AFSC/RACE/SAP: Detailed Crab Data From NOAA Fisheries Service Annual Eastern Bering Sea Summer Bottom Trawl Surveys 1975 - 2018

This dataset contains detailed crab data collected from the annual NOAA/NMFS/AFSC/RACE crab-groundfish bottom trawl survey of the eastern Bering Sea continental shelf. The standard survey area, surveyed each year since 1975, encompasses a major portion of the eastern Bering Sea shelf between the 20 meter and 200 meter isobaths and from the Alaska Peninsula to the north of St. Matthew Island. The study area is divided into a grid with cell sizes of 20 x 20 nautical miles (37 x 37 kilometers). Sampling takes place within each 20 x 20 nautical mile grid cell. In areas surrounding St. Matthew (1983-present) and the Pribilof Islands (1981-present), grid corners were also sampled to better assess king crab concentrations. In 1975, tows were 1 hour in duration; from 1976 to present, each tow is one-half hour in duration, averaging 1.54 nautical miles (2.86 kilometers) - exact tow duration and distance fished for each haul can be found in RACEBASE.HAUL. 100% of the catch is sorted for red, blue, and golden king crab, bairdi Tanner, snow crab, hybrid Tanner, and hair crab. 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 annual bottom trawl survey of the eastern Bering Sea continental shelf.

Loaded by FGDC Metadata Uploader, batch 5412, 02-26-2015 12:34

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)

Survey vessels from 1975-1980 used a 400 mesh eastern otter trawl constructed of 36 thread 4-inch mesh in the wings, 60 thread 3-1/2 inch mesh in the intermediate, and 96 thread 1-1/4 inch mesh codend liner. The trawl was rigged with 18 eight-inch floats on the headrope and 25 fathom dandylines (10 fathom single, 15 fathom double). The footrope was 94 feet and the headrope was 71 feet in length. The doors were of the Astoria "V" type and measured 5 x 7 feet.. In 1981, one vessel (R/V Chapman) fished an 83-112 eastern otter trawl (described below), and the second vessel (R/V Alaska) fished the 400-mesh eastern otter trawl. From the 1982 survey to present, vessels have been equipped with 83-112 eastern otter trawls which have 25.3 meter (83 ft) headropes and 34.1 meter (112 ft) footropes. The footropes are 5/8 inch wire ropes wrapped with polypropylene ropes and heavy rubber hoses. Headropes contain 41- 8-inch floats. These nets are attached to tail chains with 54.9 meter (30 fathoms) paired bridles. Each lower bridle has a 0.61 meter chain extension connected to the lower wing edge to improve bottom tending characteristics. Steel "V"-doors measuring 1.8 x 2.7 meters and weighing 816 kilograms are used. The trawls are constructed of 3.5 and 4.0 inch polyethylene mesh with a 1.25 inch nylon liner in the codend. 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.

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 is designed as a systematic survey. Any data analysis must take into consideration the survey design for the results to be valid. The exact location of the trawl within the 20 x 20 nautical mile grid varies each year. In some cases, a tow will originate in one station and conclude in another. The data user may need to define set criteria for tow location from year to year. In addition, higher station density in the Pribilof (1981 to present) and St. Matthew Island (1983 to present) regions necessitate defining criteria for assigning data to grid cells to avoid biased population indices. This dataset includes data obtained from non-standard (special project, opportunistic collections, hot spot tows, 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

The study area is divided into a grid with cell sizes of 20 x 20 nautical miles (37 x 37 kilometers). Sampling takes place within each 20 x 20 nautical mile grid cell. In areas surrounding St. Matthew (1983-present) and the Pribilof Islands (1980-present), grid corners were also sampled to better assess king crab concentrations. In 1975, tows were 1 hour in duration; from 1976 to present, each tow is one-half hour in duration, averaging 1.54 nautical miles (2.86 kilometers) - exact tow duration and distance fished for each haul can be found in RACEBASE.HAUL. 100% of the catch is sorted for red, blue, and golden king crab, bairdi Tanner, snow crab, hybrid Tanner, and hair crab. Crabs are sorted by species and sex, and a sample is measured to the nearest millimeter to provide a size-frequency distribution. 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. 100% of the catch is sorted for red, blue, and golden king crab, bairdi Tanner, snow crab, hybrid Tanner, and hair crab. Crabs are sorted by species and sex, and a sample is measured to the nearest millimeter to provide a size-frequency distribution. 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 is checked for values outside range

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.