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Groundfish Assessment Program Manuals

 

Bottom Trawl Survey Protocols

The principal products of trawl surveys are fishery-independent indices of stock abundance used in stock assessment models. The essential feature of a trawl survey is that it is conducted with a high degree of precision from one trawl sample to the next, and from one survey to the next. This manual covers all aspects of preparation for trawl surveys, trawl equipment and trawl survey procedures that are consistent and in keeping with the highest standards to help ensure survey precision and data quality.  

Click to open NOAA Protocols For Groundfish Bottom Trawl Surveys, PDF file
Click image to open .PDF file

 

Safety Manual

The staff of the RACE Groundfish Assessment Program conducts fieldwork in a potentially dangerous environment: on small vessels floating in a very cold ocean. This At-Sea Safety Manual, developed by the RACE/REFM At Sea Safety Committee, identifies unsafe situations and practices that we face in our everyday field activities. Rules and strategies have been devised to minimize the dangers they present. 

Click to open At Sea Safety Manual, PDF file
Click image to open .PDF file *Draft*

 

Groundfish Species & Survey Codes

We maintain and annually update the Groundfish Species & Survey Codebook which lists the names/codes of fish and invertebrates identified on the bottom trawl surveys as well as a list of the codified survey operations, standards, and units of measure that serve as domain values in the Groundfish Program database.

Groundfish Species & Survey Codes, PDF file

Click image to open .PDF file

 

Species Identification Confidence

The quality and specificity of field identifications for many taxa have fluctuated over the history of the surveys due to changing priorities and resources. Historical trends in identification quality for each of the major Alaska Fisheries Science Center bottom trawl surveys was documented. These reports include identification confidence matrices for all fishes and invertebrates identified from respective surveys.

Click to open EBS Shelf Species ID Confidence Guide, 	PDF file EBS Slope Species ID Confidence Guide, 	PDF file AI/GOA Species ID Confidence Guide, 	PDF file

Click image to open .PDF file

 

Estimating Confidence in Trawl Efficiency and Catch Quantification

There are multiple sources of variability in the sampling efficiency of the trawl gear used for the survey, both species- and size-specific, that may affect inferences about the nature of the overall catches and relative animal densities. Furthermore, the quality and specificity of catch quantification (weighing and counting) at sea of many taxa can vary depending on the overall size of the catch and the species composition of the sample, particularly for non-commercial taxa of small size. This document is an assessment of the relative reliability of survey catch weights, numbers, and catch per unit effort estimates derived from the eastern Bering Sea shelf bottom trawl survey and is intended to serve as a guideline for researchers interested in using the survey data and results. Included within is a confidence matrix of sampling efficiency and catch quantification for all fishes and invertebrates identified during the shelf survey

Click to open EBS Shelf Estimating Confidence in Trawl Efficiency and Catch Quantification Guide, 	PDF file

Click image to open .PDF file

 

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