May 23, 2013   •  
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Charity No. 1014705

Vessel Collisions

Vessel Collisions And Cetaceans

Evidence is emerging that collisions between vessels and whales, dolphins and porpoises (cetaceans) may be happening more frequently than previously suspected and, in the case of endangered, endemic or geographically-isolated cetacean populations in particular, may pose a significant conservation threat.
 
Studies in recent years indicate that, for populations in certain areas, up to one third of whales found dead display signs of having died due to a vessel strike (Laist et al., 2001). The problem is even more serious for the critically-endangered North Atlantic right whale¹, which has a remnant population currently estimated at only 300-325 individuals. In more than half (10/18) of the post-mortem findings for right whales that died in the northwest Atlantic between 1970 and 2002 indicated that vessel collisions were a contributing cause of death (in the cases where presumed cause of death could be determined) (Moore et al. 2004).  These data are likely to grossly underestimate the actual number of animals struck, as animals struck but not recovered, or not thoroughly examined, cannot be accounted for.
 
Although fatal collisions are the main focus of these pages, non-fatal collisions - which can also cause serious injury - are also of concern. These are likely to negatively affect the viability, both of the affected individual and also its social group. There have been many reported sightings of whales and dolphins with deformed dorsal fins or flukes and/or wounds suggestive of propeller strike, indicating the scale of this problem, but also suggesting that cetaceans can and do survive at least some strikes.  However, some of these injuries may ultimately result in the death of the cetacean even if it is several years after the collision. In at least one known case, a pregnant, adult North Atlantic right whale is believed to have died as a result of an infection from ship strike wounds she obtained years earlier as a calf (‘Right Whale News’ May 2005).
 
The problem is global. While incident reporting and awareness has certainly increased, we believe that the problem has also intensified in the last half century, due to a significant rise both in the number of vessels on our seas and waterways, and also their size and speed.  Given that some of the latest models of fast ferry are capable of reaching speeds in excess of 40 knots / 74 km per hr, the potential – indeed the likelihood – of further collisions is evident.

Additional concerns include the habitat shifts which may result from environmental changes.  For example, right whales, in the Gulf of Maine, are drawn to food resources and Centropages typicus  (Copepoda: Calenoida) density is believed to be dependent on water salinity and temperature (Fransz et al., 1991). 

Shifts in food supply will likely result in shifts in right whale habitat use temporally and spatially.  This is further supported by the May 6, 2004 testimony of William Curry (Ocean and Climage Change Institute
Director at the Woods Hole Oceanographic Institution) to the US Senate Committee on Commerce, Science and Transportation.  In his testimony, Dr. Curry stated that there have been “intriguing changes in the ocean that have (been) detected in only the last two years” and that “these rapid climate shifts are linked to changes in ocean circulation-in particular, to changes in the North Atlantic that make waters there less salty.”  These shifts could result in whales moving into areas of high risk to anthropogenic threats, including ship strikes.

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