Vessel Collisions
Collisions
with vessels are an increasing threat to many species of whales in the
Sanctuary. It is likely that the rate of encounter will increase with
an increase in either vessel size or speed, the number of vessels and/or
the number of whales. Many of the large cetaceans which inhabit the
Sanctuary exhibit propeller scars or gashes indicative of collisions
with vessels. Observations indicate that northern right whales (Eubalaena
glacialis) have the highest incidence of mortality from vessel collisions.
This elevated mortality may result from particular behavioral patterns,
such as surface feeding or courtship activities, which render these
animals vulnerable and/or unresponsive to approaching vessels (NMFS,
1991). This apparent trend may also reflect the fact that northern right
whales float when dead, thus increasing the likelihood of a sighting
or of an animal washing ashore.
Studies
estimate that eight, or 27 percent of the known mortalities from the
western North Atlantic population of northern right whales have resulted
from collisions with vessels (Kenney and Kraus, 1993). In addition,
11 percent of the catalog population have scars that indicate the whales
survived a collision with a ship or its propeller (Kraus, 1990).
At least
twenty three (approx. 3.8.%) of the humpback whales (Megaptera novaeangliae)
in the Gulf of Maine (GOM) photographic ID catalog exhibit scars associated
with injury caused by ship strikes (Center for Coastal Studies, 1991).
At least four whales were reported as probably scarred due to vessel
collisions during 1989 alone (NMFS, 1991a). Similarly, it is estimated
that 22 fin whales, or approximately 7 percent of the GOM cataloged
population have scarring caused by vessel collisions (Center for Coastal
Studies, 1991).
continue
to next section
