black angelfish
Angelfish

Angelfish Twain

When we think of fisheries, we generally think of seafood. But there is another, very large, fishery that has not made it into the headlines. No international agencies are monitoring it. Yet millions of people benefit from it, both financially and aesthetically, even as it probably is having a strong impact on coral reefs, the centers of the ocean’s biodiversity.

It’s the ornamental fishery, which harvests fish and invertebrates for display in aquariums and as curiosities.

Ornamental fisheries have an impact on coral reefs

In our new paper on ornamental fisheries, we note that the impacts of these fisheries are not well understood, but they may be very large. The ornamental trade is focused on coral reefs, home to much of the world’s marine biodiversity, and involves at least 45 source countries. Every year, this fishery removes an estimated 20 to 24 million fish, many millions of corals and shells, and 9 to 10 million additional invertebrates.

Coral reefs are extremely productive and teem with colorful life. But they also use up a lot of energy, and there is a lot of competition and predation going on in reefs, resulting in relatively low net production. In contrast to cold, nutrient rich waters that can support very high fishery yields, the warm, nutrient-poor waters typical of coral reefs are probably unable to sustain large harvests.

So what to do?

We know that unassessed fisheries tend to be unmanaged fisheries that decline and collapse. So the first step toward a solution is to assess the status of ornamental stocks and the coral reefs that support them.

In our paper, we lay out a step-by-step approach for assessing and managing fisheries for which data are limited, and illustrate the methods using data from Indonesian fisheries.

First, the status of the whole coral reef is assessed – not just the fish stocks – and conservation targets aimed at maintaining or restoring healthy reefs are set.

Next, the vulnerability of the stocks and their degree of depletion are estimated. This information is combined in a decision matrix: for each category of vulnerability and depletion, a different set of management measures are implemented. For example, for a highly vulnerable species that is also highly depleted, a ban on fishing may be appropriate. For more resilient species that are less depleted, harvest might be increased to allow depleted stocks to recover.

The decision matrix can also be used to prioritize stocks for more detailed assessment, resulting in catch limits for the high priority stocks.

We hope that this new analytical framework and management system will catch on before the ornamental fishery starts to generate headlines about a new fishery crisis.