Overfishing is a major threat to coral reef fish

More than 85 percent of grouper and snapper are overfished on Florida’s coral reefs, according to a new study led by the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science. The experts report that this issue is a direct result of increasing human demand for seafood.

“The economic and ecological importance of coral reef fishes makes their sustainability a key conservation concern,” wrote the study authors. “In southern Florida, commercial and recreational fisheries are worth about $6 billion per annum and are closely tied to healthy essential habitats that are part of the regional coral reef ecosystem.”

“Threats to coral reef ecosystems are well known and include human impacts from global warming, such as bleaching and disease. Local impacts related to development and pollution also occur. However, related to fisheries in south Florida, overfishing is by far the most serious threat to their sustainability – and also around the world.”

For the investigation, the experts analyzed population data for 15 coral reef fish species over 30 years using their length-based risk analysis (LBRA) framework. The species examined for the study – five grouper species, eight snapper species, and two grunts – are central to South Florida’s fisheries. 

The study showed that all of the snapper fish, three grouper species, and both grunt species were below the 40 percent minimum spawning potential ratio. This is an index created by marine fisheries that represents what is necessary to sustain fish populations.

The researchers estimate that increasing the current minimum catch size of black grouper from 24 inches to 44 inches would boost the spawning population to 40 percent. This would be enough progress to produce the number of new juveniles needed to sustain the population.

In this scenario, the researchers said it would take approximately 10 years for the population to recover to a point where it was minimally sustainable, and 22 years to reach equilibrium where a sustainable catch becomes possible.

“The situation is analogous to your bank account,” said study lead author Professor Jerald Ault. “That is, without a significant account balance, in this case fish in the water, you can’t get meaningful interest— significant numbers of large fish to catch, but also to spawn and replenish the reef.”

The study is published in the journal Fisheries Research.

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By Chrissy Sexton, Earth.com Staff Writer