Small dolphins in a small sea: age, growth and life‑history aspects of the Black Sea common bottlenose dolphin Tursiops truncatus

Gol’din, Pavel; Gladilina, Elena

doi:10.3354/ab00617

Cited by 12 publications

(12 citation statements)

References 28 publications

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“…High summer concentration of dolphins in pelagic waters (Mikhalev, 2005) implies the existence of an offshore population. The morphological data support this hypothesis: there can be co-existing offshore and inshore putative populations in the Black Sea (Gol'din & Gladilina, 2015), as has been demonstrated for Mediterranean waters (Gaspari et al , 2015a). A few local coastal groupings have already been reported from the northern and eastern Black Sea which occur in coastal waters all year round and thus are probably resident local populations (Shpak et al , 2006; Gladilina, 2012; Gladilina et al , 2013; Gladilina & Gol'din, 2016).…”

Section: Discussionsupporting

confidence: 70%

“…In the past, in some years the occurrence of bottlenose dolphins was extremely low: their total abundance in the Black Sea was estimated at 7000 ± 3000 specimens (Sokolov et al , 1990; Yaskin & Yukhov, 1997), and in the waters of Ukraine it has been reported to be as low as 1000 specimens (Shcherbak, 1994), which meant the Black Sea bottlenose dolphins were critically endangered. Such a trend seems most unusual so far as coastal bottlenose dolphins in the Black Sea are distinct for their rapid body growth, which is indirect evidence for a high rate of generation change and rise of population abundance (Gol'din & Gladilina, 2015). However, these fluctuations seem to be logical if the metapopulation is fragmented into small portions.…”

Section: Discussionmentioning

confidence: 99%

“…One of them is located in the Black Sea, where a morphologically and genetically distinct subspecies was identified, Tursiops truncatus ponticus Barabash-Nikiforov, 1940 (Viaud-Martinez et al , 2008). The population structure of the Black Sea bottlenose dolphins is little known; it possibly includes offshore and inshore (or coastal) populations (Bushuev, 2002; Mikhalev, 2005; Gol'din & Gladilina, 2015), and among the latter there can be resident groups (Shpak et al , 2006; Gladilina, 2012; Gladilina & Gol'din, 2016), but their number, size, structure, relations and the extent of exchange are virtually unknown; an exception is a local population near Sudak which abundance was recently estimated (Gladilina & Gol'din, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Individual movements between local coastal populations of bottlenose dolphins (Tursiops truncatus) in the northern and eastern Black Sea

et al. 2016

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The Black Sea subspecies of the bottlenose dolphin (Tursiops truncatus ponticus) is threatened and has a small range. Its population structure is little known: it possibly includes a few local coastal populations. We assessed connectivity between coastal groupings in six localities along 800 km of the coastline based on records of photo-identified animals between 2004 and 2014. Abundance of these groupings, as estimated, ranged between 76 and 174 individually distinctive dolphins. In total, there were 350 identified individuals, of which 91 (26%) were resighted within the same areas. However, only three cases of individual movements between local coastal populations were recorded at the distances between 135 and 325 km. Therefore, despite the absence of physical barriers, the coastal Black Sea population is fragmented into numerous resident or locally migrating groupings with site fidelity. These local populations are loosely connected to each other with rare movements between them. This fragmentation can be a factor contributing to short-term fluctuations in abundance of Black Sea bottlenose dolphins and their decline in some localities, despite the potentially high population growth rate.

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Section: Discussionsupporting

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Individual movements between local coastal populations of bottlenose dolphins (Tursiops truncatus) in the northern and eastern Black Sea

et al. 2016

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“…The reproductive output of wild bottlenose dolphins Tursiops truncatus has been extensively explored worldwide (Fruet et al 2015, Rossi et al 2017, Baker et al 2018, especially for resident populations inhabiting estuary areas of sub-tropical regions (Shane et al 1986, Steiner & Bossley 2008, Bezamat et al 2020; however, it remains largely undocumented in the Mediterranean Sea, where bottlenose dolphins have been studied only in relatively small areas (Gol'din & Gladilina 2015, Rossi et al 2017. Bottlenose dolphins live in fission− fusion societies characterized by ex tensive maternal investment, with prolonged mother− infant relationships and juveniles occasionally associating with their mothers post-weaning (Oftedal 1997, Mann & Smuts 1998.…”

Section: Introductionmentioning

confidence: 99%

Female reproductive output in a Mediterranean bottlenose dolphin Tursiops truncatus population

Blasi¹,

Bruno²,

Boitani

2020

Aquat. Biol.

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The reproductive output of wild bottlenose dolphins Tursiops truncatus has extensively been investigated; nevertheless, it remains widely unexplored in the Mediterranean Sea. We investigated the reproductive history of female bottlenose dolphins in the Aeolian Archipelago (Italy). Thirteen years of photo-identification data were used to track the reproductive pattern of 7 females and their 16 calves. The birth period was accurately estimated within 1 mo for 6 calves (37.5%), peaking in June/July. The mean number of calves for females was 2.3 ± 1.1 (SD), ranging from 1 to 4. The mean interbirth interval was 3.5 ± 1.6 yr, ranging from 2 to 7 yr. The mean weaning age was 3.2 ± 0.6 yr, although 1 calf may have been weaned as late as its fifth birthday. Mother-calf postweaning associations were tracked for 9 calves and ranged from 4 to 10 yr of residence in the maternal group of the calf. The age of first pregnancy was 7.5 yr. The number of calves was influenced by the mean maternal group size, with females that were sighted in larger groups having more calves. However, the number of calves was not influenced by the strength of the associations of mothers with other females. Calf mortality by age 1 was high (12.5%). Two juveniles also died postweaning within 6 yr of their birth. Finally, 2 females may have died during the study, as they were not re-sighted at the end of the study. Our results highlight the need to implement urgent conservation actions to protect this bottlenose dolphin population.

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“…Bottlenose dolphins in that region are considered as an endangered species by some authors (Birkun, 2012). Bottlenose dolphins occur across all the Black Sea area; however, their regional distribution is patchy and variable (Mikhalev, 2005), and some kind of diff erentiation in body size and life history is seen within the Black Sea (Gol'din and Gladilina, 2015), as well as genetic heterogeneity (Moura et al, 2013) that raises the problem of stock identifi cation and assessment. Th ere are a few local coastal stocks, which are possibly local populations, in the northern part of the Black Sea (Gladilina et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Abundance and Summer Distribution of a Local Stock of Black Sea Bottlenose Dolphins, Tursiops truncatus (Cetacea, Delphinidae), in Coastal Waters near Sudak (Ukraine, Crimea)

Gladilina¹,

Gol’din²

2016

Vestnik Zoologii

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The first assessment of abundance of a local population of bottlenose dolphins in the Black Sea (near the Sudak coast) in 2011–2012 has been conducted: the results of a mark-recapture study of photo identified animals were complemented by a vessel line transect survey. The overall abundance of a population was estimated at between 621 ± 198 and 715 ± 267 animals (Chapman and Petersen estimates), and the majority of members of the population were recorded in the surveyed area. The summer range covered the area of a few hundred square kilometers, similar to migrating coastal stocks in other world regions. The greatest density of distribution was observed in August in sea 45–60 m deep; in addition, frequent approaches to the coastline are usual for dolphins of this stock. These trends in distribution may be partly explained by distribution of prey. Interaction with sprat trawling fisheries can be a factor shaping the local population structure. Coastal waters of Sudak and adjoining sea areas are an important habitat for bottlenose dolphins in the northern Black Sea, significant for their conservation.

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Small dolphins in a small sea: age, growth and life‑history aspects of the Black Sea common bottlenose dolphin Tursiops truncatus

Cited by 12 publications

References 28 publications

Individual movements between local coastal populations of bottlenose dolphins (Tursiops truncatus) in the northern and eastern Black Sea

Individual movements between local coastal populations of bottlenose dolphins (Tursiops truncatus) in the northern and eastern Black Sea

Female reproductive output in a Mediterranean bottlenose dolphin Tursiops truncatus population

Abundance and Summer Distribution of a Local Stock of Black Sea Bottlenose Dolphins, Tursiops truncatus (Cetacea, Delphinidae), in Coastal Waters near Sudak (Ukraine, Crimea)

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