Diving activity of a solitary wild free ranging bottlenose dolphin (Tursiops truncatus)

Solitary wild bottlenose dolphins and man frequenting the same small areas makes boat interaction more or less inevitable. Here we provide the first quantified data about solitary bottlenose dolphin diving behaviour in the presence and absence of boats. Over 110 hours were spent observing a solitary bottlenose dolphin within a 6 km2 bay on the north-western coast of Spain from April to August 2005. A generalized linear mixed model explaining 77.3% of the variability of duration of dives indicated that the animal did not vary its diving activity in function of the presence of boats. However, the length of dives was related with the behavioural events prior to dive. Dolphin activity was characterized by mean dive intervals (mean = 62.6 seconds) related to a predominance of foraging behaviour. Because of the frequent presence of boats and the manner in which they moved, the dolphin may have become accustomed to their presence. The data reported here could be used to implement precautionary management proposals that take into account the potential effects of boat presence on bottlenose dolphins.

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The first record of a piebald common bottlenose dolphin (Tursiops truncatus) in offshore waters of the north-western Black Sea

Theriologia Ukrainica ◽

10.15407/tu1911 ◽

2020 ◽

Vol 2020 (19) ◽

pp. 103-107

Author(s):

Oksana Savenko ◽

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Keyword(s):

Black Sea ◽

Coastal Waters ◽

Bottlenose Dolphin ◽

Bottlenose Dolphins ◽

The Black Sea ◽

Photo Identification ◽

Dorsal Fin ◽

The North ◽

Common Bottlenose Dolphin ◽

North Western

Piebaldism is one of three types of hypopigmentation of animals, when some areas on the skin have no pigments. Anomalously white cetaceans are rare, although they have been reported in more than 20 different cetacean species, including the common bottlenose dolphin, which in the Black Sea is recognized as an endangered endemic subspecies — the Black Sea bottlenose dolphin (Tursiops truncatus ponticus Barabash-Nikiforov, 1940). Its main habitat in the north-western Black Sea region is the coastal waters, however, these dolphins also occur offshore. Thirty cases of anomalously white bottlenose dolphins have been reported from the Black Sea, which were unevenly distributed, and only a few sightings have been reported from the north-western Black Sea. Cetacean observations were conducted in the Ukrainian part of the north-western Black Sea waters in April 2017, onboard the research vessel "Auguste Piccard". All encountered cetaceans were photographed, and individual distinctiveness of dorsal fin images was used for their photo-identification. On 13 April 2017, four groups of up to four individuals of bottlenose dolphins were encountered in the same area at a distance of 61 km south of Odesa (34 km from the nearest coast). The depth at the observation site was about 20 m. The initially observed type of dolphins’ behavior was feeding. However, two groups changed their behavior and followed the vessel by 5–6 individuals for approximately 18 minutes. The joint group consisted of adults and one juvenile individual. Among the adults, there was one piebald specimen with white patches on its dorsal fin, peduncle, and tail fluke. The piebald dolphin was photographed and photo-identified. Our research has shown that piebald Black sea bottlenose dolphins occur not only in the coastal waters, but also in offshore waters of the north-western Black Sea. However, the frequency of such hypopigmentation in local populations remains unknown. Further intensive photo-identification and genetic sampling of local stocks of the Black Sea bottlenose dolphins are necessary for the assessment of their population genetic structure and its divergence.

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Bottlenose dolphins in the north‐western Adriatic Sea: Abundance and management implications

Aquatic Conservation Marine and Freshwater Ecosystems ◽

10.1002/aqc.3450 ◽

2021 ◽

Author(s):

Giovanni Bearzi ◽

Silvia Bonizzoni ◽

Melissa A. Riley ◽

Nina Luisa Santostasi

Keyword(s):

Adriatic Sea ◽

Bottlenose Dolphins ◽

Management Implications ◽

The North ◽

North Western

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Biochemical responses of the marine mussel Mytilus galloprovincialis to petrochemical environmental contamination along the North-western coast of Portugal

Chemosphere ◽

10.1016/j.chemosphere.2006.07.057 ◽

2007 ◽

Vol 66 (7) ◽

pp. 1230-1242 ◽

Cited By ~ 180

Author(s):

Inês Lima ◽

Susana M. Moreira ◽

Jaime Rendón-Von Osten ◽

Amadeu M.V.M. Soares ◽

Lúcia Guilhermino

Keyword(s):

Environmental Contamination ◽

Mytilus Galloprovincialis ◽

Western Coast ◽

Marine Mussel ◽

Biochemical Responses ◽

The North ◽

North Western

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Spatiotemporal variation in size-structured populations using fishery data: an application to shortfin mako (Isurus oxyrinchus) in the Pacific Ocean

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2016-0327 ◽

2017 ◽

Vol 74 (11) ◽

pp. 1765-1780 ◽

Cited By ~ 17

Author(s):

Mikihiko Kai ◽

James T. Thorson ◽

Kevin R. Piner ◽

Mark N. Maunder

Keyword(s):

Coastal Waters ◽

Mixed Model ◽

Linear Mixed Model ◽

Marine Species ◽

Structured Populations ◽

Spatiotemporal Model ◽

The North ◽

Isurus Oxyrinchus ◽

Shortfin Mako ◽

Catch Rates

We develop a length-disaggregated, spatiotemporal, delta-generalized linear mixed model (GLMM) and apply the method to fishery-dependent catch rates of shortfin mako sharks (Isurus oxyrinchus) in the North Pacific. The spatiotemporal model may provide an improvement over conventional time-series and spatially stratified models by yielding more precise and biologically interpretable estimates of abundance. Including length data may provide additional information to better understand life history and habitat partitioning for marine species. Nominal catch rates were standardized using a GLMM framework with spatiotemporal and length composition data. The best-fitting model showed that most hotspots for “immature” shortfin mako occurred in the coastal waters of Japan, while hotspots for “subadult and adult” occurred in the offshore or coastal waters of Japan. We also found that size-specific catch rates provide an indication that there has been a recent increasing trend in stock abundance since 2008.

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