The effectiveness of dedicated observers in reducing risks of marine mammal collisions with ferries: A test of the technique

摘要

Collisions between marine mammals and vessels are known to take place throughout the world today, especially in areas of heavy commercial shipping (Laist et al. 2001, Jensen and Silber 2003, Van Waerebeek et al. 2006). While in many cases the frequency of collisions does not represent a threat to the animals at a population level, mortality from vessel strikes needs to be understood and incorporated into population models (ACCOBAMS 2006, Panigada et al. 2006). In at least some cases (e.g., the North Atlantic right whale, Eubalaena glacialis) vessel collisions can threaten the continued existence of a population or species (Knowlton and Kraus 2001, Knowlton and Brown 2007). While many fatal collisions involve large commercial or military ships (Wiley et al. 1995, Laist et al. 2001), many different kinds of vessels can be involved in collisions with whales. Other categories of vessels that have been implicated in ship collisions include whale watch vessels (Laist et al. 2001, Weinrich 2005), recreational vessels (Ford et al. 1994), and both traditional and high-speed ferries (Laist et al. 2001, Jensen and Silber 2003, Weinrich 2004, Panigada et al. 2006).