The physiological response of juvenile steelhead (Oncorhynchus mykiss) to prolonged heat stress was examined by exposing replicated groups of fish to 25 consecutive days at 15°C, 23°C, and 25°C followed by a 55 day recovery period at 15°C. We found that at temperatures ≥25°C, steelhead consumed significantly less food per...
Concurrent measurements of predator and prey δ¹⁵N isotope values demonstrated that a cross-shelf
isotopic gradient can propagate through a marine food web from forage species to top-tier predators and
indicate foraging areas at a scale of tens of kilometers. We measured δ¹³C and δ¹⁵N in muscle tissues of
thick-billed murres...
This study examined the potentially stressful
effects of tagging juvenile rainbow trout Oncorhynchus mykiss
with passive integrated transponder (PIT) tags by measuring
short-term (<120-h) changes in plasma concentrations of
cortisol and hepatic heat shock protein 70 (hsp70). In a
laboratory experiment, plasma cortisol levels were measured
in fish before they...
Blood levels of the egg yolk precursor vi-
tellogenin (VTG) can be used as a definitive marker for
the onset and progress of maturation in female teleosts.
In the present study, an enzyme-linked immunosorbent
assay (ELISA) was developed to measure VTG in blood
plasma from three species of temperate basses....
In the US Pacific Northwest, rockfishes Sebastes spp. have recently become a focus for increased management efforts; several species are currently managed under extreme conservation measures due to low population levels and intense fishing pressure. Rockfish recruitment is extremely variable, and a better understanding of the factors influencing recruitment and...
We sought to characterize the distribution of juvenile walleye pollock Theragra chalcogramma in an area of intense predator-prey interactions and to describe habitat features that lead to their observed distributions. The distribution of juvenile walleye pollock around the Pribilof Islands in the southeastern Bering Sea in 2008 and 2009 was...
Ontogenetic changes in resource use often delimit transitions between life stages. Ecological and individual factors can cause variation in the timing and consistency of these transitions, ultimately affecting community and population dynamics through changes in growth and survival. Therefore, it is important to document and understand behavioral and life history...
During the 2008 and 2009 breeding seasons of murres Uria spp., we combined visual observations of these predators with active acoustics (sonar), fish trawls, zooplankton net tows, and hydrographic measurements in the area surrounding breeding colonies in the southeastern Bering Sea. We acoustically detected thousands of bubble trails that were...
Differences in the chemical composition of calcified skeletal structures (e.g. shells, otoliths) have proven useful for reconstructing the environmental history of many marine species. However, the extent to which ambient environmental conditions can be inferred from the elemental signatures within the vertebrae of elasmobranchs (sharks, skates, rays) has not been...
Many multispecies models have assumed that prey density determines per-capita predator consumption rates, following a functional response relationship. However, empirical evidence suggests that a predator’s diet can also be influenced by a variety of environmental factors, including interactions with other predators. We used diet and abundance data from National Marine...