Larry Crowder is the Edward F. Ricketts Provostial Professor of Marine Ecology and Conservation at Hopkins Marine Station and a senior fellow at the Stanford Woods Institute for the Environment, both part of Stanford University. He is also a Core Faculty Partner at Stanford Center for Ocean Solutions. Previously, he was the Stephen Toth Professor of Marine Biology at Duke University. Dr. Crowder's research centers on predation and food web interactions, mechanisms underlying recruitment variation in fishes, population and food web modeling in conservation biology, and interdisciplinary approaches to marine conservation. He has studied food web processes in both freshwater and marine ecosystems, and has used observational, experimental, and modeling approaches to understand these interactions in an effort to improve management. He was principal investigator for a number of large interdisciplinary research projects including the South Atlantic Bight Recruitment Experiment (SABRE), OBIS SEAMAP (Spatial Ecological Analysis of Megavertebrate Animal Populations), and Project GLOBAL (Global Bycatch Assessment of Long-Lived Species). He has also directed and participated in a number of research, analysis, and synthesis groups at the National Center for Ecological Analysis and Synthesis (NCEAS) and for the National Research Council’s Ocean Studies Board. His recent research has focused on marine conservation, including research on bycatch, spatial ecological analysis, nutrients and low oxygen, sustainable seafood, ecosystem-based management, marine spatial planning, and governance. He is a AAAS Fellow and was awarded Duke University’s Scholar/Teacher of the year award in 2008-2009.
Specialties: Bycatch, Coastal and Nearshore Environment, Dead Zones and Hypoxia, Ecosystem Health, Estuaries, Fisheries, Land-Sea Interactions, Ocean Pelagic Organisms, Ocean Conservation, Oil Spills
Current Research and Scholarly Interests
Ecology, conservation, fisheries, protected species, ecosystem-based management
- Advanced Topics in Marine Conservation
BIOHOPK 299H (Win, Spr)
- Marine Conservation Biology
BIOHOPK 173H, BIOHOPK 273H (Spr)
- The Social Ocean: Human Dimensions of Costal and Marine Ecosystems
ENVRES 220 (Spr)
Independent Studies (13)
- Advanced Research Laboratory in Experimental Biology
BIO 199 (Sum)
- Directed Instruction or Reading
BIOHOPK 198H (Aut, Win, Spr, Sum)
- Directed Reading in Biology
BIO 198 (Aut, Win, Spr, Sum)
- Directed Reading in Environment and Resources
ENVRES 398 (Aut, Win, Spr, Sum)
- Directed Research in Environment and Resources
ENVRES 399 (Aut, Win, Spr, Sum)
- Graduate Research
BIO 300 (Aut, Win, Spr, Sum)
- Out-of-Department Advanced Research Laboratory in Experimental Biology
BIO 199X (Sum)
- Out-of-Department Directed Reading
BIO 198X (Sum)
- Out-of-Department Graduate Research
BIO 300X (Sum)
BIOHOPK 300H (Aut, Win, Spr, Sum)
- Teaching of Biological Science
BIOHOPK 290H (Win, Spr, Sum)
- Teaching of Biology
BIO 290 (Aut, Spr)
- Undergraduate Research
BIOHOPK 199H (Aut, Win, Spr, Sum)
- Advanced Research Laboratory in Experimental Biology
Prior Year Courses
- Advanced Topics in Marine Conservation
BIOHOPK 299H (Win, Spr)
- Marine Conservation Biology
BIOHOPK 173H, BIOHOPK 273H (Spr)
- Marine Conservation Biology - Seminar and Discussion Only
BIOHOPK 173HA, BIOHOPK 273HA (Spr)
- Marine Conservation Biology
BIOHOPK 173H, BIOHOPK 273H (Spr)
- Short Course on Ocean Policy
BIOHOPK 280 (Sum)
- Marine Conservation Biology
BIOHOPK 173H, BIOHOPK 273H (Spr)
- Advanced Topics in Marine Conservation
Graduate and Fellowship Programs
Biology (School of Humanities and Sciences) (Phd Program)
Combining fish and benthic communities into multiple regimes reveals complex reef dynamics.
2018; 8 (1): 16943
Coral reefs worldwide face an uncertain future with many reefs reported to transition from being dominated by corals to macroalgae. However, given the complexity and diversity of the ecosystem, research on how regimes vary spatially and temporally is needed. Reef regimes are most often characterised by their benthic components; however, complex dynamics are associated with losses and gains in both fish and benthic assemblages. To capture this complexity, we synthesised 3,345 surveys from Hawai'i to define reef regimes in terms of both fish and benthic assemblages. Model-based clustering revealed five distinct regimes that varied ecologically, and were spatially heterogeneous by island, depth and exposure. We identified a regime characteristic of a degraded state with low coral cover and fish biomass, one that had low coral but high fish biomass, as well as three other regimes that varied significantly in their ecology but were previously considered a single coral dominated regime. Analyses of time series data reflected complex system dynamics, with multiple transitions among regimes that were a function of both local and global stressors. Coupling fish and benthic communities into reef regimes to capture complex dynamics holds promise for monitoring reef change and guiding ecosystem-based management of coral reefs.
View details for DOI 10.1038/s41598-018-35057-4
View details for PubMedID 30446687
Uncertainty analysis and robust areas of high and low modeled human impact on the global oceans.
Conservation biology : the journal of the Society for Conservation Biology
Increasing anthropogenic pressure on marine ecosystems from fishing, pollution, climate change and other sources is a big concern in marine conservation. Scientists have thus developed spatial models to map cumulative human impacts on marine ecosystems. However, these models make many assumptions and incorporate data that suffer from substantial incompleteness and inaccuracies. Here, as opposed to using a single model, we used Monte Carlo simulations to identify which parts of the oceans are most and least impacted by anthropogenic stressors under seven simulated sources of uncertainty (factors), including errors in the input data and choices between alternative model assumptions. Most maps generated in the simulations agreed that high-impact areas were located in the Northeast Atlantic, the eastern Mediterranean, the Caribbean, the continental shelf off northern West Africa, offshore parts of the tropical Atlantic, the Indian Ocean east of Madagascar, parts of East and Southeast Asia, parts of the northwestern Pacific, and in many coastal waters; and that large low-impact areas were located off Antarctica, in the central Pacific, and in the southern Atlantic. Uncertainty in the broad-scale spatial distribution of modeled human impact was caused by the aggregate effects of several factors, rather than being attributable to a single dominant source. In spite of the identified uncertainty in human impact maps, they can - at broad spatial scales and in combination with other environmental and socioeconomic information - point to priority areas for research and management.
View details for DOI 10.1111/cobi.13141
View details for PubMedID 29797608
A dynamic ocean management tool to reduce bycatch and support sustainable fisheries
2018; 4 (5): eaar3001
Seafood is an essential source of protein for more than 3 billion people worldwide, yet bycatch of threatened species in capture fisheries remains a major impediment to fisheries sustainability. Management measures designed to reduce bycatch often result in significant economic losses and even fisheries closures. Static spatial management approaches can also be rendered ineffective by environmental variability and climate change, as productive habitats shift and introduce new interactions between human activities and protected species. We introduce a new multispecies and dynamic approach that uses daily satellite data to track ocean features and aligns scales of management, species movement, and fisheries. To accomplish this, we create species distribution models for one target species and three bycatch-sensitive species using both satellite telemetry and fisheries observer data. We then integrate species-specific probabilities of occurrence into a single predictive surface, weighing the contribution of each species by management concern. We find that dynamic closures could be 2 to 10 times smaller than existing static closures while still providing adequate protection of endangered nontarget species. Our results highlight the opportunity to implement near real-time management strategies that would both support economically viable fisheries and meet mandated conservation objectives in the face of changing ocean conditions. With recent advances in eco-informatics, dynamic management provides a new climate-ready approach to support sustainable fisheries.
View details for DOI 10.1126/sciadv.aar3001
View details for Web of Science ID 000443174800012
View details for PubMedID 29854945
View details for PubMedCentralID PMC5976278
Characterizing habitat suitability for a central-place forager in a dynamic marine environment
ECOLOGY AND EVOLUTION
2018; 8 (5): 2788–2801
Characterizing habitat suitability for a marine predator requires an understanding of the environmental heterogeneity and variability over the range in which a population moves during a particular life cycle. Female California sea lions (Zalophus californianus) are central-place foragers and are particularly constrained while provisioning their young. During this time, habitat selection is a function of prey availability and proximity to the rookery, which has important implications for reproductive and population success. We explore how lactating females may select habitat and respond to environmental variability over broad spatial and temporal scales within the California Current System. We combine near-real-time remotely sensed satellite oceanography, animal tracking data (n = 72) from November to February over multiple years (2003-2009) and Generalized Additive Mixed Models (GAMMs) to determine the probability of sea lion occurrence based on environmental covariates. Results indicate that sea lion presence is associated with cool (<14°C), productive waters, shallow depths, increased eddy activity, and positive sea-level anomalies. Predictive habitat maps generated from these biophysical associations suggest winter foraging areas are spatially consistent in the nearshore and offshore environments, except during the 2004-2005 winter, which coincided with an El Niño event. Here, we show how a species distribution model can provide broadscale information on the distribution of female California sea lions during an important life history stage and its implications for population dynamics and spatial management.
View details for DOI 10.1002/ece3.3827
View details for Web of Science ID 000426725900035
View details for PubMedID 29531695
View details for PubMedCentralID PMC5838083
Advancing the integration of spatial data to map human and natural drivers on coral reefs
2018; 13 (3): e0189792
A major challenge for coral reef conservation and management is understanding how a wide range of interacting human and natural drivers cumulatively impact and shape these ecosystems. Despite the importance of understanding these interactions, a methodological framework to synthesize spatially explicit data of such drivers is lacking. To fill this gap, we established a transferable data synthesis methodology to integrate spatial data on environmental and anthropogenic drivers of coral reefs, and applied this methodology to a case study location-the Main Hawaiian Islands (MHI). Environmental drivers were derived from time series (2002-2013) of climatological ranges and anomalies of remotely sensed sea surface temperature, chlorophyll-a, irradiance, and wave power. Anthropogenic drivers were characterized using empirically derived and modeled datasets of spatial fisheries catch, sedimentation, nutrient input, new development, habitat modification, and invasive species. Within our case study system, resulting driver maps showed high spatial heterogeneity across the MHI, with anthropogenic drivers generally greatest and most widespread on O'ahu, where 70% of the state's population resides, while sedimentation and nutrients were dominant in less populated islands. Together, the spatial integration of environmental and anthropogenic driver data described here provides a first-ever synthetic approach to visualize how the drivers of coral reef state vary in space and demonstrates a methodological framework for implementation of this approach in other regions of the world. By quantifying and synthesizing spatial drivers of change on coral reefs, we provide an avenue for further research to understand how drivers determine reef diversity and resilience, which can ultimately inform policies to protect coral reefs.
View details for DOI 10.1371/journal.pone.0189792
View details for Web of Science ID 000426363200002
View details for PubMedID 29494613
View details for PubMedCentralID PMC5832214
- Spatial management in small-scale fisheries: A potential approach for climate change adaptation in Pacific Islands MARINE POLICY 2018; 88: 350–58
- Fit to predict? Eco-informatics for predicting the catchability of a pelagic fish in near real time ECOLOGICAL APPLICATIONS 2017; 27 (8): 2313–29
- Reconstructing overfishing: Moving beyond Malthus for effective and equitable solutions FISH AND FISHERIES 2017; 18 (6): 1180–91
Ocean Research Priorities: Similarities and Differences among Scientists, Policymakers, and Fishermen in the United States.
2017; 67 (5): 418-428
Understanding and solving complex ocean conservation problems requires cooperation not just among scientific disciplines but also across sectors. A recently published survey that probed research priorities of marine scientists, when provided to ocean stakeholders, revealed some agreement on priorities but also illuminated key differences. Ocean acidification, cumulative impacts, bycatch effects, and restoration effectiveness were in the top 10 priorities for scientists and stakeholder groups. Significant priority differences were that scientists favored research questions about ocean acidification and marine protected areas; policymakers prioritized questions about habitat restoration, bycatch, and precaution; and fisheries sector resource users called for the inclusion of local ecological knowledge in policymaking. These results quantitatively demonstrate how different stakeholder groups approach ocean issues and highlight the need to incorporate other types of knowledge in the codesign of solutions-oriented research, which may facilitate cross-sectoral collaboration.
View details for DOI 10.1093/biosci/biw172
View details for PubMedID 28533565
Avoiding a crisis of motivation for ocean management under global environmental change.
Global change biology
Climate change and ocean acidification are altering marine ecosystems and, from a human perspective, creating both winners and losers. Human responses to these changes are complex, but may result in reduced government investments in regulation, resource management, monitoring and enforcement. Moreover, a lack of peoples' experience of climate change may drive some towards attributing the symptoms of climate change to more familiar causes such as management failure. Taken together, we anticipate that management could become weaker and less effective as climate change continues. Using diverse case studies, including the decline of coral reefs, coastal defences from flooding, shifting fish stocks and the emergence of new shipping opportunities in the Arctic, we argue that human interests are better served by increased investments in resource management. But greater government investment in management does not simply mean more of "business-as-usual." Management needs to become more flexible, better at anticipating and responding to surprise, and able to facilitate change where it is desirable. A range of technological, economic, communication and governance solutions exists to help transform management. While not all have been tested, judicious application of the most appropriate solutions should help humanity adapt to novel circumstances and seek opportunity where possible.
View details for DOI 10.1111/gcb.13698
View details for PubMedID 28447373
Science-based management in decline in the Southern Ocean.
2016; 354 (6309): 185-187
View details for PubMedID 27738163
- Translating sustainable seafood frameworks to assess the implementation of ecosystem-based fisheries management FISHERIES RESEARCH 2016; 182: 149-157
Bright spots among the world's coral reefs
2016; 535 (7612): 416-?
Ongoing declines in the structure and function of the world’s coral reefs require novel approaches to sustain these ecosystems and the millions of people who depend on them3. A presently unexplored approach that draws on theory and practice in human health and rural development is to systematically identify and learn from the ‘outliers’—places where ecosystems are substantially better (‘bright spots’) or worse (‘dark spots’) than expected, given the environmental conditions and socioeconomic drivers they are exposed to. Here we compile data from more than 2,500 reefs worldwide and develop a Bayesian hierarchical model to generate expectations of how standing stocks of reef fish biomass are related to 18 socioeconomic drivers and environmental conditions. We identify 15 bright spots and 35 dark spots among our global survey of coral reefs, defined as sites that have biomass levels more than two standard deviations from expectations. Importantly, bright spots are not simply comprised of remote areas with low fishing pressure; they include localities where human populations and use of ecosystem resources is high, potentially providing insights into how communities have successfully confronted strong drivers of change. Conversely, dark spots are not necessarily the sites with the lowest absolute biomass and even include some remote, uninhabited locations often considered near pristine6. We surveyed local experts about social, institutional, and environmental conditions at these sites to reveal that bright spots are characterized by strong sociocultural institutions such as customary taboos and marine tenure, high levels of local engagement in management, high dependence on marine resources, and beneficial environmental conditions such as deep-water refuges. Alternatively, dark spots are characterized by intensive capture and storage technology and a recent history of environmental shocks. Our results suggest that investments in strengthening fisheries governance, particularly aspects such as participation and property rights, could facilitate innovative conservation actions that help communities defy expectations of global reef degradation.
View details for DOI 10.1038/nature18607
View details for Web of Science ID 000380344200039
View details for PubMedID 27309809
Active dispersal in loggerhead sea turtles (Caretta caretta) during the 'lost years'
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
2016; 283 (1832)
Highly migratory marine species can travel long distances and across entire ocean basins to reach foraging and breeding grounds, yet gaps persist in our knowledge of oceanic dispersal and habitat use. This is especially true for sea turtles, whose complex life history and lengthy pelagic stage present unique conservation challenges. Few studies have explored how these young at-sea turtles navigate their environment, but advancements in satellite technology and numerical models have shown that active and passive movements are used in relation to open ocean features. Here, we provide the first study, to the best of our knowledge, to simultaneously combine a high-resolution physical forcing ocean circulation model with long-term multi-year tracking data of young, trans-oceanic North Pacific loggerhead sea turtles during their 'lost years' at sea. From 2010 to 2014, we compare simulated trajectories of passive transport with empirical data of 1-3 year old turtles released off Japan (29.7-37.5 straight carapace length cm). After several years, the at-sea distribution of simulated current-driven trajectories significantly differed from that of the observed turtle tracks. These results underscore current theories on active dispersal by young oceanic-stage sea turtles and give further weight to hypotheses of juvenile foraging strategies for this species. Such information can also provide critical geographical information for spatially explicit conservation approaches to this endangered population.
View details for DOI 10.1098/rspb.2016.0690
View details for Web of Science ID 000378318700019
View details for PubMedID 27252021
View details for PubMedCentralID PMC4920322
- Social drivers forewarn of marine regime shifts FRONTIERS IN ECOLOGY AND THE ENVIRONMENT 2016; 14 (5): 253-261
Multi-year tracking reveals extensive pelagic phase of juvenile loggerhead sea turtles in the North Pacific.
2016; 4: 23-?
The juvenile stage of loggerhead sea turtles (Caretta caretta) can last for decades. In the North Pacific Ocean, much is known about their seasonal movements in relation to pelagic habitat, yet understanding their multi-year, basin-scale movements has proven more difficult. Here, we categorize the large-scale movements of 231 turtles satellite tracked from 1997 to 2013 and explore the influence of biological and environmental drivers on basin-scale movement.Results show high residency of juvenile loggerheads within the Central North Pacific and a moderate influence of the Earth's magnetic field, but no real-time environmental driver to explain migratory behavior.We suggest the Central North Pacific acts as important developmental foraging grounds for young juvenile loggerhead sea turtles, rather than just a migratory corridor. We propose several hypotheses that may influence the connectivity between western and eastern juvenile loggerhead foraging grounds in the North Pacific Ocean.
View details for PubMedID 27729983
View details for PubMedCentralID PMC5048666
- Are we missing important areas in pelagic marine conservation? Redefining conservation hotspots in the ocean ENDANGERED SPECIES RESEARCH 2016; 29 (3): 229-237
- Filling historical data gaps to foster solutions in marine conservation OCEAN & COASTAL MANAGEMENT 2015; 115: 31-40
- Dynamic ocean management: Defining and conceptualizing real-time management of the ocean MARINE POLICY 2015; 58: 42-50
- OCEANS. Managing mining of the deep seabed. Science 2015; 349 (6244): 144-145
- Dynamic Ocean Management: Identifying the Critical Ingredients of Dynamic Approaches to Ocean Resource Management BIOSCIENCE 2015; 65 (5): 486-498
- Thresholds in Caribbean coral reefs: implications for ecosystem-based fishery management JOURNAL OF APPLIED ECOLOGY 2015; 52 (2): 402-412
Managing Small-Scale Commercial Fisheries for Adaptive Capacity: Insights from Dynamic Social-Ecological Drivers of Change in Monterey Bay
2015; 10 (3)
Globally, small-scale fisheries are influenced by dynamic climate, governance, and market drivers, which present social and ecological challenges and opportunities. It is difficult to manage fisheries adaptively for fluctuating drivers, except to allow participants to shift effort among multiple fisheries. Adapting to changing conditions allows small-scale fishery participants to survive economic and environmental disturbances and benefit from optimal conditions. This study explores the relative influence of large-scale drivers on shifts in effort and outcomes among three closely linked fisheries in Monterey Bay since the Magnuson-Stevens Fisheries Conservation and Management Act of 1976. In this region, Pacific sardine (Sardinops sagax), northern anchovy (Engraulis mordax), and market squid (Loligo opalescens) fisheries comprise a tightly linked system where shifting focus among fisheries is a key element to adaptive capacity and reduced social and ecological vulnerability. Using a cluster analysis of landings, we identify four modes from 1974 to 2012 that are dominated (i.e., a given species accounting for the plurality of landings) by squid, sardine, anchovy, or lack any dominance, and seven points of transition among these periods. This approach enables us to determine which drivers are associated with each mode and each transition. Overall, we show that market and climate drivers are predominantly attributed to dominance transitions. Model selection of external drivers indicates that governance phases, reflected as perceived abundance, dictate long-term outcomes. Our findings suggest that globally, small-scale fishery managers should consider enabling shifts in effort among fisheries and retaining existing flexibility, as adaptive capacity is a critical determinant for social and ecological resilience.
View details for DOI 10.1371/journal.pone.0118992
View details for Web of Science ID 000351425400059
View details for PubMedID 25790464
View details for PubMedCentralID PMC4366077
- A practical approach for putting people in ecosystem-based ocean planning FRONTIERS IN ECOLOGY AND THE ENVIRONMENT 2014; 12 (8): 448-456
- Current Practice and Future Prospects for Social Data in Coastal and Ocean Planning CONSERVATION BIOLOGY 2014; 28 (4): 902-911
- Increased nesting, good survival and variable site fidelity for leatherback turtles in Florida, USA BIOLOGICAL CONSERVATION 2014; 176: 117-125
- Patterns and potential drivers of declining oxygen content along the southern California coast LIMNOLOGY AND OCEANOGRAPHY 2014; 59 (4): 1127-1138
- Environmental monitoring. Harnessing DNA to improve environmental management. Science 2014; 344 (6191): 1455-1456
- A system-wide approach to supporting improvements in seafood production practices and outcomes FRONTIERS IN ECOLOGY AND THE ENVIRONMENT 2014; 12 (5): 297-305
Global patterns of marine mammal, seabird, and sea turtle bycatch reveal taxa-specific and cumulative megafauna hotspots
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2014; 111 (14): 5271-5276
Recent research on ocean health has found large predator abundance to be a key element of ocean condition. Fisheries can impact large predator abundance directly through targeted capture and indirectly through incidental capture of nontarget species or bycatch. However, measures of the global nature of bycatch are lacking for air-breathing megafauna. We fill this knowledge gap and present a synoptic global assessment of the distribution and intensity of bycatch of seabirds, marine mammals, and sea turtles based on empirical data from the three most commonly used types of fishing gears worldwide. We identify taxa-specific hotspots of bycatch intensity and find evidence of cumulative impacts across fishing fleets and gears. This global map of bycatch illustrates where data are particularly scarce--in coastal and small-scale fisheries and ocean regions that support developed industrial fisheries and millions of small-scale fishers--and identifies fishing areas where, given the evidence of cumulative hotspots across gear and taxa, traditional species or gear-specific bycatch management and mitigation efforts may be necessary but not sufficient. Given the global distribution of bycatch and the mitigation success achieved by some fleets, the reduction of air-breathing megafauna bycatch is both an urgent and achievable conservation priority.
View details for DOI 10.1073/pnas.1318960111
View details for Web of Science ID 000333985200056
View details for PubMedID 24639512
Using environmental DNA to census marine fishes in a large mesocosm.
2014; 9 (1)
The ocean is a soup of its resident species' genetic material, cast off in the forms of metabolic waste, shed skin cells, or damaged tissue. Sampling this environmental DNA (eDNA) is a potentially powerful means of assessing whole biological communities, a significant advance over the manual methods of environmental sampling that have historically dominated marine ecology and related fields. Here, we estimate the vertebrate fauna in a 4.5-million-liter mesocosm aquarium tank at the Monterey Bay Aquarium of known species composition by sequencing the eDNA from its constituent seawater. We find that it is generally possible to detect mitochondrial DNA of bony fishes sufficient to identify organisms to taxonomic family- or genus-level using a 106 bp fragment of the 12S ribosomal gene. Within bony fishes, we observe a low false-negative detection rate, although we did not detect the cartilaginous fishes or sea turtles present with this fragment. We find that the rank abundance of recovered eDNA sequences correlates with the abundance of corresponding species' biomass in the mesocosm, but the data in hand do not allow us to develop a quantitative relationship between biomass and eDNA abundance. Finally, we find a low false-positive rate for detection of exogenous eDNA, and we were able to diagnose non-native species' tissue in the food used to maintain the mesocosm, underscoring the sensitivity of eDNA as a technique for community-level ecological surveys. We conclude that eDNA has substantial potential to become a core tool for environmental monitoring, but that a variety of challenges remain before reliable quantitative assessments of ecological communities in the field become possible.
View details for DOI 10.1371/journal.pone.0086175
View details for PubMedID 24454960
- Cumulative human impacts on marine predators. Nature communications 2013; 4: 2688-?
- Improving Ocean Management through the Use of Ecological Principles and Integrated Ecosyste Assessments BIOSCIENCE 2013; 63 (8): 619-631
- Predicted habitat shifts of Pacific top predators in a changing climate NATURE CLIMATE CHANGE 2013; 3 (3): 234-238
- Impacts of fisheries bycatch on marine turtle populations worldwide: toward conservation and research priorities ECOSPHERE 2013; 4 (3)
- Moving beyond the fished or farmed dichotomy MARINE POLICY 2013; 38: 369-374
Cumulative human impacts on marine predators.
2013; 4: 2688-?
Stressors associated with human activities interact in complex ways to affect marine ecosystems, yet we lack spatially explicit assessments of cumulative impacts on ecologically and economically key components such as marine predators. Here we develop a metric of cumulative utilization and impact (CUI) on marine predators by combining electronic tracking data of eight protected predator species (n=685 individuals) in the California Current Ecosystem with data on 24 anthropogenic stressors. We show significant variation in CUI with some of the highest impacts within US National Marine Sanctuaries. High variation in underlying species and cumulative impact distributions means that neither alone is sufficient for effective spatial management. Instead, comprehensive management approaches accounting for both cumulative human impacts and trade-offs among multiple stressors must be applied in planning the use of marine resources.
View details for DOI 10.1038/ncomms3688
View details for PubMedID 24162104
An index to assess the health and benefits of the global ocean
2012; 488 (7413): 615-?
The ocean plays a critical role in supporting human well-being, from providing food, livelihoods and recreational opportunities to regulating the global climate. Sustainable management aimed at maintaining the flow of a broad range of benefits from the ocean requires a comprehensive and quantitative method to measure and monitor the health of coupled human–ocean systems. We created an index comprising ten diverse public goals for a healthy coupled human–ocean system and calculated the index for every coastal country. Globally, the overall index score was 60 out of 100 (range 36–86), with developed countries generally performing better than developing countries, but with notable exceptions. Only 5% of countries scored higher than 70, whereas 32% scored lower than 50. The index provides a powerful tool to raise public awareness, direct resource management, improve policy and prioritize scientific research.
View details for DOI 10.1038/nature11397
View details for Web of Science ID 000308095100048
View details for PubMedID 22895186
- Human Dimensions of Coral Reef Social-Ecological Systems ECOLOGY AND SOCIETY 2012; 17 (4)
- Cumulative estimates of sea turtle bycatch and mortality in USA fisheries between 1990 and 2007 BIOLOGICAL CONSERVATION 2011; 144 (11): 2719-2727
- Valuing Ecosystem Services with Fishery Rents: A Lumped-Parameter Approach to Hypoxia in the Neuse River Estuary SUSTAINABILITY 2011; 3 (11): 2229-2267
- Guiding ecological principles for marine spatial planning MARINE POLICY 2010; 34 (5): 955-966
- Sustainability and Global Seafood SCIENCE 2010; 327 (5967): 784-786
Small-Scale Fisheries Bycatch Jeopardizes Endangered Pacific Loggerhead Turtles
2007; 2 (10)
Although bycatch of industrial-scale fisheries can cause declines in migratory megafauna including seabirds, marine mammals, and sea turtles, the impacts of small-scale fisheries have been largely overlooked. Small-scale fisheries occur in coastal waters worldwide, employing over 99% of the world's 51 million fishers. New telemetry data reveal that migratory megafauna frequent coastal habitats well within the range of small-scale fisheries, potentially producing high bycatch. These fisheries occur primarily in developing nations, and their documentation and management are limited or non-existent, precluding evaluation of their impacts on non-target megafauna.30 North Pacific loggerhead turtles that we satellite-tracked from 1996-2005 ranged oceanwide, but juveniles spent 70% of their time at a high use area coincident with small-scale fisheries in Baja California Sur, Mexico (BCS). We assessed loggerhead bycatch mortality in this area by partnering with local fishers to 1) observe two small-scale fleets that operated closest to the high use area and 2) through shoreline surveys for discarded carcasses. Minimum annual bycatch mortality in just these two fleets at the high use area exceeded 1000 loggerheads year(-1), rivaling that of oceanwide industrial-scale fisheries, and threatening the persistence of this critically endangered population. As a result of fisher participation in this study and a bycatch awareness campaign, a consortium of local fishers and other citizens are working to eliminate their bycatch and to establish a national loggerhead refuge.Because of the overlap of ubiquitous small-scale fisheries with newly documented high-use areas in coastal waters worldwide, our case study suggests that small-scale fisheries may be among the greatest current threats to non-target megafauna. Future research is urgently needed to quantify small-scale fisheries bycatch worldwide. Localizing coastal high use areas and mitigating bycatch in partnership with small-scale fishers may provide a crucial solution toward ensuring the persistence of vulnerable megafauna.
View details for DOI 10.1371/journal.pone.0001041
View details for Web of Science ID 000207456100009
View details for PubMedID 17940605
Effects of stocking-up freshwater food webs
TRENDS IN ECOLOGY & EVOLUTION
2006; 21 (10): 576-584
The establishment of exotic game fishes to enhance recreational fisheries through authorized and unauthorized stocking into freshwater systems is a global phenomenon. Stocked fishes are often top predators that either replace native top predators or increase the species richness of top predators. Many direct effects of stocking have been documented, but the ecosystem consequences are seldom quantified. New studies increasingly document how species and community shifts influence ecosystem processes. We discuss here how predator stocking might increase top-down effects, alter nutrient cycles and decrease links between aquatic and surrounding terrestrial ecosystems. As fisheries management moves beyond species-specific utilitarian objectives to incorporate ecosystem and conservation goals, ecologists must address how common management practices alter food-web structure and subsequent ecosystem-level effects.
View details for DOI 10.1016/j.tree.2006.06.016
View details for Web of Science ID 000241256900008
View details for PubMedID 16828522