Ship strikes are a significant threat to large whales. In the U.S., vessel collisions are one of the leading human-caused sources of mortality for the endangered North Atlantic right whale. To address this threat, NOAA has developed regulatory and non-regulatory measures to reduce ship strikes, including modification of vessel operations, education and outreach programs, and research and monitoring activities. Stranded large whales are examined externally and internally whenever logistically feasible to assist in diagnosis and appropriate quantification of ship strikes.
Most reports of collisions between whales and vessels involve large whales, but all species can be affected. Collisions with large vessels often go unnoticed and unreported. Animals can be injured or killed, and vessels can sustain damage. Serious and even fatal injuries to passengers have occurred involving hydrofoil ferries, whale watching vessels and recreational craft.
Evidence of ship strikes comes from a range of sources including direct reports from the vessel involved, and examination of dead whales found floating at sea or washed up on the beach. In some cases, whales become lodged on the bulbous bows of large vessels and the crew may only become aware of this when the ship enters port. For every incident that is observed and reported there will be many others that are completely unseen. This makes assessing the conservation implications of ship strikes very difficult.
For some populations, such as the North Atlantic right whale whose main habitat is the busy waters off the east coast of the USA and Canada, the mortality rate is particularly high compared to the overall population size. It is thought that mortality due to ship strikes may make the difference between extinction and survival for this species, and a range of mitigation measures have been developed. There are also concerns about the high collision rates for the population of fin whales in the Mediterranean. Mitigation measures need to be approached in a collaborative way, involving governments, the various industries and leisure sectors that use marine transport and the bodies that represent them.
Many populations of whales around the world are threatened by collisions with vessels. In the PELAGOS Sanctuary, the scientific community and several ship-owners have joined forces to deal with these accidents. The REAL TIME PLOTTING OF CETACEANS (REPCET) system is a collaborative computer tool for use in commercial shipping. At present, several shipping companies operating in the sanctuary are using REPCET. Every sighting of large cetaceans by watch-keeping personnel on board a vessel equipped with REPCET is transmitted by satellite in semi-real-time to a server located on land.
Hector’s and Māui dolphins
In 2008, the Department of Conservation and Ministry for Primary Industries put in place a Hector’s and Māui dolphin Threat Management Plan (TMP) that identifies human induced threats to Hector’s and Māui dolphin populations and outlines strategies to mitigate those threats.6 This plan provides a platform in which to guide research, engagement, management and review processes.
Australia has an excellent response capacity to assist individuals and groups of whales in distress, in cases where assistance is physically and logistically possible.
In 2017 the Australian Government published The National Strategy for Reducing Vessel Strike on Cetaceans and other Marine Megafauna 2017.
This document provides guidance on how to measure and reduce the risk of vessel collisions and the impacts they may have on marine megafauna, including cetaceans.