Publications

Every fishery is embedded in a matrix of political institutions, and these institutions, together with other factors, determine the management regime that will best capture the resource’s potential rent. This chapter examines evidence on this link. Resource management structures are equivalent to property rights regimes because they delineate who has authority to decide how a resource is used and to determine how the resource’s returns are distributed among various parties. For this reason the following discussion links political conditions to the performance of specific assignments of property rights, with the focus on fisheries.

Trophic cascades triggered by fishing have profound implications for marine ecosystems and the socioeconomic systems that depend on them. With the number of reported cases quickly growing, key features and commonalities have emerged. Fishery-induced trophic cascades often display differential response times and nonlinear trajectories among trophic levels and can be accompanied by shifts in alternative states. Furthermore, their magnitude appears to be context dependent, varying as a function of species diversity, regional oceanography, local physical disturbance, habitat complexity, and the nature of the fishery itself. To conserve and manage exploited marine ecosystems, there is a pressing need for an improved understanding of the conditions that promote or inhibit the cascading consequences of fishing. Future research should investigate how the trophic effects of fishing interact with other human disturbances, identify strongly interacting species and ecosystem features that confer resilience to exploitation, determine ranges of predator depletion that elicit trophic cascades, pinpoint antecedents that signal ecosystem state shifts, and quantify variation in trophic rates across oceanographic conditions. This information will advance predictive models designed to forecast the trophic effects of fishing and will allow managers to better anticipate and avoid fishery-induced trophic cascades.

Management and conservation can be greatly informed by considering explicitly how environmental factors influence population genetic structure. Using simulated larval dispersal estimates based on ocean current observations, we demonstrate how explicit consideration of frequency of exchange of larvae among sites via ocean advection can fundamentally change the interpretation of empirical population genetic structuring as compared with conventional spatial genetic analyses. Both frequency of larval exchange and empirical genetic difference were uncorrelated with Euclidean distance between sites. When transformed into relative oceanographic distances and integrated into a genetic isolation-by-distance framework, however, the frequency of larval exchange explained nearly 50 per cent of the variance in empirical genetic differences among sites over scales of tens of kilometres. Explanatory power was strongest when we considered effects of multiple generations of larval dispersal via intermediary locations on the long-term probability of exchange between sites. Our results uncover meaningful spatial patterning to population genetic structuring that corresponds with ocean circulation. This study advances our ability to interpret population structure from complex genetic data characteristic of high gene flow species, validates recent advances in oceanographic approaches for assessing larval dispersal and represents a novel approach to characterize population connectivity at small spatial scales germane to conservation and fisheries management.

Declining ocean health, increasing human demands on marine ecosystems, and a history of management focused on individual activities, species or sectors has led to calls for more comprehensive, integrated management that considers entire coupled social-ecological systems. This transition to ecosystem-based management (EBM) for the oceans will certainly face a number of hurdles, and many practitioners struggle with how to move forward with EBM. In this paper, we assess whether the necessary science exists to support EBM. Specifically, we evaluate the state of the social and natural sciences for three research areas that are critical to EBM: (1) ecosystem services, (2) cumulative impacts, and (3) ecosystem variability and change. For each of the three research areas, we describe its importance to EBM and assess existing and emerging information and application of this knowledge, focusing on the US West Coast. We conclude that available science is not the bottleneck for moving forward with comprehensive EBM for this region, although we highlight important remaining knowledge gaps, particularly within the social sciences. Given imperfect and uncertain knowledge, EBM calls for an adaptive management approach, starting with readily available information, and continuously adapting as new information emerges. This synthesis can serve as a basis for comparison for other regions; it provides guidance for organizing information in support of EBM and outlines many novel and broadly applicable scientific approaches.

Widespread concern exists over the health of marine ecosystems given the diversity and impact of human activities affecting these systems worldwide (Halpern et al. 2008), with overfishing consistently identified as a key threat to all parts of the world's oceans (Pauly et al. 1998). Overexploitation has resulted in dire predictions about the ability of oceans to continue supporting fisheries (Worm et al. 2006), in turn leading to calls for fishery management reform (Costello et al. 2008) and increased protection to maintain some locations in a more 'pristine' ecosystem state (Lubchenco et al. 2003). No-take marine reserves, which prohibit all exploitative activities, have become widely recognized as an effective conservation tool for protecting marine resources, resulting in increases in the abundance, biomass and diversity of many species within their boundaries (Halpern 2003; Micheli et al. 2004; Lester et al. 2009). However, the ability for reserves to provide conservation or fisheries benefits to adjacent waters remains highly controversial (Roberts et al. 2001; Tupper 2002; Gell & Roberts 2003; Hilborn et al. 2004).

Marine reserves may not only protect populations within their borders but also subsidize harvested populations outside through the spillover of either adults or planktonic larvae. The conservation benefits of marine reserves are well documented, and a growing body of evidence suggests that the spillover of large adults from reserves can enhance fisheries for highly mobile species. However, the proposed benefit to fisheries through larval export, a crucial benefit for the many marine species without highly mobile adults, remains controversial. We tested for larval export by estimating larval production and recruitment patterns of a harvested intertidal mussel, Perna perna, inside - and a range of distances outside - 3 marine reserves in South Africa. Within the borders of 2 reserves, mussels were more abundant and larger than outside the reserves, with significantly higher expected production. Recruitment was highest inside these reserves and declined exponentially with distance. In the third region, where harvest outside reserve boundaries is carefully managed by community members, no differences in production or recruitment inside versus outside the reserve were found. Where production and recruitment were enhanced, we used the inverse relationship of recruitment with distance from the reserves to determine the spatial scale and magnitude of larval export. Our results suggest that larval export from these reserves enhances recruitment to fished areas within several kilometers. This study supports the idea that increased production in reserves may subsidize fisheries outside their borders, even for species with immobile adults. ©nter-Research 2009.

After a long history of overexploitation, increasing efforts to restore marine ecosystems and rebuild fisheries are under way. Here, we analyze current trends from a fisheries and conservation perspective. In 5 of 10 well-studied ecosystems, the average exploitation rate has recently declined and is now at or below the rate predicted to achieve maximum sustainable yield for seven systems. Yet 63% of assessed fish stocks worldwide still require rebuilding, and even lower exploitation rates are needed to reverse the collapse of vulnerable species. Combined fisheries and conservation objectives can be achieved by merging diverse management actions, including catch restrictions, gear modification, and closed areas, depending on local context. Impacts of international fleets and the lack of alternatives to fishing complicate prospects for rebuilding fisheries in many poorer regions, highlighting the need for a global perspective on rebuilding marine resources.

The study and implementation of no-take marine reserves have increased rapidly over the past decade, providing ample data on the biological effects of reserve protection for a wide range of geographic locations and organisms. The plethora of new studies affords the opportunity to reevaluate previous findings and address formerly unanswered questions with extensive data syntheses. Our results show, on average, positive effects of reserve protection on the biomass, numerical density, species richness, and size of organisms within their boundaries which are remarkably similar to those of past syntheses despite a near doubling of data. New analyses indicate that (1) these results do not appear to be an artifact of reserves being sited in better locations; (2) results do not appear to be driven by displaced fishing effort outside of reserves; (3) contrary to often-made assertions, reserves have similar if not greater positive effects in temperate settings, at least for reef ecosystems; (4) even small reserves can produce significant biological responses irrespective of latitude, although more data are needed to test whether reserve effects scale with reserve size; and (5) effects of reserves vary for different taxonomic groups and for taxa with various characteristics, and not all species increase in response to reserve protection. There is considerable variation in the responses documented across all the reserves in our data set — variability which cannot be entirely explained by which species were studied. We suggest that reserve characteristics and context, particularly the intensity of fishing outside the reserve and inside the reserve before implementation, play key roles in determining the direction and magnitude of the reserve response. However, despite considerable variability, positive responses are far more common than no differences or negative responses, validating the potential for well designed and enforced reserves to serve as globally important conservation and management tools.

Predictions on the efficacy of marine reserves for benefiting fisheries differ in large part due to considerations of models of either intra- or inter-cohort population density regulating fish recruitment. Here, I consider both processes acting on recruitment and show using a bioeconomic model how for many fisheries density dependent recruitment dynamics interact with harvest costs to influence fishery profit with reserves. Reserves consolidate fishing effort, favoring fisheries that can profitably harvest low-density stocks of species where adult density mediates recruitment. Conversely, proportion coastline in reserves that maximizes profit, and relative improvement in profit from reserves over conventional management, decline with increasing harvest costs and the relative importance of intra-cohort density dependence. Reserves never increase profit when harvest cost is high, regardless of density dependent recruitment dynamics. I quantitatively synthesize diverse results in the literature, show disproportionate effects on the economic performance of reserves from considering only inter- or intra-cohort density dependence, and highlight fish population and fishery dynamics predicted to be complementary to reserve management.

The Experimental Program to Stimulate Competitive Research (EPSCoR) was designed to help U.S. states with limited facilities improve their research infrastructure in order to make them more competitive for nationwide grants, such as the R01. Twenty-seven states and territories (including Puerto Rico and the U.S. Virgin Islands) have been designated EPSCoR states (1). In a recent Letter (“Declines in NIH R01 research grant funding,” 10 October 2008, p. 189), H. G. Mandel and E. S. Vesell presented the current funding statistics for R01 grants. These findings and other changes in policy (2) demonstrate the difficulty in getting R01 grants funded in the current climate. The existing funding situation encourages investigators from EPSCoR states to take their R01 grants and leave for better institutions because better institutions have the resources to obtain new R01 grants and renew R01 grants.

How can institutions in EPSCoR states retain their scientists with R01 grants under these difficult conditions? It may be necessary to offer extremely competitive financial packages to scientists from elsewhere with R01s or to change the promotion and tenure policies; perhaps scientists who have R01s could receive early promotion and tenure, or the tenure clock could be extended to give scientists more time to obtain an R01.

Recent reports suggest that most of the world's commercial fisheries could collapse within decades. Although poor fisheries governance is often implicated, evaluation of solutions remains rare. Bioeconomic theory and case studies suggest that rights-based catch shares can provide individual incentives for sustainable harvest that is less prone to collapse. To test whether catch-share fishery reforms achieve these hypothetical benefits, we have compiled a global database of fisheries institutions and catch statistics in 11,135 fisheries from 1950 to 2003. Implementation of catch shares halts, and even reverses, the global trend toward widespread collapse. Institutional change has the potential for greatly altering the future of global fisheries.

Many nearshore fish and invertebrate populations are overexploited even when apparently coherent management structures are in place. One potential cause of mismanagement may be a poor understanding and accounting of stochasticity, particularly for stock recruitment. Many of the fishes and invertebrates that comprise nearshore fisheries are relatively sedentary as adults but have an obligate larval pelagic stage that is dispersed by ocean currents. Here, we demonstrate that larval connectivity is inherently an intermittent and heterogeneous process on annual time scales. This stochasticity arises from the advection of pelagic larvae by chaotic coastal circulations. This result departs from typical assumptions where larvae simply diffuse from one site to another or where complex connectivity patterns are created by transport within spatially complicated environments. We derive a statistical model for the expected variability in larval settlement patterns and demonstrate how larval connectivity varies as a function of different biological and physical processes. The stochastic nature of larval connectivity creates an unavoidable uncertainty in the assessment of fish recruitment and the resulting forecasts of sustainable yields.

David Festa, Diane Regas, and Judson Boomhower's compelling account "Sharing the Catch, Conserving the Fish" ( Issues , Winter 2008) echoes mounting theoretical and empirical evidence on the powerful ability of economic incentives to provide resource users with strong motivation for good stewardship. The question for policymakers should no longer be if or when to implement these innovations, but how to design them to achieve biological, economic, and social objectives.
Most current fisheries management approaches generate two inherent conflicts: between a fisherman's short- and long-term interests and between the short-term incentives of a fisherman and the longer-term public good. These conflicts exist because there are strong incentives for fishermen to overfish and spend too much money doing it. These mismatches can be reversed with appropriate design of secure-access programs that align short- and long-term interests. Providing fishermen with economic incentives to conserve is smart
management. 

We characterize the optimal harvest of a renewable resource in a generalized stochastic spatially explicit model. Despite the complexity of the model, we are able to obtain sharp analytical results. We find that the optimal harvest rule in general depends upon dispersal patterns of the resource across space, and only in special circumstances do we find a modified golden rule of growth that is independent of dispersal patterns. We also find that the optimal harvest rule may include closure of some areas to harvest, either on a temporary or permanent basis (biological reserves). Reserves alone cannot correct open access, but may, under sufficient spatial heterogeneity and connectivity, increase profits if appropriate harvest controls are in place outside of reserves.

Spillover of fish from marine reserves to adjacent harvested waters may be mediated by density-independent movement, density-dependent movement, or both. If dispersal is by random movement, populations within the reserve must be regulated by density-dependent population growth (DDG). Density-dependent movement (DDM) can also regulate the population if accelerated emigration from a reserve to the surrounding fishing grounds leads to substantially increased mortality. Using spatially explicit models, we show that stock per unit area is bounded for DDG and increases with size for DDM. With DDG, spillover rate per unit area of reserve is maximized with reserves around 50% larger in linear dimension than the minimum size for population persistence. With DDM, spillover per unit area of reserve increases with reserve size. The results highlight the need for the mechanism of population regulation to be incorporated into theoretical and empirical investigations of marine reserve ecology.

Some studies suggest that fishery yields can be higher with reserves than under conventional management. However, the economic performance of fisheries depends on economic profit, not fish yield. The predictions of higher yields with reserves rely on intensive fishing pressures between reserves; the exorbitant costs of harvesting low-density populations erode profits. We incorporated this effect into a bioeconomic model to evaluate the economic performance of reserve-based management. Our results indicate that reserves can still benefit fisheries, even those targeting species that are expensive to harvest. However, in contrast to studies focused on yield, only a moderate proportion of the coast in reserves (with moderate harvest pressures outside reserves) is required to maximize profit. Furthermore, reserve area and harvest intensity can be traded off with little impact on profits, allowing for management flexibility while still providing higher profit than attainable under conventional management.

We study the dynamic harvest incentives faced by a renewable resource harvester with insecure property rights. A resource “concession” is granted for a fixed duration, after which it is renewed (with a known probability) only if a target stock is achieved. Despite the insecurity of this property right, simple concessions contracts can be designed to induce first best harvest trajectories. We examine how those contracts will depend on economic, ecological, and institutional variables, and apply theoretical insights to two concessions-managed fisheries in Baja California, Mexico.

Throughout the world “fishing the line” is a frequent harvesting tactic in communities where no-take marine reserves are designated. This practice of concentrating fishing effort at the boundary of a marine reserve is predicated upon the principle of spillover, the net export of stock from the marine reserve to the surrounding unprotected waters. We explore the consequences and optimality of fishing the line using a spatially explicit theoretical model. We show that fishing the line: (1) is part of the optimal effort distribution near no-take marine reserves with mobile species regardless of the cooperation level among harvesters; (2) has a significant impact on the spatial patterns of catch per unit effort (CPUE) and fish density both within and outside of the reserve; and (3) can enhance total population size and catch simultaneously under a limited set of conditions for overexploited populations. Additionally, we explore the consequences of basing the spatial distribution of fishing effort for a multispecies fishery upon the optimality of the most mobile species that exhibits the greatest spillover. Our results show that the intensity of effort allocated to fishing the line should instead be based upon more intermediate rates of mobility within the targeted community. We conclude with a comparison between model predictions and empirical findings from a density gradient study of two important game fish in the vicinity of a no-take marine-life refuge on Santa Catalina Island, California (USA). These results reveal the need for empirical studies to account for harvester behavior and suggest that the implications of spatial discontinuities such as fishing the line should be incorporated into marine-reserve design.

Temperature controls the rate of fundamental biochemical processes and thereby regulates organismal attributes including development rate and survival. The increase in metabolic rate with temperature explains substantial among-species variation in life-history traits, population dynamics, and ecosystem processes. Temperature can also cause variability in metabolic rate within species. Here, we compare the effect of temperature on a key component of marine life cycles among a geographically and taxonomically diverse group of marine fish and invertebrates. Although innumerable lab studies document the negative effect of temperature on larval development time, little is known about the generality versus taxon-dependence of this relationship. We present a unified, parameterized model for the temperature dependence of larval development in marine animals. Because the duration of the larval period is known to influence larval dispersal distance and survival, changes in ocean temperature could have a direct and predictable influence on population connectivity, community structure, and regional-to-global scale patterns of biodiversity.

Individual transferable quota (ITQ) regulation relies on a decentralized market mechanism and a single price to allocate access to a stock of fish. The resulting allocation will not be fully efficient if the stock being allocated is heterogeneous or if there are potential gains from centralized coordination of harvesting effort. If stocks are heterogeneous in their density, location, or unit value during the season, harvesters governed by an ITQ policy will not be indifferent to when or where they exercise their quotas. Stocks that are relatively dense and/or close to port will be preferred to those less dense or more remote. Because an ITQ policy assigns the same opportunity cost for each unit harvested, individual harvesters have an incentive to compete for higher-valued units, and such competition may dissipate part of the fishery's potential rent. A similar phenomenon arises when stock densities vary in an unknown way over space or time, so harvesters must engage in costly search. Individual harvesters governed by an ITQ policy still face a collective action problem which limits the incentive to share information on stock locations. This can lead to redundant search effort. We demonstrate that both sources of inefficiency can be eliminated either by defining ITQ rights more precisely or by an agreement among harvesters to coordinate their effort. We develop models that illustrate these effects and identify the factors that determine their likely size. Anecdotal evidence on practices adopted by fishery cooperatives is presented to illustrate the practical relevance of the issues we raise.