Poster

The Acquario di Genova holds five Harbour seals (Phoca vitulina) in a controlled environment exhibit, illuminated by a windowed skylight ceiling and artificial lighting. The first four seals (1 male and 3 females) arrived at the aquarium at the age of 3-4 months. Upon arrival and during the following two years, no signs of moulting were observed. The fifth seal (male) spent its first eight months of life in an outdoor setting and moulted only during its first summer at the aquarium. On closer investigation of the husbandry procedures, it was hypothesized that the lack of moult could mainly be due to abnormal photoperiod and/or temperature gradients.

In the first year of this study (September 1995-September 1996) water temperature settings were readjusted to a seasonal gradient of 13-22°C. During this year the seals were exposed to the same photoperiod of the preceding years consisting of natural sunlight and artificial illumination. The shortest photoperiod was 13h 29" and the longest was 16h 51". During the second year (September 1996-September 1997) the artificial lighting was eliminated and the seals were exposed to the photoperiod of Genova (Italy). This entailed a shortest light cycle of 8h 53" in December and a longest light cycle of 15h 31" in June. A completion of the moult process was observed in all five seals during May-June 1997. First apparent signs of hair shaft eruption were considered as beginning of moult and the pattern of fur replacement was documented until completion of the moult process. The shortest duration of fur replacement was 40 days and the longest was 108 days.

Blubber thickness (with ultrasound examination), weight change and caloric intake were measured on all animals during the study. Routine quarterly physical examinations and medical behaviours under training, allowed blood samples to be collected for normal check-up and hormonal analysis. Despite the lack of a regular and periodic sample collection, these hormonal readings are still indicative of a yearly trend and will be shown during the presentation.

Observations and results of this work are documented and captive husbandry implications for this species are drawn.

Acknowledgements

Prof. Ian Boyd (British Antarctic Survey), Prof. Giulio Relini (University of Genova), and Prof. Joseph Geraci (National Aquarium in Baltimore) for their scientific support and advice; Esaote Biomedica for supplying ultrasound equipment; Dr. Pierluigi Cazzola (Istituto Zooprofilattico Sperimentale, Turin) for the hormonal analysis of blood serum samples; Acquario di Genova Management and Marine Mammal Department for training and technical support.