Why do we need to understand juvenile fish habitats?

The camera is one of 12 developed for the FinVision project – a Fisheries Industry Science Partnership (FISP), funded by DEFRA and led by Dr Benjamin Ciotti . Deployed in different habitat types for days or weeks at a time, these cameras are helping us understand what habitats fish need, information critical for designing management actions and policy decisions that underpin viable fisheries and successful nature conservation.

In Europe, more than two-thirds of fish landed in commercial fisheries are known to rely on inshore habitats at some point in their life. Yet coastal areas are on the front line of human impacts such as pollution, habitat destruction and climate change. Notably, habitats like seagrass meadows, saltmarshes and kelp forests, considered to be important fish habitats, have experienced substantial declines along UK coasts. Only with knowledge of fish habitat requirements can we understand how the loss or restoration of habitats impact on fisheries sustainability and nature conservation.

Those who have spent happy summer days with nothing more than a net and a bucket may ask why so much tech is needed. People have been catching fish from the sea for millennia, so surely there are easier ways to see where fish are living? Certainly, more traditional approaches such as netting and diver surveys continue to provide essential information about juvenile fish habitat needs. But cameras like the JHaM-Cam are a necessary addition to the toolkit. They are particularly good at spotting the smallest fish that may not be seen by divers, or captured in net surveys, and can be deployed in a range of different habitat types.

Furthermore, the continued day-night, weeklong coverage is critical for capturing finescale changes in distribution. Work in the tropics suggests that habitat use of juvenile fish can be extremely dynamic, with important shifts and key processes occurring at the scale of a few hours. In coral reef fish that settle into juvenile habitats at night, for example, 60% may be lost before morning arrives. Round the clock, long-term coverage increases the chances of capturing these important events. Nature is complex, and therefore innovation must be key to advancing the approaches we use to sample the natural world – particularly when we know that current methods have inherent limitations.

As well as providing tools to gather much-needed data, the FinVision partnership is an important opportunity to widen participation in research and connect communities and institutions with the vital ecological role played by coastal habitats. Hosting a number of online and in-person training events, the project also invites members of the public to view footage and record fish sightings through a public web portal hosted by Zooniverse.

A quarter of a million clips have been analysed on the portal so far, further evidence of the staggering contributions that can be made by citizen scientists. Beyond data collection, the web portal represents an important window between two very separate, but interconnected, worlds. The web footage brings the dynamic world of marine creatures into the living room. From the violence of tidal flows, to sublime scenes of colour and tranquillity and murky confusion of coastal habitats, this is the world young fish navigate at the very start of their lives.

Seeing beneath the waves inspires curiosity and educates about the role of marine ecosystems. It also brings a view of coastal habitats into the polling booth, the board room, the council chamber. It is 29 years since the USA, through the Sustainable Fisheries Act (1996), formally recognized ‘Essential Fish Habitats’ in fisheries legislation. Similar legislation does not yet exist in the UK or Europe but momentum is building.

The 2020 Fisheries Act clearly recognises the role ecosystems play in sustaining fisheries, and the recent reorganisation around Fisheries Management Plans provides a mechanism to insert habitat considerations into management actions. Projects like FinVision can advance our understanding of the habitat needs of fish, and will be important to achieving the robust, evidence-based approach required to create sustainable fisheries.