Peer-Reviewed Journals

Bioeconomics and biodiversity in harvested metacommunities: A patch-occupancy approach.
EA Moberg, JB Kellner and MG Neubert (2015)
Ecosphere 6(11): 246.
Links: Article, Abstract
We develop a coupled economic-metacommunity model to investigate the trade-off between diversity and profit for multispecies systems. The model keeps track of the presence or absence of species in habitat patches. With this approach, it becomes (relatively) simple to include more species than can typically be included in models that track species population density. We use this patch-occupancy framework to understand how profit and biodiversity are impacted by (1) community assembly, (2) pricing structures that value species equally or unequally, and (3) the implementation of marine reserves. We find that when local communities assemble slowly as a result of facilitative colonization, there are lower profits and optimal harvest rates, but the trade-off with diversity may be either large or small. The trade-off is diminished if later colonizing species are more highly valued than early colonizers. When the cost of harvesting is low, maximizing profits tends to sharply reduce biodiversity and maximizing diversity entails a large harvesting opportunity cost. In the models we analyze, marine reserves are never economically optimal for a profit-maximizing owner. However, management using marine reserves may provide low-cost biodiversity protection if the community is over-harvested.

Optimizing for multiple species and multiple values: tradeoffs inherent in ecosystem-based fisheries management.
JB Kellner, JN Sanchirico, A Hastings and PJ Mumby (2011)
Conservation Letters 4(1): 21-30.
Links: Article, Appendices (PDF), Abstract
Although a consensus in marine science is developing on the need to adopt ecosystem-based fishery management, few studies try to quantify the context-specific gains from implementing it. Using a multi-species bioeconomic model for a Caribbean reef community, we determine the optimal harvesting rates for predator and prey species and ask how this more comprehensive optimization differs from traditional single-species approaches. We also identify tradeoffs when the objective of the manager includes nonfishing values. We find that the optimal solution when accounting for nonfishing values can include temporary or permanent fishing moratoriums in contrast to continuous fishing at low levels when only fishing profits are considered. We also show that the greatest gains from ecosystem-based fishery management are not from improved estimation of the trophic coupling, but from reforming the social and economic management of individual fish stocks and by explicitly incorporating a broader set of values into management decisions.

Disentangling trophic interactions inside a Caribbean marine reserve.
JB Kellner, SY Litvin, A Hastings, PJ Mumby and F Micheli (2010)
Ecological Applications 20(7): 1979–1992.
Links: Article, Abstract
Recent empirical studies have demonstrated that human activities such as fishing can strongly affect the natural capital and services provided by tropical seascapes. However, policies to mitigate anthropogenic impacts can also alter food web structure and interactions, regardless of whether the regulations are aimed at single or multiple species, with possible unexpected consequences for the ecosystems and their associated services. Complex community response to management interventions have been highlighted in the Caribbean, where, contrary to predictions from linear food chain models, a reduction in fishing intensity through the establishment of a marine reserve has led to greater biomass of herbivorous fish inside the reserve, despite an increased abundance of large predatory piscivores. This positive multi-trophic response, where both predators and prey benefit from protection, highlights the need to take an integrated approach that considers how numerous factors control species coexistence in both fished and unfished systems. In order to understand these complex relationships, we developed a general model to examine the trade-offs between fishing pressure and trophic control on reef fish communities, including an exploration of top-down and bottom-up effects. We then validated the general model predictions by parameterizing the model for a reef system in the Bahamas in order to tease apart the wide range of species responses to reserves in the Caribbean. Combining the development of general theory and site-specific models parameterized with field data reveals the underlying driving forces in these communities and enables us to make better predictions about possible population and community responses to different management schemes.

Spillover from marine reserves and the replenishment of fished stocks.
BS Halpern, SE Lester and JB Kellner (2010)
Environmental Conservation 36(4): 268–276.
Links: Article, Abstract
No-take marine reserves are widely recognized as an effective conservation tool for protecting marine resources. Despite considerable empirical evidence that abundance and biomass of fished species increase within marine reserve boundaries, the potential for reserves to provide fisheries and conservation benefits to adjacent waters remains heavily debated. This paper uses statistical and population models to evaluate published empirical data on adult spillover from marine reserves and shows that spillover is a common phenomenon for species that respond positively to reserve protection, but at relatively small scales, detectable on average up to 800 m from reserve boundaries. At these small scales, local fisheries around reserves were likely unsustainable in 12 of 14 cases without the reserve, and spillover partially or fully offsets losses in catch due to reserve closure in the other two cases. For reserves to play a role in sustaining and replenishing larger-scale fished stocks, networks of reserves may be necessary, but as few exist this is difficult to evaluate. The results suggest reserves can simultaneously meet conservation objectives and benefit local fisheries adjacent to their boundaries.

A Reserve Paradox: Introduced Heterogeneity May Increase Regional Invasibility.
JB Kellner and A Hastings (2009)
Conservation Letters 2(3): 115-122.
Links: Article, Abstract
No-take marine protected areas (MPAs) typically lead to population abundances that are much more spatially heterogeneous compared to conventional fisheries management. Higher abundances inside marine reserves may sustain regional populations through spillover of larvae, but this induced spatial heterogeneity can also have undesirable consequences. Displacing fishing effort into a smaller area may offset larval export from MPAs and locally reduce populations within fished areas by intensifying effort per area. Using a novel community perspective, we show that this displacement can increase the local and regional community's susceptibility to invasion by nonindigenous species. This study illustrates the types of multispecies trade-offs that are inherent to spatially explicit forms of management and highlights the pressing need to transition from single-species analyses to examining community responses to management schemes across broader biological and spatial scales. Our results demonstrate the potentially negative regional consequences of anthropogenically-driven spatial heterogeneities in aquatic and terrestrial systems.

Connectivity, Sustainability, and Yield: Bridging the Gap between Conventional Fisheries Management and Marine Protected Areas.
LW Botsford, D Brumbaugh, C Grimes, JB Kellner, J Largier, M O'Farrell, S Ralston, E Soulanille and V Wespestad (2009)
Reviews in Fish Biology and Fisheries 19(1): 69-95.
Links: Article, Abstract & Reprint (PDF)
A substantial shift toward use of marine protected areas (MPAs) for conservation and fisheries management is currently underway. This shift to explicit spatial management presents new challenges and uncertainties for ecologists and resource managers. In particular, the potential for MPAs to change population sustainability, fishery yield, and ecosystem properties depends on the poorly understood consequences of three critical forms of connectivity over space: larval dispersal, juvenile and adult swimming, and movement of fishermen. Conventional fishery management describes the dynamics and current status of fish populations, with increasing recent emphasis on sustainability, often through reference points that reflect individual replacement. These compare lifetime egg production (LEP) to a critical replacement threshold (CRT) whose value is uncertain. Sustainability of spatially distributed populations also depends on individual replacement, but through all possible paths created by larval dispersal and LEP at each location. Model calculations of spatial replacement considering larval connectivity alone indicate sustainability and yield depend on species dispersal distance and the distribution of LEP created by species habitat distribution and fishing mortality. Adding MPAs creates areas with high LEP, increasing sustainability, but not necessarily yield. Generally, short distance dispersers will persist in almost all MPAs, while sustainability of long distance dispersers requires a specific density of MPAs along the coast. The value of that density also depends on the uncertain CRT, as well as fishing rate. MPAs can increase yield in areas with previously low LEP but for short distance dispersers, high yields will require many small MPAs. The paucity of information on larval dispersal distances, especially in cases with strong advection, renders these projections uncertain. Adding juvenile and adult movement to these calculations reduces LEP near the edges in MPAs, if movement is within a home-range, but more broadly over space if movement is diffusive. Adding movement of fishermen shifts effort on the basis of anticipated revenues and fishing costs, leading to lower LEP near ports, for example. Our evolving understanding of connectivity in spatial management could form the basis for a new, spatially oriented replacement reference point for sustainability, with associated new uncertainties.

Spillover from Marine Reserves Related to Mechanisms of Population Regulation.
JB Kellner, RM Nisbet and SD Gaines (2008)
Theoretical Ecology 1(2): 117-127.
Links: Article, Abstract & Reprint (PDF)
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.

Fishing the Line Near Marine Reserves in Single and Multispecies Fisheries.
JB Kellner, I Tetreault, SD Gaines and RM Nisbet (2007)
Ecological Applications 17(4): 1039-1054.
Links: Article, Appendices (PDF), Abstract & Reprint (PDF)
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.

The California Watershed Movement: Science and the Politics of Place.
JT Woolley, MV McGinnis and J Kellner (2002)
Natural Resources Journal 42(1): 133-183.
Links: Article, Reprint (PDF)

Technical Reports

Environmental and Anthropogenic Threats to Coral Reef Ecosystems.
A Bruckner, K Buja, L Fairey, K Gleason, M Harmon, S Heron, T Hourigan, C Jeffrey, J Kellner, R. Kelty, B Leeworthy, G Liu, S Pittman, A Shapiro, A Strong, J Waddell and P Wiley (2005)
pp. 12-44. In: J Waddell (ed.), The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2005. NOAA Technical Memorandum NOS NCCOS 11. NOAA/NCCOS Center for Coastal Monitoring and Assessment’s Biogeography Team. Silver Spring, MD. 522pp.
Links: Complete Report (PDF)

A Biogeographic Assessment of the Channel Islands National Marine Sanctuary: A Review of Boundary Expansion Concepts for NOAA’s National Marine Sanctuary Program.
NOAA National Centers for Coastal Ocean Science (NCCOS) (2005) Prepared by NCCOS’s Biogeography Team in cooperation with the National Marine Sanctuary Program. Silver Spring, MD. NOAA Technical Memorandum NOS NCCOS 21. 215pp.
Links: Complete Report (PDF)
  • Introduction. C Caldow, J Kellner, MJ Allen, S Airamé, S Gaines. pp. 1-16.
  • Physical and Oceanographic Setting. J Kellner, J Christensen, R Clark, C Caldow, M Coyne. pp. 17-56.
  • Biogeography of Marine Birds. O Jensen, H Carter, G Ford, J Kellner, J Christensen. pp. 135-165.
  • Integration. R Clark, C Caldow, J Christensen, J Kellner. pp. 199-210.


Spatial dynamics of marine reserves: The importance of fish movement and harvester redistribution.
JB Kellner (2004) University of California, Santa Barbara.
Links: Download at ProQuest, Abstract
This dissertation explores the role of fish movement, population regulation and the spatial patterns of fishing effort in shaping the distribution of fish within marine reserves and across their boundaries. The interplay between spillover and fishing effort is investigated through the integration of spatially-explicit models and empirical patterns of fish abundances found in the marine reserve literature.

Chapter 1 examines how the mechanism of population regulation can influence the build-up of standing stock within a marine reserve and the spillover rate to adjacent fished areas. Two forms of population regulation are compared, density-dependent population growth and density-dependent movement. Standing stock per unit area is bounded for density-dependent population growth, and increases with size for density-dependent movement. With density-dependent population growth, spillover rate per unit area of reserve is maximized with reserves around 50% larger in linear dimension than the minimum size for population persistence. Spillover per unit area of reserve increases with reserve size for populations regulated by density-dependent movement.

Chapter 2 explores the implications of fishing-the-line at the boundary of a marine reserve. The model shows that fishing-the-line is the optimal harvesting strategy for both consolidated and competitive multispecies fisheries near marine reserves when mobile species spillover from the reserve. The consequences of basing the distribution of fishing effort for a multispecies fishery upon the optimality of the most mobile species which exhibits the greatest spillover are explored. The chapter concludes with a comparison between model predictions and empirical findings from a study of game fish in the vicinity of a no-take marine life refuge on Catalina Island, California.

Chapter 3 reviews the patterns of density, biomass and harvesting effort near marine reserve boundaries found in the empirical literature. The limited number of spatial studies demonstrates that fish density, biomass and fishing effort generally decline with distance from the protected area. A theoretical model incorporating a linear decline of fishing effort away from the reserve reveals that this spatial pattern of harvesters can either approximate the empirical patterns of decaying fish density away from the protected area, or produce dips in fish density close to reserve boundary.

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