Bird Food

August 13, 2015 Posted by: Emma Johnson
kittiwakes_on_ice
If you've spent much time in front of Margerie Glacier or Johns Hopkins Glacier, you've probably noticed this: the glacier calves and the black-legged kittiwakes and other gulls flock to the waters where the ice fell. What is going on? Is it actually possible that there is food in that silty water? 

It is and here it is: 
capelin_krill_northern lampfish
Results of a near-surface trawl catch at the head of Tarr Inlet, including krill and small forage fish, such as juvenile capelin and northern lampfish. 

The water in front of Margerie Glacier is filled with frill and small forage fish: food for black-legged kittiwakes and other gulls. 

Yumi Arimitsu, a Juneau-based researcher, has studied the forage fish in Glacier Bay extensively. She notes that many of these fish are mesopelagic species that are normally found in deep water during the day. However, they are found in the upper 30 meters of the water column near glaciers. The high turbidity and dark cold conditions are similar to what would found in deep water elsewhere. Capelin, for example, stay in cold water and in Glacier Bay they actually move inshore to cold water refugia with nice spawning habitat like the sandy beaches of Reid Inlet. 

 Information and image courtesy of Yumi Arimitsu, USGS researcher, via Sean Neilson. 

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Last updated: August 13, 2015

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