Research Document - 1999/063
Proposed acoustic survey design for the 4WX herring spawning components.
By G. Melvin and M. Power
Abstract
Over the past several years the 4WX herring stock complex has been assessed using input from industry based acoustic surveys and fishing excursions. Unfortunately, the data have been collected in somewhat of an ad hoc manner. The results, while providing valuable information on the abundance of herring on specific spawning grounds, are not comparable from year to year due to restricted coverage and only provide a minimum biomass of the fish observed on the day surveyed. To overcome this problem, data from the fishery are used to identify potential survey areas from the distribution of catches during the spawning season. The survey coverage area is further reduced by isolating the locations which contains more than 90% of reported landings. Thereafter, standard random transects are selected within the survey area and a protocol recommended for instances when fish are observed beyond the survey boundaries. Standarization of the survey area provides a means to compare observations from year to year and forms the basis for an index of abundance in years to come.
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