PARENT SESSION
Oral Session #43: Fish: Ecology and Conservation.
Presiding: B. Harvey
Tuesday, August 6. 1:00 PM to 4:45 PM. Cochise Meeting Room, TCC.

Bouncing beams off brittle bones: Age determination and electron microprobe analysis of Strontium levels in otoliths from Least Cisco (Coregonus sardinella) in Arctic Alaska.

Seigle, John^*,1, Ford, Jesse¹, ¹ Oregon State University, Corvallis, Oregon

ABSTRACT- As part of a study investigating contaminant transport mechanisms in the arctic, our research crew sampled fish from several lakes on the North Slope of Alaska during the summer and fall of 2000 and 2001. Study sites coincided with native subsistence camps scattered throughout the North Slope south from Barrow but north of the Brooks Range and east to the Colville River. These fish are important to subsistence diets of native communities but little is known about the life history and especially the migratory habits of some of these species. Age structure of Least Cisco (Coregonus sardinellaB) from Ikroagvik Lake (N 71° 14.319, W 156° 39.298) near Barrow was determined through otolith analysis. These age data were then compared to Strontium levels across the built in timeline of otoliths using electron microprobe technology. Peaks in Strontium levels over time have been used as indicators of ocean migration events. Our microchemistry data were matched with age-specific data to provide a complex history of the migratory habits of any given fish. It was determined that only 10% of our sample fish from Ikroagvik were actually migrating to the sea even though this lake lies within 5 km of the ocean. Known sea-run fish captured in a nearby lagoon were tested and 100% of these fish expressed marine signals. Further results from Ikroagvik and other lakes of the North Slope will be discussed.

KEY WORDS: Otolith, Whitefish, Least Cisco, Strontium