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Summary

Short Citation
Alaska Fisheries Science Center, 2024: AFSC/RACE/SAP: Detailed Crab Data From NOAA Fisheries Service Annual Eastern Bering Sea Summer Bottom Trawl Surveys 1975 - 2018, https://www.fisheries.noaa.gov/inport/item/17108.
Full Citation Examples

Abstract

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.

Distribution Information

Access Constraints:

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

Use Constraints:

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.

Controlled Theme Keywords

biota, oceans

Child Items

Type Title
Entity EBSCRAB

Contact Information

Point of Contact
Robert Foy
robert.foy@noaa.gov

Metadata Contact
Christie Lang
christie.lang@noaa.gov

Extents

Geographic Area 1

-178.74067° W, -157.97861° E, 68.3° N, 53.81867° S

More elaborate than a keyword.

Time Frame 1
1975-06 - 2015-08

Item Identification

Title: AFSC/RACE/SAP: Detailed Crab Data From NOAA Fisheries Service Annual Eastern Bering Sea Summer Bottom Trawl Surveys 1975 - 2018
Short Name: AFSC/RACE/SAP: Detailed Crab Data From NOAA Fisheries Service Annual Eastern Bering Sea Summer Bottom Trawl Surveys 1975 - 2018
Status: In Work
Abstract:

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.

Purpose:

Provide crab data from the annual bottom trawl survey of the eastern Bering Sea continental shelf.

Notes:

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)

Supplemental Information:

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.

Keywords

Theme Keywords

Thesaurus Keyword
ISO 19115 Topic Category
biota
ISO 19115 Topic Category
oceans

Temporal Keywords

Thesaurus Keyword
UNCONTROLLED
None summer

Spatial Keywords

Thesaurus Keyword
UNCONTROLLED
None Alaska
None Bering Sea
None Chukchi Sea
None Norton Sound

Physical Location

Organization: Alaska Fisheries Science Center
City: Seattle
State/Province: WA
Country: USA

Data Set Information

Data Set Scope Code: Data Set
Data Set Type: Oracle Database
Maintenance Frequency: Annually
Data Presentation Form: Table (digital)
Entity Attribute Overview:

RACE Shellfish Assessment Program eastern Bering Sea shelf crab database EBSCRAB

Entity Attribute Detail Citation:

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

Distribution Liability:

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.

Support Roles

Data Steward

CC ID: 224478
Date Effective From: 2015-09-23
Date Effective To:
Contact (Person): Foy, Robert
Email Address: robert.foy@noaa.gov
Contact Instructions:

robert.foy@noaa.gov

Distributor

CC ID: 187829
Date Effective From: 2015-02-26
Date Effective To:
Contact (Person): Foy, Robert
Email Address: robert.foy@noaa.gov
Contact Instructions:

robert.foy@noaa.gov

Metadata Contact

CC ID: 187827
Date Effective From: 2015-02-26
Date Effective To:
Contact (Person): Lang, Christie
Email Address: christie.lang@noaa.gov
Contact Instructions:

christie.lang@noaa.gov

Originator

CC ID: 187830
Date Effective From: 2015-02-26
Date Effective To:
Contact (Organization): Alaska Fisheries Science Center (AFSC)
Address: 7600 Sand Point Way N.E., Building 4
Seattle, WA 98115
USA
Email Address: afsc.webmaster@noaa.gov
Phone: (206) 526-4000
Fax: (206) 526-4004
URL: https://www.fisheries.noaa.gov/about/alaska-fisheries-science-center
Business Hours: 0700-1700 Pacific Time

Point of Contact

CC ID: 187828
Date Effective From: 2015-02-26
Date Effective To:
Contact (Person): Foy, Robert
Email Address: robert.foy@noaa.gov

Extents

Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 187826
W° Bound: -178.74067
E° Bound: -157.97861
N° Bound: 68.3
S° Bound: 53.81867
Description

More elaborate than a keyword.

Extent Group 1 / Time Frame 1

CC ID: 187825
Time Frame Type: Range
Start: 1975-06
End: 2015-08

Access Information

Security Class: Unclassified
Data Access Procedure:

unknown

Data Access Constraints:

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

Data Use Constraints:

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.

Distribution Information

Distribution 1

CC ID: 239076
Download URL: https://console.cloud.google.com/storage/browser/_details/nmfs_odp_afsc/RACE/SAP/Detailed%20Crab%20Data%20From%20NOAA%20Fisheries%20Service%20Annual%20Eastern%20Bering%20Sea%20Summer%20Bottom%20Trawl%20Surveys%201975%20-%202018.csv
Distributor:
Description:

Note: Dataset migrated by Dan Woodrich (AFSC data management coordinator) on 12/14/2021. Contact: Daniel.woodrich@noaa.gov

URLs

URL 1

CC ID: 238732
URL: http://www.afsc.noaa.gov/Publications/AFSC-TM/NOAA-TM-AFSC-308.pdf
URL Type:
Online Resource
File Resource Format: pdf
Description:

AFSC Technical Memorandum summarizing results of the 2014 eastern Bering Sea trawl survey for commercially important crab species

URL 2

CC ID: 238760
URL: http://www.afsc.noaa.gov/RACE/groundfish/species_codebook.pdf
URL Type:
Online Resource
File Resource Format: pdf
Description:

Listing of codes used for fish and invertebrates identified in RACE Division surveys.

Technical Environment

Description:

Oracle

Data Quality

Completeness Measure:

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.

Completeness Report:

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.

Conceptual Consistency:

Data is checked for values outside range

Quality Control Procedures Employed:

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

Data Management

Have Resources for Management of these Data Been Identified?: No
Approximate Percentage of Budget for these Data Devoted to Data Management: Unknown
Do these Data Comply with the Data Access Directive?: Yes
Is Access to the Data Limited Based on an Approved Waiver?: No
If Distributor (Data Hosting Service) is Needed, Please Indicate: yes
Approximate Delay Between Data Collection and Dissemination: unknown
If Delay is Longer than Latency of Automated Processing, Indicate Under What Authority Data Access is Delayed:

No delay

Actual or Planned Long-Term Data Archive Location: NCEI-MD
Approximate Delay Between Data Collection and Archiving: Unknown
How Will the Data Be Protected from Accidental or Malicious Modification or Deletion Prior to Receipt by the Archive?:

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.

Lineage

Process Steps

Process Step 1

CC ID: 232575
Description:

Trawl samples take place within 20 x 20 nautical mile grid cells throughout the eastern Bering Sea shelf. 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.

Process Contact: Alaska Fisheries Science Center (AFSC)
Phone (Voice): (206) 526-4000
Email Address: afsc.webmaster@noaa.gov

Process Step 2

CC ID: 232576
Description:

All crab were removed from the catch, sorted by species and sex, and a total catch weight was obtained for each species. Tanner and snow crab hybrids are identified by a combination of characteristics including curve of the epistome margin, eye color, carapace shape, and space between or shape of the rostrum horns. A random subsample of the total catch occurred when an exceptionally large number (> 300) of a species was caught in a tow. The subsample varies in size and composition depending on the particular tow. The subsample may have occurred at the level of the entire catch or at the level of a particular size and sex category once the catch was sorted. The total weights of the sampled crab and non-sampled crab were recorded and an expansion factor was calculated to determine the final number of each species in the catch.

Individual crab carapaces were measured (± 1 mm) to provide a size-frequency distribution of each sample. Crab sizes are reported as carapace width (CW) excluding spines for Tanner and snow crab, and carapace length (CL) for all king crab and hair crab. Since 2006, individual weights were measured for blue king crabs every year, red king crab and snow crab in odd years, and for Tanner crab in even years to add to the existing length-weight data and to monitor temporal variability in length-weight regressions. For every haul in 2014, data were collected on up to five intact crab per each of the following categories: 1) male

Tanner crab, 2) ovigerous Tanner crab, and 3) non-ovigerous female Tanner crab. Because of their relative rarity, weight data were collected for all intact blue king crabs encountered that met the sampling requirements (i.e., whole, live crab without regenerating limbs). Weights were collected from representative size ranges throughout the spatial distribution of each species.

Measurements were regionally stratified and tally sheets ensured all size ranges were equally sampled within each region.

In the absence of specific age data, shell condition classification by length and sex is necessary for apportioning stock abundance and biomass for determination of stock status, analytical stock assessment, and for establishing annual management controls. Shell condition class serves as a

semi-quantitative index of molt status and time in shell post-molt. For all EBS crab stocks, and particularly those which exhibit a terminal molt at maturity (i.e., Chionoecetes spp.), shell condition is a requisite for setting overfishing limits and harvest quotas. Carapace shell condition was assessed for each crab sampled and assigned to one of six classes according to specific

criteria (0 = premolt or molting, 1 = soft and pliable, 2 = new hardshell both firm and clean, 3 = oldshell slightly worn, 4 = oldshell worn, 5 = very oldshell).

Clutch assessment is used to estimate spawning stock biomass and overall reproductive health and to monitor demographic changes in the mating population. All female crab abdomens were evaluated to determine reproductive condition based on the color of the eggs (0 = no eggs, 2 =

purple, 3 = brown, 4 = orange, 5 = purple-brown, 6 = pink), the condition of the eggs (0 = no eggs, 1 = uneyed, 2 = eyed, 3 = dead, 4 = empty egg cases), and the size of the egg clutch (0 = immature, 1 = mature female no eggs, 2 = trace to 1/8, 3 = 1/4, 4 = 1/2, 5 = 3/4, 6 = full).

For mature females, egg clutch and egg condition codes were used to identify the stage in the molt-mate cycle, where the presence of eyed embryos, empty egg cases, or absence of eggs (barren, hereafter) in mature-sized females were indications of an incomplete cycle while mature females brooding uneyed embryos indicated completion of the cycle.

Process Contact: Alaska Fisheries Science Center (AFSC)
Phone (Voice): (206) 526-4000
Email Address: afsc.webmaster@noaa.gov

Process Step 3

CC ID: 232577
Description:

Data collected at sea is uploaded to an Oracle database and subjected to a thorough QA/QC process.

Process Contact: Alaska Fisheries Science Center (AFSC)
Phone (Voice): (206) 526-4000
Email Address: afsc.webmaster@noaa.gov

Process Step 4

CC ID: 232582
Description:

Catch-per-unit-effort CPUE), abundance, and biomass estimates are calculated by species and by stock. Area swept is calculated as the product of the distance trawled while the net had bottom contact by the mean net width over the duration of the tow. CPUE is expressed in terms of number (or weight) of crab per square nautical mile.

Biomass estimates are calculated for the number of individual male and female crab species at each 1 mm size category using the weight-size relationships developed by the AFSC’s Kodiak Laboratory. Prior to 2010, the weight-size relationships were based on limited data (< 500 samples for all species) and estimates from survey data total weights. In 2010 the relationships were revised based on species-specific length and weight data collect during EBS surveys from 2006 to 2010 from > 1,000 measurements made for each species. Length and weight data currently being collected on the survey annually will be used to assess relative changes to the relationship overtime and correlated with

environmental variables. The size-weight relationships are described by the expression: W = a Lb, where W is the total weight in grams, L is either CL or CW in millimeters, a is the intercept in log scale and b is the slope. Parameters a and b for the size-weight relationships are estimated from a linear regression fitted to log-transformed size-weight data.

The weights calculated at each 1 mm size category are summed within the legal male, sublegal male, mature and immature size categories for each species and sex caught at a station. The crab biomass within a district or section stratum was estimated by averaging crab densities from all stations within the defined district or section stratum and multiplied by the total area of the district or section stratum specific to that stock. Total biomass was calculated using a stratified design based on management units (standard density, high density, Alaska Department of Fish&Game-defined districts, or section stratum). Population biomass estimates were calculated in each stratum and then summed among strata. Variance of the total biomass estimate for each size class was calculated by summing the variance of each stratum. The 95% confidence intervals were calculated using the standard error of the total population multiplied by 1.96.

Process Contact: Alaska Fisheries Science Center (AFSC)
Phone (Voice): (206) 526-4000
Email Address: afsc.webmaster@noaa.gov

Child Items

Rubric scores updated every 15m

Rubric Score Type Title
Entity EBSCRAB

Catalog Details

Catalog Item ID: 17108
GUID: gov.noaa.nmfs.inport:17108
Metadata Record Created By: Doug Turnbull
Metadata Record Created: 2012-12-05 14:10+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2024-01-15 12:08+0000
Metadata Record Published: 2018-11-26
Owner Org: AFSC
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2018-11-26
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2019-11-26