Research Document - 1999/078
Preliminary Results of a Longline Survey in Georges Bank.
By T.L. Johnston and J.J. Hunt
Abstract
The objective of the Georges Bank groundfish longline survey, which has been underway since 1995, has been to provide a relevant index of abundance for Georges Bank cod and haddock. In order to ensure the validity of the survey, it was necessary to develop certain sampling protocol that would assure that any changes in catch rates between sets and between years could be attributed to changes in stock abundance and not to methods by which the population was sampled. Despite efforts to prioritize the importance of following protocol, there were several variations in sampling practices. Variability in fishing locations, numbers of hooks, and soak times were apparent throughout the survey. It is unknown what effects these variables have on the outcome of the survey, or what effect any attempts to standardize using data manipulation have on the results. However, similarities do exist between population estimates from the Virtual Population Analysis (VPA) and catch from the longline survey. Survey catch values have consistently followed trends that appear in VPA estimates, and a positive correlation exists. An index typically requires several years of consistent sampling before it can be used to evaluate trends in stock status, but so far the longline survey appears to demonstrate a potential for providing a relevant index of cod and haddock abundance.
Accessibility Notice
This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.
- Date modified: