The Economic Value of Sea Otters and Recreational Tourism in a California Estuary

The recovery of marine megafauna can lead to improved ecosystem function and services, but not all stakeholders may benefit equally. Quantifying the local economic value of a species’ presence may appeal to broader range of stakeholders when developing conservation strategies. This study aims to examine the economic effect recreational activities can have on a local region, and to determine what role the presence of southern sea otters (Enhydra lutris nereis) had on the value visitors placed on the visit and the area’s preservation. We surveyed visitors to Elkhorn Slough, a small estuary in California known for diverse wildlife, modeled direct and indirect economic contributions to local economics, and evaluated perceptions and value placed on the area and wildlife. Annually, visitors contributed approximately $3.2 million (USD) in direct spending, with an additional$1.85 million in indirect economic gains, which could support over 300 full-time, part-time, and seasonal jobs to the region. Whether sea otters were observed during a trip influenced how visitors ranked their importance, and the perceived value of the estuary and sea otters. Combined, this study quantified what recreational visitors could contribute to local economies and that sea otters play a role in what visitor’s value about their visit. These results provide additional support to the benefits of species presence at a local scale. We discuss how these types of studies can be used as part of larger species and ecosystem management plans, particularly considering species recovery and range expansion

Structure and mechanism of diet specialisation: testing models of individual variation in resource use with sea otters

Studies of consumer-resource interactions suggest that individual diet specialisation is empirically widespread and theoretically important to the organisation and dynamics of populations and communities. We used weighted networks to analyze the resource use by sea otters, testing three alternative models for how individual diet specialisation may arise. As expected, individual specialisation was absent when otter density was low, but increased at high-otter density. A high-density emergence of nested resource-use networks was consistent with the model assuming individuals share preference ranks. However, a density-dependent emergence of a non-nested modular network for core resources was more consistent with the competitive refuge model. Individuals from different diet modules showed predictable variation in rank-order prey preferences and handling times of core resources, further supporting the competitive refuge model. Our findings support a hierarchical organisation of diet specialisation and suggest individual use of core and marginal resources may be driven by different selective pressures.Keywords: Sea otter, Bipartite networks, Nestedness, Modularity, Prey preference, Diet specialisatio

Evidence for a Novel Marine Harmful Algal Bloom: Cyanotoxin (Microcystin) Transfer from Land to Sea Otters

“Super-blooms” of cyanobacteria that produce potent and environmentally persistent biotoxins (microcystins) are an emerging global health issue in freshwater habitats. Monitoring of the marine environment for secondary impacts has been minimal, although microcystin-contaminated freshwater is known to be entering marine ecosystems. Here we confirm deaths of marine mammals from microcystin intoxication and provide evidence implicating land-sea flow with trophic transfer through marine invertebrates as the most likely route of exposure. This hypothesis was evaluated through environmental detection of potential freshwater and marine microcystin sources, sea otter necropsy with biochemical analysis of tissues and evaluation of bioaccumulation of freshwater microcystins by marine invertebrates. Ocean discharge of freshwater microcystins was confirmed for three nutrient-impaired rivers flowing into the Monterey Bay National Marine Sanctuary, and microcystin concentrations up to 2,900 ppm (2.9 million ppb) were detected in a freshwater lake and downstream tributaries to within 1 km of the ocean. Deaths of 21 southern sea otters, a federally listed threatened species, were linked to microcystin intoxication. Finally, farmed and free-living marine clams, mussels and oysters of species that are often consumed by sea otters and humans exhibited significant biomagnification (to 107 times ambient water levels) and slow depuration of freshwater cyanotoxins, suggesting a potentially serious environmental and public health threat that extends from the lowest trophic levels of nutrient-impaired freshwater habitat to apex marine predators. Microcystin-poisoned sea otters were commonly recovered near river mouths and harbors and contaminated marine bivalves were implicated as the most likely source of this potent hepatotoxin for wild otters. This is the first report of deaths of marine mammals due to cyanotoxins and confirms the existence of a novel class of marine “harmful algal bloom” in the Pacific coastal environment; that of hepatotoxic shellfish poisoning (HSP), suggesting that animals and humans are at risk from microcystin poisoning when consuming shellfish harvested at the land-sea interface

INCORPORATING DIVERSE DATA AND REALISTIC COMPLEXITY INTO DEMOGRAPHIC ESTIMATION PROCEDURES FOR SEA OTTERS

Abstract. Reliable information on historical and current population dynamics is central to understanding patterns of growth and decline in animal populations. We developed a maximum likelihood-based analysis to estimate spatial and temporal trends in age/sex-specific survival rates for the threatened southern sea otter (Enhydra lutris nereis), using annual population censuses and the age structure of salvaged carcass collections. We evaluated a wide range of possible spatial and temporal effects and used model averaging to incorporate model uncertainty into the resulting estimates of key vital rates and their variances. We compared these results to current demographic parameters estimated in a telemetry-based study conducted between 2001 and 2004. These results show that survival has decreased substantially from the early 1990s to the present and is generally lowest in the north-central portion of the population’s range. The greatest temporal decrease in survival was for adult females, and variation in the survival of this age/sex class is primarily responsible for regulating population growth and driving population trends. Our results can be used to focus future research on southern sea otters by highlighting the life history stages and mortality factors most relevant to conservation. More broadly, we have illustrated how the powerfu

CHINN.et.al_SeaOtter_Dryad

These are original data from Chinn et al. 2018. This .csv file has data for measured concentrations of Total Antioxidant, Cortisol, Corticosterone, IgM, IgG, Total T4, Total T3, Reverse T3 analytes measured in northern and southern sea otters from California, Washington, and Alaska, USA

Southern Sea Otter Rehabilitation: Lessons and Impacts from the Monterey Bay Aquarium

As biodiversity continues to decline across the globe, conservation of wildlife species and the ecosystems they inhabit is more important than ever. When species dwindle, ecosystems that depend on them are also impacted, often leading to a decrease in the life-giving services healthy ecosystems provide to humans, wildlife, and the global environment. Methods of wildlife conservation are complex and multi-faceted, ranging from education and advocacy to, research, restoration, and rehabilitation. Here, we review a conservation program focused on helping recover the federally listed threatened southern sea otter (Enhydra lutris nereis) population. We describe the development of unique rehabilitation methods and steps taken to advance the program’s conservation impact. Understanding this evolution can inform conservation efforts for other vulnerable species and their ecosystems

Appendix A. Estimation of reproduction parameters from radio-tagged sea otters in central California.

Estimation of reproduction parameters from radio-tagged sea otters in central California

Southern Sea Otter Rehabilitation: Lessons and Impacts from the Monterey Bay Aquarium

As biodiversity continues to decline across the globe, conservation of wildlife species and the ecosystems they inhabit is more important than ever. When species dwindle, ecosystems that depend on them are also impacted, often leading to a decrease in the life-giving services healthy ecosystems provide to humans, wildlife, and the global environment. Methods of wildlife conservation are complex and multi-faceted, ranging from education and advocacy to, research, restoration, and rehabilitation. Here, we review a conservation program focused on helping recover the federally listed threatened southern sea otter (Enhydra lutris nereis) population. We describe the development of unique rehabilitation methods and steps taken to advance the program’s conservation impact. Understanding this evolution can inform conservation efforts for other vulnerable species and their ecosystems

Appendix A. Intra-vibrissae isotopic variation for individual sea otters from Monterey Bay, California, USA.

Intra-vibrissae isotopic variation for individual sea otters from Monterey Bay, California, USA

Microcystin-LR concentrations (ppb) at the top, middle, and bottom of seawater tanks at two exposure concentrations (Tank 2 and Tank 3¹) and varying postexposure intervals.

1<p>All samples from Tank 1 (seawater control) tested negative for microcystin-LR. All 3 tanks were flushed with fresh seawater starting 96 H postexposure).</p>2<p>nd  =  microcystin concentration was below minimum detection limits on liquid chromatography-tandem mass spectrophotometry.</p