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Sep 09 2014

The great cormorant (Phalacrocorax carbo); a bird of luck or a nightmare

Photo credit: Magd Al-Bawaab (Egypt)

Review: Abdel Rahman El Gamal (Founder of the website)

 

The great cormorant (Phalacrocorax carbo), has also several names such as the great black cormorant, the black cormorant, the large cormorant, the black shag, and “Aggag” in Arabic. The great cormorant is a large black bird with a typical range from 2.6 to 3.7 kg.

Distribution and habitats: The great cormorant has an extremely large range and can be found on all continents except South America and Antarctica. The bird habitats should have trees, bushes, reedbeds or bare ground for nesting. The species inhabits marine environments (sheltered coastal areas, saltpans, coastal lagoons, wetlands, and mangrove swamps) as well as fresh and brackish water lakes, reservoirs, rivers, flood waters, and swamps.

Interesting facts:

Flying: there are indications that the distance of unbroken flights for cormorant birds can reach about 600 km which are reached in around 12 hours of continuous flying.

Diving: the great cormorants catch fish by diving from the surface. Typically, the bird preys mainly on benthic fish species which occur at depths of up to 10 meters.

Migration:Depending on the severity of the winter in Northern Europe, some cormorants may just move few hundred kilometers southwards whereas others fly across the Mediterranean to the coast of North Africa.

Cormorant fishing: The use of cormorant if fishing on behalf of fishermen has been practiced around the globe especially in China and Japan. In such practice, fishermen tie a line tightly enough around the birds’ throats to prevent swallowing of their catch of fish and enable the fishermen to retrieve the fish by forcing open the cormorants’ mouths.

Feeding habits: Cormorants are exclusively fish eaters.  They may occasionally eat crustaceans, amphibians, and molluscs. Based on different citations, the daily food intake (DFI) for a bird specimen is about 500g of fish. However, much more fish will be required during the breeding season to enable the birds feeding their young. The birds feed exclusively during the day (diurnal).

Hunting and conservation measures: Fishermen in the past felt the damage caused by the cormorants on fishery stocks ended by hunting down to extinction in Europe during the 19th century calling for conservative measures that led to a large increase in the populations of cormorants across Europe during the last 30-40 years.  In EU Member States all wild bird species including the cormorants are protected by the EU Birds Directive. However, under certain circumstances, there is a room licensing to kill cormorants when the bird danger turns serious and the heavy losses of fish in fish farms or fisheries can be demonstrated. Based on that, annual licenses are granted to shoot specified numbers of cormorants. As expected, killing a bird without such license is still illegal.

Cormorants and fishery/aquaculture in Egypt: Costal areas in Egypt fall in the annual migration trip of the great cormorant. Significant losses in fish stocks whether in fishery have been reported (e.g. Bardawil lagoon). The matter turns even worse in regard to fish farms that got attacked by the bird. Based on reliable sources, I have been told that a single touch-down of cormorant was sufficient to take few tons of fish of harvestable size. I knew also that farms try whenever possible to reduce the number of such unwanted visits paid by the bird. Because the management of fish farms using deal with marine fish of two-year growing season (seabass, seabream and meagre), it becomes impossible to avoid one unpleasant visit of cormorant. Thus, farms practice various methods to scare the birds and prevent their landing in the premises of their farm. Almost all methods focus on noise creation whether using false shooting (sound shooting), motorcycling and pick-up driving along pond dykes, or using the bird scarers which broadcast specific tunes against cormorants.  The photos attached show fishermen while scaring a fleet of cormorant using sound shooting while the shown specimen of cormorant shows the fish prey that was in the bird’s digestive tract. Because of their numbers, size and their means of hunting, cormorants are believed to cause greater damage to some fisheries in a shorter time compared to other fish-eating birds.

Let us conclude by the contrasting views in which cormorants are regarded as good luck when they gather near a village or settlement while thinking of possible attack of the bird is a nightmare to fishermen and fish farmers.

References:Bird Life, European Commission, Wikipedia

Great cormorant 02 Great cormorant 01

 

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