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The case of the vanishing seabirds

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A marbled murrelet chick, stuffed and mounted at the California Academy of Sciences. Peter Halasz/Wikimedia Commons.
New evidence from the UW's Burke Museum shows why the iconic NW marbled murrelet is declining. And what it might mean for seagulls, herons and other seabirds.


About 20 years ago an improbable avian protagonist emerged in the “War in the Woods” — the battle over whether to log or preserve the remaining old-growth forests along the Pacific Coast. A beguiling little seabird called the marbled murrelet became the new spotted owl — a flagship species and an ESA-enabled champion for forest protection.


... What the researchers found was impressive, and alarming. In the 19th and early 20th centuries, marbled murrelets relied heavily on sardines and anchovies — fat, fatty jumbo packages of nutrition. But the North Pacific sardine fishery, immortalized in John Steinbeck’s "Cannery Row," collapsed in the 1940s, thanks to overfishing and (at that time) cooling waters. It has yet to recover. Northern anchovy stocks also shrank — by 75 percent since 1974 alone. Market squid, another traditional murrelet staple, have also been overfished in recent years. Too many bars serving fried calamari.


... The murrelets have responded as any self-respecting threatened species would — by eating what they can get. Sand lance — skinny little inshore fish that are much smaller and lower-calorie than sardines — have become a bigger and bigger part of their diet. More recently, they’ve shifted to ephausids, or krill. These fingernail-size swimming crustaceans are even less substantial. According to the Berkeley paper, it takes 80 krill to replace the calories in one average sardine and 45 to replace one anchovy. In the lingo, the murrelets are experiencing a “declining trophic level” — i.e., they’re moving down the food chain.

View the full article from Crosscut

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