State of the Sea
INTRO: With animals like sea lions and sea otters in trouble, and salmon returns declining, marine scientists met recently in Anchorage to assess the health of Alaska's oceans. Alaska's seas are still cleaner than most, but just like other places, the oceans that nearly surround the state have their share of problems. As Doug Schneider reports in this week's Arctic Science Journeys Radio, one scientist says research on the ocean's smallest fish is needed to understand the big changes happening in the marine environment.
STORY: It often seems that there's no shortage of research being done in Alaska waters. We often hear about studies on whales, seals and other marine mammals. And studies of commercially important fish like halibut and salmon are also common.
But despite a wealth of data, researchers who gathered at a recent Anchorage conference on Alaska's oceans and watersheds said they don't know the intricate details of just how the ocean food chain works and what factors influence it. Doug DeMaster is director of the Alaska Fisheries Science Center. He says more needs to be learned about this and large-scale ecosystem changes triggered by events like climate warming and El Niño, for example.
DEMASTER: "One of the real goals that this ocean community is trying to achieve is understanding the processes that dictate what the species composition will be in the marine community. We're pretty sure that the Gulf of Alaska has to be separate from the Bering Sea and the Chukchi Sea and Beaufort Sea. But what we really need is to integrate all these bottom-up forces, the regime shift, and the way primary production moves up through the ecosystem, as well as the way predators affect community structure."
One issue that concerns ocean scientists is the Pacific Decadal Oscillation, a little-understood climate change event that occurs once every few decades and has the potential to cause what scientists call a "regime shift," or a complete re-ordering of the food chain. Such an event occurred in the 1970s in the North Pacific, and there are signs that another oscillation is in the works. Such a change could have a major impact on Alaska's ocean ecosystem. But DeMaster says it's unclear what species will do well and what species won't.
DEMASTER: "In the late 70s we had a regime shift, a Pacific Decadal Oscillation. We went from a cold period to a warm period. At that point, you saw the community dominated by shrimp change all the way over to a community dominated by cod, pollock and flatfish. Now we've seen another big shift in sea surface temperature. But we don't know if we can expect a return to the old shrimp-dominated community or if we're going to see something else."
To better understand the health of Alaska's oceans, DeMaster says researchers need to start paying more attention to little-studied species such as forage fish. Those are the small fish, like herring and capelin, that swim in huge schools and that are prey to larger fish, marine mammals, and seabirds. DeMaster says forage fish function as a kind or early warning system for the ocean's health.
DEMASTER: "Without knowing what's going on with forage fish, you just can't make an educated guess, much less an accurate or reliable prediction about what's going to happen. Well, to figure all that out you can't just look at the very bottom and the very top. You need the middle layers. And the middle layers are where the forage fish are. And other than herring, in this state they aren't fished commercially. On the other hand, they're very important for understanding why particular species of commercial and subsistence importance are going up or down."
Funding to study commercially unimportant fish is usually hard to come by. But new money from Congress designated to study Steller sea lions and the fish they eat is now allowing researchers to begin tracking forage fish. Scientists like DeMaster say studying these oceans' little fish could help them answer big questions about the health of the state's oceans.
OUTRO: This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. With help this week from science writer Sonya Senkowsky, I'm Doug Schneider.
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