Marine Resources Assessment Group Americas Inc.

Saint Petersburg, FL, United States

Marine Resources Assessment Group Americas Inc.

Saint Petersburg, FL, United States
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Ainsworth C.H.,Marine Resources Assessment Group Americas Inc. | Morzaria-Luna H.,Marine Resources Assessment Group Americas Inc. | Kaplan I.C.,National Oceanic and Atmospheric Administration | Levin P.S.,CSIRO | And 5 more authors.
Marine Policy | Year: 2012

The Northern Gulf of California is an area important for small-scale fisheries in terms of economic activity and food security, but widespread non-compliance with fisheries regulations impedes effective management of resources and conservation efforts. Where a previous study evaluated quantitatively a theoretical situation in which all regulations are perfectly followed, this article compares a suite of recently proposed ecosystem-based management (EBM) policies against the expected benefits of full enforcement of current regulations. Policies evaluated include no-take marine protected areas (MPAs), breeding period closures, changes in hook size and fishing effort, and gear-specific spatial closures. No-take MPAs yield ecological benefits over a wide range of MPA sizes and characteristics, but do not increase overall catch. Seasonal closures are effective at reducing overfishing for the depleted leopard grouper (Mycteroperca rosacea); changing the hook size of artisanal longlines does not increase catch of either the target species or the assemblage, and gear-specific fishery closures for crab traps near Puerto Peñasco are effective at reducing overfishing of blue crab (Callinectes bellicosus and C. arcuatus). In general, full enforcement of existing regulations outperforms these EBM policies in terms of conservation benefits, but it may be less palatable to stakeholders as it requires major reductions in catch. © 2012 Elsevier Ltd.

Ainsworth C.H.,Marine Resources Assessment Group Americas Inc. | Ainsworth C.H.,University of South Florida | Morzaria-Luna H.N.,Frank Orth and Associates | Kaplan I.C.,National Oceanic and Atmospheric Administration | And 2 more authors.
Journal of Applied Ecology | Year: 2012

The Northern Gulf of California is an ecologically important marine area with a high degree of biodiversity, endemism and productivity. Mounting conservation concerns have prompted researchers to propose new management regulations, restricting fishing and protecting sensitive species. Compliance with existing regulations is poor. Rules that are currently in place, if followed, may go a long way towards achieving the ecological goals of management. We conduct a review of existing fisheries regulations in this area. Then, using a spatially explicit marine ecosystem model (Atlantis), we estimate the benefits of compliance with existing fisheries regulations. Under a full compliance scenario, we find large increases in protected species biomass within 25years and a slowed rate of ecosystem degradation because of fishing. However, full compliance costs the fishing industry about 30% of its annual revenue. We parse out the benefits offered by management instruments (including spatial management protections, seasonal fishery closures, gear restrictions, cessation of illegal fishing and vessel buy-out programmes) and conclude that a suite of measures is needed to address major conservation objectives. Synthesis and applications. This exercise quantifies the benefits of improved fisheries enforcement and provides a benchmark by which the value of future regulatory amendments can be assessed. Where compliance with existing regulations is poor, conservation goals may be better served by strengthening enforcement than by enacting new rules and legislation. © 2011 The Authors. Journal of Applied Ecology © 2011 British Ecological Society.

Ainsworth C.H.,Marine Resources Assessment Group Americas Inc. | Ainsworth C.H.,University of South Florida | Samhouri J.F.,Pacific States Marine Fisheries Commission | Samhouri J.F.,National Oceanic and Atmospheric Administration | And 5 more authors.
ICES Journal of Marine Science | Year: 2011

Although there has been considerable research on the impacts of individual changes in water temperature, carbonate chemistry, and other variables on species, cumulative impacts of these effects have rarely been studied. Here, we simulate changes in (i) primary productivity, (ii) species range shifts, (iii) zooplankton community size structure, (iv) ocean acidification, and (v) ocean deoxygenation both individually and together using five Ecopath with Ecosim models of the northeast Pacific Ocean. We used a standardized method to represent climate effects that relied on time-series forcing functions: annual multipliers of species productivity. We focused on changes in fisheries landings, biomass, and ecosystem characteristics (diversity and trophic indices). Fisheries landings generally declined in response to cumulative effects and often to a greater degree than would have been predicted based on individual climate effects, indicating possible synergies. Total biomass of fished and unfished functional groups displayed a decline, though unfished groups were affected less negatively. Some functional groups (e.g. pelagic and demersal invertebrates) were predicted to respond favourably under cumulative effects in some regions. The challenge of predicting climate change impacts must be met if we are to adapt and manage rapidly changing marine ecosystems in the 21st century. © 2011 International Council for the Exploration of the Sea.

Satterthwaite W.H.,Marine Resources Assessment Group Americas Inc. | Satterthwaite W.H.,University of California at Santa Cruz | Kitaysky A.S.,University of Alaska Fairbanks | Mangel M.,University of California at Santa Cruz | Mangel M.,University of Bergen
Marine Ecology Progress Series | Year: 2012

We examined the reproductive ecology of black-legged kittiwakes Rissa tridactyla in several breeding colonies in the North Pacific to test if inter-annual changes in the Pacific Decadal Oscillation (PDO), Winter Ice Cover (ICI), or local sea-surface temperature (SST) predict changes in productivity (fledglings per nest) or nutritional stress (corticosterone). We explored the implications of the observed variation in productivity and stress for projected population dynamics based on a previously demonstrated corticosterone-survival relationship. Although productivity was highly variable (0 to 0.9 fledglings nest-1), the relationships between productivity and environmental indices were weak, with local SST providing slightly more explanatory power than PDO or ICI, suggesting that local factors rather than large-scale climate variability may determine variation in productivity. The relationships between stress and environmental indices were stronger than the relationship between productivity and environment. The measured response of stress to environment showed opposite signs between the southern and northern colonies, and typically implied annual mortality rates varying from 11 to 17%. The observed relationships between climate and stress indicate that anticipated warming might bring at least short-term demographic benefits for kittiwakes in the Bering shelf region, while having negative impacts on birds breeding in the Gulf of Alaska and western Aleutians. We predict decline (without immigration) for colonies with the lowest productivity and conclude that climate variability is likely to affect survival of North Pacific kittiwakes on a region-specific basis. Longevity of these birds may not always be sufficient to buffer their populations from low reproductive performance. © Inter-Research 2012.

Ainsworth C.H.,Marine Resources Assessment Group Americas Inc. | Kaplan I.C.,National Oceanic and Atmospheric Administration | Levin P.S.,National Oceanic and Atmospheric Administration | Mangel M.,University of California at Santa Cruz
Ecological Applications | Year: 2010

Trophic ecosystem models are one promising tool for providing ecosystembased management advice. Diet and interaction rate parameters are critical in defining the behavior of these models, and will greatly influence any predictions made in response to management perturbations. However, most trophic ecosystem models must rely on a patchwork of data availability and must contend with knowledge gaps and poor quantification of uncertainty. Here we present a statistical method for combining diet information from field samples and literature to describe trophic relationships at the level of functional groups. In this example, original fieldwork in the northern Gulf of California, Mexico, provides gut content data for targeted and untargeted fish species. The field data are pooled with diet composition information from FishBase, an online data repository. Diet information is averaged across stomachs to represent an average predator, and then the data are bootstrapped to generate likelihood profiles. These are fit to a Dirichlet function, and from the resulting marginal distributions, maximum-likelihood estimates are generated with confidence intervals representing the likely contribution to diet for each predator-prey combination. We characterize trophic linkages into two broad feeding guilds, pelagic and demersal feeders, and explore differentiation within those guilds. We present an abbreviated food web for the northern Gulf of California based on the results of this study. This food web will form the basis of a trophic dynamic model. Compared to the common method of averaging diet compositions across predators, this statistical approach is less influenced by the presence of long tails in the distributions, which correspond to rare feeding events, and is therefore better suited to small data sets. © 2010 by the Ecological Society of America.

Morzaria-Luna H.N.,Marine Resources Assessment Group Americas Inc. | Ainsworth C.H.,Marine Resources Assessment Group Americas Inc. | Ainsworth C.H.,University of South Florida | Kaplan I.C.,National Oceanic and Atmospheric Administration | And 2 more authors.
PLoS ONE | Year: 2013

High bycatch of non-target species and species of conservation concern often drives the implementation of fisheries policies. However, species- or fishery-specific policies may lead to indirect consequences, positive or negative, for other species or fisheries. We use an Atlantis ecosystem model of the Northern Gulf of California to evaluate the effects of fisheries policies directed at reducing bycatch of vaquita (Phocoena sinus) on other species of conservation concern, priority target species, and metrics of ecosystem function and structure. Vaquita, a Critically Endangered porpoise endemic to the Upper Gulf of California, are frequently entangled by finfish gillnets and shrimp driftnets. We tested five fishery management scenarios, projected over 30 years (2008 to 2038), directed at vaquita conservation. The scenarios consider progressively larger spatial restrictions for finfish gillnets and shrimp driftnets. The most restrictive scenario resulted in the highest biomass of species of conservation concern; the scenario without any conservation measures in place resulted in the lowest. Vaquita experienced the largest population increase of any functional group; their biomass increased 2.7 times relative to initial (2008) levels under the most restrictive spatial closure scenario. Bycatch of sea lions, sea turtles, and totoaba decreased > 80% in shrimp driftnets and at least 20% in finfish gillnet fleets under spatial management. We found indirect effects on species and ecosystem function and structure as a result of vaquita management actions. Biomass and catch of forage fish declined, which could affect lower-trophic level fisheries, while other species such as skates, rays, and sharks increased in both biomass and catch. When comparing across performance metrics, we found that scenarios that increased ecosystem function and structure resulted in lower economic performance indicators, underscoring the need for management actions that consider ecological and economic tradeoffs as part of the integrated management of the Upper Gulf of California.

Samhouri J.F.,Pacific States Marine Fisheries Commission | Levin P.S.,National Oceanic and Atmospheric Administration | Ainsworth C.H.,Marine Resources Assessment Group Americas Inc.
PLoS ONE | Year: 2010

Background: One of the greatest obstacles to moving ecosystem-based management (EBM) from concept to practice is the lack of a systematic approach to defining ecosystem-level decision criteria, or reference points that trigger management action. Methodology/Principal Findings: To assist resource managers and policymakers in developing EBM decision criteria, we introduce a quantitative, transferable method for identifying utility thresholds. A utility threshold is the level of humaninduced pressure (e.g., pollution) at which small changes produce substantial improvements toward the EBM goal of protecting an ecosystem's structural (e.g., diversity) and functional (e.g., resilience) attributes. The analytical approach is based on the detection of nonlinearities in relationships between ecosystem attributes and pressures. We illustrate the method with a hypothetical case study of (1) fishing and (2) nearshore habitat pressure using an empirically-validated marine ecosystem model for British Columbia, Canada, and derive numerical threshold values in terms of the density of two empirically-tractable indicator groups, sablefish and jellyfish. We also describe how to incorporate uncertainty into the estimation of utility thresholds and highlight their value in the context of understanding EBM trade-offs. Conclusions/Significance: For any policy scenario, an understanding of utility thresholds provides insight into the amount and type of management intervention required to make significant progress toward improved ecosystem structure and function. The approach outlined in this paper can be applied in the context of single or multiple human-induced pressures, to any marine, freshwater, or terrestrial ecosystem, and should facilitate more effective management.

Ainsworth C.H.,National Oceanic and Atmospheric Administration | Ainsworth C.H.,Marine Resources Assessment Group Americas Inc.
Marine and Coastal Fisheries | Year: 2011

Ecosystem-based fisheries management requires data on all parts of the ecosystem, and this can be a barrier in data-poor systems. Marine ecologists need a means of drawing together diverse information to reconstruct species abundance trends for a variety of purposes. This article uses a fuzzy logic approach to integrate information from multiple data sources and describe biomass trends for marine species groups in the northern Gulf of California, Mexico. Forty-two species groups were analyzed, comprising fish, invertebrates, birds, mammals, turtles, and algae. The most important new data series comes from recent interviews with fishers in the northern part of the gulf. Respondents were asked to classify the abundance of various targeted and untargeted marine species groups from 1950 to the present. The fuzzy logic method integrates their responses with catch-per-unit-effort series, intrinsic vulnerability to fishing determined from life history parameters, biomass predicted by a Schaefer harvest model, and other simple indices. The output of the fuzzy logic routine is a time series of abundance for each species group that can be compared with known trends. The results suggest a general decline in species abundance across fished and unfished taxa, with a few exceptions. Information gathered from interviews indicated that older fishers tended to recognize a greater relative decrease in species abundance since 1970 than did younger fishers, providing another example of Pauly's (1995) shifting cognitive baselines. © American Fisheries Society 2011.

Morzaria-Luna H.N.,Marine Resources Assessment Group Americas Inc. | Ainsworth C.H.,Marine Resources Assessment Group Americas Inc. | Ainsworth C.H.,University of South Florida | Kaplan I.C.,National Oceanic and Atmospheric Administration | And 2 more authors.
PLoS ONE | Year: 2012

Background: Minimizing fishery bycatch threats might involve trade-offs between maintaining viable populations and economic benefits. Understanding these trade-offs can help managers reconcile conflicting goals. An example is a set of bycatch reduction measures for the Critically Endangered vaquita porpoise (Phocoena sinus), in the Northern Gulf of California, Mexico. The vaquita is an endemic species threatened with extinction by artisanal net bycatch within its limited range; in this area fisheries are the chief source of economic productivity. Methodology/Principal Findings: We analyze trade-offs between conservation of the vaquita and fisheries, using an end-to-end Atlantis ecosystem model for the Northern Gulf of California. Atlantis is a spatially-explicit model intended as a strategic tool to test alternative management strategies. We simulated increasingly restrictive fisheries regulations contained in the vaquita conservation plan: implementing progressively larger spatial management areas that exclude gillnets, shrimp driftnets and introduce a fishing gear that has no vaquita bycatch. We found that only the most extensive spatial management scenarios recovered the vaquita population above the threshold necessary to downlist the species from Critically Endangered. The scenario that excludes existing net gear from the 2008 area of vaquita distribution led to moderate decrease in net present value (US$ 42 million) relative to the best-performing scenario and a two-fold increase in the abundance of adult vaquita over the course of 30 years. Conclusions/Significance: Extended spatial management resulted in the highest recovery of the vaquita population. The economic cost of proposed management actions was unequally divided between fishing fleets; the loss of value from finfish gillnet fisheries was never recovered. Our analysis shows that managers will have to confront difficult trade-offs between management scenarios for vaquita conservation.

Li L.,University of British Columbia | Ainsworth C.,Marine Resources Assessment Group Americas Inc. | Pitcher T.,University of British Columbia
Progress in Oceanography | Year: 2010

We tested what degree harbour seal (Phoca vitulina) populations compete with fisheries for commercially harvested species, and to what degree seal populations depend on exploited species as prey. In the Strait of Georgia (SoG), harbour seals mainly feed on fisheries target species, Pacific herring (Clupea pallasii) and Pacific hake (Merluccius productus), while herring is also a main prey of hake. Using an Ecopath model constructed based on 2005 conditions, we ran three scenarios: altering herring fishing mortality, removing seal populations and sensitivity analyses of the herring vulnerability parameter. Our results show that with more herring available, the seal population will increase greatly, but with less herring available, the seal populations in the SoG decreases gradually. Our model suggests that the total biomass of commercial fish populations in the SoG may decrease substantially with seals absent. A cull of harbour seals may not increase total fisheries catch in the SoG. Herring benefit from seal predation on herring's largest predator, hake, so that herring may decline when seals are removed. However, this result is highly dependent on model parameterization. When juvenile herring are considered less vulnerable to hake predation (i.e., when we assume there are many refuges in which to hide), the herring population is less negatively impacted by seal removals. This indicates that survival during this crucial life-stage is important to herring abundance. The model also suggests that, with seals removed, the ecosystem would be dominated by hake. © 2010 Elsevier Ltd.

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