On the use of omnidirectional sonars and downwards-looking echosounders to assess pelagic fish distributions during and after midwater trawling


TitleOn the use of omnidirectional sonars and downwards-looking echosounders to assess pelagic fish distributions during and after midwater trawling
Publication TypeJournal Article
Year of Publication2013
AuthorsStockwell, JD, Weber, TC, Baukus, AJ, Jech, JM
JournalICES Journal of Marine Science
Volume70
Issue1
Pagination196 - 203
Date Published01/2013
ISSN1054-3139
Abstract

Small pelagic fish can play an important role in the structure and function of ecosystems, and there is increasing interest in their non-market value. At the scale of fish aggregations, however, the impact of fishing has received relatively little attention, with most effort devoted to impacts of vessel and gear avoidance on stock size estimates. We used concurrent deployment of a downwards-looking echosounder (Simrad ES60 system) and an omnidirectional sonar (Simrad SP90 system) during commercial pairtrawling operations for Atlantic herring (Clupea harengus) in the Gulf of Maine to examine their potential for studying the impacts of fishing on herring aggregations. We compared a number of aggregation metrics to illustrate similarities and differences between the two systems, and then qualitatively examined their properties during and after pairtrawling events to illustrate potential applications. Our results suggest that using both downwards-looking and omnidirectional systems provides complementary information on fish aggregation metrics. Future applications of these systems in before–after–control-impact (BACI) designs may help inform management agencies when evaluating potential impacts of fishing at the time and space scales of pelagic fish aggregations.

DOI10.1093/icesjms/fss139
Short TitleICES Journal of Marine Science
Status: 
Published
Attributale Grant: 
RACC
Grant Year: 
Year2