The Invisible Fabric of Nature

Part of the mission of Mystic Aquarium is to inspire people to care for and protect our ocean planet through education, research and exploration. Dr. Peter J. Auster, Senior Research Scientist at the aquarium, recently co-authored a fascinating study in the Proceedings of the National Academy of Sciences titled "Integrating the Invisible Fabric of Nature into Fisheries Management."

The study clearly demonstrates that the ecosystems of our oceans are changing dramatically. When we look at the churning sea, we may not realize that it is home to a network of interacting species. By disrupting the delicate balance these species enjoy, we face their permanent loss, which could be catastrophic.

By examining case studies of several distressed ecosystems that have irrevocably changed because of overfishing and environmental changes, Dr. Auster and his colleagues maintain that what scientists call a "tipping point" occurred in these ecosystems. It is the moment that a previously rare phenomenon becomes rapidly and dramatically more common. This major review of fisheries research examines the domino effect that takes place when too many fish are harvested from one habitat.

Among the ecosystems featured in the study is the Northern Benguela ecosystems off Nambia. The sardine and anchovy population collapsed in the 1970s from overfishing. In their place came bearded goby and jellyfish. Sea animals in the region, including penguins, gannets and hake, which had previously feasted on sardines and anchovies, began to die out because the bearded goby and jellyfish didn't contain the same nutrients. The African penguins and Cape gannets declined by 77 percent and 94 percent, respectively. Cape hake and deep-water hake production plummeted from 725,000 metric tons in 1972 to 110,000 metric tons in 1990. The population of Cape fur seals also fluctuated dramatically.

If cod is one of your favorite fish, you may see it become extinct in your lifetime. Closer to home in the Western Atlantic, the collapse of the cod populations in the 1990s was caused by overfishing. Even closing many of the fisheries didn't bring the cod population back. Sea urchins benefited when the cod that preyed on them slowly disappeared. But the Maine sea urchin fishery industry began to suffer the same fate as the cod as the crab population began to increase. Areas of coastal Maine experienced a total destruction of sea urchins by crabs. It is not certain that the decline of cod and sea urchins can be reversed.

"The complex web of species interactions matters in terms of sustainably managing fisheries and conserving biological diversity," Dr. Auster reported. "We need to better understand how predation, competition and other types of species interactions operate within marine communities in order to produce better forecasts for fisheries managers and avoid wholesale changes in marine ecosystems that lead to ecological and economic dysfunction."

Dr. Auster and his colleagues are alarmed by what happened, and we should be as well. We need to study the impact of overfishing because fish are just one of many species in the ecosystem of the ocean. By destroying this ecosystem through a lack of understanding about how species are interconnected, we face the grim possibility that some of the sea's inhabitants will become extinct.

All the authors of the paper are involved in management and policy research in their community. Dr. Auster works with the New England Fisheries Management Council, making recommendations for broad ecosystem-based management. Dr. Auster and his colleagues believe that pulling case studies together from around the world illustrates vividly what is happening to the world's fragile ecosystem.

What's the next step? "We need to spend our time avoiding these tipping points rather than trying to find ways to flip back, which may not be possible. Such issues need to be a bigger part of the fishing management conversation and translated into actions," said Dr. Auster.

Our oceans are a precious resource as well as a source of food for the Earth's 8 billion inhabitants. It is vital that our government officials recognize that every action has consequences, and that overfishing has proven to be a shock to our fragile ecosystem. We must take drastic measures now to stop overfishing or we risk losing a valuable source of food. We can't afford to wait or make the same mistakes over and over again.

We need to ask ourselves: What kind of world do we want to leave to our children?