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Ralston S.,Southwest Fisheries Science Center | Punt A.E.,University of Washington | Hamel O.S.,National Oceanic and Atmospheric Administration | Devore J.D.,Pacific Fishery Management Council | Conser R.J.,Southwest Fisheries Science Center
Fishery Bulletin | Year: 2011

Quantifying scientific uncertainty when setting total allowable catch limits for fish stocks is a major challenge, but it is a requirement in the United States since changes to national fisheries legislation. Multiple sources of error are readily identifiable, including estimation error, model specification error, forecast error, and errors associated with the definition and estimation of reference points. Our focus here, however, is to quantify the influence of estimation error and model specification error on assessment outcomes. These are fundamental sources of uncertainty in developing scientific advice concerning appropriate catch levels and although a study of these two factors may not be inclusive, it is feasible with available information. For data-rich stock assessments conducted on the U.S. west coast we report approximate coefficients of variation in terminal biomass estimates from assessments based on inversion of the assessment of the model's Hessian matrix (i.e., the asymptotic standard error). To summarize variation among stock assessments, as a proxy for model specification error, we characterize variation among multiple historical assessments of the same stock. Results indicate that for 17 ground-fish and coastal pelagic species, the mean coefficient of variation of terminal biomass is 18%. In contrast, the coefficient of variation ascribable to model specification error (i.e., pooled among-assessment variation) is 37%. We show that if a precautionary probability of overfishing equal to 0.40 is adopted by managers, and only model specification error is considered, a 9% reduction in the overfishing catch level is indicated. Source


Kaplan I.C.,National Oceanic and Atmospheric Administration | Levin P.S.,National Oceanic and Atmospheric Administration | Burden M.,Pacific Fishery Management Council | Fulton E.A.,CSIRO
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2010

Any fishery management scheme, such as individual fishing quotas (IFQs) or marine protected areas, should be designed to be robust to potential shifts in the biophysical system. Here we couple possible catch scenarios under an IFQ scheme with ocean acidification impacts on shelled benthos and plankton, using an Atlantis ecosystem model for the US West Coast. IFQ harvest scenarios alone, in most cases, did not have strong impacts on the food web, beyond the direct effects on harvested species. However, when we added the impacts of ocean acidification, the abundance of commercially important groundfish such as English sole (Pleuronectes vetulus), arrowtooth flounder (Atheresthes stomias), and yellowtail rockfish (Sebastes flavidus) declined up to 20%-80%, owing to the loss of shelled prey items from their diet. English sole exhibited a 10-fold decline in potential catch and economic yield when confronted with strong acidification impacts on shelled benthos. Therefore, it seems prudent to complement IFQs with careful consideration of potential global change effects such as acidification. Our analysis provides an example of how new ecosystem modeling tools that evaluate cumulative impacts can be integrated with established management reference points and decision mechanisms. Source


Cope J.M.,National Oceanic and Atmospheric Administration | Thorson J.T.,National Oceanic and Atmospheric Administration | Wetzel C.R.,National Oceanic and Atmospheric Administration | DeVore J.,Pacific Fishery Management Council
Fisheries Research | Year: 2015

Fisheries management aimed to support sustainable fisheries typically operates under conditions of limited data and analytical resources. Recent developments in data-limited analytical methods have broadened the reach of science informing management. Existing approaches such as stock reduction analysis and its extensions offer simple ways to handle low data availability, but are particularly sensitive to assumptions regarding relative stock status. This study develops and introduces a prior on relative stock status using Productivity-Susceptibility Analysis vulnerability scores. Data from U.S. west coast groundfish stocks (n= 17) were used to develop and then test the performance of the new relative stock status prior. Traditional simulation testing via an operating model was not possible because vulnerability scoring could not be simulated; we instead used the "best available scientific information" (BASI) approach. This approach uses fully-realized stock assessments (deemed the best available scientific information by management entities) and reduces data content available to simpler models. The Stock Synthesis statistical catch-at-age framework was used to nest within the full assessment two simpler models that rely on stock status priors. Relative error in derived estimates of biomass and stock status were then compared to the BASI assessment. In general, the new stock status prior improved performance over the current application of stock status assumed at 40% initial biomass. Over all stocks combined, stock status showed the least amount of bias, while initial biomass was better estimated than current biomass. The BASI approach proved a useful and possibly complimentary approach to simulation testing with operating models in order to gain insight into modelling performance germane to management needs, particularly when system components (e.g., susceptibility scoring) cannot be easily simulated. © 2014. Source


News Article
Site: http://www.rdmag.com/rss-feeds/all/rss.xml/all

Federal officials finalized rules Monday for a West Coast ban on catching forage fish, the small fish that larger species, seabirds and marine mammals depend on for food. The ban on new commercial fisheries will protect little schooling fish that play a critical role in the marine food web but that are not actively fished or managed, the National Marine Fisheries Service said. It marks the first action under a new approach to fisheries management that considers how one species affects others in the ecosystem. The ban does not affect existing fisheries for forage fish, such as sardines and anchovies. It covers species including Pacific sand lance, silversides and certain varieties of herring, smelt and squid. The restrictions apply to federal waters from 3 to 200 miles off Washington, Oregon and California, and do not affect fishing authorized by tribes. Fishermen generally do not target forage fish in federal waters, and no West Coast fishing boats are known to be considering efforts do so. But global demand is increasing for their use in fish meal or oil to feed livestock or farmed fish, which could put pressure on the species, said Paul Shively, who directs West Coast ocean conservation efforts for the Pew Charitable Trusts. The protections represent a real change in the way ocean resources are managed, conservation groups said. "Instead of responding to a fishery crisis, they're being proactive," said Ben Enticknap, senior scientist with the conservation group Oceana. "Too often, fisheries start up and nothing is done to manage them in a sustainable way until the population crashes and by then, it's too late." The Pacific Fishery Management Council, which oversees fisheries for dozens of species along the West Coast, adopted the ban last March by unanimous vote. The NOAA published final rules Monday to implement the ban, which takes effect May 4. Shively said he hopes the move clears the way for other regions and state agencies to adopt similar protections. Under the rules, commercial fishing for the small species cannot be developed until the Pacific Fishery Management Council weighs scientific information and considers potential effects to other fisheries, fishing communities and the marine ecosystem. The rules limit the amount of forage fish that could be caught incidentally while fishing for other targeted species. It also includes provisions that allow future experiments with targeting forage fish under certain conditions. Glenn Spain, with the Pacific Coast Federation of Fishermen's Associations, said protecting forage fish that are the basis of the food chain is "an obvious no-brainer."


Cope J.M.,National Oceanic and Atmospheric Administration | Devore J.,Pacific Fishery Management Council | Dick E.J.,Southwest Fisheries Science Center | Ames K.,Pacific Fishery Management Council | And 7 more authors.
North American Journal of Fisheries Management | Year: 2011

The Magnuson-Stevens Fishery Conservation and Management Act (MSA) requires active management of all stocks at risk of overfishing or otherwise in need of conservation andmanagement. In the Pacific Fishery Management Council groundfish fishery management plan, about two-thirds of the more than 90 managed stocks are currently without traditional assessments to help define stock status in relation to management targets. Stock complexes are often employed for management purposes in such situations. The guidelines issued in respons to the 2006 MSA amendments defined a complex as a group of stocks with similar geographic distributions, life histories, and vulnerabilities to fisheries. This work uses productivity-susceptibility analysis (PSA) to measure the vulnerabilities of 90 managed groundfish stocks, 64 of which are currently managed within stock complexes. These stock complexes are reevaluated by first using a partitioning cluster analysis to group the stocks by depth and latitude. Vulnerability reference points are then established based on the PSA results to determine vulnerability groups of low, medium, high, and major concern within each ecological group. This method is a simple and flexible approach to incorporating vulnerability measures into stock complex designations while providing information with which to prioritize stockand complex-specific management. © American Fisheries Society 2011. Source

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