Discipline: Biological Sciences
Subcategory: Climate Change
Autumn Chong - University of Hawaii at Hilo
The Arctic ecosystem in the Pacific is a rising concern due to increased climate change. Marine mammals and fish are common harvested species by native Alaskans from the Arctic marine ecosystem. Arctic Cod (Boreogadus saida), is a sea ice associated bony fish commonly consumed by marine predators. Arctic cod are a high energy source for the Arctic marine predators. Amongst the marine predators in the Arctic marine food web, ice seals (i.e. Ringed, Pusa hispida, Spotted seals, Phoca largah, and Bearded seals, Erignathus barbatus) most often forage on Arctic cod at different depths of the ocean. Ice seals feeding at different depths of the ocean lead to hypothesize Ringed, Bearded, and Spotted seals consume different sizes of Arctic cod. However, determining the size of fish consumed by ice seals is difficult because otoliths are dominantly found after digestion in seal stomachs. A study done by Frost and Lowry of Arctic cod otoliths have shown a known relationship between the fork length of an Arctic cod and their otolith length (1981). The Arctic cod fork length equation was used to determine size of Arctic cod fish consumed by ice seals. Adult seal stomach samples harvested by native Alaskan villagers, were donated by the Alaska Department of Fish and Game (ADF&G) ice seal monitoring program and used to measure otoliths. Otoliths were measured to calculate the size of Arctic cod consumed by ice seals. A multi linear regression analysis was used to compare if there were differences of sizes of Arctic cod consumed amongst seal species, sex of seals, locations, and seasons. The backward selection technique in SAS showed that there was no significant difference of size of fish consumed by sex (p>0.05) or species of seals (p>0.05), but there were significant differences in Arctic cod consumed by seals at different locations (p<0.01) and during different seasons (p<0.01). A final regression confirmed seals consumed larger sized Arctic cod at southern Native Alaskan villages and during the Fall season. In turn, seals were consuming smaller sized fish at the northern Native Alaskan villages and during the Spring season. These results provide additional knowledge to ongoing ice seal diet studies. Future research involves the amount of energy seals utilize from Arctic cod to monitoring ice seal populations, due to change of environmental conditions in the Pacific Arctic region.
Funder Acknowledgement(s): I thank ADF&G AMMP for facility and lab for this project. J. Crawford and L. Foster for their help. Mahalo piha. Funding was provided by EPP NOAA.
Faculty Advisor: Hōkū Pihana,