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A Fish Migration Model
Birgitt Schonfisch
1
and Michael Kinder
2
1
Biomathematics, University of Tubingen, Auf der Morgenstelle 10,
72076 Tubingen, Germany,
birgitt.schoenfisch@uni-tuebingen.de
,
http://www.uni-tuebingen.de/uni/bcm/schoenfe.html
2
University of applied sciences Koblenz,
RheinAhrCampus, Sudallee 2, 53424 Remagen, Germany
kinder@rheinahrcampus.de
,
http://www.rheinahrcampus.de/fachbereiche/fb2/mut02.html
Abstract.
Today most german rivers are flow regulated by dams. They
form a barrier for migrating fish species like salmon and are one cause
for sustainable disturbances of the ecosystem even to extinction of sev-
eral fish species. Our question is how to distribute financial resources to
improve fish passage systems to obtain a maximal effect. We present a
concept to model up- and downstream fish migration with an individual
based approach. It allows us to test different strategies of resource dis-
tribution. We give an example modelling a part of the river Moselle in
Germany and discuss further extensions.
1
Introduction
Several fish species migrate during their life cycle between fresh- and seawater.
Two groups are distinguished: anadromous fish hatch in freshwater,spend most
of their life in the sea and return to freshwater to spawn. Common examples are
salmon,smelt,shad,striped bass,and sturgeon. Catadromous species,like most
eels,live in freshwater and spawn in seawater. Dams built today for shipping traf-
fic,hydropower usage and flow regulation at most rivers all over the world hinder
migration of these fish. They form a barrier for upstream migration,although
often for example fish ladders are installed. And even though downstream pas-
sage is usually less problematic,especially if young small fish travel,populations
suffer substantial loss [2]. Consequently populations of migrating fish decrease
and in the river Moselle for example several species including salmon are even
extinct.
Our model is motivated by plans to increase inland navigation on river
Moselle,a large and shippable stream flowing from France to the river Rhine
in Germany. Beside an enlargement of weirs and sluices an improvement of fish
passage systems is discussed. The interest in this river is high since at its headwa-
ters in Luxembourg there are suitable spawn habitats for salmon (
salmo salar
).
Also the water quality in rivers Rhine and Moselle would allow a return of the
salmon. 180 adult salmon have been observed in the river Rhine and its tribu-
taries Sieg und Saynbachs between 1990 and 1999 and salmons have been caught
