Posted by mariej on 08/02/2006 11:43 am

The following posting is from Carroll, who is onboard in the Bering Sea... 

Yesterday morning, we left our harbor at Security Cove and sailed around the cape into Bristol Bay. We took a chance on the weather that seems to have paid off. The sea’s been much calmer than forecast for the last two days, allowing us to do our research in earnest. We spent yesterday doing killer whale research along the north coast of the Bay, then headed out to the center of the Bay last night to begin a new search pattern for humpbacks.

Our own luck notwithstanding, Bristol Bay is one of the best places in the Bering Sea to find marine mammals. At least nine species of whale and dolphin inhabit the Bay at some time of the year, including humpbacks, killer whales, minkes, and the critically endangered North Pacific right whale. There are seals and sea lions here as well: steller sea lions and harbor seals year round, and ice-dependent species like the ringed seal, spotted seal and walrus in the winter. Most of the ice-dependent species follow the ice north as it retreats each summer, though a few hundred walrus bulls stay in the Bay all summer long. We saw some of them from a distance yesterday as we were looking for killer whales.

But it’s an open question how much longer Bristol Bay will support species, like the walrus, that depend on the ice for their survival. For more than three decades, scientists have tracked the coming and going of the sea ice in the center of Bristol Bay. In the early 1970s, the area between 57-58 degrees North latitude, at the heart of the Bay, had more than 5% ice cover for an average of 130 days each spring. By the end of the 1980s, this had fallen to an average of 67 days. In 1996, a consistent period of abnormally warm temperatures began, and since the year 2000, sea ice has been virtually absent within the monitored region.

The loss of the ice has serious consequences for species that have evolved to rely on it. The walrus is a good example. For the walrus, it’s not just the amount of ice that matters, but where the ice is. Walrus forage on the sea floor, diving up to 600 feet to dig clams and other invertebrates from the muddy bottom of the ocean. As the ice retreats farther north, breaks up earlier, there’s less ice cover over the shallow waters where the walrus forage, forcing them to range far from the ice to feed. Unfortunately, walrus mothers need the ice edge to rest, and to leave their calves while they go in search of food. When the distance between the ice and the shallow feeding grounds grows too great, this becomes impossible. This spring, a research vessel in the Arctic Ocean discovered nine separate walrus calves abandoned in the water, far from shore. The researchers on board found water temperatures in the area 6 degrees warmer than what they’d found just four years before. Warm enough to speed the melting of the ice over shallow water. In areas where the ice remained, the waters were too deep for walrus to feed.

Other pinnipeds that depend on the ice, like the ringed and bearded seals, may face a similar threat. But the changes in sea ice affect not only the walrus and seals, but the ecosystem as a whole. When ice is present in March, it encourages the early bloom of ice-associated plankton. The colder waters of the late winter allow this plankton to fall to the seabed, where it benefits bottom feeders like walrus and gray whales, and bottom tending fish like turbot, flounder and sole. During years without ice, however, including almost every year for the last decade, the plankton bloom does not occur until May or June. Warmer waters trap the plankton in the upper layers of the ocean, where it benefits more pelagic fish, like the pollock.

This might be good news for all the species that rely on pollock as part of their diet, if their other prey species weren’t declining at the same time. And if pollock weren’t so heavily fished. But in reality it is overfished. And this overfishing comes at the expense of an ecosystem already stressed by massive environmental change, itself driven by our overexploitation of oil and fossil fuels.

As we keep drilling and drilling and fishing and fishing, the environment is quietly, persistently telling us something. In Bristol Bay. In the Pribilofs. At St. Lawrence Island. What began as a whisper in temperature gauges, and instrument readings and data sheets is gradually, but inevitably growing into a roar—of vanishing species, disappearing ice, and howling winds. A roar that, like the whisper, carries a simple message. It’s time to Stop. And think. And start again.

Carroll