Categories
News Sin categorizar

The dolphins in Banderas Bay

The dolphins in Banderas Bay
By: Biol. Astrid Frisch Jordán

Banderas Bay is considered a place of great importance among cetólogos commercial whalers and some from the late nineteenth century. Studies conducted in 1988 by Salinas and Bourillón in the Bay are 12 different species of Cetaceans, 9 of which belong to the suborder Odontoceti suborder Mysticeti and 3. In the odontocetes are the mottled Sthenelus (Stenella attenuata), the whirling Sthenelus (Stenella longirostris), bottlenose dolphins (Tursiops truncatus), the false killer whale (Pseudorca crassidens), rough-toothed dolphins (Steno bredanensis) dwarf sperm whale (Kogia sinus), Cuvier’s beaked whale (Ziphius cavirostris), killer whales (Orcinus orca) and Mesoplodonte. (Mesoplodon sp.) Of the baleen whales are the humpback (Megaptera novaeangliae), the Bryde (Balaenoptera edeni) and gray whales (Eschrichtius robustus), the latter being an occasional visitor.

 

The greatest concentration of species occurs during winter and summer decrease significantly in the spring, and being the most common species Stenella attenuata, Stenella and Tursiops truncatus longisrostris. Tursiops truncatus and Stenella attenuata are present all year and both species have been recorded in the coastal form (Stenella attenuata and Tursiops truncatus gilli graffmani). Among these species, one of the best known and appreciated is the bottlenose dolphin, known by some as the famous “Flipper.” Bottlenose dolphins belong to the Order Cetacea, suborder Odontoceti and Family Delphinidae. The genus Tursiops Tursi comes from the Latin meaning porpoise and the Greek suffix meaning ops face and the truncatus species comes from the Latin root meaning truncated truncated, this in relation to their short snout, compared with those of other dolphins.

The bottlenose dolphins or tursiones are medium in size ranging from 2.4 to the 4.2mts. are robust, short face, conical and thick. The dorsal fin is triangular, slightly falcate and broad-based. Their coloration is highly variable, but usually the back is gray to almost black (Watson, 1981; Urbán, 1983). The tursiones are distributed worldwide, avoiding high-latitude waters only. In Mexico you can find them in coastal and oceanic waters in both the Pacific and the Atlantic. In the Pacific gilli recognized subspecies of coastal habits distributed from the U.S. border to the south including the Gulf of California to the border with Guatemala, extending throughout Central America and the subspecies nuannu habits in the ocean tropical Pacific (Walker, 1981; Urbán, 1983).

In Bahia de Banderas are distributed throughout the bay, and you can submit birth throughout the year, being the most common time of the autumn-winter. The tursiones have been observed in interspecific associations with different species and in the specific case of the bay have been found with Sthenelus spotted (Stenella attenuata), false killer whales (Pseudorca crassidens), killer whales (Orcinus orca) and humpback whales ( Megaptera novaeangliae). They are known as an opportunistic species in their habits, and type of animals being fed is very diverse and includes fish, molluscs and crustaceans, in the case of Bahia de Banderas have been observed feeding mainly on horse mackerel (Caranx hippos) and mackerel (Scomber japonicus). Usually found in groups of less than 15 dolphins and grouped in herds consisting of several mature females and their offspring up to age 2, where regular, adult males and subadults, and young females swim in the periphery.

 

 

There are also herds of juveniles, which in some cases can be single sex. Sometimes several herds can meet in one group forming large flocks of up to several hundred people traveling together during very varied. They have a complex social organization open structure where members can be exchanged continuously and, in the case of coastal species may also possess a defined home range. However, different species and even different populations of the same species have variety in their social structure in response to environmental conditions, such as availability and distribution of food, the density of predators and physical characteristics of the environment (Scott et al . 1990). It seems that females play a more important role than males in the training and integration of the groups. It is usually associated with other females in groups known as very stable bands.

 

 

Descripción: C:UsersClauDocumentsWoRkecobacsitioimagenesnovedades-01-c.jpgOn the other hand, males are not associated with any particular band, rather they move from one band to another in search of receptive females, and this search can even take them beyond the limits of their communities. Sometimes males can associate in groups even more stable than those of females in pairs or threes, apparently in such associations to cooperate males corral steal them females or other males, and to establish some control over the community and thus have greater reproductive success (Connor et al. 1992). Similar associations between males are also present in some primate species with a strong dominance hierarchy, as is the case of macaques, chimpanzees and baboons, where such associations to improve their social status and access to receptive females and to defend them from other young males. In all cases the male partnerships are part of a strategy to obtain greater reproductive benefit (Felix, 1997).

 

 

Bottlenose dolphins are also known for their interactions with ships, as they enjoy the advantage of the waves and currents they generate, but it is important not to harass them because we can interfere with activities of breeding or feeding.Remember that you can not use jet skis or engage in commercial and sport fishing or close to the dolphins. Please do not throw any kind of objects into the water, especially plastics, cigarette butts or any synthetic material as they can cause problems for animals if the were to accidentally swallow. We want the dolphins still cheering the waters of our beautiful bay, they are counting on you to survive.