Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Pelagic Fish Distribution and Dynamics in Coastal Areas in the Baltic Sea Proper
Stockholm University, Faculty of Science, Department of Systems Ecology.
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Pelagic fish distribution and diel behaviour patterns were studied in coastal areas in the north-western Baltic Sea Proper to understand more about how fish distribution and behaviour might affect planning and analyses of results of hydroacoustic surveys (Papers I and II). The vertical distribution of fish at night from spring to autumn showed seasonal and annual trends that could be explained by predictable and consistent seasonal changes, e.g., in temperature and stratification. Horizontal fish distributions did not show any trends probably owing to a lack of such seasonal characteristics. The observed vertical fish distribution over the diel cycle showed that hydroacoustic surveys at night were to be preferred over daytime surveys. At night, fish did not school and were generally less aggregated resulting in less variable hydroacoustic backscattering values and a higher percentage of single echo detections. By starting the surveys one hour after sunset and stopping one hour before sunrise, confusion between day- and nighttime behaviour in fish could be avoided. At night, fish occupied mid-water layers to a higher extent than surface and bottom layers, which was beneficial for the quality of the hydroacoustic data, particularly with respect to the hydroacoustic blind and dead zones (i.e. surface and bottom, respectively).

To quantify seasonal changes in pelagic fish abundance, densities and size distributions, nighttime hydroacoustic surveys were done every second week from spring through autumn in 2000 and 2001 (Paper III). There was a drastic increase in fish abundance and densities that started in early July and peaked in mid-August in both years. Analyses of the hydroacoustic data in relation to gillnet and trawl catches showed that the increase was caused mainly by young-of-the-year (YOY) herring. This age class is commonly not well represented in catches using traditional sampling methods like gillnets and trawling. Consequently, hydroacoustic data that have high precision and accuracy may improve quantitative estimates and our understanding of the biology in coastal nursery areas.

Baltic herring spawn in coastal areas and the density of metamorphosed YOY individuals may provide an early estimate of year-class strength. By analysing the relationship between parameters known to affect recruitment success and year-class strength in age 2 herring (YCS) a model that predicted herring recruitment was developed (Paper IV). The model explained 93 % of the variation in the number of age 2 herring over the period 1985-2000 and included the parameters YOY densities, climate (North Atlantic Oscillation index) and spawning stock biomass (SSB). Thus YCS could be predicted two years earlier than today and three years before entering the fishery. Up to the present, three new years (2001-2003) have become available for testing the model. For one of these years the predicted YCS was notably different from the assessed YCS. The reason for this is not fully understood, but for all three years SSB was outside the range used in the original model. Including the three new years into the data series resulted in a poorer explanation of the observed recruitment variation (55 %). A comparison of the standardized regression coefficients of both models showed increased significance for the parameter YOY (from 0.47 to 0.61).

Place, publisher, year, edition, pages
Stockholm: Institutionen för systemekologi , 2005. , 23 p.
Keyword [en]
herring, Baltic, hydroacoustic, distribution, behaviour
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:su:diva-442ISBN: 91-7155-037-2 (print)OAI: oai:DiVA.org:su-442DiVA: diva2:193925
Public defence
2005-04-29, hörsalen, Frescati backe, Svante Arrhenius väg 21 A, Stockholm, 09:00
Opponent
Supervisors
Available from: 2005-04-07 Created: 2005-04-07Bibliographically approved
List of papers
1. Pelagic fish distribution in relation to water temperature and wind direction; a study in a Baltic Sea coastal bay
Open this publication in new window or tab >>Pelagic fish distribution in relation to water temperature and wind direction; a study in a Baltic Sea coastal bay
Manuscript (Other academic)
Identifiers
urn:nbn:se:su:diva-23671 (URN)
Note
Part of urn:nbn:se:su:diva-442Available from: 2005-04-07 Created: 2005-04-07 Last updated: 2010-01-13Bibliographically approved
2. Diel patterns in pelagic fish behaviour and distribution observed from a stationary, bottom- mounted and upward-facing transducer
Open this publication in new window or tab >>Diel patterns in pelagic fish behaviour and distribution observed from a stationary, bottom- mounted and upward-facing transducer
2004 In: ICES Journal of Marine Science, ISSN 1054-3139, Vol. 61, no 7, 1100-1104 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-23672 (URN)
Note
Part of urn:nbn:se:su:diva-442Available from: 2005-04-07 Created: 2005-04-07Bibliographically approved
3. Seasonal dynamics in pelagic fish abundance in a Baltic Sea coastal area
Open this publication in new window or tab >>Seasonal dynamics in pelagic fish abundance in a Baltic Sea coastal area
2004 In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, Vol. 60, no 4, 541-547 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-23673 (URN)
Note
Part of urn:nbn:se:su:diva-442Available from: 2005-04-07 Created: 2005-04-07Bibliographically approved
4. Predicting herring recruitment from young-of-the-year fish densities, spawning stock biomass, and climate
Open this publication in new window or tab >>Predicting herring recruitment from young-of-the-year fish densities, spawning stock biomass, and climate
2003 In: Limnology and Oceanography, ISSN 0024-3590, Vol. 48, no 4, 1716-1720 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-23674 (URN)
Note
Part of urn:nbn:se:su:diva-442Available from: 2005-04-07 Created: 2005-04-07Bibliographically approved

Open Access in DiVA

fulltext(1661 kB)8252 downloads
File information
File name FULLTEXT01.pdfFile size 1661 kBChecksum SHA-1
77b949b419607fea278b4a0eff54bed04e9e4e1b5a7f4b9e03635a947a84554c0caa3946
Type fulltextMimetype application/pdf

By organisation
Department of Systems Ecology
Biological Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 8252 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 988 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf