Multi-scale analysis reveals changing distribution patterns and the influence of social structure on the habitat use of an endangered marine predator, the sperm whale Physeter macrocephalus in the Western Mediterranean Sea

Pirotta, Enrico; Brotons, José María; Cerdà, Margalida; Bakkers, Sanne; Rendell, Luke

doi:10.1016/j.dsr.2019.103169

Cited by 26 publications

(35 citation statements)

References 55 publications

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“…Maps of predicted distribution were produced based on output from the models, as done in other Mediterranean areas (e.g. Pirotta et al, 2011; 2020; Bonizzoni et al, 2014; 2019), resulting in the identification of important habitat and distribution hotspots where management action must be taken as a matter of priority to protect cetaceans and marine biodiversity (EC, 1992; 2008; 2014).…”

Section: Introductionmentioning

confidence: 99%

Bottlenose dolphins (Tursiops truncatus) in the north‐western Adriatic Sea: Spatial distribution and effects of trawling

Bonizzoni¹,

Furey

Bearzi

2020

Aquatic Conservation

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Many species and populations of odontocetes have modified their behaviour to take advantage of feeding opportunities provided by fishing activities, with depredation of fishing gear being the most common type of adaptation. The northern Adriatic Sea has been identified as an important marine mammal area because of a regular occurrence of common bottlenose dolphins. Boat surveys were conducted within a 3,000 km2 sector of the Adriatic Sea off the coast of Veneto, Italy, between April and October 2018–2019. Based on 76 days at sea, 10,711 km of navigation, and 81 h 26 min of dolphin tracking, this study contributes novel quantitative information on dolphin spatial distribution, and on their occurrence in the wake of beam trawlers, otter trawlers, and midwater pair trawlers. A combined generalized additive model and generalized estimation equation framework indicated that trawling—along with other physiographic, biological and anthropogenic variables—influenced dolphin distribution. In days of trawling, the chance of encountering dolphins increased by ~4.5 times (95% confidence interval 1.8–11.0) near active beam trawlers, by ~16.0 times (7.1–36.0) near otter trawlers, and by ~28.9 times (12.0–69.6) near midwater pair trawlers. Spatial modelling was used to create maps of predicted distribution, suggesting differences in habitat use between trawling and no‐trawling days. Spatial modelling for all days identified a dolphin distribution hotspot of 832 km2, situated off the Po river delta. Evidence contributed by this study can be used to inform management action within one of the world's areas most heavily impacted by fishing and other human encroachment. Such management action would help enforce the European Union's Habitats Directive and Marine Strategy Framework Directive, while also informing EU's Maritime Spatial Planning.

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Section: Introductionmentioning

confidence: 99%

Bottlenose dolphins (Tursiops truncatus) in the north‐western Adriatic Sea: Spatial distribution and effects of trawling

Bonizzoni¹,

Furey

Bearzi

2020

Aquatic Conservation

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“…We shall refer to this mutually reinforcing overlap of social-, habitat-, and ecological-partitioning as social niche partitioning. This process has been observed among various vertebrate groups, including terrestrial mammals, e.g., Hapalemur griseus in Madagascar [39], marine mammals, e.g., the sympatric communities of killer whales in the Pacific Northwest and Southern Ocean [31,32] and sperm whales in the Mediterranean [40], as well as in other taxa (see next paragraph). For many such cases, we know that niche partitioning is the direct result of behavioral traits that are socially learned and shared, and thus constitute a form of culturally-mediated niche partitioning [31,[41][42][43][44][45].…”

Section: Introductionmentioning

confidence: 83%

Social survival: humpback whales (Megaptera novaeangliae) use social structure to partition ecological niches within proposed critical habitat

Wray¹,

Keen

O’Mahony

2020

Preprint

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Animal culture and social bonds are relevant to wildlife conservation because they influence patterns of geography, behavior, and strategies of survival. Numerous examples of socially-driven habitat partitioning and ecological-niche specialization can be found among vertebrates, including toothed whales. But such social-ecological dynamics, described here as ‘social niche partitioning’, are not known among baleen whales, whose societies -- particularly on foraging grounds -- are largely perceived as unstructured and incidental to matters of habitat use and conservation. However, through 16 years of behavioral and photo-identification observations of humpback whales (Megaptera novaeangliae) feeding within a fjord system in British Columbia, Canada, we have documented long-term pair bonds (lasting up to 12 years) as well as a complex societal structure, which corresponds closely to persistent patterns in feeding strategy, long-term site fidelity (extended seasonal occupancy and annual rate of return up to 75%), specific geographic preferences within the fjord system, and other forms of habitat use. Randomization tests of network congruency and clustering algorithms were used to test for overlap in patterns of social structure and habitat use, which confirmed the occurrence of social niche partitioning on the feeding grounds of this baleen whale. In addition, we document the extensive practice of group bubble net feeding in Pacific Canada. This coordinated feeding behavior was found to strongly mediate the social structure and habitat use within this humpback whale society. Additionally, during our 2004 – 2019 study, we observed a shift in social network structure in 2010 – 2012, which corresponded with environmental and demographic shifts including a sudden decline in the population’s calving rate. Our findings indicate that the social lives of humpback whales, and perhaps baleen whales generally, are more complex than previously supposed and should be a primary consideration in the assessment of potential impacts to important habitat.

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“…Over centuries and across the Galápagos Archipelago, sperm whales were consistently found in deep, relatively cool waters off the western flanks of the continental shelf (Hope & Whitehead, 1991; Whitehead & Hope, 1991), where highly productive waters are sustained by topographically‐induced upwelling of the Equatorial Undercurrent (Houvenaghel, 1978; Palacios et al, 2006). Sperm whales have shown an affinity for highly productive areas and steep slopes of oceanic islands at large spatiotemporal scales across the Pacific (Gaskin, 1973; Jaquet, 1996; Rendell, Whitehead & Escribano, 2004), Caribbean (Milligan, 2013) and the Mediterranean (Pirotta et al, 2020). In this study, whales were found in waters deeper than in the Gulf of California (Jaquet & Gendron, 2002), where the maximum depths are about 1,500 m, but at similar depths of over 3,000 m as observed in the Mediterranean (Pirotta et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

“…Since direct observations of sperm whale prey are rare (Davis et al, 2007 but see Benoit‐Bird, Moline & Southall, 2017), their habitat has previously been described through environmental proxies associated with prey‐aggregating processes, such as upwelling, fronts, and mesoscale eddies (Jaquet & Whitehead, 1996; Praca et al, 2009; Pirotta et al, 2011; Wong & Whitehead, 2014; Pirotta et al, 2020). The degree to which sperm whale distribution correlates with these variables depends on the spatial scale.…”

Section: Introductionmentioning

confidence: 99%

Historical and contemporary habitat use of sperm whales around the Galápagos Archipelago: Implications for conservation

Eguiguren

Pirotta

Boerder

et al. 2020

Aquatic Conservation

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Sperm whales have occupied the waters off the Galápagos Islands, Ecuador, for at least the past 200 years. During the 19th century, they were the target of intensive whaling that severely depleted the population. In recent times, after commercial whaling ended, sperm whales in the region remain vulnerable to multiple threats, especially potential entanglement in fishing gear, which may hinder their ability to recover from the whaling era. As a highly mobile, long‐lived species, long‐term analysis of the habitat use of sperm whales is necessary to establish effective conservation and management strategies. Here, contemporary (1985–2014) and historical (1830–1850) sperm whale habitat use off the Galápagos Islands was analysed and contrasted to the extent of the Galápagos Marine Reserve (GMR). Contemporary habitat use and its variability over time were modelled as a function of geographic, oceanographic, and topographic variables using generalized additive models. The fine‐scale habitat (<50 km) used by sperm whales was associated with topographic (i.e. depth and slope) and oceanographic characteristics (i.e. relative sea surface temperature and standard deviation of sea surface temperature), but these preferences varied over time. While historical and contemporary data indicate that sperm whale habitat primarily occurred within the boundaries of the GMR, in recent years, whales were found up to 30.1% of the time outside the GMR, potentially overlapping with commercial fisheries operating in the area. The dynamic nature of the relationship of this nomadic species with its habitat highlights the need of large‐scale conservation efforts across the Eastern Tropical Pacific region, including the wide‐scale enforcement of regulations requiring the use of Automatic Identification System in fishing vessels, the promotion of on‐board fisheries observer programmes, the development of adaptive management strategies, and international collaboration to identify and mitigate threats.

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Multi-scale analysis reveals changing distribution patterns and the influence of social structure on the habitat use of an endangered marine predator, the sperm whale Physeter macrocephalus in the Western Mediterranean Sea

Cited by 26 publications

References 55 publications

Bottlenose dolphins (Tursiops truncatus) in the north‐western Adriatic Sea: Spatial distribution and effects of trawling

Bottlenose dolphins (Tursiops truncatus) in the north‐western Adriatic Sea: Spatial distribution and effects of trawling

Social survival: humpback whales (Megaptera novaeangliae) use social structure to partition ecological niches within proposed critical habitat

Historical and contemporary habitat use of sperm whales around the Galápagos Archipelago: Implications for conservation

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