ECO PRO A Diver’s Guide to Responsible Seafood – by Alex Brylske, Ph.D., President, Ocean Education International, LLC
I wrote a short article last year titled “Don’t Be the Grouper Sandwich Guy,” ex- plaining how those who consider themselves environmentalists can un- knowingly make bad choices when visiting seafood restaurants. It sparked
Top-Down Vs. Bottom-Up : To understand the ecologi- cal role fish play on coral reefs, you must consider both top- down and bottom-up perspectives. The top-down view involves high-level predators, such as groupers and snap- pers, vital to a reef’s structure and stability. These species regulate prey populations and prevent an overabundance of smaller species, which can lead to ecological imbalance. Ex- perience has proven that removing too many apex predators can trigger a “trophic cascade” of adverse effects, disrupting the entire food web. For instance, large predators such as groupers and snap- pers help regulate the populations of mid-level predators, including smaller reef fish and invertebrates. Without these natural checks, these populations can explode, increasing predation on juvenile herbivores. This depletion, in turn, di- minishes their ability to control algal growth, allowing algae to overgrow and smother coral reefs.
significant interest from readers who wanted to learn more about why responsible seafood consumers should avoid eat- ing specific kinds of coral reef fish. Here, I’ll explore the issue more thoroughly. To begin, the most critical concept in understanding coral reef fisheries is their extreme vulnerability to overfishing. In fact, in the regions where coral reef fisheries are man- aged–and in many places, they receive no management at all–they are almost all overfished. As one eminent coral reef ecologist, Dr. Callum Roberts, attests, “By virtue of their
complexity, reef fisheries are the most difficult in the world to manage.” At first glance, that may seem counterintuitive because, after all, coral reefs are the most pro- ductive ecosystems on the planet. However, they are also examples of “high gross/low net” ecosystems. In other words, while coral reefs can produce an enormous amount of biomass, there is little left to export out of the system because the reef has
Overfishing of top predators also disrupts the reproductive dynamics of reef species. Many high-level predators grow slowly and reproduce infrequently, making them particularly vulner- able to population declines. When these species are over- fished, their populations struggle to recover, further destabilizing the ecosystem. For example, ask yourself, “How often do I see
so many mouths to feed. The analogy I use is that coral reefs are analogous to an enormous restaurant. Each day, it gen- erates incredible quantities of food, but it also provides meals for all the staff and their families three times a day. As a result, there’s little left over for the customers. It is now abundantly clear from research that overfishing is one of the most severe threats to these delicate environ- ments, mainly when fishers target fish species that play es- sential roles in maintaining ecological balance. Therefore, responsible seafood consumers committed to conserving coral reefs must be mindful of which species they consume. So, by avoiding fish that serve crucial ecological functions— both high-level predators and herbivorous species—we can help sustain reef ecosystems for future generations.
large groupers when I dive?” Take it from someone with al- most six decades of experience diving coral reefs; they once were very common. There is also another lesser-known consequence of the elimination or decreasing numbers of top predators. Aside from their role in culling sick and less fit individuals, groupers and large snappers play a key role in maintaining community health through their behavior, and have adverse consequences when they are no longer present or reduced in number. Top predators create what ecologists refer to as the “landscape of fear.” This phenomenon became evident with the drastic ecological alteration of Yellowstone Na- tional Park following the introduction of wolves in the 1990s. Since then, similar results have been observed in ma-
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