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Dataset Title: | Groundfish Data for U.S. West Coast (2003-2005) |
Dataset ID: | nwioosGroundfish |
Institution: | NOAA NWFSC |
Information: | Summary | Variables | Background | Data Access Form |
Attributes { s { longitude { String _CoordinateAxisType "Lon"; Float64 actual_range -125.8555, -117.2767; String axis "X"; Float64 colorBarMaximum -115.0; Float64 colorBarMinimum -135.0; String ioos_category "Location"; String long_name "Longitude"; String standard_name "longitude"; String units "degrees_east"; } latitude { String _CoordinateAxisType "Lat"; Float64 actual_range 32.5708, 48.4525; String axis "Y"; Float64 colorBarMaximum 55.0; Float64 colorBarMinimum 30.0; String ioos_category "Location"; String long_name "Latitude"; String standard_name "latitude"; String units "degrees_north"; } time { String _CoordinateAxisType "Time"; Float64 actual_range 1.0413792e+9, 1.1045376e+9; String axis "T"; Float64 colorBarMaximum 2005.0; Float64 colorBarMinimum 2003.0; String Description "Year the survey cycle was performed."; String ioos_category "Time"; String long_name "Survey Year"; String standard_name "time"; String time_origin "01-JAN-1970 00:00:00"; String units "seconds since 1970-01-01T00:00:00Z"; } haul_id { Float64 actual_range 2.003030016e+11, 2.00503009536e+11; String ioos_category "Identifier"; String long_name "Haul Identifier"; } scientific_name { String ioos_category "Taxonomy"; String long_name "Scientific Name"; } common_name { String ioos_category "Taxonomy"; String long_name "Common Name"; } position_description { String Description "Type of position reported for the haul, typically the gear track midpoint or the vessel track midpoint."; String ioos_category "Location"; String long_name "Position Description"; } catch_range_min { Float64 actual_range 0.0, 4530.0; Float64 colorBarMaximum 4500.0; Float64 colorBarMinimum 0.0; String Description "Catch range minimum (catch per unit effort in kilograms per square meter)."; String ioos_category "Fish Abundance"; String long_name "Catch Range Min"; String units "kg km-2"; } catch_range_max { Float64 actual_range 0.0, 257606.0; Float64 colorBarMaximum 250000.0; Float64 colorBarMinimum 0.0; String Description "Catch range maximum (catch per unit effort in kilograms per square meter)."; String ioos_category "Fish Abundance"; String long_name "Catch Range Max"; String units "kg km-2"; } map_legend { Float64 colorBarMaximum 250000.0; Float64 colorBarMinimum 0.0; String Description "Indicates the catch per unit effort range that characterizes the haul catch for a species. Catch ranges are bounded by whole number standard deviation increments. Zero catch is indicated in a distinct category."; String ioos_category "Fish Abundance"; String long_name "Map Legend"; String units "kg km-2"; } } NC_GLOBAL { String cdm_data_type "Point"; String Conventions "COARDS, CF-1.0, Unidata Dataset Discovery v1.0"; Float64 Easternmost_Easting -117.2767; Float64 geospatial_lat_max 48.4525; Float64 geospatial_lat_min 32.5708; String geospatial_lat_units "degrees_north"; Float64 geospatial_lon_max -117.2767; Float64 geospatial_lon_min -125.8555; String geospatial_lon_units "degrees_east"; String history "2009-02-17 http://nwioos.coas.oregonstate.edu:8080/dods/drds/Groundfish% 20Survey%202003-2006 2009-02-17 http://coastwatch.pfeg.noaa.gov/tabledap/nwioosGroundfish.das"; String infoUrl "http://nwioos.coas.oregonstate.edu:8080/dods/drds/Groundfish%20Survey%202003- 2005.info"; String institution "NOAA NWFSC"; String license "The data may be used and redistributed for free but is not intended for legal use, since it may contain inaccuracies. Neither the data Contributor, ERD, NOAA, nor the United States Government, nor any of their employees or contractors, makes any warranty, express or implied, including warranties of merchantability and fitness for a particular purpose, or assumes any legal liability for the accuracy, completeness, or usefulness, of this information."; Float64 Northernmost_Northing 48.4525; String sourceUrl "http://nwioos.coas.oregonstate.edu:8080/dods/drds/Groundfish%20Survey%202003- 2006"; Float64 Southernmost_Northing 32.5708; String standard_name_vocabulary "CF-1.0"; String summary "The data available for downloading is summarized data from the 2003-2005 U.S. West Coast Bottom Trawl Survey (WCGTS) of Groundfish Resources off Washington, Oregon and California. SUMMARY The Northwest Fisheries Science Center's Fishery Resource Analysis and Monitoring Division (FRAM) completed the sixth in an annual series of groundfish bottom trawl surveys in 2003. The survey was conducted June 24 to October 23, 2003 and targeted the commercial groundfish resources inhabiting depths of 55 to 1,280 meters [m], (30 - 700 fathoms [fm]) from the area off Cape Flattery, Washington (latitude [lat.] 48°10'N) to the U.S.-Mexican border (lat. 32°30'N) using chartered West Coast commercial trawlers. These ongoing series of annual surveys, conducted by FRAM since 1998, are designed to monitor long-term trends in distribution and abundance of west coast groundfish, especially those species of management concern. The 2003 survey represents the first year in which the depth range was expanded to include both the continental shelf (55 - 183 m) and continental slope (183 - 1,280 m) area and the first year in which a stratified-random sampling design was adopted. In 2003, 620 primary sampling sites, and associated secondary sites, were selected randomly prior to the start of the survey. Trawling locations were allocated according to a stratified-random sampling design that divided the region into two geographic areas (north and south of Pt. Conception, CA and three depth zones (strata). The objective was to provide a representative sample of the various groundfish species and relative numbers in each stratum. By selecting random stations within certain depth zones, towable ground has an equal probability of being sampled during the survey. Thus, the method produces unbiased estimates of the relative stock size. In 2003, a total of 574 successful tows were completed out of 643 attempts. Simrad ITI net mensuration data, as well as global positioning system (GPS) navigation data and bottom contact sensor data, used to document performance (e.g. bottom tending), were obtained for most tows. An Aberdeen-style net with a small mesh (2\" stretched measure or less) liner in the codend (to retain smaller specimens) was used to sample fish biomass. Target duration of each tow was 15 minutes. Tow duration was the time between touchdown and lift-off of the trawl net from the seafloor based on readings from bottom contact sensors. Catches were sorted to species, aggregate or other appropriate taxonomic level and then weighed using an electronic, motion-compensated scale. A total of 517 species or families (fish and invertebrates) were identified within the survey area. Although biological sampling effort continues to include Dover sole (Microstomus pacificus), shortspine thornyhead (Sebastolobus alascanus), longspine thornyhead (Sebastolobus altivelis), and sablefish (Anoplopoma fimbria), focus has increasingly shifted to encompass all groundfish species of management concern. Up to 100 length measurements, sex determinations, and individual weights and up to 25 age structures were collected per haul for these species. SURVEY METHODS Survey Period and Sampling Area The 2003 WCGTS was conducted in two completed cycles of operations, or passes, between June 24 and October 23, 2003 from the areas off Cape Flattery, Washington (lat. 48°10'N), to the U.S. - Mexican border (lat. 32°30'N). Four West Coast bottom trawlers were chartered through the standard competitive bid process. The Fishing Vessel (FV) Ms. Julie and the FV Captain Jack were used during the first survey period, from June 24 to August 13, 2003, and two additional vessels, the FV Excalibur and the FV Blue Horizon, were used during the second survey period, from August 31 to October 23, 2003. All vessels started their operations off Cape Flattery, and then progressed south along the coast, finishing the completed cycle south of San Diego, CA[w1]. Vessels and Sampling Gear The four chartered fishing vessels ranged in size from 65 to 92 feet (19.8 to 28.0 meters) and in power from 450 to 775 horsepower. Each vessel was rigged as a stern trawler; with a rear gantry housing one or two net reels to set and retrieve trawl gear. Vessels were outfitted with split trawl winches and equipped with modern electronics including global positioning systems (GPS), multiple depth sounders, radars, and other navigational aids. Prior to the start of the survey, the NWFSC provided each vessel with two 5/8\" steel core trawl cables, each 2,288 m (1,250 fm) in length. Cables were measured side-by-side and marked at 25 fm increments while being spooled onto the vessel's winches. The markings provided real-time verification of the release of equal warp length from both winches while setting a tow. All vessels were provided with two standard Aberdeen-style nets built and rigged to operate within strict specifications in compliance with protocols established for bottom trawl surveys (Stauffer 2004). The Aberdeen trawl is routinely used by fishers throughout the survey region and was chosen after substantial analysis of trawl performance over various towing situations. The Aberdeen trawl demonstrated relatively stable performance over the range of conditions expected during the survey (West et al. 1998). Each net was outfitted with a small-mesh liner (1 ½\" stretched measure, #24 twisted polypropylene) in the codend to retain smaller fish. Various aspects of the mechanical performance of the nets (e.g., spread between net wings, vertical distance from the center of the headrope to the bottom, distance from the headrope to the footrope, and clearance between the footrope and bottom) were recorded using acoustic and bottom contact instruments hung from the net during each deployment. Additional information was recorded on operational conditions such as: depth, amount of towing cable deployed, towing speed, tow duration, and weather conditions. Trawl Station Allocation From 1998 through 2002 selection of sample sites for the WCGTS was based on a fixed transect design. Following an evaluation of the transect-based survey design by assessment and survey scientists, a stratified-random sampling design was adopted in 2003. The survey area was partitioned into ~12,000 adjacent cells of equal area (1.5 nm long. by 2.0 nm lat., Albers Equal Area projection) with each vessel assigned a primary subset of 155 [w2]randomly selected cell sites. In 2003, sampling density was assigned to areas defined by International Pacific Fishery Council Management Areas and specified depth categories. In 2003, sampling locations were allocated by assigning 16 - 25 % of the effort within each INPFC area. This allocation scheme was adopted to maintain a level of sampling effort in the slope area (184 - 1,280 m) comparable to prior years and to account for bathymeyric disparity between the areas. The survey area was further stratified into three depth zones (55 - 183 m, 184 - 549 m and 550 - 1,280 m). Emphasis was placed on continuing a level of effort in the 184 - 549 m and 550 - 1,280 m depth strata similar to past surveys while maintaining a minimum of 30 tows per strata. The total number of sites targeted for the survey year was apportioned across geographic area and depth categories, based on the above scheme, and then primary stations were drawn from the survey cell pool, by strata, using a pseudo random number generator. Each cell was sequentially assigned to an individual vessel. The process was repeated to identify two alternate sampling sites per location; additional constraints were imposed to ensure alternate sites were neither so close to an untrawlable primary site that they exhibit the same untrawlable features, nor were at an impractical transit distance. In 2003, 620 primary sites were selected with each vessel assigned 155 tows (one tow per cell). A total of 574 successful tows were completed out of 643 attempts[w3]. Trawling Protocol Standard trawl operations were followed to minimize differences in sampling (fishing) efficiency across the range of conditions encountered during the survey and over time (Stauffer, 2004). By established conventions, trawling operations were limited to the daylight period, i.e., initial tow each day began (net on seafloor) following official sunrise, and the last tow of the day ended (net off seafloor) before official sunset. Once a vessel was in the pre-selected sampling area (1.5 by 2.0 nm cell), the captain was instructed to observe the following search rules to identify a specific tow site: 1) search within the specified depth range; 2) remain fully within the specified area; and 3) complete the search for trawlable ground within 1 hour. If no trawlable site was found within the 1-hour limit, the cell was noted in the log as untrawlable and the vessel proceeded to the secondary cell. If the secondary cell also proved untrawable, the tertiary cell was attempted next. If a tow was attempted but judged unsatisfactory, or if the tow was aborted, a reasonable attempt was made to redo the tow within the primary site before proceeding to alternate sites. All fishing operations, including vessel operations and gear performance were monitored using a suite of trawl instrumentation systems. The NMFS-supplied differential global positioning system (GPS) navigation unit (Northstar 500 [Footnote1] or the vessel's speed indicators were used to monitor towing speed for each survey haul (target 2.2 knots over ground). All hauls were additionally monitored using the Simrad Integrated Trawl Instrumentation (ITI [Footnote 2]) system. Four sensors from the ITI trawl system were attached to the net prior to setting the gear. Two instruments were mounted on the center of the net headrope: the trawleye provided information on the vertical opening of the trawl, distance to the seafloor, and footrope clearance above the bottom, and the temperature-depth sensor recorded ambient temperature and the depth of the trawl headrope. Paired wing units (communication sensor and remote sensor) were attached on the port and starboard wings of the net to measure wing spread. Extreme or prolonged periods of abnormal wing spread were indicative of net performance problems. Wing spread provided an indicator of the net's contact with the bottom and whether adequate scope (amount of wire deployed) was utilized. With too little scope the gear tends bottom poorly, while too much scope may impact the proper spread of the doors. The captain, relying on past experience and judgment, determined the initial scope at the start of each tow. Guidelines for initial scope, tailored to local conditions and vessels, were provided for use at the discretion of the captain. Since the ITI trawl instruments displayed gear performance in real time adjustments to the scope were made if necessary. Scope was adjusted by deploying additional wire until the gear made stable, consistent bottom contact according to the ITI display. The Simrad ITI also provided geo-referenced trawl positions relative to ship position, supplying a means to track the trawl location along the seafoor throughout each tow. A pair of bottom contact sensors (BCSs) and a secondary temperature/depth recorder (Seabird SBE39 [Footnote 3]) were also deployed on every haul. The BCSs were attached four feet from the center-point of the footrope, on either side of the net. The BCSs recorded the angle of incline of the net, indicating when the net landed on and lifted off bottom and provided redundancy in the event that the ITI failed to perform adequately. The Seabird temperature/depth recorder was attached to the head rope in an ABS plastic sleeve. The BCS and Seabird temperature/depth data were reviewed following every haul to provide additional information on bottom contact and trawl performance. In addition to monitoring trawl performance, the data from the sensor systems (Simrad ITI, BCS and Seabird) were used to calculate net dimensions (net height and net width), duration of the tow, and distance fished. While gear was being set, vessel speeds varied from 2.2 to 5 kn. After the net made contact with the bottom, vessel speed was targeted at 2.2±0.5 kn. The haul officially began when the net was in proper fishing configuration and maintained steady contact with the bottom. The haul ended when the net lifted off the bottom after the start of haulback. Tow duration was targeted at 15 minutes. The Simrad ITI trawl eye was used to monitor ground-gear contact during a haul, but the actual bottom time was determined using data from the BCS. Position data, collected at 2-second intervals for each haul using a GPS, were used to monitor ground speed, track the vessel path, and estimate distance fished. Average vessel speed over ground and distance fished were calculated from the position data and the trawl's actual bottom time. All features of the \"trawl event\" (i.e. from commencement of the deployment of the net to the completion of retrieval of the net) including net mensuration information, GPS data, trawl location, scope, vessel depth, trawl gear depth, and sea state conditions, were logged using a customized software program called 'Towlogger'. Following every haul, data were reviewed to determine a performance rating for each tow. A tow was classified as unsatisfactory if gear was severely damaged during a haul since damage to the gear might affect catch composition. Moreover, if gear performance was otherwise deemed unacceptable (e.g. large quantities of mud or jellyfish, lost or abandoned fishing gear ensnared in the net, net off bottom for an extended period during the tow etc.), the tow was also rated as unsatisfactory. Unsatisfactory hauls were not included in this data set. Sampling Procedures and Biological Data Collection Catches were sorted to species or other appropriate taxonomic levels and then weighed in aggregate using an electronic, motion-compensated scale (Marel, hf. [Footnote 4]). Subsamples of important management species were randomly selected for individual measurements (length and weights) and biological sampling (age structures and sex determinations). Up to 100 sex determinations and length measurements (to the nearest cm) were collected per haul from each of these species. Although fork length (or total length) was generally measured for most species, anal length was recorded for Pacific grenadier (Coryphaenoides acrolepis) and spotted ratfish (Hydrolagus colliei). Otoliths were most commonly removed to determine age; however, exceptions to the use of otoliths included collection of: fin rays from lingcod (Ophiodon elongates) and second dorsal spines from spiny dogfish (Squalus acanthias). Fish were randomly selected for aging from the subset of fish chosen for length determination. Up to 25 individuals per species were targeted for otolith (or other age structure) removal per haul. Individual lengths and weights were collected from all fish selected for age structure removal. For other species, only total counts and aggregate weights were recorded, except when additional information was collected for special projects (including stomach contents, tissue samples, fecundity, and toxicology). Data were logged wirelessly into a ruggedized Itronix3 notebook computer (Itronix Corp. [Footnote 5]) using the Fisheries Scientific Computing System (FSCS) version 1.6. Any unidentified species were labeled, frozen or preserved in formalin and retained for later identification. After all biological data were collected; marketable fish were placed in the hold of the vessel, iced and then delivered to a shoreside processing facility within 5 days. Species with no commercial value or those with catch prohibitions were returned to the sea as soon as possible. [Footnote 1] Northstar Technologies, 30 Sudbury Rd., Acton, MA 01720. [Footnote 2] Kongsberg Simrad Mesotech Ltd., 1598 Kebet Way, Port Coquitlam, BC V3C 5M5, Canada. [Footnote 3] Sea-Bird Electronics, Inc., 1808 136th Place NE, Bellevue, WA 98005 USA [Footnote 4] Marel, hf., Hofdabakki 9, 110 Reykjavik, Iceland. +354 563 8000. [Footnote 5] Itronix Corp.12825 E. Mirabeau Parkway, Spokane Valley, WA 99216-1464 CONTACT Beth Horness Northwest Fisheries Science Center Fisheries Resource Analysis and Monitoring Division 2725 Montlake Blvd. E Seattle WA 98112"; String time_coverage_end "2005-01-01T00:00:00Z"; String time_coverage_start "2003-01-01T00:00:00Z"; String title "Groundfish Data for U.S. West Coast (2003-2005)"; Float64 Westernmost_Easting -125.8555; } }
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