By Lewis Smith
New approaches to conservation need to be found if large predatory fish on coral reefs are to be saved, researchers have warned.
Overfishing is causing “fundamental” changes to the balance of species on reefs, with fish like groupers and snappers particularly threatened.
Groupers and snappers are highly sought-after dishes in restaurants “the world over”, though less so in the UK, but overfishing has severely reduced their populations in many areas,
Researchers from the UK, Canada and Australia concluded after studying 253 coral reefs that such species can only support “light fishing”.
Fish at the top of the food chain, they said, are “easily overfished and require a different approach if they are to be conserved, or are to be part of long-term fish catches”.
Professor Nick Graham of the Lancaster Environment Centre, Lancaster University, said: "Given the fragile state of the world's coral reefs it is important to understand how human activity, such as fishing, impacts upon coral reef ecology.
“Coral reefs are home to 30 percent of marine species, they play a key role in food security in the Tropics and are iconic, fascinating ecosystems in their own right."
"Our study has shown these top-level predatory fish are only likely to be viable in overall lightly fished reefs, for example the Great Barrier Reef. To both conserve these top-of-the-food-chain fish, and to maintain the fisheries which depend upon them, overall fish biomass on the coral reef needs to remain high."
"Previous research by our team has identified target levels of biomass which sustain fisheries for a diverse array of species, while maintaining ecosystem structure. This current work identifies a higher target for fisheries that aim to target predatory fish. Key to these targets is the objective of maintaining the ecosystem at the same time as supporting fisheries and livelihoods."
Dr Aaron MacNeil of the Australian Institute of Marine Science, and Dalhousie University added as the results of the study were published in the journal Current Biology: "These results give us better insight into how we can maintain the integrity of reef ecosystems while sustaining the livelihoods of local fishers.
“Understanding how humans alter energy flows within coral reefs gives us another tool for deciding how much fish we can safely take for ourselves.”
Picture: snappers on a reef. Credit: Nick Graham