Tchitù : Study and Conservation of the Indo-Pacific bottlenose dolphins using the Southern lagoon of New Caledonia

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Financement : CCCE (Comité Consultatif Coutumier Environnemental)

Context
Recently recognized as a species in its own, the Indo-Pacific bottlenose dolphin is one of the most frequently observed cetaceans in the coastal waters of New Caledonia. Studies conducted over the past twenty years on this species have shown demographic and genetic isolation and the existence of a minimum of six distinct populations around the Grande Terre, main island of New Caledonia. Because of its coastal habitat, this species is threatened by anthropogenic pressures such as fragmentation or degradation of its habitat. The peripheral location of New Caledonia at the southeastern limit of its range increases the vulnerability of the species, as populations are potentially less resilient and more vulnerable.
Twenty years of data have been collected on this species in the Southern Lagoon but to date the population or populations that are present there remain unknown to the scientific actors as well as the managers. This lack of knowledge does not allow to establish a strategy of conservation of this species and to ensure their preservation.

Objectives
A first analysis of the data collected between 1997 and 2008 made it possible to count about 130 individuals. However, the data collected during the last ten years remain to be analyzed in order to be able to estimate the current composition of this population, to understand how it uses the Southern Lagoon and to know the exchanges between the different groups of dolphins within this vast area. In addition, a genetic analysis performed on Southern Lagoon dolphins between 2008 and 2009 showed that they have genetic similarities with some adjacent populations such as Noumea. The study of the potential exchanges between the Indo-Pacific bottlenose dolphins of the Southern Lagoon and those of the adjacent regions will help to understand the spatio-temporal evolution of the population structure of the Southern Lagoon and to estimate its degree of isolation.
Variations in the composition of the population may result from natural or anthropogenic disturbances. The main threats to marine mammals are disturbance from shipping, habitat degradation and fishing. In New Caledonia Southern Lagoon, maritime traffic has expanded significantly between 1995 and 2008, increasing the potential risk of interaction with marine mammals in this region. The study of the anthropogenic pressure on bottlenose dolphin population can be made from the analysis of the marks present on their dorsal fins: these marks may be due to interactions between animals but they may also indicate collisions or interactions with fishing gear. Thus, this analyze will help to estimate the potential pressures on the population.


Funded by the CCCE (Customary Environmental Advisory Committee), the TCHITU project will provide a state of knowledge of this population by answering the following questions:


- What is the composition of the Indo-Pacific bottlenose dolphin population?
- How does this population use the vast area of Southern Lagoon?
- Are there exchanges with neighboring populations?
- What potential anthropogenic pressures is this population subject to?



Financement :

CCCE (Comité Consultatif Coutumier Environnemental)


Partners :

CCCE (Comité Consultatif Coutumier Environnemental)

Opération Cétacés