Differences in feeding selectivity and efficiency between young-of-the-year European perch (Perca fluviatilis) and roach (Rutilus rutilus) — field observations and laboratory experiments on the importance of prey movement apparency vs. evasiveness

Abstract

Differences in feeding selectivity and efficiency between young-of-the-year European perch (Perca fluviatilis) and roach (Rutilus rutilus) -field observations and laboratory experiments on the importance of prey movement apparency vs. evasiveness Jiří Peterka & Josef MatěnaBiology Centre of the Academy of Sciences of the Czech Republic, Institute of Hydrobiology, Na Sádkách 7, CZ-37005 České Budějovice, and Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic; e-mail: jpeterkacz@yahoo.com Abstract: Feeding selectivity and efficiency of young-of-the-year European perch and roach were compared under field and laboratory conditions. In laboratory experiments, the importance of prey evasiveness versus prey movement conspicuousness for fish selectivity was evaluated with respect to changing Cladocera/Copepoda prey ratio. Feeding efficiency was additionally investigated in relation to feeding time (5, 10, 20 min) and prey density (approx. 50, 200, 700 ind. L −1 ). In Římov Reservoir, the diet of both fish species was nearly exclusively composed of crustacean zooplankton. In roach, diet shifted from rotifers and bosminids in May, towards Daphnia sp. and Leptodora kindtii in June and July. Daphnia contributed almost exclusively to the roach diet since June, composing on average more than 94% of total prey. Cyclopoid copepods, occurred in the roach's diet only on the first sampling date; later on both cyclopoid and calanoid copepods were completely absent. On the other hand, copepods played an important role in the diet of perch. In early and mid-June when their share in the zooplankton was particularly high, copepods contributed by more than 50% to the diet of perch. Although their contribution dropped with their decline in zooplankton in June/July, by the end of July they again comprised about one third of perch's diet. In both fish species, the increase in numbers of cladocerans in their diet was related to increase in SL. In roach, the numbers of consumed prey were doubled every twenty days during the investigated period. In perch the increase was not so consistent, but significantly higher efficiency of perch was reported on three out of six sampling dates. In laboratory experiments, roach showed a distinct avoidance for copepods and a preference for cladocerans. Both prey categories were only fed non-selectively when they dominated the prey mixture. Perch selectivity was more diversified. Contrary to roach, perch were fed copepods non-selectively on a balanced prey ratio. Further, with an increasing share of Cladocera, a situation resembling that of roach and Copepoda was avoided. However, when the share of copepods in the prey mixture dropped below ten percent, they were consumed non-selectively and with their ongoing decline in the prey mixture their preference even increased. Feeding efficiency differed significantly between perch and roach when foraging on copepods exclusively or on a prey mixture where copepods predominated. In the short time feeding experi...

The food of roach, Rutilus rutilus (Actinopterygii: Cypriniformes: Cyprinidae), in a biomanipulated water supply reservoir

“…The most significant changes in roach food composition are found in steep-sided canyon-shaped valley reservoirs, Roach diet in a reservoir 19 68.9 ± 12.7 189.4 ± 63.9 63.7 ± 24.6 222.2 ± 73.1 35.7 ± 13.2 122.1 ± 17.6 38.2 ± 11.4 185.1 ± 65.5 Hammer (1985), Ponton and Gerdeaux (1988), Giles et al (1990), and Peterka and Matěna (2009) all found roach to specialise in feeding on crustacean zooplankton at such sites only Richeux et al (1992) found, by contrast, in the deep lake of Pareloup (Massif Central, France) that smaller roach (10-21 cm) had a diet chiefly of detritus and zooplankton, whilst oldest individuals were detritivores. While roach typically select zooplankton in deep reservoirs, its ability to feed on detritus may also provide it with an energetic advantage, increasing the carrying capacity for this species in lakes where detritus occurs and is accessible.…”

Feeding preference of threadsail filefish Stephanolepis cirrhifer on moon jellyfish and lobworm in the laboratory

“…Peterka & Matena (2009) demonstrated that prey selection in young-of-the-year roach Rutilus rutilus (Linne) was determined by prey evasiveness. In our study, the movement of jellyfish was restricted because they were tethered by a string.…”

Feeding behaviour determining differential capture success of evasive prey in underyearling European perch (Perca fluviatilis L.) and roach (Rutilus rutilus (L.))

“…The diet and feeding behaviour of perch and roach juveniles has been investigated both in the field and laboratory, and differences in the feeding efficiency for the two most frequent zooplankton taxa i.e. cladocera and copepoda have been reported repeatedly (Winfield et al, 1983;Hammer, 1985;Winfield & Townsend, 1988;Mark et al, 1989;Bergman, 1990;Matěna, 1995;Macháček & Matěna, 1997;Vašek et al, 2006;Peterka & Matěna, 2009). The highest ecological consequences have the findings of Persson (1987), who found juveniles of roach more efficient foragers over perch when feeding on Daphnia sp.…”