Quick Action Needed to Avoid Gathering Wave of Ocean Extinctions, Says Dr. Ellen Pikitch
Executive Director of Institute for Ocean Conservation Science gave lecture at recent marine science seminar in School of Marine and Atmospheric Sciences
April 13, 2009
by Sze Chun Chan
The world’s oceans have long been an epicenter of man’s fascination. Their vast distances and incomprehensible depths are the stuff of myths and legends. Oceans have the power to decimate entire cities, but also give us the means to sustain the world’s population. Seemingly infinite in might and riches, it’s hard to think that man could have any immediate influence on the oceans’ future. Dr. Ellen Pikitch, too, found it hard to believe until about 20 years ago. But in her April 13 lecture as part of a seminar series in Stony Brook University’s School of Marine and Atmospheric Sciences (SoMAS), the Executive Director of the Institute of Ocean Conservation Science discussed a worrisome but realistic topic: that the future of the world’s oceans is looking grim.
“Unless things really change in a big hurry, we’re ready to see a big wave of ocean extinctions,” she warned the full-house audience of professors and students in the Endeavor 120 lecture hall for the seminar series, sponsored by the Consortium for Inter-Disciplinary Environmental Research (CIDER) at SoMAS. Dr. Pikitch, whose lecture was entitled “The Gathering Wave of Ocean Extinctions,” was followed by a presentation by Carl Safina, President of the Blue Ocean Institute at SoMAS.
An expert on ocean conservation science and fisheries management, self-professed “certified shark-hugger,” and SoMAS professor, Dr. Pikitch has done much for the world’s oceans. Her research alerted policy makers to the need for a worldwide ban on the trade of wild sturgeon caviar in 2006, resulted in a ban on U.S. imports of beluga sturgeon caviar, and contributed to the adoption of the U.S. Shark Finning Prohibition Act of 2000. Dr. Pikitch, however, feels she still has a lot more work to do.
The world’s oceans have already lost 90 percent of their top predators, Dr. Pikitch said, and some of the longest reigning fisheries have collapsed. A 2003 study by Nicholas Dulvy and colleagues, entitled “Extinction vulnerability in marine populations,” noted 113 documented marine extinctions up to that time, Dr. Pikitch told the audience. Fishing contributed to 55 percent of these marine extinctions and habitat destruction contributed to 33 percent, according to the study, published in Fish and Fisheries. As recently as the 1990s, fisherman noted large numbers of fish along the U.S. eastern seaboard and European coast. Today, fish populations are dramatically smaller, and the size of each fish pulled out of the oceans is now smaller than 20 to 30 years ago, according to research from Cemagref Public Agricultural and Environmental Research Institute in Lyon, France. The biggest fishes of the ocean are being literally fished out, Dr. Pikitch said, displaying a cartoon of two divers in front of a treasure chest filled with riches and pointing to a lone fish. “Holy &*$#, a fish!” they say, ignoring the treasure chest.
Between 1950 and 2000, fishermen targeted large fish and large mammals like whales. As time went on, fishermen had no choice but to target smaller species – known as “fishing down the food web” -- as larger predators began disappearing. Today, the majority of fish being caught are substantially smaller than a decade or two ago. With parts of oceans being fished out, fishing fleets simply move from one region of the ocean to the next.
Bottom trawling, a particularly destructive type of fishing, is causing a tremendous level of devastation in the marine environment. Bottom trawling involves dragging huge fishing nets near or along the seafloor. Besides catching target species, these trawls also capture species not being sought (bycatch) and scrape the ocean floor. For more sensitive locations in the ocean, like the Lophelia reefs of the north Atlantic, bottom trawling destroys a very diverse habitat, Dr. Pikitch said. The Lophelia reefs are very slow growing and take “hundreds of years to build.” In four minutes, a Lophelia reef can be transformed from a very diverse and rich habitat to a pile of rubble, and will not be able to recover within any of our lifetimes. According to Dr. Pikitch, half of the world’s continental shelves are bottom-trawled – a zone encompassing 150 times the size of deforested land.
Sturgeons and sharks, two of the most vulnerable marine animals, are at the forefront in the wave of extinctions, Dr. Pikitch explained. Part of her work has been to identify the traits of species that make them more likely to go extinct than others. Some of the largest fish are the likeliest candidates. Among those is the beluga sturgeon, a species that produces the most expensive grade of caviar in the world.
“These fish are so valuable it’s almost a curse,” said Dr. Pikitch.
Beluga caviar has been illegal in the U.S. since the import ban was enacted, but is currently sold for 200 to 300 dollars per ounce in other countries. “One fish was found to have 900 pounds of eggs in her body,” Dr. Pikitch said. “At 100 dollars an ounce, that’s 100 million dollars. The odds of her staying alive are pretty small.”
The beluga sturgeon can reach very large sizes and live up to 100 years. It takes anywhere from five to twenty-five years to reach sexual maturity and has a very low rate of reproduction. A combination of its life history characteristics, habitat loss, pollution, poor management, and over-harvesting has led to the beluga’s steep decline. To add to the problem, fishermen can make more money selling a whole beluga on the black market than through legal channels, so they are tempted to continue to exploit the fish and sell them illegally.
Like sturgeons, sharks are also ancient fish that are highly exploited. They have been around for more than 400 million years, are at the top of the food chain as apex predators, and are relatively rare. Though many people may be unaware of this, sharks are essential for putting fish and shellfish on the dinner table. They eat mid-level predators that eat smaller sea animals, keeping populations in check and maintaining a well-balanced food web.
Sharks also have low reproduction rates. They have a gestation (pregnancy) period that can last up to two years, produce few offspring, and have low reproductive potential. Like sturgeons, sharks share the curse of being valuable to humans. They are killed in the millions for their fins to make shark fin soup, a highly sought-after delicacy in Asian countries. Off the coast of Hong Kong, 73 million sharks were killed for their fins alone in a year. A single bowl of shark fin soup can cost up to 100 U.S. dollars.
Another factor that makes sharks very vulnerable is that they have very predictable aggregations, or places where they dwell and spawn at particular times of the year. Fishermen can camp out in these parts of the oceans and kill sharks en masse. Adding insult to injury, climate change is becoming a factor. Changing temperatures are forcing shifts in habitat.
“If things are going the way they appear to be going, we may be seeing a lot more extinctions going around soon,” Dr. Pikitch said. But despite this gathering wave of ocean extinctions, she remains hopeful that it is not too late to turn things around. Educating people as to the problems, and solutions, is one of the most important things that can be done to conserve our oceans and their inhabitants.
“The key is, can we keep enough species alive between now and then so that we don’t lose them forever?,” Dr. Pikitch asked. “Biodiversity needs to be kept as much as possible so that the world we leave to a more educated population will be richer.”
Sze Chun (J.C.) Chan is a Summer 2009 intern in the Communications Office of the Institute for Ocean Conservation Science.