Little Galloo Island, Lake Ontario: Two decades of studies on the diet, fish consumption, and management of double-crested cormorants

Johnson, James H.; McCullough, Russell D.; Farquhar, James; Mazzocchi, Irene M.

doi:10.1016/j.jglr.2015.03.030

Cited by 7 publications

(7 citation statements)

References 26 publications

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“…Cormorants were implicated in the decline of sportfish populations in some areas of the Great Lakes region (Burnett et al, 2002;Lantry et al, 2002;Rudstam et al, 2004;Fielder, 2008;Dorr et al, 2010). Cormorant diets, however, have been shown to be diverse, and sport species may not be the principle species consumed (Craven and Lev, 1987;Diana et al, 2006;Johnson et al, 2010Johnson et al, , 2015bDeBruyne et al, 2012DeBruyne et al, , 2013. This complexity in diet complicates interpretation of predation significance on sportfish populations.…”

Section: Introductionmentioning

confidence: 99%

Exploring potential effects of cormorant predation on the fish community in Saginaw Bay, Lake Huron

DeBruyne

Fielder

Roseman

et al. 2017

Journal of Great Lakes Research

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Stakeholders and fishery managers expressed concern that double-crested cormorant Phalacrocorax auritus predation may be a factor in the recent poor survival of yellow perch Perca flavescens in Saginaw Bay. We quantified cormorant diets from two nesting colonies in Saginaw Bay during April-September in 2013 and 2014, with special emphasis on impacts to yellow perch. Cormorants (n=691) were collected when returning to colonies after foraging. Stomachs were removed and preserved in the field. Diet items were identified, enumerated, and measured (n=23,373). Cormorant diets from Saginaw Bay indicate a heavy reliance on round goby and Notropis species as prey during the breeding season, consistent with other areas of the Great Lakes where round goby and cormorants coincide. Respectively, the three most common prey species observed by number (%) and biomass (%) pooled across years and sites were round goby Neogobius melanostomus (56.6%, 42.1%), emerald shiner Notropis antherinoides (25.2%, 12.5%), and yellow perch (8.0%, 14.1%). Diet composition was more variable at Spoils Island than at Little Charity Island. Overall cormorant consumption (estimated using cormorant consumption demand rates) of yellow perch was compared to walleye consumption. Cormorant consumption of age-1 yellow perch was 13-17% as much as mean walleye consumption of yellow perch in 2013 and 8-11% in 2014. The cumulative effects of walleye and spring cormorant predation likely represent a recruitment bottleneck for yellow perch in Saginaw Bay. Future studies determining age-specific abundance of yellow perch would facilitate better determination of cormorant predation significance.

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Section: Introductionmentioning

confidence: 99%

Exploring potential effects of cormorant predation on the fish community in Saginaw Bay, Lake Huron

DeBruyne

Fielder

Roseman

et al. 2017

Journal of Great Lakes Research

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“…It is certainly true, however, that cormorant predation is perceived to compete with human interests, and this perceived competition has indeed contributed to conflict between cormorants and humans in the eastern USA (Kuentzel et al 2012;Wires 2014). Proceeding to P3, there is evidence associating lethal management of cormorants with recovery in valued fish populations (Fielder 2010;Schultz et al 2013;Johnson et al 2015). However, these findings are context-specific, and the research has been critiqued for the presence of confounding variables and study design biases (Diana 2010;Schultz et al 2013;Johnson et al 2015).…”

Section: Resultsmentioning

confidence: 99%

“…Proceeding to P3, there is evidence associating lethal management of cormorants with recovery in valued fish populations (Fielder 2010;Schultz et al 2013;Johnson et al 2015). However, these findings are context-specific, and the research has been critiqued for the presence of confounding variables and study design biases (Diana 2010;Schultz et al 2013;Johnson et al 2015). Therefore, the truth of P3 also remains unclear.…”

Section: Resultsmentioning

confidence: 99%

Ethical Foundations for the Lethal Management of Double-Crested Cormorants (Phalocrocorax auritus) in the Eastern United States: An Argument Analysis

Batavia¹,

Nelson

2018

Waterbirds

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Lethal management of Double-crested Cormorants (Phalocrocorax auritus) has been implemented in many areas of the United States. In this paper, the philosophical method of argument analysis is used to assess ethical premises underlying the proposition that Double-crested Cormorant populations should be culled to reduce pressures on wild fisheries in the Great Lakes region of the eastern USA. This influential argument has been used to justify the destruction of more than half a million Double-crested Cormorants and hundreds of thousands of their nests and eggs. Three versions of the argument are formulated and assessed. It is shown that each of the arguments presupposes some form of anthropocentrism, an ethical stance considered by many in the scholarly community to be philosophically untenable and ethically inappropriate. It is suggested, consequently, that the arguments analyzed do not constitute an ethically sound basis for lethal management of Double-crested Cormorants in the Great Lakes region of the eastern USA.

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“…However, in studies where cormorant control has been implemented and fisheries outcomes evaluated, fishery improvements have been observed (Fielder 2010;Dorr et al 2012b;Schultz et al 2013;Johnson et al 2015;Coleman et al 2016). The strength of evidence varies for each study and in many cases is complicated by other contributing factors.…”

Section: Fisheriesmentioning

confidence: 99%

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

Dorr

Fielder

2017

Fisheries

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For centuries, people have viewed double‐crested cormorants Phalacrocorax auritus negatively, and human persecution coupled with environmental contamination severely reduced numbers of cormorants throughout North America. Shifts in paradigms for management of our natural resources resulted in reductions in environmental contaminants and regulatory protection of cormorants, allowing for an amazing population resurgence of this adaptable fish‐eating bird. However, for cormorants, as with some other native wildlife species the populations of which have rebounded due to conservation efforts, there have been cormorant‐societal conflicts with respect to commercial and natural resources such as aquaculture and sport fisheries. Increasing resource conflicts caused cormorants to be a priority with agencies responsible for their management, resulting in development of policy to facilitate addressing stakeholder concerns. Subsequent research and management in regard to cormorant issues have been subject to considerable challenges and debate. In this feature, we discuss the primary resource damage issues associated with cormorants, management efforts and outcomes, what we have learned, and the future with regard to cormorant management.

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Little Galloo Island, Lake Ontario: Two decades of studies on the diet, fish consumption, and management of double-crested cormorants

Cited by 7 publications

References 26 publications

Exploring potential effects of cormorant predation on the fish community in Saginaw Bay, Lake Huron

Exploring potential effects of cormorant predation on the fish community in Saginaw Bay, Lake Huron

Ethical Foundations for the Lethal Management of Double-Crested Cormorants (Phalocrocorax auritus) in the Eastern United States: An Argument Analysis

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

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