<abstract xmlns="http://www.w3.org/1999/xhtml"><p>Increases in the population abundance of the piscivorous great cormorant (<italic>Phalacrocorax carbo</italic>) has led to conflicts with fisheries. Cormorants are blamed for decreased fish catches in many lakes in Poland. The aim of this paper is to describe to role of pikeperch (<italic>Sander lucioperca</italic>) in the diet of cormorants nesting in a colony on the island in Lake Warnołty. Since the breeding colony is located in the vicinity of Lake OEniardwy, the largest lake in Poland, the cormorants use the resources in this lake. In 2009-2016, 18,432 regurgitated fish were collected, of which 593 were pikeperch. The share of pikeperch among fish collected in 2009-2012 did not exceed 2%, but from 2013 this increased substantially to maximum of 38.2% in 2015. The smallest pikeperch had a standard length of 8.4 cm, and the largest 42.5 cm. Pikeperch mean length differed by year, and the length distribution was close to normal. The sizes of the regurgitated pikeperch indicate that cormorants prey almost exclusively on juvenile specimens. The results of the present study indicate that cormorant predation has a significant impact on pikeperch populations in lakes in the vicinity of the colony, and the great cormorants are possibly a significant factor in the effectiveness of pikeperch management. When planning for the management of fish populations in lakes subjected to cormorant predation pressure, it should be borne in mind that predation by this piscivorous bird species impacts the abundance and size-age structure of fish populations.</p></abstract>

Increases in the population abundance of the piscivorous great cormorant (Phalacrocorax carbo) has led to conflicts with fisheries. Cormorants are blamed for decreased fish catches in many lakes in Poland. The aim of this paper is to describe to role of pikeperch (Sander lucioperca) in the diet of cormorants nesting in a colony on the island in Lake Warnołty. Since the breeding colony is located in the vicinity of Lake OEniardwy, the largest lake in Poland, the cormorants use the resources in this lake. In 2009-2016, 18,432 regurgitated fish were collected, of which 593 were pikeperch. The share of pikeperch among fish collected in 2009-2012 did not exceed 2%, but from 2013 this increased substantially to maximum of 38.2% in 2015. The smallest pikeperch had a standard length of 8.4 cm, and the largest 42.5 cm. Pikeperch mean length differed by year, and the length distribution was close to normal. The sizes of the regurgitated pikeperch indicate that cormorants prey almost exclusively on juvenile specimens. The results of the present study indicate that cormorant predation has a significant impact on pikeperch populations in lakes in the vicinity of the colony, and the great cormorants are possibly a significant factor in the effectiveness of pikeperch management. When planning for the management of fish populations in lakes subjected to cormorant predation pressure, it should be borne in mind that predation by this piscivorous bird species impacts the abundance and size-age structure of fish populations.

Great cormorant (<italic>Phalacrocorax carbo</italic>) predation on pikeperch (<italic>Sander lucioperca</italic> L.) in shallow eutrophic lakes in Poland

Department of Lake Fisheries, Giżycko, Inland Fisheries Institute in Olsztyn

Department of Ichthyology, Hydrobiology, and Aquatic Ecology, Inland Fisheries Institute in Olsztyn

Fisheries & Aquatic Life

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Great cormorant () predation on pikeperch ( L.) in shallow eutrophic lakes in Poland

Increases in the population abundance of the piscivorous great cormorant (Phalacrocorax carbo) has led to conflicts with fisheries. Cormorants are blamed for...

Great cormorant (Phalacrocorax carbo) predation on pikeperch (Sander lucioperca L.) in shallow eutrophic lakes in Poland

Published Online: Jul 22, 2017

Page range: 123 - 130

Received: May 08, 2017

Accepted: Jun 16, 2017

DOI: https://doi.org/10.1515/aopf-2017-0012

Keywords
lake, Percidae, lake fisheries, fish assemblages

© 2017 Archives of Polish Fisheries

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Great cormorant (Phalacrocorax carbo) predation on pikeperch (Sander lucioperca L.) in shallow eutrophic lakes in Poland

Published Online: Jul 22, 2017

Page range: 123 - 130

Received: May 08, 2017

Accepted: Jun 16, 2017

DOI: https://doi.org/10.1515/aopf-2017-0012

Keywordslake, Percidae, lake fisheries, fish assemblages

© 2017 Archives of Polish Fisheries

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
lake, Percidae, lake fisheries, fish assemblages