Is Centrophorus squamosus a highly migratory deep-water shark?

Abstract

Deep-water sharks are considered highly vulnerable species due to their life characteristics and very low recovery capacity against overfishing. However, there is still limited information on the ecology or population connectivity of these species. The aim of this study was to investigate if the species Centrophorus squamosus could make long displacements and thus confirm the existence of connectivity between different deep-water areas. In addition, the study was the first attempt to use tagging techniques on deep-water sharks, since it has never been undertaken before. Five C. squamosus were tagged with satellite tags (PAT) in the El Cachucho Marine Protected Area (Le Danois Bank) located in waters of the North of Spain, Cantabrian Sea (NE Atlantic). Data from four of these tags were recovered. One of the sharks travelled approximately 287nm toward the north east (French continental shelf) hypothetically following the continental slope at a mean depth of 901±109m for 45 days. Two other sharks spent almost 4 months traveling, in which time they moved 143 and 168nm, respectively, to the west (Galician coast). Finally, another leafscale gulper shark travelled to the NW (Porcupine Bank) during a period of 3 months at a mean depth of 940±132m. Depth and temperature preferences for all the sharks are discussed. Minimum and maximum depths recorded were 496 and 1848m, respectively. The temperature range was between 6.2 and 11.4°C, but the mean temperature was approximately 9.9±0.7°C. The sharks made large vertical displacements throughout the water column with a mean daily depth range of 345±27m. These preliminary results support the suggestion of a whole population in the NE Atlantic and confirm the capacity of this species to travel long distances.