School sharks, also known as tope or grey boy, commonly inhabit New Zealand’s coastal waters out to the continental shelf. They are often seen inshore during summer when mature individuals move into coastal areas and harbours to breed and feed. Ranging in size from 30 to 180cm, school sharks can be identified by their translucent snout and body colouration (greyish above and white below).
Like other shark species, school sharks are vulnerable to overfishing and habitat degradation. Unfortunately, many school shark populations worldwide have collapsed because of these threats, leading the International Union for Conservation of Nature (IUCN) to re-classify school sharks, globally, as critically endangered.
Luckily, 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 NZ, is one area that is likely important to NZ school sharks. During the summer, juvenile, mature and pregnant female school sharks are observed there in high abundance. This suggests that this harbour may contain important school shark habitats, including a potential nursery for new born sharks.
In the face of increasing hsuman impacts in the region, the Kaipara Harbour's importance to NZ school sharks requires urgent assessment. PhD student Alex Burton is currently researching school sharks’ spatial and seasonal abundance, movements, demographic structure, diet and heavy metal vulnerability 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 and from the Kaipara Harbour as well as within the harbour. To do this, he is using two types of tags: satellite tags, which transmit data on the movements of sharks over the course of one year via satellite, and plastic ‘spaghetti’ tags.
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 Tindale Marine Research Charitable Trust (TMRCT) inshore tagging programme.
There are many ways Kiwis can get involved with Alex’s project. If you catch a fish that has been tagged, please take note of the tag number, date captured, overall length, capture location, capture depth and report it to the TMRCT. If possible, please also re-release the fish. Furthermore, you can start tagging fish yourself by signing up to the programme via the website. Another way to help is through talking to other people about getting involved. The more the merrier!
If you would like to contact Alex about his project, you can contact him on 0224005009 or via email, [email protected]
16 January 2021