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Information on the annual variability in abundance and growth of juvenile groundfish can be useful for predicting fisheries stocks, but is often poorly known owing to difficulties in sampling fish in their first year of life. In the Western Gulf of Alaska (WGoA) and Eastern Bering Sea (EBS) ecosystems, three species of puffin (tufted and horned puffin, Fratercula cirrhata, Fratercula corniculata, and rhinoceros auklet, Cerorhinca monocerata, Alcidae), regularly prey upon (i.e., "sample") age‐0 groundfish, including walleye pollock (Gadus chalcogramma, Gadidae) and Pacific cod (Gadus microcephalus, Gadidae). Here, we test the hypothesis that integrating puffin dietary data with walleye pollock stock assessment data provides information useful for fisheries management, including indices of interannual variation in age‐0 abundance and growth. To test this hypothesis, we conducted cross‐correlation and regression analyses of puffin‐based indices and spawning stock biomass (SSB) for the WGoA and EBS walleye pollock stocks. For the WGoA, SSB leads the abundance of age‐0 fish in the puffin diet, indicating that puffins sample the downstream production of the WGoA spawning stock. By contrast, the abundance and growth of age‐0 fish sampled by puffins lead SSB for the EBS stock by 1–3 years, indicating that the puffin diet proxies incoming year class strength for this stock. Our study indicates connectivity between the WGoA and EBS walleye pollock stocks. Integration of non‐traditional data sources, such as seabird diet data, with stock assessment data appears useful to inform information gaps important for managing US fisheries in the North Pacific. [ABSTRACT FROM AUTHOR]

Understanding climate change impacts on top predators is fundamental to marine biodiversity conservation, due to their increasingly threatened populations and their importance in marine ecosystems. We conducted a systematic review of the effects of climate change (prolonged, directional change) and climate variability on seabirds and marine mammals. We extracted data from 484 studies (4808 published studies were reviewed), comprising 2215 observations on demography, phenology, distribution, diet, behaviour, body condition and physiology. The likelihood of concluding that climate change had an impact increased with study duration. However, the temporal thresholds for the effects of climate change to be discernibly varied from 10 to 29 years depending on the species, the biological response and the oceanic study region. Species with narrow thermal ranges and relatively long generation times were more often reported to be affected by climate change. This provides an important framework for future assessments, with guidance on response‐ and region‐specific temporal dimensions that need to be considered when reporting effects of climate change. Finally, we found that tropical regions and non‐breeding life stages were poorly covered in the literature, a concern that should be addressed to enable a better understanding of the vulnerability of marine predators to climate change. [ABSTRACT FROM AUTHOR]

The relationship between trophic position and dietary patterns on the level of metal and organochlorine contamination of the food web in the Gulf of Farallones was investigated. By using stable isotope analysis on the egg albumken of four different bird species, a link was established between feeding location and contaminant level.

Abstract We considered the status of Xantus' Murrelet (Synthliboramphus hypoleucus), a rare seabird of the western United States and Mexico, under the World Conservation Union quantitative criteria for listing as [...]

Abstract The worldwide population of Xantus' Murrelets is likely less than 10,000 birds. Breeding populations are restricted to offshore islands from Pt. Conception, California to Central Baja California, Mexico. The [...]

Abstract Rhinoceros Auklets (Cerorhinca monocerata) were once plentiful in California, but presently only three offshore islands, Castle Rock, the Farallon Islands, and Ano Nuevo Island, provide nesting habitat for approximately [...]

Forecasting abundance and understanding year class strength is key to the ecosystem-based fisheries management of herring and other small pelagic fish. Using the San Francisco Bay herring population, we tested the hypothesis that abundance (spawning stock biomass; SSB) could be predicted prior to the commencement of annual fisheries using estimates of i) previous SSB (SSB lag1 ), ii) young-of-the-year production (YOY), and iii) environmental conditions. A time series model including SSB lag1 , YOY lagged 3 years (YOY lag3 ), and environmental conditions in the season before spawning explained 67% of the variance in annual biomass, with better predictive error in comparison with simpler models. YOY lag3 was by far the strongest predictor. It was robust over the entire study period (1980–2017) and also for a more limited period (1991–2017) when observed variance in SSB increased. We attribute the predictive power of YOY productivity to age structure, as almost 70% of the population is comprised of young fish. We hypothesize that an age truncation effect, probably resulting from a combination of long-term environmental effects and fisheries impacts, supports this model, which effectively predicts year class strength. Assuming the population age structure remains the same in the future, our model provides management with an early warning indicator of upcoming SSB with a 3-year lead, which could be applied in harvest control rules. [ABSTRACT FROM AUTHOR]

• Currents and temperature affect ecosystem productivity in Unimak Pass, Alaska. • Seabirds showed stronger responses to environmental variability than responses at lower trophic levels. • Linkages between productivity at lower trophic levels and seabirds were variable. • Breeding success of murres and storm-petrels may be used to monitor some aspects of ecosystem productivity. Understanding bio-physical relationships for areas of high biodiversity in marine systems can illuminate potential impacts of environmental change on concentrations of marine life. A biodiversity hotspot of singular significance in the North Pacific Ocean is Unimak Pass, Alaska, where millions of seabirds, hundreds of cetaceans, and thousands of pinnipeds concentrate each summer to forage on rich zooplankton and forage fish resources. We synthesized a large number of disparate datasets from different sources to examine the effect of current flows and temperature on productivity across trophic levels in Unimak Pass on the seasonal time scale. Our results verify the importance of these factors. This study is one of few to investigate how seabird reproductive success may vary relative to ocean currents, and corroborates other studies showing trait-mediated responses of seabirds to variation in oceanographic conditions, but at the local scale of an Aleutian pass. Somewhat surprisingly, seabird species with larger foraging ranges appeared to respond most to variability in ocean parameters at the seasonal scale. Our hypothesis that spring conditions promote summer productivity was not supported. Instead, contemporaneous conditions in summer had more and stronger effects on seabird production and foraging density. An important caveat of our study is that these relationships remain mechanistically poorly understood due to a lack of data on lower trophic levels and corresponding information on prey use and other aspects of trophic ecology across species. Nonetheless, we have shown that the breeding success of some seabird species on Aiktak Island, as well as seasonal average foraging densities of migratory shearwaters and other species, track currents and temperature variability in Unimak Pass, and may thus be useful as ecological indicators to the robustness of local pelagic food webs, and therefore ecosystem status assessments, in the region. [ABSTRACT FROM AUTHOR]

Understanding aggregation dynamics of forage species is important for evaluating biophysical scaling in marine ecosystems and heterogeneity of trophic interactions. In particular, zooplankton aggregations are fundamental units of many pelagic systems, but are difficult to observe continuously through space and time. Using an established modeling framework that encompasses a coupled regional oceanographic and individual-based modeling system, we test the hypothesis that persistence (duration) of krill aggregations is dependent on their size, intensity, and location of formation within the coastal upwelling region of the California Current. In support of this hypothesis, we found that aggregation size is positively related to intensity, whereas persistence has a parabolic response to aggregation size and intensity, indicating the likelihood that large and highly persistent aggregations are rare. Persistence of krill aggregations also depends on formation location within coastal upwelling areas. We found that krill aggregations were more likely to form near a major seabird colony and that some coastal upwelling areas act as sources of aggregations for other areas. Observations of seabird aggregations were used to evaluate the potential structural realism of predicted krill aggregations. Seabird aggregations displayed marked coherence with predicted krill aggregations in space, providing important criteria on the scaling and availability of krill aggregations to breeding and migratory species. Predicting scales of krill aggregation dynamics will benefit ecosystem assessments, and numerical modeling of predator foraging and marine spatial management aimed at ensuring protection of ecologically important areas. [ABSTRACT FROM AUTHOR]

Worldwide, in recent years capture fisheries targeting lower-trophic level forage fish and euphausiid crustaceans have been substantial (∼20 million metric tons [MT] annually). Landings of forage species are projected to increase in the future, and this harvest may affect marine ecosystems and predator-prey interactions by removal or redistribution of biomass central to pelagic food webs. In particular, fisheries targeting forage fish and euphausiids may be in competition with seabirds, likely the most sensitive of marine vertebrates given limitations in their foraging abilities (ambit and gape size) and high metabolic rate, for food resources. Lately, apparent competition between fisheries and seabirds has led to numerous high-profile conflicts over interpretations, as well as the approaches that could and should be used to assess the magnitude and consequences of fisheries-seabird resource competition. In this paper, we review the methods used to date to study fisheries competition with seabirds, and present “best practices” for future resource competition assessments. Documenting current fisheries competition with seabirds generally involves addressing two major issues: 1) are fisheries causing localized prey depletion that is sufficient to affect the birds? (i.e., are fisheries limiting food resources?), and 2) how are fisheries-induced changes to forage stocks affecting seabird populations given the associated functional or numerical response relationships? Previous studies have been hampered by mismatches in the scale of fisheries, fish, and seabird data, and a lack of causal understanding due to confounding by climatic and other ecosystem factors (e.g., removal of predatory fish). Best practices for fisheries-seabird competition research should include i) clear articulation of hypotheses, ii) data collection (or summation) of fisheries, fish, and seabirds on matched spatio-temporal scales, and iii) integration of observational and experimental (including numerical simulation) approaches to establish connections and causality between fisheries and seabirds. As no single technique can provide all the answers to this vexing issue, an integrated approach is most promising to obtain robust scientific results and in turn the sustainability of forage fish fisheries from an ecosystem perspective. [ABSTRACT FROM AUTHOR]