Description and interpretation of precocious strandings of Harbour Seals (Phoca vitulina, Linnaeus 1758) in the baie de Somme (Picardie, France)

• Main Authors: THIERY, Philippe, Kiszka, Jeremy
• Format: Article in Journal/Newspaper
• Language: French
• Published: HAL CCSD 2005
• Subjects: Haul out site; Somme France; Phoca vitulina; Nature reserve; Animal conservation; Young animal; Perturbation; Tourism; Recreational activity; Colony; Weaning; Picardie; Bay; Stranding; Mortality; Reposoir; Somme; Réserve naturelle; Protection faune; Animal jeune; Tourisme; Activité récréative; Colonie; Sevrage; Baie; Echouage; Mortalité; envir; socio; Phoques; harbour seal; veau marin
• Online Access: https://hal.archives-ouvertes.fr/hal-03529939/file/bitstream_114252.pdf; https://hal.archives-ouvertes.fr/hal-03529939

International audience The most important French Harbour Seal (Phoca vitulina) colony occurs in the Somme estuary, on the eastern French Channel coast, in northern France (max. 76 ind. in 2001). This colony has increased in number for at least ten years and currently produces more than half of the pups born along the French coast. The estuary is exposed to strong human pressure, with mass summer tourism and recreational activities inducing habitat reduction and disturbances. To study the interactions between Harbour Seals and human activities in this area, a conservation and study programme was set up in 1990 by the association Picardie Nature. This permitted the observation and follow up of reproduction and pups born within the estuary. From 1992 to 2001, 59 pups were studied. During this period, 52% of pups were naturally weaned, 32% stranded alive and 16% stranded dead. Despite births being regular temporally and increasing, pup production stayed low (12% ± 0.06), notably when compared to other French Harbour Seal colonies. Strandings accounted for up to 52.9% of pups produced in a year. This phenomenon — combining low pup production and precocious strandings relatively important during the summer period — leads to two hypotheses. The absence of high tide haul out sites in saltmarsh areas, provoked by a massive utilization of upstream parts of the estuary by recreational activities, potentially reduces mother-pup’s preferential habitat, so prevents births and good pup production. In addition, recreational activities and the development of tourism seems also to prevent the efficiency of pup weaning with recurrent disturbances in summer. This shows that this peripheral group is highly vulnerable despite the designation of the estuary as a Nature Reserve in 1994. The implementation of specific management strategies of the Habitat Directive should consider this phenomenon. La plus importante colonie française de Phoque veau-marin (Phoca vitulina) se trouve en baie de Somme (nord de la France). avec un effectif ...