AFSC/RACE/SAP: Detailed Crab Data From NOAA Fisheries Service 2012 Chukchi Sea Bottom Trawl Surveys

This dataset contains detailed crab data collected from the 2012 NOAA/NMFS/AFSC/RACE crab-groundfish bottom trawl survey of the Chukchi Sea. 71 survey stations were successfully completed during the bottom trawl survey. The survey area extended north and east from the Bering Strait to Barrow Canyon, bounded to the west by the U.S.-Russia Maritime Boundary and east to the 10-m bathymetry limit along the Alaska coastline. Demersal populations were sampled by trawling at stations centered within 55.56 x 55.56 km (30 x 30 nautical miles) grid cells covering the survey area. 100% of the catch is sorted for commercially important crab species. Crabs are sorted by species and sex, and a sample is measured to the nearest millimeter to provide a size-frequency distribution (see note under use constraints for analyzing catches where crab were subsampled for measurement). Carapace width is measured for Tanner crabs, and carapace length is measured for king and hair crabs.

Provide crab data from the 2012 bottom trawl survey of the Chukchi Sea.

Loaded by FGDC Metadata Uploader, batch 5413, 02-26-2015 12:44

The following FGDC sections are not currently supported in InPort, but were preserved and will be included in the FGDC export:

- Taxonomy (FGDC:taxonomy)

- Lineage (FGDC:lineage)

Funding for this survey was provided in part by the Bureau of Ocean Energy Management (BOEM) Arctic Ecosystem Integrated Survey (Arctic Eis) contract agreement number M12PG00018. Survey efforts were conducted aboard the 43.5 m FV Alaska Knight, a twin-engine, houseforward, commercial stern trawler with Kort nozzles allowing for suitable control of the vessel at slow trawling speeds (3.0 knots). The bottom trawl used for sampling was an 83-112 Eastern trawl, which has a 25.3 m

(83 ft) headrope and a 34.1 m (112 ft) footrope. Survey trawls were towed behind 816 kg, 1.8 x 2.7 m, steel V-doors and 54.9 m (30 fathoms) paired bridles. Each lower bridle had a 61 cm chain extension connected to the lower wing edge to improve bottom-tending characteristics. The footrope was fished without roller gear and consisted of a wrapped 0.8 cm (5/16 in.) chain to maximize bottom contact. The body of the net was constructed from

nylon with stretched mesh sizes 10.2 cm (4 in.) in the wings and body and 8.9 cm (3.5 in.) in the intermediate and codend. The codend also had a liner of 3.2 cm (1.25 in.) mesh. Samples were collected by bottom trawling at each station for a target fishing time of 15 minutes at a speed of 1.54 msec-1 (3 knots). When possible, the tow was conducted near the center of a 55.6 x 55.6 km grid cell, and the vessel maintained a constant heading during the tow. Note that, while 100% of the total catch is sorted for all commercially important crab species, it may not be possible to measure all crabs. This is noted in the SAMPLING_FACTOR data field: a sampling factor of 1 indicates that all crab were measured; a sampling factor greater than 1 indicates that crabs were subsampled for measurement. To calculate the total number of crab caught by haul, sum the sampling_factor.

Oracle database

RACE Shellfish Assessment Program eastern Bering Sea shelf crab database EBSCRAB

Refer to the pdf document Crab Code Instructions" provided with this dataset for a detailed descript

The user is responsible for the results of any application of this data for other than its intended purpose.NOAA denies liability if the data are misused.

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There are no legal restrictions on access to the data. They reside in public domain and can be freely distributed.

Population size estimates make the assumption that 100% of the species within the path of the trawl are captured. In fact, the situation is more complex. As with any fishing gear, the survey trawl exhibits some size selectivity. Some crab may escape under the footrope of the net. Survey abundance estimates are probably best seen as relative measures of abundance. This survey was designed as a systematic survey based on a 55.6 km (30 nautical mile (nmi)) square grid pattern with the

planned trawl stations located at the approximate center of each grid cell. Any data analysis must take into consideration the survey design for the results to be valid. This dataset includes data obtained from non-standard (special project, beam trawl,opportunistic collections, etc.) tows, and data that may have been collected from poor performance tows. Note that, while 100% of the total catch is sorted for all commercially important crab species, it may not be possible to measure all crabs. This is noted in the SAMPLING_FACTOR data field: a sampling factor of 1 indicates that all crab were measured; a sampling factor > 1 indicates that crabs were subsampled for measurement. To calculate the total number of crab caught by haul, sum the sampling_factor. This database should not be copied or distributed without its associated metadata file. User must read and fully comprehend the metadata prior to use. Use of these data is not restricted; however, organizations, agencies, units of government, or other users are responsible for the appropriate application of these data. Acknowledgement of NOAA/NMFS/AFSC ,as the source from which these data were obtained, in any publications and/or other representations of these data is suggested.

Oracle

Population size estimates make the assumption that 100% of the species within the path of the trawl are captured. In fact, the situation is more complex. As with any fishing gear, the survey trawl exhibits some size selectivity. Some crab may escape under the footrope of the net. Survey abundance estimates are probably best seen as relative measures of abundance. This survey was designed as a systematic survey based on a 55.6 km (30 nautical mile (nmi)) square grid pattern with the

planned trawl stations located at the approximate center of each grid cell. Any data analysis must take into consideration the survey design for the results to be valid. This dataset includes data obtained from non-standard (special project, beam trawl,opportunistic collections, etc.) tows, and data that may have been collected from poor performance tows. Note that, while 100% of the total catch is sorted for all commercially important crab species, it may not be possible to measure all crabs. This is noted in the SAMPLING_FACTOR data field: a sampling factor of 1 indicates that all crab were measured; a sampling factor > 1 indicates that crabs were subsampled for measurement. To calculate the total number of crab caught by haul, sum the sampling_factor.

Data set includes data collected from standard and non-standard hauls (special projects, opportunistic collections, etc.). Users of this dataset should be familiar with the haul type codes used in RACEBASE.HAUL (linked to CRAB.EBSCRAB via hauljoin field) before performing analyses

Data is checked for values outside range

All data is submitted through a thorough QA/QC process. Data is checked for outliers, impossible values, and invalid values.

No delay

IT Security and Contingency Plan for the system establishes procedures and applies to the functions, operations, and resources necessary to recover and restore data as hosted in the Western Regional Support Center in Seattle, Washington, following a disruption.

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