Cormorant diet in relation to temporal changes in fish communities

Boström, Maria; Östman, Örjan; Bergenius, Mikaela; Lunneryd, Sven-Gunnar

doi:10.1093/icesjms/fss002

Cited by 31 publications

(22 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The size ranges of perch and pikeperch eaten by cormorants agree with the results of previous studies where cormorants were found to prefer slender, 5-36 cm prey (Lunneryd and Alexandersson, 2005;Liordos and Goutner, 2007;Čech et al, 2008;Boström et al, 2012b). Looking at the whole prey size spectrum, the majority of consumed perch fall on the left hand side of the median, while most pikeperch fall to the right hand side of the median.…”

Section: Diet and Size Distributionsupporting

confidence: 89%

“…For the birds in colonies located in these areas or near them, pikeperch is an important prey species. Lehikoinen (2005) and Boström et al (2012b) found few pikeperch in their study in the northern Baltic Sea, but Eschbaum et al (2003) found high quantities of pikeperch consumed by cormorants in the shallow areas (mean depth < 10 m) off the west coast of Estonia.…”

Section: Diet and Size Distributionmentioning

confidence: 90%

See 1 more Smart Citation

Perch (Perca fluviatilis) and pikeperch (Sander lucioperca) in the diet of the great cormorant (Phalacrocorax carbo) and effects on catches in the Archipelago Sea, Southwest coast of Finland

Salmi¹,

Auvinen²,

Raitaniemi³

et al. 2015

Fisheries Research

View full text Add to dashboard Cite

Section: Diet and Size Distributionsupporting

confidence: 89%

Section: Diet and Size Distributionmentioning

confidence: 90%

Perch (Perca fluviatilis) and pikeperch (Sander lucioperca) in the diet of the great cormorant (Phalacrocorax carbo) and effects on catches in the Archipelago Sea, Southwest coast of Finland

Salmi¹,

Auvinen²,

Raitaniemi³

et al. 2015

Fisheries Research

View full text Add to dashboard Cite

“…The diet study is based on several hundred stomachs from each area. But the interval of the relative contribution of some fish species to total biomass can be 50–100% of the estimated value [26]. Although the number of breeding birds is rather well documented we had to use estimates from other studies on number of foraging days of non-breeding and overwintering birds.…”

Section: Discussionmentioning

confidence: 99%

Estimating Competition between Wildlife and Humans–A Case of Cormorants and Coastal Fisheries in the Baltic Sea

et al. 2013

Self Cite

View full text Add to dashboard Cite

Cormorants and other wildlife populations have come in real or perceived conflicts with humans over exploited fish stocks. From gut contents of cormorants, and using an extension of the Catch equation, we estimated the degree of short term competition between great cormorants and coastal fisheries in two areas along the Swedish Baltic Sea. Cormorants consumed 10 and 44%, in respective area, of the fish biomass of six fish species harvested by humans; eel, flounder, herring, perch, pike, and whitefish. On average, cormorants consumed smaller individuals than harvested in fisheries. But for perch, cod and flounder, cormorants consumed harvestable sized fish corresponding >20% of human catches. Our competition model estimated the direct decrease in fisheries catches due to cormorant predation to be <10% for all species except flounder (>30%) and perch (2–20%). When also including the indirect effects of cormorant predation on smaller fish that never reached harvestable size, the estimated decrease in fisheries catches at least doubled for perch (13–34%) and pike (8–19%). Despite large uncertainties, our model indicates that cormorants may locally have a direct impact on human catches of at least flounder, and when incorporating indirect effects also on perch and pike. The study indicates that the degree of competition between cormorants and humans varies substantially between areas. We also included economical values in the model and concluded that for the commercially most important species, eel and cod, the estimated economic impact of cormorants on fisheries was low.

show abstract

“…Based upon these enrichment factors, cormorants seem to be feeding at least five levels above producers in this system, likely on piscivorous fish. Recent studies have shown that showing cormorants consume a variety of fish species, including large numbers of benthivores (which consume invertebrates as well as small fish) such as three-spine stickleback ( Gasterosteus aculeatus ), roach ( Rutilus rutilus ), and eelpout ( Zoarces viviparous ) as well as piscivorous predators (mostly perch ( Perca fluviatilis) ), though diet composition varies widely depending on the season and on local fish abundances [38], [39].…”

Section: Discussionmentioning

confidence: 99%

Seabird Guano Fertilizes Baltic Sea Littoral Food Webs

et al. 2013

View full text Add to dashboard Cite

Nutrient enrichment in coastal marine systems can have profound impacts on trophic networks. In the Baltic Sea, the population of Great Cormorant (Phalacrocorax carbo sinensis) has increased nearly exponentially since the mid-1990s, and colonies of these seabirds can be important sources of nitrogen enrichment for nearby benthic communities due to guano runoff. In this study we used stable isotope analyses and diet mixing models to determine the extent of nitrogen enrichment from cormorant colonies, as well as to examine any possible changes in herbivore diet preferences due to enrichment. We found significantly higher levels of δ15N in samples from colony islands than control islands for producers (the dominant macroalga Fucus vesiculosus, filamentous algae, and periphyton) and herbivores, as well as a positive correlation between enrichment and nest density in colony sites. We also found that enrichment increased over the breeding season of the cormorants, with higher enrichment in late summer than early summer. While the amount of total nitrogen did not differ between colony and control sites, the amount of guano-based nitrogen in algae was >50% in most sites, indicating high nitrogen enrichment from colonies. Herbivores (the isopod Idotea balthica and the gastropod Theodoxus fluviatilis) preferred feeding upon the dominant macroalga Fucus vesiculosus rather than on filamentous algae or periphyton in both control and colony, and there was a significant increase in periphyton consumption near colony sites. Overall, guano from cormorant colonies seems to have effects on both producers and herbivores, as well as the potential to modify algae-herbivore interactions.

show abstract

Cormorant diet in relation to temporal changes in fish communities

Cited by 31 publications

References 17 publications

Perch (Perca fluviatilis) and pikeperch (Sander lucioperca) in the diet of the great cormorant (Phalacrocorax carbo) and effects on catches in the Archipelago Sea, Southwest coast of Finland

Perch (Perca fluviatilis) and pikeperch (Sander lucioperca) in the diet of the great cormorant (Phalacrocorax carbo) and effects on catches in the Archipelago Sea, Southwest coast of Finland

Estimating Competition between Wildlife and Humans–A Case of Cormorants and Coastal Fisheries in the Baltic Sea

Seabird Guano Fertilizes Baltic Sea Littoral Food Webs

Contact Info

Product

Resources

About