Habitat Switch and Niche Overlap in Coregonid Fishes: Effects of Zooplankton Abundance

Abstract

Vendace (Coregortus albula) in Lake Mjøsa lived in the pelagic zone and gillnet catches were correlated with water temperature (r2 = 0.457, p < 0.005). Whitefish (Coregonus lavaretus) exploited both epibenthic and pelagic areas. Whitefish with body lengths between 25 and 35 cm moved from the epibenthic to pelagic zone during summer; other length groups remained in epibenthic habitats. The pelagic fish returned to epibenthic areas in the autumn. Cladocerans were important food items for both fish species in the pelagic zone. The large copepod Limnocalanus macrurus was eaten only by vendace whereas surface insects were more important prey for whitefish. This suggests that vendace is the more specialized zooplanktivore. The pelagic gillnet catch of whitefish and the pelagic habitat overlap between whitefish and vendace increased with increasing zooplankton densities at depths between 0 and 50 m (r2 = 0.609 and 0.494, respectively, p < 0.01). During spring and autumn we observed a time lag between the change in zooplankton abundance and habitat switches of whitefish. The fish moved to the more profitable habitat several days after food availability had changed, indicating an element of learning in choice of habitat.

A test of food web hypotheses by exploring time series of fish, zooplankton and phytoplankton in an oligo-mesotrophic lake

“…Furthermore, since almost all correlations between biomasses of zooplankton and phytoplankton groups were weak, it is suggested that inter-annual differences in pelagic fish density had no cascading influence on the phytoplankton in Lake Stechlin. Vendace are primarily zooplanktivorous fish (Naesje et al, 1991;Bohn and Amundsen, 2001). In empirical studies it was demonstrated that the feeding by vendace and the related whitefish (Coregonus spp.)…”

Diel and habitat-dependent resource utilisation of deep-sea fishes at the Great Meteor seamount (subtropical NE Atlantic): niche overlap and support for the sound-scattering layer-interception hypothesis

“…The data fit well into the theoretically determined bounds. Compared to reference data from estuarine and limnetic habitats (Naesje et al 1991, Thiel et al 1996, the isogram of 1.44 is a good approximation of maximum allowable overlap and minimum necessary distance in the fish communities considered.…”

Growth and Diet of Introduced Coregonid Fish Coregonus Peled (Gmelin) and Coregonus Lavaretus (L.) in Two Belgian Reservoir Lakes

“…On the other hand C. lavaretus was also reported as exclusively zooplanktivorous [29,43,44,2]. Some authors describe a diet composed of zooplankton and adult and larval insects [36,28,31,32]. According to these results adults of C. lavaretus can adapt their diet as exclusively zooplanktivorous, benthic or mixed in relation to the prey availability in their habitat.…”