Food selection of Coregonus lavaretus in a brackish water ecosystem

Abstract

This study examined how variability in the abundance and biomass structure of benthic invertebrates affected the feeding choice of the whitefish Coregonus lavaretus on a hard bottom habitat of the brackish Baltic Sea. In general, crustaceans such as Idotea balthica and Gammarus spp. were preferred over molluscs. Although being the most numerous taxon in the invertebrate samples, Mytilus trossulus was the lowest ranking in C. lavaretus food preference. The availability of benthic invertebrate prey set the dietary range of fish but the selectivity largely described fish feeding within this range. There was no clear link between fish predation and the dominance structure of benthic invertebrate communities, suggesting that species composition, abundance and biomass of invertebrate species had no impact on the feeding selectivity of the fish. Thus, while fish predation may not affect the dominant species within a benthic community, due to strong selectivity fish may impose strong pressure on some rarer but highly preferred invertebrate prey species.

Stomach content of whitefish, Coregonus lavaretus (Actinopterygii: Salmoniformes: Salmonidae), off the Åland Islands, Baltic Sea

“…As previously suggested (Verliin et al 2011) the twilight activity of whitefish and Idotea spp. coincide.…”

“…However, we have no data on the prey abundance at the samples sites. Notably, at the Åland Islands as in the Baltic Sea as a whole, food items of whitefish strongly alter over space and time, apparently due to growing habitat and seasonal differences in growth rates of the food species, verifying whitefish being opportunistic generalist omnivore and epibenthic feeder (Verliin et al 2011). Mytilus trossulus was one of the less consumed food items found.…”

“…Mytilus trossulus was one of the less consumed food items found. Notably, M. trossulus had the lowest ranking in C. lavaretus food preference at Neugrund Shallow, Gulf of Finland although being highly available (Verliin et al 2011). Simultaneous analysis of available food items and consumed ones is needed to collect knowledge on whitefish food preferences.…”

“…European whitefish, Coregonus lavaretus (Linnaeus, 1758), are opportunistic generalist epibenthic omnivores, but can show selective feeding behaviour within the available invertebrate prey dietary range (Jacobsen 1982, Tolonen 1997, Verliin et al 2011). Whitefish are sightfeeding predators with a diurnal or crepuscular feeding activity (Reebs 2002).…”

“…In June, July, and August 1964 stomachs of whitefish from the northern Åland Islands contained molluscs, insects, and fish eggs with species frequencies strongly varying over the months (Himberg 1995). Verliin et al (2011) investigated the food preferences of whitefish sampled from a hard bottom area in the neighbouring western part of the Gulf of Finland (Neugrund Shallow, Estonia). They found that whitefish is a selective feeder that prefers crustaceans, particularly isopods to other benthic invertebrates.…”