Coastal Flow in the Northern Gulf of Alaska as Observed by Dynamic Topography and Satellite-Tracked Drogued Drift Buoys

Section: Discussionmentioning

confidence: 99%

Nutrients and primary production along the eastern Aleutian Island Archipelago

Mordy

Stabeno

Ladd

et al. 2005

“…, 1999). The Alaska Coastal Current (ACC) is characterized by warmer, more saline waters and flows southward in the GOA (Royer et al. , 1979), nearshore along the south side of the Alaska Peninsula and links to the shelf waters of the eastern Bering Sea through Unimak Pass (Stabeno et al.…”

Section: Discussionmentioning

confidence: 99%

An ecological classification of Alaskan Steller sea lion (Eumetopias jubatus) rookeries: a tool for conservation/management

Call¹,

Loughlin

2005

As the western stock of Steller sea lions continues to decline, government managers may place additional controls on commercial fisheries as protective measures. Currently, management decisions regarding rookeries are based largely on the geographic location of a site, and little effort has been made to describe sea lion rookeries in an ecosystem context. We provide a broad ecological characterization of rookeries for the western stock of Steller sea lions, which can be used in making management decisions to facilitate their recovery. We gathered data on habitat (bathymetry, sea surface temperature, substrate type, and orientation), diet and population trends from available literature and National Marine Fisheries Service databases (1990-98), and we used a Geographic Information System to group sea lion rookeries into ecologically related regions. Ecological attributes were assigned to rookeries within a 10-nm radius of land. Regions were determined using cluster analysis. Five distinct classes of rookeries (i.e. potential management regions) were identified based on their relatedness to the ecological factors we defined. Several of the regional breaks occur at major oceanic passes including Amchitka, Samalga, and Unimak Passes and are associated with ocean currents.

“…1). The ACC is driven by winds and freshwater discharge from the coastal regions around the Gulf of Alaska (Royer et al. , 1979; Royer, 1979) and flows southwestward along the south side of the Alaska Peninsula (Schumacher and Reed, 1986; Reed, 1987; Hinckley et al.…”

Section: Introductionmentioning

confidence: 99%

Marine environment of the eastern and central Aleutian Islands

Ladd

Hunt

Mordy

et al. 2005

126

179

To examine the marine habitat of the endangered western stock of the Steller's sea lion (Eumetopias jubatus), two interdisciplinary research cruises (June 2001 and May to June 2002) measured water properties in the eastern and central Aleutian Passes. Unimak, Akutan, Amukta, and Seguam Passes were sampled in both years, and three additional passes (Umnak, Samalga, and Tanaga) were sampled in 2002. In the North Pacific (and to a lesser extent in the Bering Sea), a strong front in water properties was observed near Samalga Pass in June of both years, with significantly warmer, fresher, and more nitrate‐poor water east of Samalga Pass than west of the pass. These water properties reflect differences in source waters (Alaska Coastal Current versus Alaskan Stream), mixing depth, and Bering Sea influence. Strong cross‐Aleutian gradients were also observed with warmer, fresher water on the North Pacific side of the archipelago. The nutrient content of the waters flowing through the passes, combined with the effects of mixing within the passes, influences the transport of nutrients into the Bering Sea. As water moves away from the strong mixing of the passes and becomes more stratified, phytoplankton can take advantage of the enhanced nutrient concentrations. Thus, the northern side of the Aleutian Islands (especially in the lee of the islands) appears to be more productive. Combined with evidence of coincident changes in many ecosystem parameters near Samalga Pass, it is hypothesized that Samalga Pass forms a physical and biogeographic boundary between the eastern and central Aleutian marine ecosystems.