Distribution, abundance, and movements of the bottlenose dolphin (Tursiops truncatus) in the Pelagos Sanctuary MPA (north-west Mediterranean Sea)

Abstract

ABSTRACT1. The Pelagos Sanctuary is the largest marine protected area of the Mediterranean Sea (87 500 km 2 ), and is located in the north-west part of the basin. The presence of the bottlenose dolphin in this area is well documented but its distribution and abundance are not well known.2. The present study collected and analysed data from 10 different research groups operating in the Pelagos Sanctuary from 1994 to 2007. Photo-identification data were used to analyse the displacement behaviour of the dolphins and to estimate their abundance through mark-recapture modelling.3. Results show that the distribution of bottlenose dolphin is confined to the continental shelf within the 200 m isobath, with a preference for shallow waters of less than 100 m depth.4. Bottlenose dolphins seem to be more densely present in the eastern part of the sanctuary and along the north-west coast of Corsica.5. Bottlenose dolphins show a residential attitude with excursions usually within a distance of 80 km (50 km on average). A few dolphins exhibit more wide-ranging journeys, travelling up to 427 km between sub-areas.6. The displacement analysis identified two (sub)populations of bottlenose dolphins, one centred on the eastern part of the sanctuary and the other one around the west coast of Corsica.7. In 2006, the eastern (sub)population was estimated to comprise 510-552 individuals, while 368-429 individuals were estimated in the Corsican (sub)population. It was estimated that in total, 884 -1023 bottlenose dolphins were living in the Pelagos Sanctuary MPA in the same year.8. The designation of a number of Special Areas of Conservation (SACs) under the Habitats Directive is discussed as a possible tool to protect the bottlenose dolphin in the Pelagos Sanctuary and in the whole of the Mediterranean Sea.

How does ocean seasonality drive habitat preferences of highly mobile top predators? Part I: The north-western Mediterranean Sea

“…It was only around the Tuscan Archipelago, eastern Corsica and in the Ligurian Sea that coastal waters were used throughout the year. This contrast in seasonal distribution has, to our knowledge, never been described in the NWMS, since the bottlenose dolphin is considered inhabiting mainly continental shelves: previous studies reported bottlenose dolphins to be present only over the shelf, within the 200 m isobath [29,33]. In contrast, we showed here that, even in summer, bottlenose dolphins were also frequent in offshore waters up to 1,000 m deep.…”

Habitat‐driven population structure of bottlenose dolphins, Tursiops truncatus, in the North‐East Atlantic

“…; Gnone et al . ). According to mark–recapture studies, resident coastal population sizes were likely to be around 600–800 individuals for each of the two populations (M. Louis, unpublished data for the Normandy resident group, López ; Pesante et al .…”

“…Some coastal groups are resident but movements were reported between Corsica and France (Gnone et al . ), indicating that individuals crossed pelagic waters. The pelagic habitat use was confirmed by aerial surveys conducted during winter where bottlenose dolphins were mainly sighted in deep‐water (>200 m) areas (SAMM, 2011/2012, E. Pettex, personal communication).…”

“…Gnone et al . ). There is a distributional hiatus in the NEA, that is, resident coastal populations are mainly observed in shallow waters less than 40 m deep, while the sightings of large‐scale surveys are mainly concentrated on the outer shelf, the shelf‐edge (depths from 200 to 4000 m) and oceanic waters.…”

Long-term acoustic monitoring of bottlenose dolphins, Tursiops truncatus, in marine protected areas in the Spanish Mediterranean Sea

“…To date, there is no Mediterranean-wide abundance estimate for bottlenose dolphins. The only large scale studies were focused in the NW Mediterranean Sea (Forcada et al, 2004;Gnone et al, 2011;Lauriano et al, 2014) and found an overall low density of bottlenose dolphins, with animals rarely found in pelagic waters. Most groups occurred in coastal areas of the main insular systems, the Balearic Islands, Corsica, Sardinia, and around small islands near the continent.…”