Lack of Angling‐Sized Yellow Perch in a Canadian Boreal Lake: Potential Influences of Growth Rate, Diet, and Predation by Double‐Crested Cormorants

Abstract

Fisheries for yellow perch Perca flavescens are economically important in North America, but in many lakes this species does not attain sizes desirable to anglers (total length [TL] . 250 mm). We investigated factors potentially contributing to the lack of angling-sized yellow perch in Dore Lake, Saskatchewan. This large boreal lake has a long history of exploitation and is subject to current controversy regarding the impact of double-crested cormorants Phalacrocorax auritus on its fisheries. We found that yellow perch in Dore Lake attained greater maximum ages (mean 6 SD ¼ 7.4 6 1.0 years) but smaller maximum sizes (215 6 7 mm TL) than other yellow perch populations. Thus, the lack of anglingsized yellow perch in Dore Lake is probably the result of slow growth rates rather than short life spans. Double-crested cormorants preyed heavily on yellow perch, but predation was highly skewed toward much smaller sizes (,100 mm TL) than those preferred by anglers. Stomach contents and stable nitrogen isotopes confirmed that yellow perch in Dore Lake undergo expected ontogenetic diet shifts and become predominantly piscivorous at around age 3. Analysis with stable isotopes also revealed long-term dietary differences between age-2 and age-3 yellow perch captured in littoral versus offshore habitats, suggesting some degree of intrapopulation variability in resource and habitat use among yellow perch in Dore Lake.

Cormorant predation on PIT-tagged lake fish

“…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). The lack of consensus between results from different studies is a clear sign of the level of complexity of this issue and to enable predictions about the effect of cormorant predation we need to better understand the complex predator-prey relations involved.…”

Fisheries restoration potential for a large lake ecosystem: using ecosystem models to examine dynamic relationships between walleye, cormorant, and perch

“…Cormorants have been linked to declines in fish populations (Fielder 2010, Dorr et al 2012, delayed fish population recovery (Barks et al 2010), and reduced fishery potential (Rudstam et al 2004). To this point, most research on cormorant-fishery conflicts has focused on single-species assessments of predation impacts on fish stocks and stock recovery after cormorant management (but see Mills et al 2003, Miehls et al 2009).…”

“…Expanding cormorant populations are regularly linked to declines in important fisheries such as the yellow perch (perch; Perca flavescens) fishery in the Les Cheneaux Islands region of Lake Huron (Fielder 2008), and both perch and walleye (Sander vitreus) fisheries in Oneida Lake in New York, USA (Rudstam et al 2004). In other areas, cormorant populations expanded after important fisheries collapsed, such as the alewife (Alosa pseudoharengus) fisheries in south-central Connecticut, USA (Dalton et al 2009) and perch fisheries in Dore Lake, Saskatchewan, Canada (Barks et al 2010). Where cormorants caused fishery reductions, cormorant control has generally improved prey fish survival enough to allow their recovery (Fielder 2010).…”

Relative demand by double-crested cormorants and anglers for fish production from lakes on Manitoulin Island, Lake Huron

“…4 in Barks et al, 2010). Yellow perch growth was limited in Dore Lake with perch achieving final sizes smaller than those preferred by anglers (Barks et al, 2010).…”

“…Yellow perch growth was limited in Dore Lake with perch achieving final sizes smaller than those preferred by anglers (Barks et al, 2010). Given this observation, food web limitations and/or risk sensitive foraging in relatively unproductive littoral habitat may have limited any possible gains through compensatory survival and expected higher growth for perch in Dore Lake (Barks et al, 2010). The magnitude or even occurrence of compensatory growth for yellow perch in Manitoulin Island lakes is unknown.…”