Use of chemical tracers in assessing the diet and foraging regions of eastern North Pacific killer whales

Top predators in the marine environment integrate chemical signals acquired from their prey that reflect both the species consumed and the regions from which the prey were taken. These chemical tracers—stable isotope ratios of carbon and nitrogen; persistent organic pollutant (POP) concentrations, patterns and ratios; and fatty acid profiles—were measured in blubber biopsy samples from North Pacific killer whales (Orcinus orca) (n = 84) and were used to provide further insight into their diet, particularly for the offshore group, about which little dietary information is available. The offshore killer whales were shown to consume prey species that were distinctly different from those of sympatric resident and transient killer whales. In addition, it was confirmed that the offshores forage as far south as California. Thus, these results provide evidence that the offshores belong to a third killer whale ecotype. Resident killer whale populations showed a gradient in stable isotope profiles from west (central Aleutians) to east (Gulf of Alaska) that, in part, can be attributed to a shift from off-shelf to continental shelf-based prey. Finally, stable isotope ratio results, supported by field observations, showed that the diet in spring and summer of eastern Aleutian Island transient killer whales is apparently not composed exclusively of Steller sea lions.

Regional differences in the spatial and temporal heterogeneity of oceanographic habitat used by Steller sea lions

Over the past three decades, the decline and altered spatial distribution of the western stock of Steller sea lions (Eumetopias jubatus) in Alaska have been attributed to changes in the distribution or abundance of their prey due to the cumulative effects of fisheries and environmental perturbations. During this period, dietary prey occurrence and diet diversity were related to population decline within metapopulation regions of the western stock of Steller sea lions, suggesting that environmental conditions may be variable among regions. The objective of this study, therefore, was to examine regional differences in the spatial and temporal heterogeneity of oceanographic habitat used by Steller sea lions within the context of recent measures of diet diversity and population trajectories. Habitat use was assessed by deploying satellite-depth recorders and satellite relay data loggers on juvenile Steller sea lions (n = 45) over a five-year period (2000–2004) within four regions of the western stock, including the western, central, and eastern Aleutian Islands, and central Gulf of Alaska. Areas used by sea lions during summer months (June, July, and August) were demarcated using satellite telemetry data and characterized by environmental variables (sea surface temperature [SST] and chlorophyll a [chl a]), which possibly serve as proxies for environmental processes or prey. Spatial patterns of SST diversity and Steller sea lion population trends among regions were fairly consistent with trends reported for diet studies, possibly indicating a link between environmental diversity, prey diversity, and distribution or abundance of Steller sea lions. Overall, maximum spatial heterogeneity coupled with minimal temporal variability of SST appeared to be beneficial for Steller sea lions. In contrast, these patterns were not consistent for chl a, and there appeared to be an ecological threshold. Understanding how Steller sea lions respond to measures of environmental heterogeneity will ultimately be useful for implementing ecosystem management approaches and developing additional conservation strategies.

Agriculture Builders of Nebraska Annual Meeting

Anthony McAuliffe was acting commander of the 101st Airborne Division during the Battle of the Bulge in World War II. December 22, 1944, he was in charge of the-defense of Bastogne when advancing German forces called upon his garrison to surrender.

Refuge Update – March/April 2009, Volume 6, Number 2

Table of Contents: America’s Birds: In an Alarming State Snakes Alive! Title Sub Title East Coast Wetlands Are Disappearing Chief’s Corner: What We Do Now Extreme Makeover for Bird Sightings by Mike Carlo Taking Care of Our World War II Legacy by Lisa Matlock Whatever Happened to . . . . San Francisco Bay Wetland Restoration Projects Recalling the Battle of Long Island Sound by David Klinger Bold Approaches for Climate Change How Alligator River Refuge Is Planning and Adapting by Mike Bryant Rapid Climate Change Is Transforming the Arctic by David Payer Tracking Change on Wildlife Refuges by Kathy Granillo Where SLAMM Foretells a Wetter Future Reviving the Land – and the Air by Bob Ford and Pete Jerome Connecting the Conservation Landscape a New Priority by Mike Scott and Bob Adamcik Awards for Refuge System Palmyra Atoll Refuge Becomes Ramsar Site Not So Strategic Habitat Conservation: A True Story by David Viker Putting Food on Alaskan Tables by Andy Aderman