scholarly journals Vocal behaviour of the Great Cormorant Phalacrocorax carbo sinensis during the breeding season

Bird Study ◽  
2021 ◽  
pp. 1-9
Author(s):  
Saara Mäkelin ◽  
Magnus Wahlberg ◽  
Anna N. Osiecka ◽  
Claire Hermans ◽  
Thorsten J.S. Balsby
2016 ◽  
Vol 73 (1) ◽  
pp. 84-93 ◽  
Author(s):  
Outi Heikinheimo ◽  
Pekka Rusanen ◽  
Katja Korhonen

Estimates of the mortality rates caused by cormorants are needed to assess the impact on fish stock dynamics and fisheries. In this study, we calculated the annual instantaneous mortality caused by great cormorants (Phalacrocorax carbo sinensis) on young pikeperch (Sander lucioperca), using data from Archipelago Sea, southwestern coast of Finland. The pikeperch are vulnerable to cormorant predation mainly at the ages 2–4. The annual instantaneous mortality caused by cormorants was between 0.04 and 0.13, and the estimated effect on the pikeperch stock size at recruitment to the fishery ranged from 4% to 23%, respectively. The average annual cormorant-induced mortality accounted for 5%–34% of the total mortality in these age groups. The sensitivity analyses proved that the rates of mortality from other sources largely affect the estimated mortality from cormorant predation. In cases with strong fluctuations in the abundance of the prey fish stocks, ignoring the size and density dependence of the natural mortality may lead to overestimation of the importance of cormorants as competitors of fisheries.


2013 ◽  
Vol 49 (1) ◽  
pp. 194-196 ◽  
Author(s):  
Piotr Minias ◽  
Krzysztof Kaczmarek ◽  
Tomasz Janiszewski ◽  
Janusz Markowski

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