Vessel collisions with large whales: Behavioural responses and areas of risk

Collisions between ships and whales (‘ship strikes’) are regularly reported throughout the world’s oceans. In the majority of cases, this results in mortality, major injury or physical trauma. At the population level, ship strikes can thus be an impediment to whale population growth. This is of particular concern for small, threatened populations and/or those utilising ‘high risk’ areas where high numbers of both whales and ships occur simultaneously.

Although several mitigation techniques have been trialled, no single technology currently exists that will eliminate ship strike. Reducing the spatial overlap of both high numbers of whales and high numbers of vessels through the identification of high risk areas remains the best means of reducing incidents. However, strike rates are thought to be under-reported due to missed or unreported collisions. There are also considerable numbers of ‘near misses’, where whales encounter a vessel but avoid a collision. Understanding such events could provide the necessary context for deciphering whale behaviours that lead to ship strike.

Therefore, there is a need to develop innovative methods that reliably assess the true incident rate of ship strikes, describe the context of near misses, identify areas of high risk, and describe the behaviour of whales during ship encounters.