External Organisations

  • Lund University, Sweden
  • Municipality of Viborg, Denmark

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This project supports the research area fishmigration. In many shallow lakes cyprinid fishes like roach (Rutilus rutilus)and bream (Abramis brama) aggregate in inlet- and outlet streams duringwinter. Up to 85 % the bream and roach may leave the lake and individualsmay stay out of the lake for periods up to 7 months during winter. Howeverthere is interannual variation in the part of the population that participatesin this so called partial migration. Since 2005 DTU Aqua has investigatedpatterns of seasonal migrations of cyprinids in three Danish lakes and thereby,in combination with international collaborators, furthered our knowledge on thebehavior of some of the most common fish species in Denmark. This has resultedin numerous publications/reviews about partial migration. By expanding theinvestigation period to include 2011-2016 we have increases the length of thetime series leading to a better understanding of the annual variation inmigration patterns. In addition we included the effects of seasonal preymigration on top predator fitness in the study. Top predators such as pike (E. lucius) are important species inrecreational fisheries, and in order to optimize fisheries management itscrucial to understand the biology of these predators, Since the migratingcyprinids are important prey for the pike and since previous results have shownthat pike do not follow the prey into the stream, the migration of cyprinidsare likely to affect seasonal patterns of predator fitness. Overall, thisproject increases our knowledge on fish behavior and fish population dynamicsin lakes and thereby expands our tool box for management of lacustrine fishes. 

During the project period focus has been on threeareas (the last two as part of a PhD project with deadline in 2017):

Mechanismsbehind partial migration
The risk of predation from birds and fish as well asthe distribution of feeding resources are two very likely explanatorycomponents in spatial ecology of fish in general and  partial migration in specific. DTU Aqua havepublished several studies and reviews focusing on these as well as othermechanisms involved in partial migration such as body morphology, sex,individual variations in boldness and temperature 

Theinfluence of cyprinid partial migration on top-predator pike feeding dynamics
Pike feeding patterns and prey availability in anumber of open and closed lakes are monitored from early fall to late spring.This could reveal that pike in open lakes where prey abundance fluctuate duringseason require more management attention i.e. due to restricted growth and/orincreased cannibalism in periods with low prey abundance. 

Migrationbetween neighboring lakes
Two of the three focal lakes in which we aremonitoring seasonal migrations are situated only 3 km apart and connected by asmall stream. So far it has become obvious that from time to time large amountsof fish move from one lake to another. By continuing to pit tag and monitorfish migration we are likely to observe more of these mass migration events,which in turn facilitate a better understanding of why and when these massmigrations occur. Clearly, the level of fish exchange between neighboring lakesis an important factor to consider when it comes to management of lakes. 

The project is coordinated by DTU Aqua.

The project is funded by the Danish Rod and Net Fishing License Funds.





StatusCurrent
Period01/01/201131/12/2016

Keywords

  • Research area: Freshwater Fisheries and Ecology
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ID: 2286875