Aage Kristian Olsen Alstrup

Investigating fish migration, mortality and physiology to improve conservation planning of anadromous salmonids: a case study on the endangered North Sea houting (Coregonus oxyrinchus)

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  • Morten Hertz, Aalborg University
  • ,
  • Lasse Fast Jensen, Aalborg University, Denmark
  • Cino Pertoldi, Aalborg University, Denmark
  • Kim Aarestrup, Danmarks Tekniske Universitet
  • ,
  • Søren N. Thomsen, Aalborg University, Denmark
  • Aage Kristian Olsen Alstrup
  • H. Asmus, Alfred Wegener Institute, Germany
  • S.S. Madsen, University of Southern Denmark, Denmark
  • Jon Christian Svendsen, DTU, Denmark
Understanding migratory behavior, mortality and physiology is essential for conservation of many species, in particular anadromous fish. In this study, freshwater and marine migrations of the endangered salmonid North Sea houting (Coregonus oxyrinchus, Linnaeus, 1758) were investigated using telemetry. Furthermore, samples were collected from North Sea houting and from resident and anadromous populations of the closely related European whitefish (Coregonus lavaretus, Linnaeus 1758) to compare hyperosmotic tolerances. On average, North Sea houting spent 193 days at sea where the mortality was 36%. Most fish returned from sea in the autumn, and river entry correlated negatively with river temperature and positively with discharge. Fish spent an average of 49 days in the estuarine area. Migration speeds declined when fish traversed artificial lakes. Migration speeds were not a repeatable trait in individual fish, but correlated positively with water temperature. Fish arrived at putative spawning areas in November. In the post-spawning state, Na+/K+-ATPase activities were elevated in North Sea houting and anadromous whitefish compared to resident whitefish, while osmolality was elevated only in North Sea houting. Our study provides important information for conservation planning related to the Habitat Directive of the European Union that lists the North Sea houting as critically endangered.
Original languageEnglish
JournalCanadian Journal of Zoology
Pages (from-to)1126-1136
Publication statusPublished - 19 Nov 2019

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