time to update you all before we see the return of the adult school sharks to coastal waters over the next few months.
For the movement section of our research, we are still looking into the movement of school sharks around New Zealand, to see how various school shark aggregation points in New Zealand (e.g., the Kaipara Harbour) are connected.
To track their movements, we are using a combination of the following: Mini-PAT satellite tags, dart tags, and citizen science.
At the start of March this year, six Mini-PAT tags were deployed onto mature female school sharks in the Kaipara Harbour.
During their one-year deployment, they will collect data on the movements of sharks.
After this deployment period, the tag will detach from the shark and transmit data via satellite.
Since their deployment, a couple of tags have been prematurely released and we have got some interesting data on their movements and habitat use.
Thanks to the efforts of the public, we have also had one of these tags returned.
There are still a couple of tags that have been released and are yet to be recovered.
If you find one of these tags floating in the water or on the beach, please collect the tag, record the tag serial number (pictured above), and contact us ASAP for instructions on what to do with the tag.
We still have Mini-PAT tags deployed on school sharks and over the coming months, we will be attaching a few more Mini-PAT tags to mature individuals in the Kaipara Harbour.
If you or any of your friends, fishers, and/or members catch one of these tagged sharks, please record the following details along with any photos or interesting observations you make e.g., scars, gender (see below), etc.
If possible, please try and release the shark again, as it will help to continue the research.
1. Date captured,
2. Tag serial number,
3. Overall length measurement,
4. GPS location,
5. Depth of water
If a school shark with a satellite tag dies before release, please collect the tag, record the details of the tag and shark as mentioned above, and contact us ASAP for instructions on what to do with the tag.
The other tagging method we are using involves the attachment of green, serial numbered, dart tags to school sharks (without a prominent neonatal scar), re-releasing them, and working with the Tindale Marine Research Charitable (TMRCT).
However, unlike satellite tags, we are relying on the public and fishers to report recaptures of tagged school sharks through the TMRCT inshore tagging programme.
Thanks to the TMRCT taggers, New Zealanders, NIWA, and the awareness that has been created about the project and tagging programme, school sharks around the country are being tagged with these dart tags, as well as tagged individuals being recaptured and reported.
For more details on some of the school shark recaptures, see the TMRCT 20/21 summer report (https://tindaleresearch.org.nz/wp-content/uploads/2021/04/12-TMRCT-summer-report-2021.pdf).
If you or any of your friends, fishers, and/or members capture a school shark, with a dart tag attached, please record the details mentioned above.
If possible, please try and release the shark again, as it will help to continue the research.
Please report these details via the online recapture form at: https://tindaleresearch.org.nz/tagging-program/fish-tag-recovery-form/
Alternatively, you can email the details to firstname.lastname@example.org
If you or anyone you know would like to start tagging school sharks, I am now replacing dart tags that have been attached to school sharks.
To learn how to tag a school shark, the TMRCT has videos and instructions on how to tag sharks on their Facebook page and website, respectively.
Please report these details to the online recapture form or email mentioned above.
You can tell the sex of a shark by looking at the pelvic fins/region (see below).
If the shark has a pair of finger-like projections/extensions of the pelvic fins, commonly referred to as claspers, then it is a male.
If claspers are absent, then it is a female.
Moreover, when you tag a school shark, if you can take pictures of the following and also send them through, it would be most appreciated.
The individual (from the side),
and the individual’s pectoral region (ventral/belly view, individuals up to 80cm, overall length).
A ventral view of the pectoral region of a juvenile school shark showing the neonate/yolk sac scar.
One of the newer parts of the project is looking into the life history of school sharks.
We would also appreciate help with this side of the project through the reporting of school shark sightings and captures.
If you are unable to tag captured individuals or you spot a school shark washed up on a beach, if safe to do so, it would be appreciated if you could record the details and take the photos mentioned above.
Please report and send these details and photos to email@example.com.
In other news, we have also been developing our awareness poster.
You can find the latest version of the poster attached.
We have also recently established the New Zealand School Sharks Facebook page to keep people up to date with the project and how they can get involved.
It is also where we will primarily mention when we are going land-based fishing to tag school sharks.
If you are able to, it would be greatly appreciated if you or your friends, members, and/or fishers could circulate info about the project and/or the attached poster to help create awareness about the project and how people can get involved. The more involved, the better.
If you would like me to send posters to hand out to members, fishers, and/or the general public in your area, please let me know.
If you have any questions, would like to learn more about the project, or would like to have a chat in general, please do not hesitate to contact me. I’m always happy to talk sharks.
My contact phone number is 0224005009 if you would prefer to call over emailing me.
On another note, if you or anyone you know is interested in or would like to get involved in the TMRCT inshore tagging programme they can visit this link
https://tindaleresearch.org.nz/tagging-program/ or can ring 0274760687
Thank you for your ongoing support.
School of Natural and Computational Sciences
This post was last modified on 04/09/2021 2:45 pm
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