William J. Sydeman

William J. Sydeman
Farallon Institute for Advanced Ecosystem Research · Marine Ecology

PhD Ecology UC Davis 1999

About

257
Publications
95,155
Reads
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20,848
Citations
Additional affiliations
January 2008 - June 2008
Sonoma State University
Position
  • Professor (Associate)
Description
  • Biological Oceanography
July 2007 - present
Farallon Institute for Advanced Ecosystem Research
Farallon Institute for Advanced Ecosystem Research
Position
  • President and Senior Scientist
Description
  • I am a marine ecologist. Farallon Institute is a small, independent, non-profit marine ecological research laboratory. I founded the business in 2007 with atmospheric oceanographer Nate Mantua and fisheries scientist Alec MacCall.

Publications

Publications (257)
Article
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Eastern Boundary Upwelling Systems (EBUS) are regions where wind-driven coastal upwelling brings deep cold, nutrient-rich water to the surface and may be characterized by a coastal 'footprint' of sea surface temperature (SST) cooler than their surroundings. Previous studies have shown that EBUS coastal temperatures are responding differently to glo...
Article
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Introduction Seabirds are abundant, conspicuous members of marine ecosystems worldwide. Synthesis of distribution data compiled over time is required to address regional management issues and understand ecosystem change. Major challenges when estimating seabird densities at sea arise from variability in dispersion of the birds, sampling effort over...
Article
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The world's eastern boundary upwelling systems (EBUSs) contribute disproportionately to global ocean productivity and provide critical ecosystem services to human society. The impact of climate change on EBUSs and the ecosystems they support is thus a subject of considerable interest. Here, we review hypotheses of climate-driven change in the physi...
Chapter
Conserving the prey base for seabirds is complex. Many seabirds have diverse diets consisting of fish, squid, and mesozooplankton which themselves are strongly influenced by oceanographic and ecosystem processes, and fishery influences must be considered in this context. The first challenging step in management is the need to demonstrate a negative...
Chapter
Mostly indirectly, but also through direct mechanisms, climate change is becoming an increasingly significant threat to seabird populations globally. Marine ecosystems and associated trophic linkages are being influenced by changing climatic conditions, while breeding colonies are being subjected to an increasing frequency of heat waves, storms, an...
Article
We present a response to Butterworth and Ross-Gillespie's (2022) comment on our perspectives on how forage fish fisheries are impacting the endangered African penguin (Sphenicus demersus), and corresponding management options. Butterworth and Ross-Gillespie overstate model uncertainties and downplay the clear ecological and conservation significanc...
Article
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Ocean memory, the persistence of ocean conditions, is a major source of predictability in the climate system beyond weather time scales. We show that ocean memory, as measured by the year-to-year persistence of sea surface temperature anomalies, is projected to steadily decline in the coming decades over much of the globe. This global decline in oc...
Article
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Ocean memory, the persistence of ocean conditions, is a major source of predictability in the climate system beyond weather time scales. We show that ocean memory, as measured by the year-to-year persistence of sea surface temperature anomalies, is projected to steadily decline in the coming decades over much of the globe. This global decline in oc...
Article
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Bull kelp, Nereocystis luetkeana , is an iconic kelp forest species of the Northeast Pacific that provides a wide range of ecosystem services to coastal marine species and society. In northern California, U.S.A., Nereocystis abundance declined sharply in 2014 and has yet to recover. While abiotic and biotic stressors were present prior to 2014, the...
Article
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Forage fish are a critical component of marine ecosystems because they integrate energy across trophic levels within marine food webs. Many studies have highlighted the importance of this group, and past research efforts have focused largely on studying forage fish within offshore and estuarine areas. In contrast, limited information is available f...
Article
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Marine fish populations commonly exhibit low-frequency fluctuations in biomass that can cause catch volatility and thus endanger the food and economic security of dependent coastal societies. Such variability has been linked to fishing intensity, demographic processes and environmental variability, but our understanding of the underlying drivers re...
Article
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In a scientifically-transformative project, South Africa implemented a decade-long field experiment to understand how fisheries may be affecting its most iconic seabird, the African penguin Spheniscus demersus. This unique effort prohibits the take of anchovy and sardine within relatively small areas around four African penguin breeding colonies, t...
Article
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Krill are an abundant and globally distributed forage taxon in marine ecosystems, including the California Current Ecosystem (CCE). The role of krill in trophodynamics depends on both abundance and size (biomass), but the impact of extreme climate events on krill body size is poorly understood. Using samples collected from 2011 to 2018, we tested t...
Article
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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...
Preprint
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Oceanic features, such as mesoscale eddies that entrap and transport water masses, create heterogeneous seascapes to which biological communities may respond. To date, however, our understanding of how internal eddy dynamics influence plankton community structuring is limited by sparse sampling of eddies and their associated biotic communities. In...
Technical Report
Full-text available
North Pacific Marine Science Organization (PICES) Special Publication
Article
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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 puf...
Article
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The Northeast Pacific is a highly heterogeneous and productive ecosystem, yet it is vulnerable to climate change and extreme events such as marine heat waves. Recent heat wave induced die-offs of fish, marine mammals, and seabirds in the Gulf of Alaska were associated with the loss of large, lipid-rich copepods, which are a vital food resource for...
Article
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Plain Language Summary From 2013 to 2016, an exceptional California drought co‐occurred with extreme northeast Pacific (NEP) marine heatwaves (MHWs), leading to significant social‐economical‐ecological impacts. The evolution of this event led us to examine California drought co‐occurring with MHWs in the California Current (CC) and in the Gulf of A...
Article
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The California Current System (CCS) has experienced large fluctuations in environmental conditions in recent years that have dramatically affected the biological community. Here we synthesize remotely sensed, hydrographic, and biological survey data from throughout the CCS in 2019–2020 to evaluate how recent changes in environmental conditions have...
Article
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Our synthesis combines inferences from a long-term fisheries monitoring survey and principles of ecosystem oceanography to inform and benefit biodiversity monitoring and modeling studies within the California Current Large Marine Ecosystem. We review the history, research, and application of the Rockfish Recruitment and Ecosystem Assessment Survey,...
Article
Sampling seabirds The vastness of the worlds' oceans makes them difficult to monitor. Seabirds that forage and breed across oceans globally have been recognized as sentinels of ocean health. Sydeman et al. looked across seabird species of both the Northern and Southern Hemispheres and found varying patterns. Northern Hemisphere species exhibited gr...
Article
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Spatial structuring of mid-trophic level forage communities in the Gulf of Alaska (GoA) is poorly understood, even though it has clear implications for the health of fisheries and marine wildlife populations. Here, we test the hypothesis that summertime (May-August) mesozooplankton communities are spatially-persistent across years of varying ocean...
Article
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Forage fish populations often undergo large and rapid fluctuations in abundance. However, most of their predators are buffered against such fluctuations owing to their slower pace of life, which allows them to maintain more stable populations, at least during short periods of food scarcity. In this study, we investigated top‐down processes exerted...
Article
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Due to their global distribution, high biomass and energy content, euphausiids (krill) are important prey for many mid and upper trophic level marine organisms. Understanding drivers of krill habitat is essential for forecasting range shifts, and to better understand the response of krill predators to climate change. We hypothesized that the distri...
Article
The central stock of northern anchovy (CSNA; Engraulis mordax), the most abundant small pelagic fish in the southern California Current, is key to ecosystem functions. We review drivers of its population dynamics in relation to management. Springtime upwelling intensity lagged by 2 years co-varied positively with CSNA biomass, as did the abundance...
Article
Full-text available
The central stock of northern anchovy (CSNA; Engraulis mordax), the most abundant small pelagic fish in the southern California Current, is key to ecosystem functions. We review drivers of its population dynamics in relation to management. Springtime upwelling intensity lagged by 2 years co-varied positively with CSNA biomass, as did the abundance...
Article
Ecosystem based fisheries management is a priority nationally and beyond, yet lack of robust approaches has hampered its implementation. Even though forage fishes are critically important in marine ecosystems, few examples of applied ecosystem-based information exist. We created a multi-pronged approach to ecosystem considerations in fisheries mana...
Article
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Climate change and increased variability and intensity of climate events, in combination with recovering protected species populations and highly capitalized fisheries, are posing new challenges for fisheries management. We examine socio-ecological features of the unprecedented 2014–2016 northeast Pacific marine heatwave to understand the potential...
Article
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About 62,000 dead or dying common murres (Uria aalge), the trophically dominant fish-eating seabird of the North Pacific, washed ashore between summer 2015 and spring 2016 on beaches from California to Alaska. Most birds were severely emaciated and, so far, no evidence for anything other than starvation was found to explain this mass mortality. Thr...
Article
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The rapid pace of environmental change in the Anthropocene necessitates the development of a new suite of tools for measuring ecosystem dynamics. Sentinel species can provide insight into ecosystem function, identify hidden risks to human health, and predict future change. As sentinels, marine apex (top) predators offer a unique perspective into oc...
Article
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Climatic drivers of the size and body condition of forage fish in the North Pacific are poorly known. We hypothesized that length and condition of forage fish in the Gulf of Alaska (GoA) vary in relation to ocean temperature on multiple scales. To test this hypothesis, we analyzed morphometric data for capelin (Mallotus catervarius) and Pacific san...
Article
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Forage fishes are ecologically and economically important in marine ecosystems worldwide and thus are a focal topic for ecosystem-based fisheries management. In the California Current Large Marine Ecosystem (CCLME), the community dynamics of forage populations have been studied at regional spatial scales, but not across regions. To evaluate indicat...
Article
Large recent decreases of Cape gannets Morus capensis, Cape cormorants Phalacrocorax capensis and African penguins Spheniscus demersus in South Africa resulted in their being listed as Endangered. These seabirds, endemic to the Benguela upwelling system (BUS), primarily rely on anchovy Engraulis encrasicolus and sardine Sardinops sagax for food, ye...
Article
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The California Current Ecosystem (CCE) has been in a primarily warm state since 2014, and this pattern largely continued into 2019. The CCE experienced a mild El Niño from late 2018 into 2019, and basin-scale indicators reflected this condition (elevated Oceanic Niño Index and Pacific Decadal Oscillation; Table 1). Despite the El Niño, spring upwel...
Article
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Following the marine heat wave of 2014–16, the California Current System (CCS) trended towards more typical conditions north of Point Conception, California, from mid-2017 to mid-2018, but became highly abnormal in the south by mid-2018. Two basin scale indices (Pacific Decadal Oscillation and Oceanic Niño Index) were close to neutral, but the Nort...
Article
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The California Current Ecosystem (CCE) is a productive eastern boundary upwelling system that supports a wide variety of forage stocks. Decadal and interannual variability in the environment influence forage species, which in turn affects predators. The recent diet of California sea lions (Zalophus californianus; CSL) from Central California was de...
Article
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...
Article
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Anchovy Engraulis encrasicolus is economically important and ecologically critical to the structure and function of the Benguela Current ecosystem, as it transfers energy from plankton to piscivorous fishes, seabirds, and marine mammals. Like other small pelagic fishes, annual recruitment strength varies substantially, but the drivers of these fluc...
Article
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Submarine canyon systems are ubiquitous features of marine ecosystems, known to support high levels of biodiversity. Canyons may be important to benthic-pelagic ecosystem coupling, but their role in concentrating plankton and structuring pelagic communities is not well known. We hypothesize that at the scale of a large marine ecosystem, canyons pro...
Article
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We develop a multi-model approach to explore how abundance of a forage fish (Pacific sardine Sardinops sagax) impacts the ecosystem and predators in the California Current, a region where sardine and anchovy Engraulis mordax have recently declined to less than 10% of contemporary peak abundances. We developed or improved applications of three ecosy...
Article
Along the western margin of North America, the winter expression of the North Pacific High (NPH) strongly influences interannual variability in coastal upwelling, storm track position, precipitation, and river discharge. Coherence among these factors induces covariance among physical and biological processes across adjacent marine and terrestrial e...
Article
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The tufted puffin (Fratercula cirrhata) is a generalist seabird that breeds throughout the North Pacific and eats more than 75 different prey species. Using puffins as samplers, we characterized the geographic variability in pelagic food webs across the subarctic North Pacific from the composition of ~10,000 tufted puffin meals (~56,000 prey items)...
Article
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Climate-related shifts in marine mammal range and distribution have been observed in some populations; however, the nature and magnitude of future responses are uncertain in novel environments projected under climate change. This poses a challenge for agencies charged with management and conservation of these species. Specialized diets, restricted...
Article
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This report examines the ecosystem state of the California Current System (CCS) from spring 2016–spring 2017. Basin-scale indices suggest conditions that would support average to below average coast-wide production across the CCS during this time period. Regional surveys in 2016 sampled anomalously warm surface and subsurface waters across the CCS....
Article
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Forage fish generate economic benefits through directed fisheries, but also generate benefits through their role as prey to other valued species (large piscivorous fish, seabirds, and marine mammals). Previous evaluations of the ecosystem consequences of forage fish fisheries used models with coarse taxonomic resolution of forage fish and their pre...
Article
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...
Article
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Seabirds are thought to be reliable, real-time indicators of forage fish availability and the climatic and biotic factors affecting pelagic food webs in marine ecosystems. In this study, we tested the hypothesis that temporal trends and interannual variability in seabird indicators reflect simultaneously occurring bottom-up (climatic) and competito...
Article
The California Current System (CCS) has two independent seasonal modes of upwelling variability, summer and winter, driven by different atmospheric processes. The variability of upwelling winds during winter is particularly important as strong, episodic events, driven by atmospheric teleconnections with the equatorial Pacific that are active in thi...
Article
The influence of climate variability on Eastern Boundary Upwelling Ecosystems (EBUEs) is evident through changes in productivity and shifts in species' distributions, yet to date, metrics of upwelling variability appropriate for comparative ecosystem studies have yet to be implemented. Here, we present synoptic-scale upwelling indices to quantify i...
Article
Updated abundance estimates of the central subpopulation of northern anchovy (Engraulis mordax) are developed from California Cooperative Oceanic Fisheries Investigations (CalCOFI) data on egg and larval densities for 1951–2011, with new estimates for 2012-2015. We followed the approach of MacCall et al. (2016; Fish. Res.) which corrected for a hyp...
Article
Marine ecosystems are complex adaptive systems with physical and biological processes operating on multiple spatial and temporal scales. Here, we present an operational regional indicator for California's continental shelf system and investigate its skill in predicting a variety of biological responses across trophic levels. This updated Multivaria...
Article
MacCall et al. (2016) recently published an estimate of the biomass of the central stock of northern anchovy (Engraulis mordax) off the coast of California, and found that this stock experienced a population crash from 2009-2015. However, anecdotal observations concurrent to the collapse suggested that anchovy were extremely abundant. We used centr...
Preprint
Full-text available
Trends in Pacific herring biomass
Article
Long-term studies of predator food habits (i.e., 'predator-based sampling') are useful for identifying patterns of spatial and temporal variability of forage nekton in marine ecosystems. We investigated temporal changes in forage fish availability and relationships to ocean climate by analyzing diet composition of three puffin species (horned puffi...
Article
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Human impacts (e.g., fishing, pollution and shipping) on pelagic ecosystems are increasing, causing concerns about stresses on marine food webs. Maintaining predator-prey relationships through protection of pelagic hotspots is crucial for conservation and management of living marine resources. Biotic components of pelagic, plankton-based, ecosystem...