The diet and growth of
larval and juvenile pikeperch (Stizostedion lucioperca (L.)): A
comparative study of fishponds and a reservoir
J. Peterka, J. Matína, J. Lipka-2003
Aquaculture
International, 11(4):
337-348
Abstract:
Diet of larval and juvenile pikeperch (Stizostedion
lucioperca) reared in ponds was investigated and compared with the diet
of pikeperch from a reservoir. The standard length of first feeding
pikeperch larvae in ponds was 6.1 mm, on average, and although rotifers were
present in the diet, their numerical contribution can be considered as
insubstantial. Rotifers were soon replaced by nauplii of cyclopoid copepods,
which were highly positively selected and contributed largely to the diet up
to a larval length of 10 mm. Daphnia spp. were consumed from the
onset of exogenous feeding, but were not positively selected until 15 mm.
Another smaller cladoceran Bosmina longirostris was highly
negatively selected and did not contribute significantly to the diet. A
clear positive selection for larger relatively to smaller prey and a
preference for Daphnia from a body length of 15 mm onwards could be
observed. In the reservoir, rotifers were not found in the diet of pikeperch
larvae even in the smallest individuals. Dominant food items were nauplii
and 1st copepodite instar of Eudiaptomus gracilis and Cyclops
spp. Cladocerans – Daphnia galeata
and to a lesser extent Diaphanosoma brachyurum appeared in the
pikeperch diet at a length of about 10 mm. A shift from copepods to Daphnia
spp. and especially Leptodora kindtii could be recognised in
pikeperch at a length of 20 mm. When comparing our data from nursing ponds
with the data from Římov reservoir,
similar trends in diet composition were observed.
Growth of
pikeperch was found significantly faster in nursing ponds than in the
reservoir. Slow growth of reservoir pikeperch was probably an artefact due
to the prolonged spawning period in the reservoir. Larvae and juveniles from
later spawnings decreased the average size of the population over the
studied period. In nursing ponds lowest average standard length at harvest
was found in the pond with the highest numbers of fish, and vice versa in
the pond with the lowest numbers the largest standard length was recorded.
This result corresponds to the increased intracohort food competition among
juvenile pikeperch with increasing stocking density.
(Hydrobiological
Institute AS CR, Na Sádkách
7, 370 05 České
Budějovice,
Czech Republic; E-mail: jpeterkacz@yahoo.com)