Download or read book Using Oregon Trawl Logbooks to Study Spatial and Temporal Characteristics of Commercial Groundfish Species Associations written by Yong Woo Lee and published by . This book was released on 1997 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: Species associations of fifteen major commercial groundfish species in the northeastern Pacific ocean and their spatial and temporal characteristics were studied using Oregon bottom trawl logbook data, 1987 to 1993. Screening procedures were used to remove questionable data from the original logbook files, which resulted in the exclusion of information from 46% of the total available tows. Two multivariate methods, detrended correspondence analysis (DCA) and Ward's method of hierarchical cluster analysis were used to derive the association patterns of species and species groups. A general linear model that was developed for the primary DCA axis suggested that the species associations are strongly correlated with depth, but minimally correlated with the other environmental variables that were examined (latitude, season, and year). The weak correlations between DCA axis 1 and the temporal variables indicate that species associations in the study region are fairly persistent over time. The same multivariate techniques were used to examine possible sampling effects due to changes in the participating trawl vessels that contributed logbook information. Depth and latitudinal distributions of species occurrence in the logbook were similar to distributions derived from National Marine Fishery Service triennial bottom trawl survey. However, the analysis also showed that the depth coverage by the survey is not broad enough to accurately characterize associations among species that are currently subject to commercial fishing activity.
Download or read book Evaluation of a U S West Coast Groundfish Habitat Conservation Regulation Via Analysis of Spatial and Temporal Patterns of Trawl Fishing Efforts written by Marlene A. Bellman and published by . This book was released on 2004 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent emphasis on linkages between essential fish habitat and fish stock productivity has raised concerns about the management of fishing activities such as trawling, which have the potential to impact fish habitat. Knowing specifically where and how intensively trawl effort has occurred over time provides ecologists with the necessary background for habitat impact and recovery studies, and provides fishery managers with an assessment of how habitat conservation objectives are being met. The objectives of this study were to (1) examine the extent to which the 2000 Pacific Fishery Management Council footrope restriction has shifted and reduced trawl fishing effort on Oregon fishing grounds, (2) to relate these changes in distribution to the benthic habitat type over which they occur, and (3) to develop methods for enhancing fine-scale spatial review of targeted fishing effort. Density analysis of available trawl start locations provided a spatial and temporal understanding of how fishing efforts increased and decreased in relation to habitat distribution and fishery management actions between 1995 and 2002. Trawl effort patterns exhibit significant inter-annual variability and patchy distribution. Areas of increased fishing effort were still evident between years, despite an overall decline in trawl tows across the time scale of this study. Tow end point locations for the years 1998-2001 were retrieved from manual logbooks for five reference sites located in the proximity of rock habitat features. Trawl towlines were mapped from start to end point and demonstrated a marked enhancement of fine-scale fishing effort resolution, with increased ability to identify effort shifts over benthic habitat. Distinct spatial shifts in fishing intensity (measured as km towed) away from rock habitat were evident at all reference sites, with an average reduction of 86%. Some slight shifts into surrounding unconsolidated sediments also occurred, indicating effort displacement as well as reduction. Fishing intensity was calculated from commercial trawl and research trawl survey towlines to achieve the most accurate assessment of fishing impacts and potential habitat recovery areas. Research trawling intensity was less than 1% of commercial trawl effort originating from the same sites. A brief comparison of Oregon vessel towlines and California vessel towlines demonstrated similar targeted fishing patterns by both fleets, except at one site. Results indicate that the footrope restriction, in conjunction with associated landing limits, was effective in protecting rocky habitats from trawl fishing impacts. Reference areas were identified where essential fish habitat (EFH) recovery is likely occurring off the coast of Oregon. Substantial regulatory changes continue in this fishery, with trip limits and gear restrictions continuously adjusted. Continued monitoring and review of spatial trawl data would assist in fishery management decision-making and assess conservation objectives for depleted groundfish and associated habitats. Future research should incorporate analysis of catch data and expand the review of trawl towlines for the entire US West coast groundfish fishery. The trawl towline spatial analysis developed in this work is a credible method for reviewing fishing effort at the scale of the fishery and in relation to detailed habitat data. The research presented here provides an example of how an interdisciplinary approach and critical assessment of data can work to resolve marine management challenges.
Download or read book Proposed Acceptable Biological Catch and Optimum Yield Specifications and Management Measures for the 2007 2008 Pacific Coast Groundfish Fishery and Amendment 16 4 Rebuilding Plans for Seven Depleted Pacific Coast Groundfish Species written by and published by . This book was released on 2006 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Selecting Locations for Marine Harvest Refugia written by Marcia Fraser Macomber and published by . This book was released on 2000 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study examined the logbook record of the Oregon trawl fishery using a geographic information system (GIS) to determine the spatial and temporal distribution of English sole, Pleuronectes vetulus. The original logbook data for the years 1981,1982,1994,1995,1996 were filtered twice to provide both a general description of trends in the distribution of tows and catch parameters, and a more explicit ecological description of English sole catch dynamics. Tow distribution maps were used as a basis to evaluate the utility of the logbook data as a means to identify potential locations for harvest refugia. The spatial pattern of the trawl fishery changed dramatically between 1981-82 and 1994-96, although fishing activity was concentrated near ports of origin in all years. The fleet moved offshore and northward and the species composition of tows shifted from shallow water species toward deeper water fisheries. The English sole fishery remained distinct from the trawl fishery, although English sole tows and yields declined. High densities of English sole tows and the largest percentage annual English sole catch-per-unit-effort (CPUE) occurred in waters offshore Astoria, within 46 - 47°, in all years. Eight geographical regions were ranked according to their value to the production of English sole and their importance to the fishery. Sites of potential harvest refugia were selected based on their ability to contribute to the goal of long-term sustainability of the English sole fishery, by providing a buffer against errors in fishery management. Four sites were identified as potential locations, three sites in the offshore waters of the ports of Astoria, Newport and Brookings, and a fourth site in the nearshore zone along the Oregon coast, within the 50-fathom contour. The study concluded that logbook data will be useful to future planning of marine harvest refugia along the Pacific coast, because the data provide insights into fishing behavior and the relative amounts of fishing intensity that occur in different geographic regions. In addition, use of logbook data provide an opportunity for involvement of the fishing industry in the marine harvest refugia planning.
Download or read book Canadian Journal of Fisheries and Aquatic Sciences written by and published by . This book was released on 2005 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Trawling and Dredging on Seafloor Habitat written by National Research Council and published by National Academies Press. This book was released on 2002-08-09 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concerns over the potential ecological effects of fishing have increased with the expansion of fisheries throughout the marine waters of the United States. Effects of Trawling and Dredging on Seafloor Habitat describes how assessment of fishing impacts depends on gear type, number and location of bottom tows, and the physical and biological characteristics of seafloor habitats. Many experimental studies have documented acute, gear-specific effects of trawling and dredging on various types of habitat. These studies indicate that low mobility, long-lived species are more vulnerable to towed fishing gear than short-lived species in areas where the seabed is often disturbed by natural phenomena. Trawling and dredging may also change the composition and productivity of fish communities dependent on seafloor habitats for food and refuge. The scale of these impacts depends on the level of fishing effort. This volume presents color maps of fishing effort for all regions with significant bottom trawl or dredge fisheries-the first time that such data has been assembled and analyzed for the entire nation.
Download or read book Integration of Oceanographic Information Off the Washington and Oregon Coasts Into West Coast Groundfish Ecology and Fisheries Management written by Maria Jośe Juan Jordá and published by . This book was released on 2006 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt: To date, the use of oceanographic data in fisheries management has been limited by the scarcity and the difficulty of accessing complete oceanographic datasets. Consequently, fish stocks are managed with limited knowledge about the habitat where fish live and incomplete understanding of what oceanographic conditions affect their populations. With the long-term goal to improve science for ecosystem-based management of the West Coast groundfish fishery, this study had three objectives. First, the assembling and merging of disperse oceanographic datasets for temperature, salinity, chlorophyll-a and current velocity from the 1930s to the year 2004 off the Washington and Oregon coasts. Second, the generation of oceanographic data products relevant for fisheries research, consisting of the computation and the plotting of climatological monthly means, standard deviations and coefficients of variation for a variety of ocean variables at several depths. Third, the development of an exploratory example of how oceanographic information collected in this study can be of use to improve the science and management of groundfish. Thus, a study was developed to investigate if groundfish distribution and abundances are associated with any ocean habitat or individual oceanographic variables, using a combination of univariate, classification and ordination techniques. The fish data were derived from a routine bottom trawl survey conducted by the National Oceanic and Atmospheric Administration Northwest Fisheries Science Center (NOAA-NWFSC). Five ocean habitats with distinct physical and biological characteristics were identified off the Washington and Oregon coast: Offshore Habitat, Upwelling Habitat, Highly Variable Upwelling Habitat, River Plume Habitat, and Highly Variable Habitat. These ocean habitats were characteristic of cold-regime summer upwelling conditions. Overall, the analyses suggested that the species composition differ among the five ocean habitats. Some species were highly indicative of some habitats; however, overall the associations were weak due to the high degree of overlap of ocean habitats in terms of species composition. All the analyses were consistent in associating shallower species with the shallowest habitats (the Highly Variable, River Plume and Upwelling habitats) and the deeper species with the deeper habitats (the Offshore and the Highly Variable Upwelling habitats), suggesting that groundfish are adapted to wide environmental ranges. In addition, the overall abundance and diversity of groundfish was higher in the shallower habitats. In contrast, groundfish species showed strong associations with individual environmental factors, primarily depth, surface chlorophyll-a, and salinity and temperature at the bottom of the seafloor, indicating that groundfish distributions are mainly organized along depth gradients. Latitudinal variations in upwelling intensity, river discharge and productivity along the coast were also important factors influencing shallow species distributions and abundances. For example, three regions with high chlorophyll-a concentrations were associated with large abundances of specific groundfish species. These regions were found over Heceta Bank, over the Juan de Fuca canyon and in the Columbia River Plume. This study began with the assembly of several ocean variables and the development of some preliminary ocean data products relevant to fisheries studies. However, the addition of other ocean variables, such as dissolved oxygen, and the computation of new ocean products, such as mixed-layer depth, and thermocline depth and strength, would be valuable. Future work should involve more interdisplinary studies between fisheries and oceanography, the integration of oceanographic information off the west coast of the U.S., and the collection of concurrent ocean data at each fish trawl location.
Download or read book The Economics of Spatial Choice and Displacement Case Study of the Oregon Bottom Trawl Groundfish Fishery written by Branka Valcic and published by . This book was released on 2007 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fishery policy makers would often benefit from information on how a policy might change fishermen behavior before the policy is implemented. Discrete choice models may be used to make predictions about these potential changes. Most of the simulation work done so far, however, has not been validated. This dissertation contributes to the literature by comparing simulated behavioral response with actual response to implemented RCAs.
Download or read book Essential Fish Habitat Designation and Minimization of Adverse Impacts Pacific Coast Groundfish Fishery Management Plan written by and published by . This book was released on 2005 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Impacts of climate change on fisheries and aquaculture written by Food and Agriculture Organization of the United Nations and published by Food & Agriculture Org.. This book was released on 2019-01-06 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report indicates that climate change will significantly affect the availability and trade of fish products, especially for those countries most dependent on the sector, and calls for effective adaptation and mitigation actions encompassing food production.
Download or read book Case Studies in Fisheries Self governance written by Ralph Edwin Townsend and published by Food & Agriculture Org.. This book was released on 2008 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: This special issue focuses on the Scientific forum held at the beginning of the International Technical Conference on Animal Genetic Resources for Food and Agriculture, which took place in Interlaken, Switzerland, in September 2007
Download or read book Discards in the World s Marine Fisheries written by Kieran Kelleher and published by Food & Agriculture Org.. This book was released on 2005 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication gives an updated review of the quantity of discards in the world's marine fisheries, using information from a broad range of fisheries in all continents. A number of policy issues are discussed including a 'no discards' approach to fisheries management, the need for balance between bycatch reduction and bycatch utilisation initiatives, and concerns arising from incidental catches of marine mammals, birds and reptiles. The report also highlights the need for more robust methods of estimating discards, and the development of bycatch management plans.
Download or read book Improving Fish Stock Assessments written by National Research Council and published by National Academies Press. This book was released on 1998-02-27 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ocean harvests have plateaued worldwide and many important commercial stocks have been depleted. This has caused great concern among scientists, fishery managers, the fishing community, and the public. This book evaluates the major models used for estimating the size and structure of marine fish populations (stock assessments) and changes in populations over time. It demonstrates how problems that may occur in fisheries dataâ€"for example underreporting or changes in the likelihood that fish can be caught with a given type of gearâ€"can seriously degrade the quality of stock assessments. The volume makes recommendations for means to improve stock assessments and their use in fishery management.
Download or read book Fishers Knowledge in Fisheries Science and Management written by Nigel Haggan and published by United Nations Educational, Scientific & Cultural Organization. This book was released on 2007 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drawing on a number of case studies from around the world, this publication considers how the local knowledge and practices of indigenous fishing communities are being used in collaboration with scientists, government managers and non-governmental organisations to establish effective frameworks for sustainable fisheries science and management. It seeks to contribute towards achieving the goal of establishing international responsibility for the ethical collection, preservation, dissemination and application of fishers' knowledge.
Download or read book The Benefits of Marine Protected Areas written by Australian Government - Department of the Environment and Heritage - Environment Australia and published by . This book was released on 2003 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Final recovery plan for the steller sea lion Eumetopias jubatus written by and published by . This book was released on 1994 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dragging Our Assets written by Scott Wallace and published by . This book was released on 2007 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt:
