Seagulls attack whales in Patagonia

Seagulls attack whales in Patagonia

The lives of the southern right whale (Eubalaena australis) and the kelp gull (Larus dominicanus) pass through the southern hemisphere sea..

In Australia, South Africa, New Zealand and South America they are seen, both of them. Among some of them a problematic phenomenon occurs, which motivated a scientific investigation in Chubut, Argentina. The problem has not been resolved yet, but valuable information has been obtained.

The person who developed the research was the deputy director of the Center for the Study of Marine Systems (CESIMAR - CONICET), Dr. Marcelo Bertellotti, of the Applied Ecophysiology Laboratory, a specialist in biology applied to the management and conservation of marine species under pressure from human use, and expert in the relationship between the kelp gull and the southern right whale - common names by which these species are known.

In Puerto Madryn, Chubut province, Argentina, the city where he lives and works, I had the opportunity to interview him, while simultaneously, whales were seen on the beautiful coast of the Golfo Nuevo.

Marcelo has been consulted on numerous occasions by different journalistic media, because the final report of his work -which ended four years ago- has been published in several scientific articles and was the subject of two doctoral theses, one of them by Dr. in biology Ana Fazio, specialized in aquatic birds and the other in charge of Dr. Carla Fiorito in Veterinary Medicine, who studied the injuries generated in whales.

So the conclusions are known, however, in each season in which the whales arrive in this area, the phenomenon is repeated and continues to attract attention due to the insistence and lack of solution. For that reason I chose to interview him.

The phenomenon I am referring to is the "attack" of seagulls on the back of whales. And regarding the term in quotes, Marcelo makes an observation:in reality it is parasitism because one species benefits -the seagull- while the other is harmed -the whale-.

Enthusiastic, he begins to tell me that now the postulate seems simple, but when the phenomenon deepened in the 1990s, it was not, the population of seagulls that feed both on fish and dead fish discarded from the fishing industry grew, just as the whale population was growing, with long time on the surface suckling or mating on these beautiful southern shores of the Atlantic Ocean.

The hypothesis regarding the assault mechanism was installed at that time and Marcelo says thatAt this point I can say that seagulls are very intelligent, they have the ability to learn, they copy others, they attack and eat the skin and blubber of whales,They are generalists and opportunists, they eat everything and everything that appears at the moment.Concept that turned out to be a conclusion of value in the investigative work.

Seagulls were observed to preferentially assault calves, whose skin is younger. Marcelo clarifies that the skin of the whale has a very resistant integumentary system (the outer covering of the body, which contains the skin) and that it can shed that skin periodically. But puppies do not have as much body development and neither do their immune systems put to the test. Thus, they become preferred prey, and the "pecks" on the back remove skin at a deep level, causing an entry route through which different microorganisms enter, producing infections, with the consequent inflammations.There are adults who do not have injuries, but 100% of newborn individuals are injured.

It is difficult to cure them, but they recover themselves. They have a complex metabolism and a very special skin, which regenerates and flakes permanently and quickly, thus recovering. However, biopsies were taken because diseases associated with "pecking", by some virus, or by a very particular bacteria, which can be transmitted between them, were recorded.We have discovered three diseases not described before,stated the scientist.

The research was also based on their communication with colleagues in South Africa and Australia, verifying thatonly in the Golfo Nuevo and in the Golfo San José do the attacks occur.With this concept we coexist without the situation having changed too much ...

We talked about the experiment, which has already been widely publicized; it was carried out at sea and on land and started in 2005; in principle they observed the frequency of attacks, for that purposeWe partner with tourism companies, with one of our observers at each whale watching trip. El Doradillo was the place for observations from land, and embarked it was in Puerto Pirámides; we analyze the rate and intensity of attack (how many pecks per unit of time). The experimental test on seagull management, proposed by the administration of the province, was to eliminate individual seagulls associated with the whales; this position generated controversy… we wondered if it would make sense… it would have been about 100, 200, 300 specialist seagulls that attacked some whales and not all, since first we had to know if only a few “specialist” seagulls attack the whales, or if on the contrary all had the potential to do so, but it is not an appropriate practice for seagulls. At the same time, social pressure was growing, also from whaling companies, on the grounds that visitors want to see whales in a "pristine" environment and the permanent attacks of seagulls, undermine the quality of the watching experience.

In 2013, an intervention plan was developed to eliminate problem individuals, treating only attacking gulls, under the assumption that not all do. There were three years of selective elimination, a phenomenon of “you off " For the spanish people.Three thousand seagulls were shot with expert shooters from the security forces, who used shotguns and bullets to hunt ducks ... some individuals were extracted, while others arrived. During the resting stage, the frequency of attacks decreased markedly. This management only had an impact in Puerto Pirámides, while in El Doradillo there were no differences. When the experiment was over, everything went back to the way it was before.

Dr. Bertellotti stated thatThere are other less bloody methods, because shooting is not a solution, they can be controlled in a non-agonizing way.It canintervene in the colonies of gulls in which there are up to thousands of pairs reproducing, intervene on the nests, on the eggs, infertilizing them ... in this way, no chicks would be produced ... but it would have to be done for at least ten years to see a reduction in the seagull population ... These methods are complex to implement with poorly trained human resources, with limited financial resources and with the probability of other environmental problems arising.

(By the way, these days, this method is being used in Madrid to eliminate hundreds of parrots, of Argentine origin, which have become a plague in the Spanish capital.)

The scientist commented at the end of our interview, thatArgentina is a signatory of the International Whaling Commission, with a representative from the Foreign Ministry. The purpose is to maintain the moratorium on whaling, which is now as in "stand by", every year it is discussed if the ban is lifted ... and with the right whale there are no definitions because there is a lot of pressure ... The population argument wielded by Argentina, which considers that the population has not yet finished recovering is ancient ... there are nine thousand whales in the world, there are many more than the initial 300-500 and they are not in danger of extinction. The reality is that live whales have a special meaning for our culture, regardless of their abundance (or scarcity) so people and scientists are opposed to their hunt. This ethical argument about the population is currently proposed by Australia.

The meeting ended in front of the sea, while a few whales jumped and moved on the surface under a bright spring sun.

By Prof. Marilina Scarlata
Director of Scientific Dissemination Association Friends of National Parks
Member of the Education and Communication Commission (CEC- IUCN)

Video: PATAGONIA: Swimming with Sea Lions and Whale Watching in Argentina (October 2020).