Guiana Dolphin

  1. Guiana Dolphin Electricity
  2. Guiana Dolphin Habitat
  3. Guiana Dolphin From The Front

Sep 03, 2013 Guiana dolphins live around the coast of South America and resemble the common bottlenose. Researchers discovered a depression on their rostrum (snout) that can detect electrical impulses given off by the muscles of fish. Scientists liken the sensitivity of its electroreception to that of a platypus. Vessel GUIANA DOLPHIN is a Tug, Registered in Niue. Discover the vessel's particulars, including capacity, machinery, photos and ownership. Get the details of the current Voyage of GUIANA DOLPHIN including Position, Port Calls, Destination, ETA and Distance travelled - IMO 9562788, MMSI 542476110, Call Sign E6RR2. The vessel GUIANA DOLPHIN (IMO: 9562788, MMSI: 542476110) is a Dredging or underwater ops It's sailing under the flag of NU Niue. In this page you can find informations about the vessels current position, last detected port calls, and current voyage information. French Guiana, an overseas department and region of France. Guyana, formerly known as British Guiana from 1831 until 1966, after the colonies of Berbice, Essequibo, and Demerara, taken from the Netherlands in 1814, were merged into a single colony. Suriname, formerly Dutch Guiana, until 1814 together with Berbice, Essequibo and Demerara.

IUCN status

Near Threatened

General

The Guiana Dolphin was previously listed as Data Deficient (DD) because the data available at the time on abundance, trends, and mortality levels or rates were considered inadequate for assigning it to a single Red List category (Secchi 2012). However, even though there is still a great deal of uncertainty concerning all of those parameters, the species does not fit the description of DD as given in the Red List Guidelines. Specifically, the Guiana Dolphin represents a case where, considering all available evidence, Least Concern, Near Threatened (NT) and Vulnerable are equally plausible and therefore, following the Red List Guidelines, the species is listed as NT, approaching Criterion A2d+3d+4d.The global population is likely too large (>10,000) and widespread (coastal marine and estuarine waters of eastern Central America and northeastern South America including the southern Caribbean Sea) for it to qualify for a threatened category under criterion B, C, or D, and there is no quantitative analysis of extinction risk that would allow consideration under criterion E. Therefore, the sole criterion of relevance is A, the decline criterion. Although Guiana Dolphins are affected by several threat factors including bycatch in fisheries, deliberate capture for bait, pollution, and habitat deterioration (see Crespo et al. 2010), no formal assessment has been carried out to evaluate the likelihood of population decline. There are no areas or local populations with time series of abundance estimates that have been used to quantify decline rates, but substantial declines have been reported or are suspected in some areas. For example, Guanabara Bay, Rio de Janeiro, Brazil has a small, declining population thought to number fewer than 40 individuals (Azevedo et al. 2017). Another example is Baía de Sepetiba, Brazil, where high densities were reported in 2002-2003 (Flach et al. 2008) but since then the local population is believed to have declined markedly (Leonardo Flach, pers. comm.). The area that was surveyed in the early 2000s has experienced extensive port development associated with the discovery of oil reserves offshore, dramatically increasing boat traffic and thus increasing the mortality of Guiana Dolphins (Flach et al. 2011). A researcher working in Baia Norte, Brazil reports that the large aggregations of Guiana Dolphins formerly seen there are no longer present and now there are only small groups (Paulo Flores, pers. comm).A rangewide decline in population size of 20-25% over three generations is plausible given the nature and scale of threats described by Crespo et al. (2010). Artisanal fishing with gillnets and other gear known to cause incidental mortality of Guiana Dolphins occurs throughout most of the species’ range, and the reported bycatch is high in the few areas where monitoring has occurred. The use of dolphin products as shark bait and “charms” (Cunha and Solé-Cava 2007) means that there are incentives to catch Guiana Dolphins deliberately and to make use of (and probably not report) those caught incidentally in fisheries. These dolphins’ near-shore, often estuarine, distribution ensures that some populations are exposed to high levels of pollution, particularly near large cities such as Sao Paulo and Rio de Janeiro in southeastern Brazil. The threats, which are generally increasing, are not being addressed in most parts of the species’ range. Despite some progress investigating subpopulation structure, relevant information is insufficient for subpopulation assessments under IUCN Red List criteria.

Habitat

Preferred habitats for Guiana Dolphins appear to be estuaries, bays, and other shallow, sheltered coastal waters. The southernmost limit of this species, at Santa Catarina State, southern Brazil (Simões-Lopes 1986), is thought to be defined by the low sea-surface temperature under influence of the Malvinas/Falkland Current (Flores and da Silva 2009), though no supporting data exist for this. In Guanabara Bay, the dolphins prefer the deeper channels (25 m depth) and avoid areas shallower than about 6 m (Azevedo et al. 2007). In open coastal areas, they seem to avoid deep waters (e.g., Edwards and Schnell 2001), although they can be sighted several kilometers from shore in areas where the continental shelf is shallow or in waters over offshore banks such as Abrolhos Bank, up to 70 km off the coast of Bahia State, northeastern Brazil (Rossi-Santos et al. 2006). In the Orinoco River, dolphins seen as far up as Ciudad Bolivar, Venezuela, probably belong to this species (Flores and da Silva 2009). Guiana Dolphins are also often seen at the mouth of the Amazon River. Fresh water from the Amazon River reaches hundreds of kilometers into the sea (Muller-Karger et al. 1988, in Cunha et al. 2010), so the animals sampled in Pará were actually living in fresh water. It would be interesting to analyze samples from intermediate locations along the Amazon River to determine how far upstream Guiana Dolphins occur and whether there is sympatry in any region with Tucuxis. Guiana Dolphins are patchily distributed (Borobia et al. 1991, Flores and da Silva 2009, Da Silva et al. 2010) as evident from the relatively small individual home ranges. In the species southernmost limit at Baia Norte, estimated home ranges were only about 10-15 km² (Flores and Bazzalo 2004). In the Cananéia estuary, São Paulo state, where Guiana Dolphins were found in water depths ranging from 1 to 23 m (Santos and Rosso 2007), observed home ranges varied from 0.8 to 244 km² based on the application of four tested methods (Oshima and Santos 2016). Guiana Dolphins consume both marine and estuarine species such as demersal and pelagic fishes of the families Sciaenidae, Clupeidae, Mugilidae, Trichiuridae, and Batrachoididae, as well as neritic cephalopods of the family Loliginidae (Borobia and Barros 1991, da Silva and Best 1994, 1996; Santos et al. 2002, Di Beneditto and Ramos 2004, Rosas et al. 2010). They also prey on penaeid shrimps (Santos et al. 2002) and crabs (Flores and da Silva 2009). Young age classes of teleost fishes, including over 60 species, are usually the most important items in the diet (Flores and da Silva 2009). In northern Rio de Janeiro, for example, lengths of prey fish ranged from 1.2 to 106.9 cm and mantle lengths of cephalopods varied from 3.4 to 22.2 cm (Di Beneditto and Ramos 2004). Sciaenids that produce relatively loud sounds by swim bladder contraction were observed to be common prey items. Feeding occurs both individually and in large groups. Predators of Guiana Dolphins may include Killer Whales (Orcinus orca) (Bittencourt 1983) and sharks, although there are no confirmed records for sharks other than an observed predation attempt by a Bull Shark (Carcharhinus leucas) (Santos and Gadig 2009).Males reach sexual maturity at 6-7 years of age and body lengths of 170–180 cm. Females mature at 5-7 years of age and body lengths of 160–169 cm (Di Beneditto and Ramos 2004, Rosas et al. 2010). Calving is year-round and gestation lasts 11–12 months, with calves ranging in size from 92 to 106 cm at birth (Di Beneditto and Ramos 2004, Rosas and Monteiro-Filho 2002, Rosas et al. 2010). No marked seasonality in ovulation or timing of births has been observed (Santos et al. 2001, Rosas and Monteiro-Filho 2002, Di Beneditto and Ramos 2004, Rosas et al. 2010). Calving intervals may be as long as three years and nine months (Santos 2010). The breeding system is promiscuous (Rosas and Monteiro-Filho 2002) within a fusion-fission society (Santos and Rosso 2008). Females older than 25 years have senescent ovaries (Rosas and Monteiro-Filho 2002). Maximum observed age (uncalibrated growth layer groups) was 29 years for males and 30 for females (Rosas et al. 2003, Santos et al. 2003, Di Beneditto and Ramos 2004). The generation length is estimated at 15.6 years (Taylor et al. 2007). Group sizes range between 1 and 40 individuals, and groups of 2-10 were most common in Guanabara Bay (Azevedo et al. 2007). In the Cananeia estuary, group size varied from lone individuals to aggregations of up to 60 (mean ± standard deviation: 12.4 ± 11.4 individuals; Santos and Rosso 2007). Larger aggregations of more than 400 individuals were observed at Ilha Grande, Paraty, and Sepetiba, Rio de Janeiro (Da Silva et al. 2010). No seasonal variation in group size has been reported. Nursery groups were twice as large as non-calf groups in Guanabara Bay and much more frequent in the Cananeia estuary. In the Cayos Miskito Reserve, Nicaragua, the mean group size was three (Edwards and Schnell 2001). Flores and da Silva (2009) reported that Guiana Dolphins do not associate with Bottlenose Dolphins (Tursiops truncatus) in Brazilian waters, and there are records of aggression of Bottlenose Dolphins towards Guiana Dolphins in Santa Catarina State (Wedekin et al. 2004).
(c) IUCN

South American fresh-water dolphins, tucuxi are as enchanting as they sound: playful, vivacious and highly social.

Known as the ‘other dolphin’ of the Amazon, there is still a lot to be learned about tucuxi, including their range. Part of the Sotalia genus, the two supposed-populations have now been recognized as separate species: the freshwater tucuxi and the marine Guiana dolphin.

Other names:

Sotalia, Gray dolphin

MaleFemaleCalf
Maximum length1.5m1.5m0.7m
Maximum weightUnknown53kgUnknown

What do tucuxi look like?

Guiana Dolphin Electricity

Guiana DolphinGuiana dolphin diagram

Tucuxi are highly aesthetic dolphins who aren’t dissimilar to bottlenose dolphins in appearance. Smaller than Guiana dolphins, they only grow to a dainty 1.5 metres long and weigh around 50kg. Whilst their bodies are coloured in muted tones of blues and greys, their bellies are much lighter in shades of ivory, grey or pink. Stood proudly on their backs, tucuxi have low, triangular dorsal fins. To their sides, they bear broad flippers whilst their faces have pronounced beaks. Although tucuxi can be up to 30% smaller than the Guiana dolphins, their ranges overlap and it’s nigh on impossible to tell them apart when only brief glimpses are seen.

What is life like for Tucuxi?

Whilst they have been seen in larger groups, tucuxi are most often found in small pods of just a few individuals. Together, they are extremely sociable and execute impressive stunts such as spyhopping, lobtailing, flipper-slapping and porpoising. They are, however, not so keen on socialising with people. Not ones to bow-ride or seek out human interaction, they prefer not to be approached and generally keep themselves to themselves. When they dive, tucuxi tend to only stay down for short periods of time, usually lasting 30 seconds to one minute. As well as other tucuxi, these dolphins are also happy to mingle with botos, the majestic, pink river dolphins.

The estimated population size for tucuxi is unknown.

Dolphin

What do Tucuxi eat?

Guiana

Tucuxi eat a wide variety of freshwater fish and crustaceans.

Where are tucuxi found?

Tucuxi have made themselves at home throughout the Amazon basin and possibly in the Orinoco River too and are found therefore in rivers throughout Colombia, Peru, Ecuador and Brazil. Although protected in some areas because of their legendary importance, in other areas tucuxi are deliberately targeted by fishermen who view them as threats to their trade and for use in traditional medicine. As well as this, they also face very real dangers in the form of pollution, accidental bycatch and getting caught in fishing gear, human interference, habitat loss and the constructions of dams.

Under threat

The eyes and genital organs from tucuxi are used by some local people as aphrodisiacs.

Diagram

Guiana Dolphin Habitat

The main threats...

  • Pollution – toxic chemicals along with plastic, litter and oil spills seriously harming their health and their ability to have young.
  • Fishing gear – tucuxi get accidentally caught in fishing nets and lines, injuring or even killing them.
  • Hunting - tucuxi are killed for their body parts or because fishermen see them as competition.

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Guiana Dolphin From The Front

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