Larry Crowder - Academia.edu (original) (raw)

Papers by Larry Crowder

Population models can be useful tools for decision makers because they can quantify the relative ... more Population models can be useful tools for decision makers because they can quantify the relative effectiveness of different management options (Heppell et al. 2000b). This is particularly critical for long-lived species such as sea turtles, where a scientist\u27s entire career may only span one or two turtle generations. Researchers have modeled the dynamics of a wide range of species and have addressed a variety of management applications, from simple biomass-based models in fisheries (Hilborn and Walters 1992) to population viability analysis (Beissinger and Westphal1998; Boyce 1992) for endangered species. In all cases, the models serve as hypodiesis-testing tools, where a series of potential outcomes is assessed based on a set of parameters and assumptions. While some models attempt quantitative predictions of population dynamics, such as the extinction probabilities in many population viability analyses, these models also serve as heuristic tools to compare the relative magnitude of population changes, even when quantitative predictions are not possible (Groom and Pascual 1998)

Science, 2015

Contracts are being granted, but protections are lagging

University of California Press eBooks, Dec 31, 2019

Conservation science and practice, Mar 19, 2019

Limited data on the spatial, environmental, and human dimensions of small‐scale fisheries hinder ... more Limited data on the spatial, environmental, and human dimensions of small‐scale fisheries hinder conservation planning, so the incorporation of fishers' local ecological knowledge may be a valuable way to fill data gaps while legitimizing management decisions. In Peru, vulnerable and poorly assessed juvenile smooth hammerhead sharks (Sphyrna zygaena) are the most commonly caught shark species in a small‐scale drift gillnet fishery. We conducted semistructured interviews with 87 hammerhead fishers in three major Peruvian ports to elucidate the spatiotemporal niche of the hammerhead fishery and environmental drivers of juvenile hammerhead catch. We also built a biophysical model of hammerhead distribution that correlated remotely sensed environmental variables with a spatially explicit fishery observer dataset. Overall, we found a consensus between fishers' knowledge and species distribution modeling. Sea surface temperature and chlorophyll‐a emerged as important environmental drivers of juvenile hammerhead catch, with both fishers' knowledge and the biophysical model identifying similar habitat preferences (~20–23°C and log chl‐a >−1.6 mg/m3). Participatory mapping of fishing grounds also corresponded to the spatiotemporal patterns of predicted hammerhead distribution. This study points to the utility of combining fishers' knowledge and biophysical modeling for spatial, temporal, and/or dynamic management of these sharks in Peru and in other data‐poor fisheries globally.

Progress in Oceanography, Feb 1, 2023

Frontiers in Marine Science

Nature Communications

The response of aquatic and terrestrial organisms to climate change can depend on biological sex.... more The response of aquatic and terrestrial organisms to climate change can depend on biological sex. A key challenge is to unravel the interactive effects of sex and climate change at the individual and population levels and the cascading effects on communities. This new understanding is essential to improve climate adaptation and mitigation strategies. Challenges posed by climate change threaten ecosystems, the crucial benefits they provide to people, and, ultimately, human livelihoods and lives. Global change impacts ecological systems and processes across continents and oceans, resulting in changes to the phenology, distribution and behavior of organisms, persistence and dynamics of populations, and structure and function of species assemblages and ecosystems. In the Anthropocene, a deeper understanding of the biological impacts of climate change, as well as innovative solutions, are needed to reverse climate-induced biodiversity loss. One largely ignored dimension in research and conservation is how organisms respond differently to climate change depending on biological sex 1,2. Sex is frequently not reported or tested, likely because researchers are not aware of sex-based differences, assume that including sex-specific information would not influence experimental results or are unable to obtain sex-specific data 3. Here, we discuss examples of sex-based differences across aquatic and terrestrial domains. We argue that studying sex-based differences from organisms to populations and communities may generate new insights into resilience and vulnerability to climate stressors that may otherwise not be recognized. Sex influences the responses of organisms, populations, and communities to climate change nature communications (2023) 14:4787 | 1

Ecosphere

Synthesis research in ecology and environmental science improves understanding, advances theory, ... more Synthesis research in ecology and environmental science improves understanding, advances theory, identifies research priorities, and supports management strategies by linking data, ideas, and tools. Accelerating environmental challenges increases the need to focus synthesis science on the most pressing questions. To leverage input from the broader research community, we convened a virtual workshop with participants from many countries and disciplines to examine how and where synthesis can address key questions and themes in ecology and environmental science in the coming decade. Seven priority research topics emerged: (1) diversity, equity, inclusion, and justice (DEIJ), (2) human and natural systems, (3) actionable and use‐inspired science, (4) scale, (5) generality, (6) complexity and resilience, and (7) predictability. Additionally, two issues regarding the general practice of synthesis emerged: the need for increased participant diversity and inclusive research practices; and in...

Climatic Change

As the impacts of climate change on human society accelerate, coastal communities are vulnerable ... more As the impacts of climate change on human society accelerate, coastal communities are vulnerable to changing environmental conditions. The capacity of communities and households to respond to these changes (i.e., their adaptive capacity) will determine the impacts of climate and co-occurring stressors. To date, empirical evidence linking theoretical measures of adaptive capacity to community and household responses remains limited. Here, we conduct a global meta-analysis examining how metrics of adaptive capacity translate to human responses to change (Adapt, React, Cope response) in 22 small-scale fishing case studies from 20 countries (n = 191 responses). Using both thematic and qualitative comparative analysis, we evaluate how responses to climate, environmental, and social change were influenced by domains of adaptive capacity. Our findings show that adaptive responses at the community level only occurred in situations where the community had Access to Assets, in combination with other domains including Diversity and Flexibility, Learning and Knowledge, and Natural Capital. In contrast, Access to Assets was nonessential for adaptive responses at the household level. Adaptive households demonstrated Diversity and Flexibility when supported by strong Governance or Institutions and were often able to substitute Learning and Knowledge and Natural

BioScience, 2021

The media can be key in informing individuals around topics not easily observable, such as remote... more The media can be key in informing individuals around topics not easily observable, such as remote environmental issues and wildlife. Sea turtles are enigmatic animals that attract public attention, but they have faced severe population declines worldwide. Assessing how the news reports on sea turtle conservation is critical in evaluating how a concerned layperson may perceive threats affecting these animals and can provide insights on how experts can better engage with the media. We collected online articles about sea turtles from 2003 to 2019, recording the frequency by which various threats were mentioned as hazardous to sea turtles, the types of solutions noted in response to these threats, and common quoted messengers. We found that the media disproportionately reports on the threats of pollution and resource use. Importantly, this may not align with scientific consensus of top conservation concerns for these animals and can be problematic if it leads to a misinformed public.

Fisheries Oceanography, 2021

Recreational fisheries in the Eastern Tropical Pacific (ETP) have increased in popularity since t... more Recreational fisheries in the Eastern Tropical Pacific (ETP) have increased in popularity since the 1970s, contributing to the eco‐tourism industries of many Central American economies. However, pelagic gamefish face several direct and indirect threats which can affect population health and sustainability. We use daily catch logs from three recreational fishing lodges in Guatemala, Costa Rica, and Panama as records of change in blue marlin (Makaira nigricans) and sailfish (Istiophorus platypterus) sightings per unit effort (SPUE) between 2010 and 2019. Using cross‐correlational analysis, we compared billfish SPUE to the El Niño Southern Oscillation (ENSO) Index and local oceanographic conditions (sea surface temperature [SST] and chlorophyll [chl a]) to understand how billfish availability to recreational fishers is related to environmental conditions at different time lags. Blue marlin occurrence was negatively correlated with the ENSO at time lags of 9–22 months in Guatemala and C...

Science, 2021

Sustainably managed wild fisheries support food and nutritional security, livelihoods, and cultur... more Sustainably managed wild fisheries support food and nutritional security, livelihoods, and cultures (1). Harmful fisheries subsidies-government payments that incentivize overcapacity and lead to over-fishing-undermine these benefits yet are increasing globally (2). World Trade Organization (WTO) members have a unique opportunity at their ministerial meeting in November to reach an agreement that eliminates harmful subsidies (3). We-a group of scientists spanning 46 countries and 6 continents-urge the WTO to make this commitment. To curb overfishing, biodiversity degradation and loss, and CO2 emissions, and to safeguard food and livelihoods, WTO members must prohibit fisheries subsidies that cause harm, such as those that lower the cost of fuel and vessel construction and those that provide price support to keep market prices artificially high (2). Subsidies to distant-water fishing fleets must be eliminated to prevent overfishing on the high seas and in waters under national jurisdiction. Such subsidies threaten low-income countries that rely on fish for food sovereignty (4, 5). Exceptions to the rulesknown as special and differential treatment-should be considered for small-scale fishers that use low-impact gears or that fish for subsistence, but only if decoupled from incentivizing overfishing (6). An effective agreement must eliminate subsidies for fuel (7), distant-water and destructive fishing fleets (4, 5), and illegal and unregulated vessels in line with the aims of Sustainable Development Goal 14.6 (8). To ensure accountability, it should also support low-income countries' efforts to meet their commitments and transition to sustainable management. Finally, the agreement should require transparent data documentation and enforcement measures (9). We call on the heads of state of the High Level Panel for a Sustainable Ocean Economy, the Comprehensive and Progressive Agreement for Trans-Pacific Partnership, and the United States-Mexico-Canada Agreement-who have already committed to eliminating harmful subsidies (10-12)-as well as other trade blocs and individual countries, to declare their support now for an agreement that enshrines these recommendations. WTO members must harness their political mandate to protect the health of the ocean and the well-being of society.

Frontiers in Marine Science, 2021

The North Pacific Loggerhead sea turtle (Caretta caretta) undergoes one of the greatest of all an... more The North Pacific Loggerhead sea turtle (Caretta caretta) undergoes one of the greatest of all animal migrations, nesting exclusively in Japan and re-emerging several years later along important foraging grounds in the eastern North Pacific. Yet the mechanisms that connect these disparate habitats during what is known as the “lost years” have remained poorly understood. Here, we develop a new hypothesis regarding a possible physical mechanism for habitat connectivity – an intermittent “thermal corridor” – using remotely sensed oceanography and 6 juvenile loggerhead sea turtles that formed part of a 15 year tracking dataset of 231 individuals (1997–2013). While 97% of individuals remained in the Central North Pacific, these 6 turtles (about 3%), continued an eastward trajectory during periods associated with anomalously warm ocean conditions. These few individuals provided a unique opportunity to examine previously unknown recruitment pathways. To support this hypothesis, we employed...

World Seas: an Environmental Evaluation, 2019

Predicting Future Oceans, 2019

Already threatened by overfishing, habitat loss, and inadequate systems of governance [1], the sh... more Already threatened by overfishing, habitat loss, and inadequate systems of governance [1], the shocks and stressors associated with global environmental change represent a significant and daunting challenge for fishing communities worldwide [2À4]. Previous research on the 271

Conservation Letters, 2020

The U.S. Congress is currently discussing the Shark Fin Sales Elimination Act to eliminate shark ... more The U.S. Congress is currently discussing the Shark Fin Sales Elimination Act to eliminate shark fin trade at the federal level. This bill was introduced in 2017 and has been proceeding very slowly in Congress because of mixed reviews from the scientific community. Debate exists on whether shark conservation and management are effectively addressed with tightened trade controls for imported shark products or blanket bans that outright end U.S. participation in the shark fin trade. Here we contribute to this debate with a review and analysis of economic, nutritional, ethical, and legal arguments, as well as of the shark fisheries status and shark fin trade. We show that the United States has a limited commercial interest in shark fisheries and contributes to the shark fin trade mainly as a facilitator. A fin trade ban has few tangible economic drawbacks but would have a considerable conservation impact. While making all shark fisheries sustainable is the ultimate goal, in practice th...

ICES Journal of Marine Science, 2019

Interannual oceanic oscillations, climate change, and extreme events present a significant and co... more Interannual oceanic oscillations, climate change, and extreme events present a significant and complex challenge to management of pelagic fisheries. In recent years, anomalous oceanographic and atmospheric conditions have been reported across the northeast Pacific, yet research results concerning the biophysical mechanisms impacting specific organisms, populations, and fishery systems remain scarce. Here we discuss trends within the Gulf of California’s jumbo squid fishery in the context of relevant climate drivers, ecological dynamics, and mesoscale oceanographic processes. Following the 2009–2010 El Niño event, the jig-based fishery collapsed as squid adopted the small size-at-maturity phenotype characteristic of this species in the equatorial portion of its range. Analysis of regional sea surface temperatures and heights indicates a pronounced shift in the oceanographic trajectory of the system between the 2009–2010 and 2015–2016 El Niño events, whereas in situ hydrographic sampl...

Diversity and Distributions, 2019

AimAnimal tracking can provide unique insights into the ecology and conservation of marine specie... more AimAnimal tracking can provide unique insights into the ecology and conservation of marine species, such as the partitioning of habitat, including differences between life history stages or sexes, and can inform fisheries stock assessments, bycatch reduction and spatial management such as dynamic management.LocationNortheast Pacific Ocean.MethodsWe used satellite tracking data from 47 blue sharks (Prionace glauca) from the Northeast Pacific to determine movements and home range along the west coast of North America, and sex–size class (immature females, mature males) specific habitat preferences using boosted regression trees. Using a suite of static and dynamic environmental variables, we determined distribution and habitat preferences across summer and fall for each sex–size class.ResultsWe found that there was spatial segregation between sex–size classes particularly in the summer months with immature females found largely north of 33°N, and males south of 35°N. In fall, females ...