An Assessment of Fish Predation on the Zebra Mussel, Dreissena Polymorpha (Pallas 1771) After Recent Colonisation of Two Managed Brown Trout Lake Fisheries in Ireland

Dietary contributions of the alien zebra mussel Dreissena polymorpha in British freshwater fish suggest low biological resistance to their invasion

“…Across the five fish species analysed here, only roach, a fish ubiquitous to British lowland freshwaters (Britton, 2007), had predictions that zebra mussels were contributing strongly to their diet. The population level model prediction of 44% is consistent with Prejs et al (1990), who suggested a predator-prey interaction between the two species, and Millane et al (2012) who detected roach consumed them in Table 3 Mean predicted dietary contributions, and their standard deviation and 5 and 95% credible intervals, from Bayesian mixing models (population and individual level models) of the prey resources of invertebrates (Gammaridae and Chironomidae), macrophytes ('plants') and zebra mussels to the diet of common bream and perch at site 1 Lough Sheelin, Ireland, in all seasons. For the other fish species, zebra mussels were never predicted to comprise of more than 29% of their diets at the population level.…”

“…This was also noted by Shcherbina & Bezmaternykh (2019), who also suggested that zebra mussel colonies also provide refuge for macro-invertebrates, increasing the difficulty of prey detection for perch during foraging. Roach were suggested in the literature as an important consumer of zebra mussels (Prejs et al, 1990;Millane et al, 2012) and, while they were only analysed in one site, the diet predictions here suggested all of the analysed fish had consumed some zebra mussels in recent months. However, this included individuals of below 160 mm length, whereas empirical studies have suggested a clear size threshold where these fish would not generally prey upon them (Prejs et al, 1990).…”