Biophysical modeling of larval Baltic cod (Gadus morhua) growth and survival
H.-H.
Hinrichsen, C. Möllmann, R. Voss, F.W. Köster, G. Kornilovs-2002
Can. J. Fish. Aquat. Sci., 59(12): 1858-1873
Abstract:
A
coupled hydrodynamic–trophodynamic individual-based model of drift and
feeding was utilized to analyze the intra- and inter-annual variability in
growth and survival of cod (Gadus morhua) larvae in the central
Baltic Sea. Highly temporally and spatially resolved simulated flow fields
were used to investigate the potential drift of larval cod from the centre
of spawning effort in the Bornholm Basin towards their nursery areas through
temporally resolved three-dimensional idealized prey fields. Stomach content
analyses of larval cod from the Bornholm Basin revealed calanoid copepod
nauplii and early copepodite stages to be the preferred prey organisms. The
results of the model runs indicate that larval cod changed from a nonlimited
to a food-limited stage because of the strong decrease in abundance of the
calanoid copepod Pseudocalanus elongatus during the last two decades.
The modeling study revealed retention and dispersal from the main spawning
ground to be a key process influencing larval survival. When P. elongatus
was available in the prey fields, high cod larval survival rates occurred in
spring and early summer. In contrast, when P. elongatus was not
available, hatched larvae had only high survival probabilities later in the
year or if they were transported into shallower coastal regions.
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