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Short Citation:
Alaska Fisheries Science Center, 2022: AFSC/RACE/GAP/Palsson: Gulf of Alaska and Aleutian Islands Biennial Bottom Trawl Survey estimates of catch per unit effort, biomass, population at length, and associated tables, https://www.fisheries.noaa.gov/inport/item/22956.

Item Identification

Title: AFSC/RACE/GAP/Palsson: Gulf of Alaska and Aleutian Islands Biennial Bottom Trawl Survey estimates of catch per unit effort, biomass, population at length, and associated tables
Short Name: AFSC/RACE/GAP/Palsson: GOA and AI Biennial Bottom Trawl Survey estimates of catch per unit effort, biomass, population at length,
Status: In Work
Publication Date: Unknown
Abstract:

The GOA/AI Bottom Trawl Estimate database contains abundance estimates for the Alaska Biennial Bottom Trawl Surveys conducted in the Gulf of Alaska and the Aleutian Islands in alternate years. The estimates build upon raw and summary data available from the RACEBASE database and include calculated catch-per-unit-effort (cpue)s for principal species of groundfish and key invertebrates for each survey region. The cpues are averaged by survey strata, and then average cpues are multiplied by stratum areas which results in estimates of biomass and numerical abundance. Length and age data are combined with abundance to estimate the population at length and sex and population at age and sex.

Purpose:

The cpues, biomass, and age and size composition estimates are used by NOAA Fisheries scientists in stock assessments of groundfish and invertebrate species managed by the North Pacific Fisheries Management Council.

Notes:

Loaded by FGDC Metadata Uploader, batch 5253, 12-23-2014 14:18

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

- Spatial Reference Information (FGDC:spref),

- Spatial Data Organization Information (FGDC:spdoinfo)

- Lineage (FGDC:lineage)

Keywords

Theme Keywords

Thesaurus Keyword
UNCONTROLLED
ISO19115 biota
ISO19115 Oceans

Spatial Keywords

Thesaurus Keyword
UNCONTROLLED
None Alaska
None Aleutian Islands
None Gulf of Alaska

Physical Location

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

network\Oracle database and AKFIN

Data Set Information

Data Set Scope Code: Data Set
Data Set Type: Oracle Database
Maintenance Frequency: As Needed
Data Presentation Form: Table (digital)
Entity Attribute Detail URL: http://www.akfin.org/

Support Roles

Data Steward

CC ID: 182561
Date Effective From: 2015
Date Effective To:
Contact (Person): Palsson, Wayne
Email Address: wayne.palsson@noaa.gov
Contact Instructions:

E-mail data steward

Distributor

CC ID: 182562
Date Effective From: 2015
Date Effective To:
Contact (Person): Palsson, Wayne
Email Address: wayne.palsson@noaa.gov

Metadata Contact

CC ID: 255660
Date Effective From: 2015
Date Effective To:
Contact (Person): Roberson, Nancy
Address: 7600 Sand Point Way NE
Seattle, WA 98115
USA
Email Address: nancy.roberson@noaa.gov

Point of Contact

CC ID: 258270
Date Effective From: 2015-11-30
Date Effective To:
Contact (Person): Palsson, Wayne
Email Address: wayne.palsson@noaa.gov

Extents

Currentness Reference: observed

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 182560
Description

Gulf of Alaska and Aleutian Islands

Extent Group 1 / Time Frame 1

CC ID: 182559
Time Frame Type: Continuing
Start: 1980
Description:

Biennial

Access Information

Security Class: Restricted
Security Classification System:

Must have a user account

Data Access Procedure:

Go to the AKFIN website http://www.akfin.org/ and create a user account.

Data Access Constraints:

"FISMA Controls are in place to protect stored data from unauthorized access and/or disclosure"

Distribution Information

Distribution 1

CC ID: 258268
Download URL: http://www.akfin.org/
Distributor:

Distribution 2

CC ID: 840679
Download URL: https://access.afsc.noaa.gov/data-zips/22956_RooperCTD.zip
Distributor:
File Type: Zip

Technical Environment

Description:

oracle tables

Data Quality

Conceptual Consistency:

not applicable

Quality Control Procedures Employed:

unknown

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?: No
Is Access to the Data Limited Based on an Approved Waiver?: No
Approximate Delay Between Data Collection and Dissemination: Unknown
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 diserruption."

Lineage

Lineage Statement:

NOAA’s Alaska Fisheries Science Center conducts the Alaska Biennial Bottom Trawl Survey of the Gulf of Alaska (GOA) and Aleutian Islands (AI) in alternate years. These surveys have been conducted since 1980 in the AI and since 1984 in the GOA and conform to NOAA Protocols for Groundfish Bottom Trawl Surveys of the Nation’s Fishery Resources (2004, G. Stauffer compiler, NOAA Technical Memorandum NMFS-SPO-65). The survey consists of three chartered commercial fishing vessels that tow a bottom trawl at randomly-selected stations stratified by region, depth, and in the case of the GOA, habitat.

For the GOA survey, the sampling frame is known trawlable or new sites throughout the survey area, stratified by management areas; by shelf, slope, or gully habitats; and by depth zones including 0-100 m, 101-200 m, 201-300 m, 301-500 m, 501-700 m, and 701-1000 m (for GOA survey methodology, see von Szalay et al. 2010 Data Report: 2009 Gulf of Alaska Bottom Trawl Survey, NOAA Technical Memorandum NMFS-AFSC-208).

For the AI survey, the sampling frame is past successfully towed stations, stratified by management region and the same GOA depth zones but only as deep as 500 m (for GOA survey methodology, see von Szalay et al. 2011. Data Report : 2010 Aleutian Islands Bottom Trawl Survey. NOAA Technical Memorandum NMFS-AFSC-215). At each station the research trawl is set for a targeted period of 15 min and if the tow is successful, the catch is processed. Catch processing includes identifying, counting, and weighing all living taxa, collecting length measurement for commercially and ecologically important groundfish and invertebrate species, and collecting other materials, such as age structure, for laboratory or other scientific analysis. For each tow, detailed data are collected about the characteristics of the sample including position, time, depth, surface and bottom temperatures, and net characteristics. Sensors on the net measure how the net is fishing, and we track the contact of the foot rope with the seafloor, the width of the net at the wing tips, and the height of the headrope.

Tow-by-tow data are entered into computer databases or acquired electronically. Once the survey is completed, the data are error checked and finalized into a database known as RACEBASE.

These data are further processed into estimates of abundance in terms of biomass and numbers of organisms.

Estimates of abundance are based upon the area-swept technique whereby the catch per unit of effort (cpue) is computed for each successful station as the weight or count of each species divided by the area that the net contacted the seafloor during the tow. These calculated cpues are then averaged among the stations in each stratum and then multiplied by the calculated area of the stratum (as measured from digitized nautical charts and a geographic information system).

The product of these terms is an estimate of the biomass or numerical abundance (see von Szalay et al. 2010 Data Report: 2009 Gulf of Alaska Bottom Trawl Survey, NOAA Technical Memorandum NMFS-AFSC-208 and von Szalay et al. 2011. Data Report : 2010 Aleutian Islands Bottom Trawl Survey. NOAA Technical Memorandum NMFS-AFSC-215 for more complete methods).

The abundance estimates for the strata are combined by area-depth categories for convenient analysis. In addition, the population-at-length is estimate by applying length-sex frequency observations to the population abundance estimates. As age structures are evaluated for age determination, the population-at-size estimates are used with an age-length key to estimate the population-at-age structure of selected species.

Catalog Details

Catalog Item ID: 22956
GUID: gov.noaa.nmfs.inport:22956
Metadata Record Created By: Nancy Roberson
Metadata Record Created: 2014-12-23 14:18+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2022-08-09 17:11+0000
Metadata Record Published: 2016-05-18
Owner Org: AFSC
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2016-05-18
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2017-05-18