Studying the fish in Tristan da Cunha’s waters

Community shares their knowledge and skills

The fisheries officers were generous with their knowledge and skills, and I gained valuable experience working with them. They taught me how to carry out age and growth sampling in the Fisheries Department laboratory.  I was even able to spend five days on the MV Edinburgh to see how samples are collected whilst the fisheries team completed their transects. It was amazing to see how adaptable the Fisheries Department had to be in the face of changing weather and limited resources.

The passion of the Tristan community for their marine life was evident in their generosity and support of the project. The fishermen were enthusiastic about the project and kindly provided samples from their bait and by-catches. The community came to the rescue when we needed numerous coffee jars for the bespoke water sampler designed by Emil Pirzenthal, a marine engineer currently working on the island.

The support and knowledge of the islanders guided me in photographing various species and collecting water samples from intertidal rock pools around the harbour area and at Runaway Beach which lies to the west of the village.

Why monitor fish diversity and stocks?

Tristan’s fish stocks provide a vital food source for the islanders and they are a key part of Tristan’s marine ecosystem.

Whilst Tristan’s marine environment is considered pristine, it is vulnerable to human threats such as pollution or the accidental introduction of invasive species which can lead to species extinctions and declines. It’s therefore important that we consistently monitor and protect our marine environments.

Understanding the diversity of species across Tristan is a key step in monitoring and protecting fish populations and allows the Tristan da Cunha Government and fisheries managers to make appropriate decisions to conserve stocks.

Meet the main species of fish in Tristan’s waters

The nearshore marine environment is dominated by eight fish species:

• Five finger (Nemodactylus monodactylus)
• Wrasse (Suezichthys ornatus)
• Two rockfish species (Sebastes capensis and Helicolenus mouchezi)
• Telescope fish (Mendosoma lineatum)
• Klipfish (Bovichtus diacanthus), which is found nowhere else in the world!
• Yellowtail (Seriola lalandi)
• Silver porgy (Diplodus argenteus), which was accidently introduced to Tristan’s waters and is a non-native, invasive species.

More about Megan’s research

Our work on Tristan focusses on the diversity of the eight dominant fish species, and was designed in collaboration with the Tristan Fisheries Department, with Fisheries Director James Glass supervising the project, along with partners at Aberystwyth University, and Queens University Belfast.

The aims of the project are to provide data to better understand the diversity of fish life in Tristan’s waters and investigate their evolutionary history and the present-day structure of stocks. This will provide baseline data to assist the Tristan fisheries department with their management goals.

Tristan is a particularly interesting system to study patterns of diversity, as the islands extreme isolation and its unique position in relation to the Antarctic Circumpolar Current and Polar Fronts, are characteristics that can potentially influence genetic diversity, and therefore the biodiversity of the islands.

For now, our research is still ongoing, but we’re excited to share our findings with you when the project is complete.

Thank you to the Tristanian community and Fisheries department for the support, guidance, and passion which have made this work possible.