John Piatt, Ph.D. (Former Employee)

Populations of the pigeon guillemot (Cepphus columba) and other piscivores have been in decline for several decades in the Gulf of Alaska and Bering Sea, and a decline in abundance of lipid-rich schooling fishes is hypothesized as the major cause. We tested this hypothesis by studying the breeding biology of pigeon guillemots during 1995-1999 while simultaneously measuring prey abundance...

The northern lampfish (Stenobrachius leucopsarus, family Myctophidae) and northern smoothtongue (Leuroglossus schmidti, family Bathylagidae) are mesopelagic fishes, defined by their vertical distribution in the mesopelagic zone (200–1000 m) during daylight hours. Northern lampfish range from the Bering Sea to southern California (Shimada, 1948), where their abundance is highest along the

Traditional field methods of assessing effects of fluctuations in food supply on the survival and reproductive performance of seabirds may give equivocal results. In this project we applied an additional tool: The measure of stress hormones in free-ranging seabirds. Food stress can be quantified by measuring base levels of stress hormones such as corticosterone in the blood of seabirds...

Parent black-legged kittiwakes (Rissa tridactyla) and their dependent chicks respond to food shortages by increasing circulating levels of corticosterone. To examine the behavioral significance of corticosterone release, we experimentally increased levels of circulating corticosterone in parents and chicks up to the levels observed during food shortages. We found that corticosterone...

We investigated the habitat of juvenile groundfishes in relation to depth, water temperature, and salinity in Kachemak Bay, Alaska. Stations ranging in depth from 10 to 70 m and with sand or mud-sand substrates were sampled with a small-meshed beam trawl in August-September of 1994 to 1999. A total of 8,201 fishes were captured, comprising at least 52 species. Most fishes (91%) had a...

Release of corticosterone in hungry kittiwake chicks facilitates begging and allows them to restore depleted energy reserves by increasing parental food provisioning. However, in order to avoid detrimental effects of chronic elevation of corticosterone, chicks might suppress adrenocortical activity in response to prolonged food shortages. In this study we examined temporal dynamics of

Human obsession with the Great Auk or Garefowl Pinguinus impennis is what this book is about, and it further fuels the fire of our fascination. As Fuller concludes in his introduction: ‘The Great Auk, large and plump, has tempted man since the dawn of history. Whatever the precise reasons for its hold on his imagination, it is a hold that has lasted, and even 150 years after the bird’s...

Some seabird populations damaged by the Exxon Valdez oil spill continue to decline or are not recovering. In order to understand the ultimate cause of seabird population fluctuations, we must measure productivity, recruitment, and adult survival. Recent APEX studies focused on measuring productivity only. Recruitment measurement demands an unrealistic study duration. We propose to...

Distinct sand lance populations occur within the relatively small geographic area of Lower Cook Inlet, Alaska. Marked meso-scale differences in abundance, growth, and mortality exist as a consequence of differing oceanographic regimes. Growth rate within populations (between years) was positively correlated with temperature. However, this did not extend to inter-population comparisons...

Seabirds are the most visible and vulnerable victims of oil pollution in marine waters. As demonstrated by the "Exxon Valdez" spill (Piatt et al. 1990), we cannot predict when or where an accident leading to pollution might occur in Alaska, or where oil will eventually end up traveling from a point source of pollution. It is therefore prudent to document the abundance and distribution of...

We examined effects of season, time of day, tide stage, tidal oscillation, and sea surface temperature on Marbled Murrelet (Brachyramphus marmoratus) abundance and distribution at sea. We also evaluated whether constraining surveys to specific time periods or tide stages would reduce temporal variability in counts. Murrelets were surveyed daily from small boats and from shore in Auke Bay...

Dedicated at-sea surveys for marine birds and mammals conducted in lower Cook Inlet in late July and early August from 1995–99 failed to locate any belugas, Delphinapterus leucas. Surveys covered a total of 6,249 linear km and were conducted in both nearshore and offshore habitats. Sightings included 791 individual marine mammals of 10 species. Both historical data and local knowledge...