The Relationship Between the Abundance of Smallmouth Bass and Double-crested Cormorants in the Eastern Basin of Lake Ontario

Cormorant predation on PIT-tagged lake fish

“…This add to the growing body of evidence that percids (Perca spp.) are particularly vulnerable to cormorant predation (Lantry et al, 2002;Eschbaum et al, 2003;Rudstam et al, 2004;Fielder, 2010;Vetemaa et al, 2010;Bacheler et al, 2011;Emmrich andDuettmann, 2011, Östman et al, 2012, but see Diana et al, 2006). The underlying reason for the apparent preference for perch could be related to the behaviour of the fish in terms of flight response (Cosolo et al, 2010).…”

“…Some studies suggest that the increasing abundance of cormorants has caused long-term declines of local fish populations (Lantry et al, 2002;Rudstam et al, 2004;Koed et al, 2006;Jepsen et al, 2010;Fielder, 2010). Other investigations from both lake and open coastal ecosystems found cormorants to have a low impact on fish communities and fisheries (Linn and Campbell, 1992;Engström, 2001;Barks et al, 2011;Lehikoinen et al, 2011;Östman et al, 2012).…”

Eating the Invaders: The Prevalence of Round Goby (Apollonia melanostomus) in the Diet of Double-Crested Cormorants on the Niagara River

“…Where cormorants are abundant and alternate prey species are not available, sport-fish populations are more likely to experience the negative influences of cormorant predation. Lantry et al (2002) calculated that cormorants annually reduced the population of age three to age five (prerecruit) small-mouth bass in Lake Ontario by 23% in 1993-4 and 36% in 1998. Based on the 1998 estimate, the cumulative effect of cormorant predation on juvenile year classes in Eastern Lake Ontario could suppress smallmouth bass recruitment by 78%.…”

Double‐Crested Cormorants: Too Much of a Good Thing?

“…The tendency for cormorant predation to mimic recruitment declines (poor reproductive success) is often given as a competing hypothesis to cormorant-caused declines of a fish population. A number of researchers have documented this reduced recruitment effect of cormorant predation on Yellow Perch (O'Gorman and Burnett 2001;Fielder 2008Fielder , 2010, Walleye Sander vitreus (Rudstam et al 2004;Dorr et al 2010;Coleman et al 2016), and Smallmouth Bass Micropterus dolomieu (Lantry et al 2002), with some describing the phenomena as a mortality bottleneck prior to recruitment (Figure 2). This predation effect may reflect foraging cormorants being tied to a breeding colony (central place foraging) for extended periods.…”