dc.contributor.author | Godø, Olav Rune | |
dc.contributor.author | Ona, Egil | |
dc.date.accessioned | 2007-07-19T08:01:33Z | |
dc.date.issued | 1999 | |
dc.identifier.uri | http://hdl.handle.net/11250/100421 | |
dc.description.abstract | To be able to take the proper and timely management actions, it is crucial to reliably
defect major changes in trends of fish stock abundance. For the assessment of
Northeast Arctic cod, the Norwegian bottom trawl survey is important for tuning the
VPA (Virtual Population Analysis). The indices are auto-correlated and the time
series show maxima with vaguely defined peaks. This might lead to a delay in
detection of the first signs of stock reduction.
Norway has conducted combined acoustic and bottom trawl surveys for the main
demersal fish stocks in the Barents Sea since 1982. The idea of combining the results
from the two surveys into one estimate of abundance has been explored, but a number
of confounding factors related to natural and affected fish behaviour has until1 now
prevented the establishment of a reliable method for combining the two indices. The
acoustic indices receive less weight or power during the tuning process than those
based on the bottom trawl survey. There are, however, specific differences in the
dynamics of the indices of the two time series that have not yet been exploited. In this
paper these differences are analysed with the aim of extracting patterns that can serve
a.s a. signal for changes in trends'of stock development. Application of the results for
monitoring the stock is discussed. | en |
dc.format.extent | 670837 bytes | |
dc.format.mimetype | application/pdf | |
dc.language.iso | eng | en |
dc.publisher | ICES | en |
dc.relation.ispartofseries | ICES CM documents | en |
dc.relation.ispartofseries | 1999/J:05 | en |
dc.subject | cod | en |
dc.subject | torsk | en |
dc.subject | fish stocks | en |
dc.subject | acoustics | en |
dc.subject | bottom trawl | en |
dc.subject | fish behaviour | en |
dc.subject | akustikk | |
dc.subject | fiskebestander | |
dc.subject | fiskeatferd | |
dc.title | Changes in acoustic abundance - a signal indicatior for stock dynamics for cod (Gadus morhua) | en |
dc.type | Working paper | en |
dc.subject.nsi | VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 | |
dc.subject.nsi | VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fisheries technology: 924 | |
dc.source.pagenumber | 6 s. | en |