Fisheries and Conservation

Multiple Stressors and Abalone Populations

Eastern boundary current systems, including the California Current Large Marine Ecosystem (CCLME), routinely experience upwelling driven low pH, low dissolved oxygen (DO) waters, with the magnitude and duration of these events increasing over the past decade. With funding from the National Science Foundation Ocean Acidification Program, we are studying the consequences of ocean acidification and other climate-related changes (DO, temperature) on near shore marine communities in the CCLME. This work allows us to better anticipate possible ecological and fishery impacts due to increasing frequency and intensity of low pH and low DO events and help to inform adaptation strategies. We utilize an individual- to population-level approach to investigate how the effects of ocean acidification on abalone, in combination with low DO and changing temperatures, will manifest at the population level, and ultimately, the services these species provide to humans. We are pursuing this goal by 1) measuring and characterizing the temporal variability of pH, DO and temperature in nearshore abalone habitat in Monterey Bay, Central California, and Isla Natividad, Mexico and using hydrodynamic modeling to predict future changes in these regimes, 2) conducting laboratory experiments to investigate the effects of multiple stressors on the reproductive success, growth, calcification, and survival of juvenile abalone, and 3) developing demographic and bio-economic models to estimate the impacts of environmental and local anthropogenic stressors on the resilience of abalone populations and to assess what management and conservation strategies, including marine reserves, may contribute to buffering the negative effects of climate change.

Resilience in Small Scale Fisheries: Baja Case Study

Small-scale fisheries employ 50 of the world's 51 million fishers and produce over half of the world's annual marine fish catch, supplying most of the fish consumed in the developing world. Despite their overwhelming social and economic importance of small-scale fisheries, these systems are poorly understood. Community-based management, co-management, and market incentives can all foster long-term stewardship and ecosystem protection, but their applicability and success to date has varied. Beginning in the 1930's, the nearshore fisheries of Baja California were organized into local cooperatives, which were granted exclusive fishing rights on local stocks, including abalone, lobsters, oysters, clams, and shrimp. Cooperatives throughout the coast operate under different permits that give them greater or lesser degrees of control over their local resources, and vary broadly in their ecological setting and in the success and sustainability of their main fisheries (primarily for lobster and abalone). Our objective is to develop an integrated framework for addressing environmental and socioeconomic processes underlying the varying success of the small-scale fisheries of Baja California. Through our involvement in these multi-disciplinary research program studying the complex biophysical and socioeconomic feedbacks within two space-based approaches to marine management and conservation, marine protected areas and exclusive fishing rights, we are hoping to be able to make significant contributions to better integrating ecological understanding into conservation of marine seascapes and associated assemblages.

Large marine protected area (MPA) effectiveness

Large MPAs (regions where fishing is restricted) have recently been established throughout the world at an unprecedented pace, yet the value of these reserves for mobile species conservation remains unclear. The rapid establishment of large MPAs, some spanning over one million km2, has nearly doubled the total area of protected ocean on Earth in just five years. However, reef shark populations continue to decline even within some of the largest MPAs, fueling debates over the ability of protected areas to aid mobile species that occasionally transit beyond MPA boundaries. We seek to better understand how mobile species may respond to MPAs of this magnitude by electronically tracking the movements of reef sharks and fishing vessels throughout the Palmyra Atoll National Wildlife Refuge, a 54,000 km2 MPA located in the central Pacific Ocean.

Human impacts on coconut crab populations

Weighing in at up to 4kg and spanning up to a meter across, the coconut crab (Birgus latro) is among the largest native land animals on many Indo-Pacific islands. This jungle-dwelling crab has been hunted for centuries, but increasing human populations and ongoing habitat destruction have recently caused substantial population declines throughout much of the species’ distribution. An improved understanding of the coconut crab's ecology and the impacts of crab hunters are critical for tailoring effective conservation measures to meet these challenges. The primary objective of this project is to improve understanding of the critical habitat, home range, and harvest rates of the coconut crab (Birgus latro). We use a combination of electronic tracking, hunter interviews, and vegetation surveys to better understand how this species interacts with the surrounding ecological community.

Sea Star Wasting Disease

In the summer of 2013, sea stars off the Washington coast began "falling off the rocks - dead by the thousands." When similar reports came in from Alaska to Baja California, it became clear this was not an isolated event. Sea star wasting disease (SSWD) is characterized by the appearance of lesions surrounded by decaying tissue, typically followed by rapid disintegration and death, often within a few days. It appears to be caused by a virus, possibly in association with high water temperatures, but the pattern of disease occurrence does not match a typical "traveling wave" scenario with disease incidence spreading from an initial case. As an alternate hypothesis, we have developed a novel model which links both infectious processes and environmental drivers via the initial dispersal of an asymptomatic infection followed by a symptomatic disease outbreak triggered by accumulated temperature stress.

Eel Management Software

The Eel management software (EMS) has been developed in order to provide a user-friendly tool to assess the effectiveness of management plans for the endangered European eel (Anguilla anguilla). This software allows evaluating both production (i.e. escapement to the sea) of silver eels and fishermen catches in a specific site, in different conditions as actual, pristine (i.e. unaffected by antropogenic impacts) and potential ones as required by the European Regulation EC 1100/2007. The flexibility of the tool allows the user to consider several environmental and management scenarios by defining the characteristics of the site, the exploitation level of the stock and the management plan constraints, and eventually comparing the results obtained under different scenarios.

Although the EMS is based on the most trustworthy and up-to-date knowledge about eel population dynamics, it is just an approximation of reality; therefore, the outputs of the model should not be considered reliable in absolute terms. In contrast, the great usefulness of this software is that it allows the user to compare the effects of different management actions, to evaluate the advantages or disadvantages (in terms of silver eels escapement and fishermen catches) of adopting different management policies and to assess the effectiveness of different management plans.