The Common Murre, an abundant North Pacific seabird, has been subject to a die off. Last year tens of thousands of these birds washed up on shores from Alaska to California…dead from starvation. Researchers have traced the cause to unusually warm waters that affected the tiny fish they eat. Elevated temperatures in sea water affected wild life in a pair of major marine ecosystems along the west coast of the U.S. and Canada. Tragically common murres are an indicator of a regions health. The die off was most likely caused by the birds not having anything to eat….no fish. The Common murre looks like a thin penguin. They can fly miles in search of schools of their finger length prey, diving on them, and swimming nearly 2 metres under water to capture them. They have a high metabolism and must eat 10-30% of their body mass daily, if not they will use up their fat reserves and drop to a critical threshold for starvation within 3 days.
The common murres eats capelin, a small forage fish from the smelt family, and juvenile polluck. both these fish were largely missing from the fish surveys conducted in 2015….and the murres paid the price.
It is hard to decide how many birds actually died, but best estimates are up to 500,000, many deaths don’t reach shore. Nearly all the birds found were emaciated. Without enough food to keep up their body mass they consumed their fat and protein, and they could not stay warm.
Starting in 2014, the temp in the upper 91 metres of water was 2.5 degrees warmer than normal. This led to a “blob” of warm water. Forage fish feed on zooplankton, and cold water develops the best eating plankton. With the blob of warm water producing low quality food for the capelin and juvenile polluck, the effects were felt up the food chain.
Warm ocean temps also affect the big North Pacific game fish, such as halibut,cod,polluck, and flounder. As the water they live in increases, their metabolism increases and they have to eat more. What do you think these fish eat……that’s right capelin and juvenile polluck. These fish are in direct competition with the sea birds and tend to eat a large amount more of the little fish.
Common murres have 230 cliff colonies in Alaska, all the colonies in the Gulf of Alaska showed widespread breeding failures. The Arctic and Aleutian colonies all bred as normal.
The ultimate cause of the die off was the warm waters. The birds died of starvation because there was no food, there was no food because there was no fish, there was no fish because there was not much food for them