Patterns of time and space utilisation in coelacanths (Latimeria chalumnae), determined by ultrasonic telemetry

Acoustic telemetry was used to examine patterns of activity and space utili sation of coelacanths, nocturnal predators which spend the day in submarine caves. Nine coelacanths (Latimeria chalumnae) were tracked, each for a per iod of I to 16 nights at Grande Comore, West Indian Ocean. Activities laste d on average 9 h, usually starting shortly after sunset and ending before s unrise. Vertically, coelacanths moved up and down at and below cave level b y following the bottom contour, mainly between 180 and 400 m depth. The dee pest record was 698 m, the shallowest 133 m. Most time was spent between 20 0 and 300 m depth. Large individuals performed deep excursions to depths be low 400 m: usually once per night. The fish spent most time in water temper atures of 15 to 19 degrees C; they rarely ventured into waters warmer than 22 degrees C measured at depths shallower than 160 m depth. Horizontally, c oelacanths stayed in narrow areas ranging from <1 to 10 km of coastline. Co elacanths are extremely slow drift-hunters with an estimated average swimmi ng speed of 3.2 m min(-1), often travelling not more than 3 km per night. T hey probably take advantage of local upwelling and downwelling and slow cur rents occurring parallel to the steep slopes. This study shows that coelaca nths are inhabitants of the subphotic zone, where they are active mainly be low the depth of their daytime refuges.