Pollock Conservation Cooperative Research Center

2008 Awarded Research Projects

Project Title: Deployment of an acoustic data logger on commercial fishing vessels to evaluate the potential of fishing-induced declines in local pollock abundance

Principal Investigator: Terrance Quinn II

Award: $36,931

Estimated Completion: January 31, 2010

Abstract

The main goal of this project was to determine if hydroacoustic data collected from sounders on commercial factory trawlers could be utilized to investigate temporal-spatial changes in the abundance and distribution of walleye pollock and the potential for local depletion in the Bering Sea. Since 2001 the PCC Research Center has funded this project for a total of $288,459.

In 2001, we developed a prototype data logger that interfaces with the ship's 38 kHz echo sounder and captures the acoustic backscatter returns. In 2002, we installed it on three catcher/processors (Island Enterprise, Kodiak Enterprise, and Alaska Ocean). The system worked quite satisfactorily. The backscatter data were post-processed and integrated with observer and logbook data. Preliminary analysis showed that the hydroacoustic information is correlated with pollock catch (Dorn et al. 2002). In 2003, an additional 4 vessels (American Dynasty, American Triumph, Ocean Rover, Starbound) were equipped with acoustic data logging systems, bringing the total number of PCC vessels equipped to 7, or nearly half the fleet.

Work since 2005 concentrated on the analysis phase of the project. This work includes classifying the searching behavior of the vessel, integrating the acoustic biomass, identifying pollock aggregations detected while searching, and evaluating what inferences, if any, can be made concerning the rate at which those aggregations are reduced in abundance. The project developed sophisticated analytical tools for inferring the temporal dynamics of pollock spatial pattern using multiple data sources. This project was a cooperative program between the University of Alaska and the University of Washington and will result in two PhD dissertations: Haixue Shen at UAF and one by Steven Barbeaux at the University of Washington. Two research papers have been accepted for publication, several more are in preparation. As these reports become published, they will be sent to PCCRC. Numerous presentations of research results have been given, including a poster presentation at an international symposium on hydroacoustics in Bergen, Norway in 2008.

This project demonstrated the feasibility of installing acoustic data loggers on catcher/processors in the EBS pollock fishery to study localized depletion of pollock. There were clear changes in pollock school characteristics during the course of the fishing season. However, it is not known whether these changes are due to biological characteristics, oceanographic effects, or fishing. Therefore, there will be need for time series of hydroacoustic data to determine whether changes are due to particular effects.

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