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Seattle, WA, United States

Lomeli M.J.M.,Pacific States Marine Fisheries Commission | Wakefield W.W.,National Oceanic and Atmospheric Administration
Fisheries Research | Year: 2012

This study examined two versions of an open escape window bycatch reduction device (BRD) designed to reduce bycatch of Chinook salmon (Oncorhynchus tshawytscha) and rockfish (Sebastes spp.) in the U.S. Pacific coast Pacific hake (Merluccius productus) fishery. Tests were conducted off central Oregon during 2009 and 2010 aboard a midwater trawler. Data on fish behavior and gear performance were observed using autonomous high-resolution low-light color video cameras and artificial lights. During this study, one of the BRD versions reduced both Chinook salmon and widow rockfish (S. entomelas) bycatch. The use of artificial light was also noted to influence the behavior of Chinook salmon. The mean escape time of Chinook salmon differed significantly between the two versions examined. Escapement of Pacific hake, the target species, was rarely observed. Results of this study suggest that there is potential for reducing Chinook salmon and widow rockfish bycatch in the Pacific hake fishery using open escape window BRDs. © 2011 Elsevier B.V.

Williams G.D.,Pacific States Marine Fisheries Commission | Levin P.S.,National Oceanic and Atmospheric Administration | Palsson W.A.,Marine Resources Unit
Marine Policy | Year: 2010

In Puget Sound, WA (USA), rockfish (Sebastes spp.) have significantly declined in abundance, with multiple petitions to list individual species under the Endangered Species Act. In order to better understand the ecological legacy of rockfish fishing to the Puget Sound ecosystem, the local history of rockfish exploitation was reviewed, focusing on the socioeconomic forces and management decisions which influenced the trajectory of landings. Rockfish have always been harvested for human consumption in the region, but over time exploitation patterns have changed from an opportunistic subsistence activity by indigenous peoples, to a year-round target of commercial and recreational interests. Annual commercial and recreational harvests together peaked (almost 400. mt) in the early 1980s as anglers' attitudes changed, gear technology improved, rockfish became more familiar to the market, human population increased, and agency programs promoted fisheries to sustain employment. Rockfishes were generally not managed intensely or with conservation goals in mind until the late 1980s, in part due to scientific shortcomings and a lack of resources. By the time management actions were deemed necessary, the greatest harvest had already occurred. However, the low intrinsic productivity of most rockfish species suggests that the legacy of fishing will remain for years to come. As managers strive to restore the integrity and resilience of Puget Sound, they must realize the significance of historical fishery removals to the ecosystem and use the proper social and economic incentives to drive individual behavior toward these ecosystem goals. © 2010.

White J.W.,University of California at Davis | White J.W.,University of North Carolina at Wilmington | Samhouri J.F.,Pacific States Marine Fisheries Commission | Samhouri J.F.,National Oceanic and Atmospheric Administration
Oikos | Year: 2011

A central goal of metapopulation ecology is to determine which subpopulations have the greatest value to the larger metapopulation. That is, where are the 'sources' that are most essential to persistence? This question is especially relevant to benthic marine systems, where dispersal and recruitment are greatly affected by oceanographic processes. In a single-species context, theoretical models typically identify 'hotspots' with high recruitment, especially high self-recruitment, as having the highest value. However, the oceanographic forces affecting larval delivery of a given species may also influence the recruitment of that species' predators, prey, and competitors. We present evidence from the Virgin Islands and Bahamas that oceanographic forces produce spatial coupling between the recruitment of planktivorous fishes, the recruitment of their predators, and the productivity of their zooplankton prey. We examined the consequences of this type of multi-trophic coupling using a simple analytical population model and a multispecies numerical simulation model with parameter values based on the Virgin Islands system. In both analyses, strong coupling caused planktivores at the highest recruitment sites to experience higher mortality (a consequence of higher predator densities) but faster growth and higher fecundity (a consequence of higher zooplankton densities) than planktivores at low recruitment sites. As such, the relative strength of oceanographic coupling between the three trophic levels strongly determined whether a particular reef acted as a source or sink. In the simulation model, density-dependent competition for zooplankton limited overall metapopulation biomass more severely than predation, so oceanographic coupling between planktivore larval supply and zooplankton productivity had a stronger effect on the metapopulation value of a patch. We argue that the potential for such tri-trophic coupling should be incorporated into future metacommunity models and has considerable implications for the design and evaluation of marine reserves. © 2011 The Authors. Oikos © 2011 Nordic Society Oikos.

Lomeli M.J.M.,Pacific States Marine Fisheries Commission | Wakefield W.W.,National Oceanic and Atmospheric Administration
Fisheries Research | Year: 2013

This study examined a flexible sorting grid excluder designed to reduce Pacific halibut (Hippoglossus stenolepis) bycatch in the US west coast groundfish bottom trawl fishery. Tests occurred off Washington during 2011 aboard a commercial trawler. A recapture net was used to quantify the retention rates of target and non-target species. Pacific halibut bycatch was reduced 61.6% by weight and 57.0% by numbers. Exclusion was greatest for Pacific halibut weighing more than 4.5. kg. A significant difference in the mean total length was also noted between Pacific halibut caught in the codend and the recapture net, with larger fish occurring in the recapture net. The retention of primary target groundfishes of marketable-size ranged from 76.7 to 89.3%. We demonstrated the capability of a flexible sorting grid excluder to reduce Pacific halibut bycatch in the groundfish bottom trawl fishery while retaining a relatively high proportion of the targeted species. © 2013 Elsevier B.V.

Claiborne A.M.,Pacific States Marine Fisheries Commission | Fisher J.P.,Oregon State University | Hayes S.A.,National Oceanic and Atmospheric Administration | Emmett R.L.,National Oceanic and Atmospheric Administration
Transactions of the American Fisheries Society | Year: 2011

We analyzed scales from returning Willamette River yearling Chinook salmon Oncorhynchus tshawytscha to explore the effects of size at release on subsequent adult returns. We tested the hypothesis that survival to adulthood is independent of size at ocean entry for yearling Chinook salmon. Significant size-selective mortality, indicated by a larger size at ocean entry among surviving adults than among all released juveniles, was observed for Chinook salmon released in 2002-2004 but not for those released in 2005. Juvenile Chinook salmon released in 2002-2004 that entered the ocean at less than 150 mm in fork length were underrepresented in the returning adult populations. We also investigated the relationships between age at maturity and size at ocean entry, timing of release, circulus spacing, and size at the end of the first ocean year. We observed significant differences in fork length at the end of the first ocean winter among returning age-4, -5, and -6 Chinook salmon; the younger returning fish were larger after their first year of ocean growth. Fork length at ocean entry and average first-ocean-year circulus spacing were significantly greater for age-4 than for age-5 and age-6 Chinook salmon but were similar for age-5 and age-6 fish. Our analyses indicate that yearling Chinook salmon may experience size-selective mortality, although the relationship between the intensity of size-selective mortality and smolt-to-adult survival remains unclear. © American Fisheries Society 2011.

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