• norsk
    • English
  • English 
    • norsk
    • English
  • Login
View Item 
  •   Home
  • Havforskningsinstituttet
  • Published externally
  • Articles
  • View Item
  •   Home
  • Havforskningsinstituttet
  • Published externally
  • Articles
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

Diurnal variation in bottom trawl survey catches: does it pay to adjust?

Hjellvik, Vidar; Godø, Olav Rune; Tjøstheim, Dag
Journal article, Peer reviewed
Thumbnail
View/Open
2002_33.pdf (4.665Mb)
URI
http://hdl.handle.net/11250/108806
Date
2002
Metadata
Show full item record
Collections
  • Articles [3336]
Original version
http://dx.doi.org/10.1139/F01-193
Abstract
The diurnal bias of bottom trawl survey catches is studied with the purpose of adjusting for it and thereby

improving the accuracy of abundance estimates. The correction term is estimated with uncertainty and thus increases

the variance of the resulting abundance estimate. To investigate this adequately, we use a stochastic model describing

diurnal fluctuations and examine the annual variation of the diurnal amplitude as a function of species and length. The

diurnal amplitude is fairly stable for large fish, and for these, the bias-corrected estimate leads to a moderate increase

in variance. For small fish, the diurnal amplitude is unstable, however, and the correction of diurnal bias occurs at the

expense of a large increase in variance. This unstable amplitude also leads to a large year-to-year variation in

catchability for small fish. For haddock (Melanogrammus aeglefinus), the diurnal amplitude depends heavily on fish

length, indicating a strong decrease in catchability with decreasing fish length.
Journal
Canadian Journal of Fisheries and Aquatic Sciences

Contact Us | Send Feedback

Privacy policy
DSpace software copyright © 2002-2019  DuraSpace

Service from  Unit
 

 

Browse

ArchiveCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsDocument TypesJournalsThis CollectionBy Issue DateAuthorsTitlesSubjectsDocument TypesJournals

My Account

Login

Statistics

View Usage Statistics

Contact Us | Send Feedback

Privacy policy
DSpace software copyright © 2002-2019  DuraSpace

Service from  Unit