Kittiwake diets and chick production signal a 2008 regime shift in the Northeast Pacific

Scott A. Hatch

doi:10.3354/meps10161

Home/Archive/USGS

USGS · 70045502

Kittiwake diets and chick production signal a 2008 regime shift in the Northeast Pacific

Scott A. Hatch

View original source ↗Export metadata ↓

Abstract

I examined ~2700 food samples collected from adult and nestling black-legged kittiwakes Rissa tridactyla from 1978 through 2011 on Middleton Island in the Gulf of Alaska. The kittiwake diet was composed chiefly of fish, but invertebrates were taken in appreciable quantities in April and May. Upon spring arrival at the colony, adult kittiwakes foraged regularly at night on vertically migrating mesopelagic prey—lanternfishes (Myctophidae), squids, crustaceans, and polychaetes—a behavior they largely discontinued by egg-laying. During incubation and chick-rearing, food samples contained mostly (~85% by weight) Pacific sand lance Ammodytes hexapterus, capelin Mallotus villosus, Pacific herring Clupea pallasii, sablefish Anopoploma fimbria, krill (Euphausiidae), and juvenile salmon Onchorynchus gorboscha and O. keta. A salient finding over the longitudinal study was the emergence, twice, of capelin as a dominant forage species—once in 2000 to 2003, and again in 2008 through 2011. Kittiwakes responded to capelin availability by producing markedly higher numbers of fledged young. The 2000 to 2003 event corresponded to a previously documented shift to cooler conditions in the NE Pacific, which apparently was relatively limited in magnitude or duration. The more recent transition appears stronger and may be more lasting. I submit that 2008 was an important turning point, marking a substantive reversal of warm conditions that began with the well-documented regime shift of 1977. That interpretation is consistent with the existence of a ~60 yr cycle in ocean and atmospheric conditions in the North Pacific. All else being equal, it predicts the next 20 to 30 yr will be favorable for species such as kittiwakes and Steller sea lions, which seemed to respond negatively to the 1977 to 2007 warm phase of the Pacific Decadal Oscillation.

Explore related subjects

Marine Ecology Progress Series Article

Source-reported bounding extent: 57.79° to 61.62° latitude; -154.34° to -141.11° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Scott A. Hatch. 2013. Kittiwake diets and chick production signal a 2008 regime shift in the Northeast Pacific. https://doi.org/10.3354/meps10161

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2025

Detection of the Diadema antillarum scuticociliatosis Philaster clade on sympatric metazoa, plankton, and abiotic surfaces and assessment for its potential reemergence

A ciliate belonging to the Diadema antillarum scuticociliatosis (DaSc)-associated Philaster clade (DaScPc) caused catastrophic long-spined urchin mass mortality in spring and summer of 2022. The ciliate can be grown in culture in both the presence and absence of D. antillarum tissues, suggesting that it may persist outside its host by consuming microorganisms or dissolved organic nutrients. We hypothesized that DaScPc was present outside its host during and after mass mortality and absent prior to 2022. We examined DaScPc in DNA extracted from 500 swabs of sym- patric metazoa and abiotic surfaces, and plankton samples, collected at 35 sites in the Caribbean in 2022 and 2023. DaScPc was detected on corals, turf algae, and a sponge, predominantly at sites with active or prior DaSc. We examined whether it was present prior to 2022 by surveying extracted DNA from Caribbean corals and water collected near corals by PCR and by mining publicly available transcriptomes and metagenomes for DaScPc rRNAs. These efforts yielded no DaScPc genes. We further hypothesized that DaScPc may recruit to the specific corals detected in field surveys, and that these may then infect naïve hosts. A mesocosm experiment to test DaScPc recruitment suggested that, while it recruited to corals, it did so inconsistently between coral species. Incubation of corals that recruited DaScPc with naïve urchins yielded inconclusive results since urchins died without characteristic DaSc signs. Overall, our results suggest that DaScPc may occur outside its urchin host, and that it may have been absent in the region prior to 2022.

Florida↗

USGS2024

Photogrammetry-based body condition for monitoring an Arctic marine mammal experiencing habitat loss

Monitoring animal body condition can provide insight on population responses to environmental change. Pacific walruses ( Odobenus rosmarus divergens ) are experiencing loss of their sea ice habitat which has decreased the time that females spend foraging during a critical period of pregnancy and lactation. Here we investigate the potential for body condition to track demographic change and be monitored via two-dimensional aerial imagery by (1) examining whether walrus somatic growth and body mass data tracked estimated historic demographic changes, (2) collecting morphometric and body mass data and aerial imagery of walruses in human care to determine if sex, age group, and body size and condition can be determined from imagery, and (3) examining aerial imagery from a large coastal haulout used primarily by females and young to estimate potential sample sizes of measurable walruses. Body mass and growth in body length decreased between the last 1970s and early 1980s concurrent with a period when the population apparently approached carrying capacity and subsequently declined. Measures from aerial imagery (1) accurately distinguished reproductive age females from subadults and adult males and (2) enabled body mass estimates with 6-7% error using either areal footprint or a combination of length and width. We found a mean of 216 ± 77 walruses appropriately positioned for measurement from aerial surveys of the haulout enabling measurements of ≥7000 individuals annually via repeated daily imagery. Our results suggest that body mass of reproductive age females and growth of dependent young may be useful indicators to augment monitoring of the Pacific walrus population and can be achieved via non-invasive aerial imagery collections.

Alaska↗

USGS2024

Assessing the population consequences of disturbance and climate change for the Pacific walrus

Climate change and anthropogenic disturbance are increasingly affecting wildlife at a global scale. Predicting how varying types and degrees of disturbance may interact to influence population dynamics is a key management challenge. Population consequences of disturbance (PCoD) models provide a framework to link effects of anthropogenic disturbance on an individual’s behavior and physiology to population-level changes. In the present study, we develop a Pacific walrus ( Odobenus rosmarus divergens ) PCoD model to encompass the population-level effects of both anthropogenic disturbance and climate change. As the Arctic becomes increasingly ice-free, walruses spend more time at coastal (vs. ice-based) haulouts, from which they must expend more energy to reach foraging areas and where they have an elevated risk of mortality. Concurrently, sea ice loss is increasing the anthropogenic footprint in the Arctic (e.g. fisheries, shipping, energy exploration), which creates additional disturbance. We applied the PCoD model to 4 scenarios (ranging from optimistic to pessimistic) which incorporate different global sea ice model projections along with varying degrees of anthropogenic disturbance. All scenarios indicated a decline in Pacific walrus vital rates by the end of the 21st century, but our results demonstrated that the intensity of that decline could be mitigated by global efforts to reduce carbon emissions, along with local management and conservation efforts to protect important coastal haulouts and foraging grounds. In summary, we introduce a flexible PCoD modeling framework in a novel context which will prove useful to researchers studying species threatened by rapid environmental change.

Marine Ecology Progress Series↗