Strandings
Marine
mammal strandings are a common occurrence along the shores surrounding
the Sanctuary, particularly on Cape Cod Bay. According to reports for
the northeast region in 1992 and 1993, there were 413 and 420 reported
strandings, respectively (NMFS, 1993). The species with the highest
reported number of strandings during the same time period included:
harbor seals (323), bottlenose dolphin (93), harbor porpoise (90), and
long-finned pilot whale (46).
In the
northeast region, species of odontocetes which are known to mass strand
include long-finned pilot whale (Globicephala melaena), bottlenose dolphin
(Tursiops truncatus), common dolphin (Delphinus delphis), and Atlantic
white-sided dolphin (Lagenorhynchus acutus) (Odell, 1987). Many reasons
have been suggested as the cause of mass strandings including complex
topographic and oceanographic conditions, pollution, weather, predators,
naturally occurring toxins, geomagnetic disturbance/navigational error,
pursuit of prey, disease, disturbance of echolocation in nearshore environment,
social cohesion, and human related injury (Geraci and Lounsbury, 1993).
While mass strandings in general may be attributed to any combination
of these factors, the specific causes related to particular stranding
events remain, as yet, a poorly understood phenomena. Although no distinct
patterns in strandings for this region have been reported, the decade
between 1981-1991 appears to have been a peak period with 10 separate
mass strandings of pilot whales occurring within a twenty mile radius
of Cape Cod. The strandings occurred between the months of September
and December, with a total of 476 animals ashore during this period
(ibid.).
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