Occurrence and spatio‐temporal distribution of sperm whale (Physeter macrocephalus) in the submarine canyon of Cuma (Tyrrhenian Sea, Italy)

Abstract

ABSTRACT1. Boat surveys aimed at studying sperm whales in the Tyrrhenian Sea were conducted between 2002 and 2011. During 768 daily surveys, a total effort of 32 602 km was achieved within an area of 8800 km 2 resulting in 92 encounters with 229 sperm whale individuals. 2. Average encounter rates of sperm whales was 0.5 groups per 100 km 2 , with a higher concentration in the vicinity of the submarine canyon of Cuma, confirming the importance for the species of this small hotspot in the Mediterranean Sea. 3. Encounter rates increased with increasing distance from the coast. It is possible that the intense boat traffic and anthropogenic disturbance in the area may be moving animals away from the coast leading to habitat loss.4. The species-habitat relationship documented in this study has implications for conservation.

Habitat suitability modeling in different sperm whale social groups

“…In addition, we principally conducted surveys during summer and early autumn, when weather conditions were most suitable, thus restricting the ability to quantify long‐term cross‐seasonal trends in sperm whale distribution and resulting in a seasonal bias in species occurrence data. However, in the study area, sperm whale occurrence was documented from March to December (Mussi et al , Pace ), suggesting an almost persistent presence during the year. Seasonality of the environment may play a major role in species distributions by altering the presence of individuals in a given place at a stated time (Murray et al ); seasonal habitat use can be influenced by modifications in ecological processes and by biological functions such as growth, feeding, and reproduction (Lambert et al ).…”

“…The more pelagic area of the Neptune's Kingdom MPA was modeled specifically after the area identified as a critical habitat for the endangered short‐beaked common dolphin ( Delphinus delphis ; Reeves et al ). However, comparison of short‐beaked common dolphin habitat to sperm whale habitat in the waters surrounding Ischia (Pace et al , Mussi et al ) shows a vast, unprotected stretch of water that could be a critical area for the currently endangered sperm whale. Recently, the area including Pontino and Campano Archipelagos was acknowledged as an Important Marine Mammal Area (IMMA; discrete portions of habitat, important to marine mammal species, that have the potential to be delineated and managed for conservation) for the sperm whale in the Mediterranean Sea by the IUCN Marine Mammal Protected Areas Task Force (IUCN‐MMPATF ; Fig.…”

“…The site is mostly furrowed by the Cuma canyon (Fig. ), a topographical system including the northwest part of Ischia Island and extending out to the submarine valley between Ischia and Ventotene (de Alteriis and Toscano , Pace et al , Mussi et al ). In the Gulf of Naples, between Ischia and Capri, the shelf is interrupted by 2 other large canyons: the Magnaghi (southeast Ischia) and the Dohrn (west‐northwest Capri), which comprise the Magnaghi‐Dohrn structure (Fig.…”

“…The highly variable seascapes within canyons influence oceanographic processes that concentrate nutrients and shape prey availability vertically in the water column (i.e., upwelling phenomena), sustaining diverse assemblages of species that play different ecological roles (Fernandez‐Arcaya et al ). The intricate topography of the study region and the canyon systems were proposed as influencing factors of the sperm whale local presence, possibly influencing the species’ distribution and affecting feeding activities (Mussi et al , Pace ).…”

“…We used a MaxEnt technique to investigate if sperm whale singletons and social groups selected for different habitats. We analyzed a combination of visual and acoustic sperm whale occurrence data (i.e., presence‐only records) collected in 2007–2015 around Ischia and Ventotene Islands (Tyrrhenian Sea, Italy), a small key Mediterranean site where sperm whale singletons, social units and groups of immature males were regularly encountered (Mussi et al , Pace et al , Pace ). Our objective was to deliver prediction maps to better understand habitat requirement in relation to the species’ sexual segregation and to predict its distribution in a region surrounding the study area where conditions are potentially suitable for the survival of the species (Phillips et al ).…”