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AFSC/REFM: Acoustic trawl cooperative survey near Shumagin Islands 2007-2013

Metadata Updated: September 2, 2022

In May of 2006, scientists from the Alaska Fisheries Science Center participated in a pilot outreach program in Sand Point, Alaska. At the meetings, fishermen raised a number of concerns about the adequacy of walleye pollock (Theragra chalcogramma) assessment. The issues appeared to be related to the contrasting observational scales of fishermen and National Marine Fisheries Service (NMFS) scientists responsible for conducting assessment surveys and population modeling. NMFS resource assessment surveys have a large spatial scale (i.e., the entire Gulf of Alaska) and occur infrequently as they are biennial summer bottom trawl and acoustic-trawl surveys, with annual or biennial winter acoustic-trawl surveys targeting key spawning areas(von Szalay, et al. 2010; Guttormsen and Yasenak, 2007; Guttormsen and Jones, 2010). The stock assessment model for pollock estimates stock abundance for the central and western Gulf of Alaska (Dorn et al., 2011). In contrast, the observational scale of fishermen is spatially restricted but temporally extensive, since they are on the water fishing throughout the year. Fishermen questioned whether NMFS assessment activities were appropriately designed to monitor the status of pollock in their area. They noted that additional surveys in different seasons and a more comprehensive acoustic-trawl survey effort in winter could help address seasonal issues such as movement between spawning and feeding areas. Cooperative research projects with the Sand Point fishing community were identified as a potential approach for addressing some of these issues, but fishermen wanted the assurance that their investment of time and effort will lead to improvements in stock assessment. The acoustic-trawl surveys described in this report resulted from collaboration between NMFS scientists, the Aleutian East Borough, and local fishermen to address issues raised during the outreach program. Acoustic-trawl surveys were conducted from a local fishing vessel in the western Gulf of Alaska during 2007-2013. To some extent, the surveys carried out during this period reflected shifting program objectives. The initial objective was simply to demonstrate the feasibility of using local fishing vessels to conduct acoustic-trawl surveys and to collect acoustic and biological information sufficient to estimate walleye pollock biomass and spatial pattern. Once this was demonstrated, the focus of the project expanded to include other objectives. Specific objectives of the project were the following: Evaluate the feasibility of conducting acoustic-trawl surveys of pollock using local fishing vessels. Evaluate the quality of acoustic data collected from the Simrad ES60 echosounder. Evaluate the appropriateness of the design of the current NMFS acoustic-trawl surveys in the western Gulf of Alaska. Specific issues to be addressed included 1) transect density in bathymetrically complex regions in the western Gulf of Alaska, 2) day/night differences in pollock density, and 3) temporal variability of pollock density during replicate transects. Evaluate the timing of the NMFS survey (mid-February) in Sanak Trough by conducting a survey in January prior to the NMFS survey. Evaluate relationships between adult pollock density, young-of-the-year pollock density, euphausiid density, and the distribution of foraging humpback whales (Megaptera novaeangliae).

The estimates of abundance and distribution of walleye pollock were developed for areas covered by cooperative acoustic-trawl surveys conducted aboard a fishing vessel

during alternate Septembers and Januarys between 2007-2013. Physical oceanographic and biological composition observations, initial findings from ancillary data collections of marine mammal observations, and dual-frequency differencing techniques to discriminate different types of acoustic backscatter were also developed.

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License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Metadata Date August 9, 2022
Metadata Created Date November 12, 2020
Metadata Updated Date September 2, 2022
Reference Date(s) (publication)
Frequency Of Update notPlanned

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Collection location map.

Additional Metadata

Resource Type Dataset
Metadata Date August 9, 2022
Metadata Created Date November 12, 2020
Metadata Updated Date September 2, 2022
Reference Date(s) (publication)
Responsible Party (Point of Contact, Custodian)
Contact Email
Guid gov.noaa.nmfs.inport:12859
Access Constraints Cite As: Alaska Fisheries Science Center, [Date of Access]: AFSC/REFM: Acoustic trawl cooperative survey near Shumagin Islands 2007-2013 [Data Date Range],, Access Constraints: The data set has been analyzed and is available for distribution. Contact the Point Of Contact. | Use Constraints: User must read and fully comprehend the metadata prior to use. Applications or inferences derived from the data should be carefully considered for accuracy. 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.
Bbox East Long -160
Bbox North Lat 55.4
Bbox South Lat 54.4
Bbox West Long -162.3
Coupled Resource
Frequency Of Update notPlanned
Graphic Preview Description Collection location map.
Graphic Preview File
Graphic Preview Type url
Harvest Object Id 7f8e06cc-7f43-46fb-8236-031397b32943
Harvest Source Id 26a29bb9-50b0-47fd-920b-edc74aa6ec76
Harvest Source Title NMFS AFSC
Licence NOAA provides no warranty, nor accepts any liability occurring from any incomplete, incorrect, or misleading data, or from any incorrect, incomplete, or misleading use of the data. It is the responsibility of the user to determine whether or not the data is suitable for the intended purpose.
Metadata Language eng
Metadata Type geospatial
Old Spatial {"type": "Polygon", "coordinates": [[[-162.3, 54.4], [-160.0, 54.4], [-160.0, 55.4], [-162.3, 55.4], [-162.3, 54.4]]]}
Progress completed
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True
Temporal Extent Begin 2007
Temporal Extent End 2013

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