The aim of this project
is to understand the spatial ecology of adult European flounder to inform
fisheries management. Specifically, the aim is to determine if adult flounder
perform spawning emigration from a shallow estuary during 2019-2020 or if the
fish exhibit residency and therefore potentially spawn locally. Local spawning
activity may benefit future flounder recruitment in the area. This study will
build upon a similar study a year ago, and useful data and knowledge can be
used from this.
Flounder is a marine species that inhabits
shallow inshore areas, including brackish and freshwater environments. Flounder
has a wide salinity and thermal tolerance and is the only species of flatfish
to be found in freshwater in Europe.
Flounder is the most
commonly distributed fish in Danish coastal waters and it is a highly valued fish
in recreational fisheries.
Even though it is
widely distributed, we still do not know much about their migration routes.
For example, is
flounder performing a spawning migration in the winter period, or do they spawn
in their local estuarine waters? Previous foreign studies have indicated that flounder
may perform late autumn or winter emigrations and may leave coastal locations
prior to spawning.
Assessing the diversity of flounder migration
patterns helps us to understand the ecology of the species and provides useful
information for fishery and coastal environmental managers.
The project will map
flounder migration in the Roskilde Fjord near Copenhagen using acoustic
telemetry. Tiny transmitters will be surgically implanted into the body cavity
of adult flounder such that the individual fish can be tracked using acoustic
receivers. Stationary acoustic receivers are positioned strategic places in the
fjord to detect the movements of the fish. Fish are going to be tagged in
Also otoliths from fish
in the same area will be used to look for salt (Kattegat)/brackish (fjord) water
The student will assist
in the field work, both with tagging the fish, retrieving data from the
acoustic receivers and then carry out analyses of the data to reveal the
movements of the tagged fish. Several environmental variables are measured and
may be used to explain the movements of the fish (e.g. water temperature and
Field work will be carried out in the period October 2019-April
2020, followed by analyses of the data taking 2-3 months and then 2-3 months
It is preferable, but not expected, one student can
participate the entire period.
Mads Christoffersen firstname.lastname@example.org