Jacob P. Kritzer

Patterns and processes in reef fish diversity

A central aim of ecology is to explain the heterogeneous distribution of biodiversity on earth. As expectations of diversity loss grow, this understanding is also critical for effective management and conservation. Although explanations for biodiversity patterns are still a matter for intense debate, they have often been considered to be scale-dependent. At large geographical scales, biogeographers have suggested that variation in species richness results from factors such as area, temperature, environmental stability, and geological processes, among many others. From the species pools generated by these large-scale processes, community ecologists have suggested that local-scale assembly of communities is achieved through processes such as competition, predation, recruitment, disturbances and immigration. Here we analyse hypotheses on speciation and dispersal for reef fish from the Indian and Pacific oceans and show how dispersal from a major centre of origination can simultaneously account for both large-scale gradients in species richness and the structure of local communities.

The Merging of Metapopulation Theory and Marine Ecology: Establishing the Historical Context

Publisher Summary The Merging of Metapopulation Theory and Marine Ecology This chapter considers three general explanations for the pattern of use of metapopulation ideas in marine ecology. The chapter examines whether there are fundamental differences between marine and terrestrial systems that limit the use of theory developed primarily in one context for use in the other context. Such an examination is done through a critical assessment of how metapopulation theory is used in terrestrial ecology and suggests likely differences in the application of metapopulation theory to marine systems. The slow adoption of a metapopulation paradigm in marine ecology might have been a direct consequence of the pattern of development of ideas. Questions in marine ecology have been explored, and the extent to which marine environmental management and conservation may have helped initiate and now continue to drive the application of metapopulation theory has been examined. Although it might be logical for marine ecology and fisheries management science to interact closely, there has been a long history of marine ecology borrowing concepts and theories from terrestrial ecology. Although marine and terrestrial systems have in common the fact that populations are patchily distributed, it is clear that marine systems differ from terrestrial ones. Marine ecology came to adopt metapopulation theory by way of its rediscovery of the importance of larval dispersal and recruitment dynamics.

The Metapopulation Ecology of Coral Reef Fishes

Publisher Summary The ecology of coral reef fishes seems to invite a metapopulation perspective. A metapopulation structure is determined by the spatial arrangement of local populations, coupled with life-history traits that allow metapopulation dynamics to be enacted. There certainly is evidence to suggest that coral reef fishes may form metapopulations, at least when metapopulations are defined with reference to spatial structure and connectivity rather than extinction recolonization dynamics. Extinction recolonization may be evident at the edge of species ranges, such as within the Capricorn Bunker group of the Great Barrier Reef. Metapopulation dynamics are viewed as something more than extinction recolonization dynamics, and greater potential is seen for the presence of metapopulations among coral reef fishes. Demographic traits and behavior can vary even among very proximal populations, or among adjacent reef zones, reflecting a part of the independence of these populations. The population dynamics that result from dispersal patterns and local demography typically show asynchrony among populations, at least as indicated by recruitment data. To provide better answers, reef fish ecologists need, first and foremost, to continue the burgeoning trend of large-scale, interdisciplinary research on larval dispersal and demographic connectivity. At the same time, one should not accept too blindly the assumption that postsettlement reef fishes are sedentary; one should be looking to test this assumption in situations where it is likely to be violated.

Fishery Management Strategies for Addressing Complex Spatial Structure in Marine Fish Stocks

Complex spatial structure is the rule rather than the exception among marine populations. In addition to defining relatively large population units that are more or less reproductively independent (i.e., stocks), the process of stock identification should also strive to recognize linkages among stocks and finer-scale internal structure within them. Considerable attention has been devoted to documenting spatial patterns and exploring their ecological implications, but less attention has been paid to the full suite of complementary fishery management tools available to account for spatial patterns. We consider different aspects of the quota-setting process through which spatial structure can be addressed, including use of spatially structured stock assessment models, management strategy evaluation, and incorporation of spatial indices into harvest control rules. One common problem is that fishery management remains essentially nonspatial, even if spatial dynamics are considered in models. Conversely, there are also instances in which management is spatially explicit but with little scientific basis, which can be an opportunity for research and adaptive management. Data demands and additional uncertainties impose limitations on the application of spatially structured models and might offset the gains achieved by more detailed model specification. Therefore, we also consider complementary or alternative approaches for spatially explicit management, including distribution of catch among management areas, marine protected areas, and nested scales of governance. We conclude that a more dynamic relationship is needed among empirical researchers, modelers, and fisheries managers to identify and respond to complex spatial structure in both fisheries science and management.

The Future of Metapopulation Science in Marine Ecology

Publisher Summary This chapter reviews the question of whether marine and terrestrial systems have such fundamentally different characteristics that metapopulation theory is useful only on land, or at least to require drastically different constructs in the concepts and models. But there are marine systems that possibly should not be seen as metapopulations. A nonexhaustive list of key research topics that need to be addressed to build a better understanding of metapopulation structure and dynamics in the sea is provided. The interaction between marine metapopulation ecology and management of living marine resources is also considered. Drawing upon metapopulation theory should continue to present new questions and guide new marine ecological research. Marine systems can, at the very least, increase the range of variation on the basic and universal set of population processes represented in metapopulation studies, and marine ecologists can substantially widen the pool of scientists focused on metapopulation issues.

Fostering effective international collaboration for marine science in small island states

1 The Center for Marine Resource Studies, The School for Field Studies, South Caicos, Turks and Caicos Islands, Department of Environment and Resource Studies, University of Waterloo, Waterloo, ON, Canada, Department of Integrative Biology, Oregon State University, Corvallis, OR, USA, 4 Environmental Defense Fund, Boston, MA, USA, 5 Environmental Sustainability Research Centre, College of Life and Natural Sciences, University of Derby, Derby, UK, Waitt Institute, Washington, DC, USA, Centro de Investigaciones de Ecosistemas Costeros, Ciego de Avila, Cuba, Department of Marine Resources, Ministry of Agriculture, Marine Resources and Local Government, Nassau, Bahamas, Centre for Resource Management and Environmental Studies, The University of the West Indies, St. Michael, Barbados

Effects of climate change on four New England groundfish species

Multiple groundfish stocks in New England remain depleted despite management measures that have been effective elsewhere. A growing body of research suggests that environmental change driven by increasing concentrations of carbon dioxide in the atmosphere and ocean is unfolding more rapidly in New England than elsewhere, and is an important factor in the failure of these stocks to respond to management. We reviewed research on effects of changes in temperature, salinity, dissolved oxygen, pH, and ocean currents on pelagic life stages, post-settlement life stages, and reproduction of four species in the New England groundfish fishery: Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), winter flounder (Pseudopleuronectes americanus), and yellowtail flounder (Limanda ferruginea). The volume of research on cod was nearly equal to that on the other three species combined. Similarly, many more studies examined effects of temperature than other factors. The majority of studies suggest adverse outcomes, with less evidence for mixed or positive effects. However, for all of the factors other than temperature, there are more knowledge gaps than known effects. Importantly, most work to date examines impacts in isolation, but effects might combine in nonlinear ways and cause stronger reductions in stock productivity than expected. Management strategies will need to account for known effects, nonlinear interactions, and uncertainties if fisheries in New England are to adapt to environmental change.

An Evaluation of Harvest Control Methods for Fishery Management

ABSTRACT Fisheries managers seek to maintain sustainable fisheries production, but successful management often requires the pursuit of multiple biological, ecological, and socioeconomic objectives simultaneously. Fisheries managers must choose among a broad range of harvest control methods (HCMs) to meet management objectives. This review identifies strengths and weaknesses of eight HCMs and evaluates their ability to meet a multitude of common biological, ecological, and socioeconomic management objectives such as protecting spawning biomass, reducing bycatch, and sustaining fishers’ profit. Evidence suggests that individual HCMs often fail to meet management objectives and may unintentionally create incentives to race to fish, discard catch and overcapitalize fishing operations. These limitations can be overcome by strategically combining multiple controls or incorporating rights-based and spatial management.

Integrating Science-Based Co-management, Partnerships, Participatory Processes and Stewardship Incentives to Improve the Performance of Small-Scale Fisheries

Small scale fisheries are critically important for the provision of food security, livelihoods, and economic development for billions of people. Yet, most of these fisheries appear to not be achieving either fisheries or conservation goals, with respect to creating healthier oceans that support more fish, feed more people and improve livelihoods. Research and practical experience have elucidated many insights into how to improve the performance of small-scale fisheries. Here, we present lessons learned from five case studies of small-scale fisheries in Cuba, Mexico, the Philippines, and Belize. The major lessons that arise from these cases are: 1) participatory processes empower fishers, increase compliance, and support integration of local and scientific knowledge; 2) partnership across sectors improves communication and community buy-in; 3) scientific analysis can lead fishery reform and be directly applicable to co-management structures. These case studies suggest that a fully integrated approach that implements a participatory process to generate a scientific basis for fishery management (e.g., data collection, analysis, design) and to design management measures among stakeholders will increase the probability that small-scale fisheries will implement science-based management and improve their performance.

Patterns of larval-stage connectivity of Atlantic cod (Gadus morhua) within the Gulf of Maine in relation to current structure and a proposed fisheries closure

&NA; The decline of the Atlantic cod, Gadus morhua, stock in the Gulf of Maine to a historically low biomass has been coupled with a severe contraction in spatial range. The stock is now largely concentrated in the western Gulf of Maine. This erosion of spatial stock structure may be a factor‐inhibiting recovery of Gulf of Maine cod. However, recent efforts to rebuild anadromous forage fish in the coastal Maine region coupled with the proposed creation of a new Eastern Maine Closed Area (EMCA), sited where localized depletion of the cod stock has been especially severe, might enable reestablishment of lost spatial structure of Gulf of Maine cod. We carried out larval transport modeling to examine the potential benefit of recovered cod spawning in the EMCA through supplying larvae to suitable juvenile settlement areas in the Gulf of Maine coastal zone and in the Cashes Ledge Closed Area (CLCA) in the central Gulf of Maine. The results indicate that an appreciable fraction of the larvae spawned in the EMCA are retained, to an age of settlement capability, in the coastal Maine region. Spawning in the EMCA may thus be a contributor of juveniles to a local, eastern Gulf of Maine, cod sub‐stock. The results further indicate that spawning in the EMCA may supply a substantial subsidy of larvae to suitable juvenile habitat in the western Gulf of Maine and the CLCA. Protection of spawning stock in the EMCA may thus provide demographic benefits for the wider Gulf of Maine cod stock. Patterns of larval‐stage connectivity between various potential spawning regions (including the EMCA) and areas of suitable juvenile habitat exhibit considerable interannual variability, which is predominantly linked to variability in the large‐scale Gulf of Maine circulation. This result underscores the value of spatially explicit management as a means of fostering the recovery of the Gulf of Maine cod stock.