Cormorant Fish Research Articles

Characteristics of Cormorant Fishing on the Nagara River in the Early Modern Period: Focusing on the Relationship with Owari Domain

Characteristics of Cormorant Fishing on the Nagara River in the Early Modern Period: Focusing on the Relationship with Owari Domain

人・動物関係におけるリバランスという視座──中国と日本の鵜飼でみられるウ類への働きかけの事例から──

人・動物関係におけるリバランスという視座──中国と日本の鵜飼でみられるウ類への働きかけの事例から──

Can cormorants count?

Can cormorants count?

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

The double-crested cormorant (Phalacrocorax auritus) colony at Little Galloo Island, Lake Ontario has been a Great Lakes focal point of controversy regarding cormorant–fish interactions for over two decades. We examined cormorant diet and fish consumption at the colony from 1992 to 2013. During this time period, two events, management actions and round goby (Neogobius melanostomus) invasion, occurred that affected the number of fish consumed by cormorants and their diet composition. The purpose of this study was to evaluate the effects of round goby on the feeding ecology of cormorants and evaluate the efficacy of management actions on meeting cormorant population targets at the colony. Round goby first appeared in the diet in 2004 (0.8%) and within one year were the primary prey (29.3%). The presence of round goby in the diet of cormorants: (1) eliminated seasonal variability in diet composition, (2) reversed seasonal trends in the number of fish consumed daily, (3) increased daily fish consumption, and (4) significantly reduced the consumption of other species including yellow perch and smallmouth bass. Management actions, such as egg oiling and culling, were also effective in reducing nesting activity and the number of cormorant feeding days at the Little Galloo Island colony. There is evidence that the combination of management actions and round goby may have allowed some population recovery of yellow perch and smallmouth bass in eastern Lake Ontario.

Phalacrocorax carbo sinensis in Europe – indigenous or introduced?

Sincemany years now it is rumoured that the inland European cormorant Phalacrocorax carbo sinensis was introduced by Dutchmen from China to Holland in the 16th century to perform cormorant fishing in Europe and thus has to be classified an Invasive Alien Species (IAS). Although this hypothesis is not based on scientific evidence it has already been referred to in scientific literature. To check its plausibility, this review confronts three essential aspects of the introduction hypothesis with German sources mainly from the Middle Ages and historical reports on European cormorant fishing. The analyses show that there is no evidence for the introduction of birds from China. Instead, a medieval breeding record as well as regular appearance of the cormorant in religious and secular literature from the Middle Ages show that the bird was at least temporarily well-known in deeper inland regions of the German-speaking area. The results raise strong doubts about the hypothesis of Phalacrocorax carbo sinensis being an introduced alien species.

Trophic position of the Neotropic Cormorant (Phalacrocorax brasilianus): integrating diet and stable isotope analysis

Stable isotope analysis has been extensively used to establish trophic relationships within avian communities of marine ecosystems. The Neotropic Cormorant (Phalacrocorax brasilianus) is a good representative of marine bird communities along the northern coasts of South America. The diet and trophic position of the Neotropic Cormorant during the non-breeding season in a tropical lagoon, Bocaripo-Chacopata, in northeastern Venezuela, was determined by using gut content analyses and stable isotope ratios of carbon (δ13C) and nitrogen (δ15N), from birds, fish and invertebrates muscle tissue. Gut content and stable isotopes both indicated that cormorants are strict piscivores, whose diet is mainly based on benthonic fish, and thus occupy a high trophic level, above that of the piscivorous fish in the same habitat. Crustaceans and mollusks were circumstantial components of cormorant diet, found in the gut of some cormorant fish prey, as shown from their δ15N isotope values. A mixing model, MixSIR, estimated that two fish species, Cetengraulisedentulous and Arius sp., were the main components of the diet. However, consumer stable isotope values fell outside the mixing polygon, suggesting that either another food source with a larger 15N value was present in the diet of the cormorant but we failed to detect it, or, that we used inaccurate discrimination factors in the model. This cormorant species is a trophic specialist. It appears that, at least during the studied period, this population fed only on fish from the lagoon or from the nearby sea.

Cormorant Fishing and Ayu, Plecoglossus altivelis in Nagara River

Cormorant Fishing and Ayu, Plecoglossus altivelis in Nagara River

Cormorant Fishing in Southwestern China: A Traditional Fishery under Siege

Cormorant Fishing in Southwestern China: A Traditional Fishery under Siege

Cormorant Fishing in China

IT is sometimes said that since the neolithic age man has made no progress in domesticating wild creatures, except for the improvements made in the breeds of animals domesticated at that time. But the domestication of the cormorant in China belongs to a much more recent period. The story has been worked out in detail by Berthold Laufer of the Field Museum of Natural History, Chicago (Field Museum Publication 300, Anthropological Series, vol. 18, 1931). The earliest mention of the use of trained cormorants for fishing refers to Japan and dates from about A.D. 607, when, presumably, such use was unknown in China. Yet the trained cormorants of Japan are scarcely more domesticated than the English cormorants which James I. delighted to watch, and for whom he appointed a ‘master of the royal cormorants’. In China the birds are completely domesticated, being bred and reared in captivity, so that they become perfectly submissive to their masters, whose commands they understand, and whom they obey with the readiness and docility of a dog. Characteristic of their domestication is the appearance amongst them of colour varieties, particularly of albinistic and pied individuals. Their eggs are always hatched by domestic fowls and not by the cormorant mother, and the young are fed on special foods until the speriod of their training for fishing begins, and this lasts for seven or eight months.

On Cormorant Fishing in Japan

On Cormorant Fishing in Japan