Abundance, distribution and behaviour of common dolphins,Delphinusspp., off north-eastern Venezuela: implications for conservation and management

Abstract

The north-eastern coast of Venezuela hosts a high diversity of megafauna, particularly related with high productivity due to coastal upwelling. This area is mainly characterized by the existence of the primary fisheries in Venezuela, mostly supported by a great abundance of small pelagic species. This would explain why the area supports a wide range of marine top predators, including cetaceans. The current status of cetacean populations off north-eastern Venezuela is uncertain, mainly because research efforts have been very sparse. There are still many gaps of information in cetacean biology to establish a solid baseline that can be used for management decisions. Common dolphins (Delphinus spp.) are widely dispersed over the whole northeast basin, including waters off Araya and Paria Peninsula and around Margarita, Coche and Cubagua Islands. Areas of higher densities for Delphinus spp. coincide with the focal location of sardine fisheries and the most-active upwelling on the north-eastern coast. Therefore, a scheme of management should consider the areas of major productivity along the coast as potential critical habitat for the species. Further data collection is recommended, increasing aspects such as trophic ecology and the continuity of behavioural sampling, paired with systematic line transect estimation.

Range extension for the common dolphin (Delphinus sp.) to the Colombian Caribbean, with taxonomic implications from genetic barcoding and phylogenetic analyses

“…The nearest population of common dolphins inhabits the Cariaco Basin off the central/eastern coast of northern Venezuela [ 17 , 23 ], some 700–1400 km to the east of the area surveyed in this study. A stranding record from western Venezuela near the Colombian border [ 55 ] was considered unusual in the review of Jefferson [ 17 ].…”

“…Particularly in the Western South Atlantic, the long-beaked morphotype has been described only based on a report published by Casinos [ 21 ], who conducted craniometric measurements on ten specimens from Venezuela, Brazil and Argentina, of which only six corresponded to the long-beaked morphotype [ 1 , 7 ]. In fact, initial morphological and genetic studies of Western South Atlantic specimens suggest that a different taxonomic classification should be considered in this region [ 4 , 11 , 14 , 22 , 23 ]. For this reason, and because the global taxonomy of long-beaked common dolphins remains unresolved, we refer to the animals observed in this report as Delphinus sp.…”

“…This is an apparently isolated, coastal population of common dolphins occurring mainly in the Cariaco Basin of eastern coast of Venezuela [ 17 ]. The species is common in waters around Margarita Island, Mochima National Park, the Gulf of Cariaco, and the Araya and Paria peninsulas [ 23 ]. Isolated records from the Gulf of Venezuela to the west and from Trinidad to the east have been considered as vagrants by Jefferson [ 17 ].…”

Cetaceans observed in Suriname and adjacent waters

“…A recent review by Jefferson et al (2009) shows that the species is expected to occur off the Guianas. The only reliable records are of a long-beaked common dolphin captured off Trinidad in April 2006 23 , a stranding in the Gulf of Paria (Oviedo et al, 2010), a sighting off Aruba (Luksenburg, 2013), and recently the species was validated for French Guiana 17 , central-western Venezuela 22 and Colombia (Palacios et al, 2012). The species has not been confirmed to occur in most of the Caribbean Sea, i.e.…”

Climate change and marine mammals

“…The north-eastern coast of Venezuela hosts a high diversity of marine megafauna, particularly related to the high productivity arising from coastal upwellings there. Oviedo et al (2010) found that areas of highest densities of common dolphins, Delphinus spp., coincided with the centre of sardine fisheries and the most active upwellings on the north-eastern coast.…”