Habitat refuges from climate change

Climate change is impacting marine ecosystems but the impact is not uniform across space or time. Habitat refuges can buffer the effects of climate change, potentially mitigating the effects on populations through lower exposure and/or by promoting local adaptation. Knowing where and to what extent refuges exist is complicated by the many different methods used for defining and measuring environmental stress which often originate in different disciplines (oceanography, physiology, ecology). This diversity in stress definitions makes it challenging to incorporate habitat refuges in marine management and conservation. 

This project is ongoing and currently focused on green and pink abalone in Baja California, Mexico and builds on decades of field observations and lab experiments conducted by scientists from Hopkins Marine Station and University of Georgia, and local fishers and managers. Photo credit: CA Boch

Sensitivities of West Coast fish stocks to environmental variability in the Pacific Ocean

There are clear signs that the physical environment of fisheries may be changing with a changing climate – especially in the California Current ecosystem. Fishery managers are interested in understanding how harvested populations will respond to fluctuating environmental conditions and if future catch limits will need to be adjusted. One question is, given the broad variation in life histories of harvested species, how should we expect these species to respond differently to the environment, and how would that response depend on the spectrum of the environment? Second, how can this information and the estimated variance of environmental impact on recruitment be used to inform management? To get at this questions I built stochastic age-structured models to describe the frequency-dependent sensitivity of 17 species fished along the US West Coast which will enable us to see how specific frequency components of the California ocean environment, such as ENSO (El Niño – Southern Oscillation), for example, influence probabilities of extinction or surpassing over-fishing limits. Photo credit: MM Provost

Sex change in Black Sea Bass

Black sea bass (Centropristis striata, BSB) are protogynous hermaphrodites: females can change sex to become male. Sex change in fish causes considerable challenges to fishery managers, especially for species that are heavily exploited. Black sea bass are an economically important species in the Mid-Atlantic Bight on the East Coast of the US. Managers consider the stock to be ‘data poor’ in part because of their unique life history. Because fishing targets larger fish – and males tend to be the largest – it’s expected that fishing mortality of males is disproportionately higher than females. At Rutgers University in Olaf Jensen’s lab, we did a mark-recapture study to find out at what size and age female BSB changed sex, and at what time of year change sex occurs. We also measured sex selectivity of hook-and-line and commercial traps, the two fishing gears used in the recreational and commercial BSB fisheries, to see if males are more susceptible to capture compared to females. Photo credit: MM Provost

• The Impacts of Fishing on Hermaphroditic and Treatment of Sex Change in Stock Assessments
• Influence of Size, Age, and Spawning Season on Sex Change in Black Sea Bass
• Evaluating the impacts of fishing on sex-changing fish: a game-theoretic approach

Shifting Fish & Fishers

In a collaboration with social scientists and other ecology graduate students in a working group called Shifting Fish and Fishers funded by the National Socio-Environmental Synthesis Center (SESNYC) we looked into the effects of shifting fish populations on US east coast fishing communities. We know that fish are moving poleward as ocean temperatures rise with climate change, it is unclear how communities that rely on these resources will respond. Using the locations of catch by fishing vessels from vessel trip reports, we look at catch and fishing patterns across space and time. Our group works closely with the “Adaptations of fish and fishing communities to rapid climate change” Coastal SEES group at Rutgers. Photo credit: MM Provost

• Adaptation strategies of coastal fishing communities as species shift poleward
• Governing fisheries in the face of change: Social responses to long-term geographic shifts in a U.S. fishery

Impact Evaluation of Marine Protected Areas

Marine Protected Areas (MPAs) are increasingly being used for fisheries management, but a key challenge is measuring their impact, or effectiveness at achieving their management or conservation goals. A key reason for this is because coral reef conditions and fish abundance are not usually assessed before MPAs are built, and therefore it is difficult to expected change with no baseline. This project focuses on building quasi-experimental methods for doing impact evaluations of MPAs in Indonesia by matching paired sites based on their physical characteristics, geographic location, and exposure to oceanographic forces that influence productivity in corals and fishes. This work is led by scientists and resource managers from the World Wildlife Fund in both the US and Indonesia. Photo credit: G Ahmadia

• Integrating impact evaluation in the design and implementation of monitoring marine protected areas