How Can Vessel Traffic Affect Cetaceans?Over the years humans have gained access to the oceans though the use of watercraft. These started as simple man-powered vessels such as canoes which have now been replaced by much faster and larger vessels. These vessels can contribute to harassment of marine life, habitat damage and if they strike a cetacean can result in serious injury or death.
Vessel Harassment
While watching cetaceans from a boat or driving in an area which they use, the boat will be having an effect on the animals. How the boat is driven (along with the amount of noise generated by the boat) will, in part, determine if the animals experience harassment or not. The proximity of the boat to the animals as well as the speed and direction in relation to the movement of the animals are all important considerations. Crowding close to animals, following when animals are obviously avoiding the vessel, cutting across the animals’ path, trying to direct or restrict their movement, are all forms of harassment.
Harassment, while it does not physically harm the animals, can cause the animals to feel unsafe and may result in their abandonment of areas which are important for feeding, breeding, safety or other activities. This can indirectly cause problems such as reduced success in hunting, poor nutrition, decreased success in reproduction or increased exposure to dangers.
Habitat damage
Vessels can contribute to habitat damage in three main ways:
- Noise pollution primarily caused by the action of the engine and propellers.
- Chemical pollution which can be caused by fuel leaks, run-off of any chemicals used on the vessle (including any contained in the bilge water) and sewage discharge.
- Marine debris such as containers, ropes, lost cargo etc washing or being thrown off the vessel. This is usually a result of a lack of awareness, poor proceedures for storage of materials and equipment on deck or inadequate waste management.
Although pollution levels from each vessel may be low (it will vary from vessel to vessel) and is usually unintentional, pollution does add up when there are many vessels in an area and can affect the wellbeing of whales, dolphins and other marine life.
Vessel Strikes
With the advent of fast and powerful vessels, many cetaceans are not able to out-swim or out-manouver a boat or ship. If drivers are not careful, boats can cause injury to whales and dolphins by colliding with them or running over them with their propellers. This can cause serious injury and sometimes death to the unfortunate cetacean.
Level of Threat Locally
Although there have been some instances of harassment of local dolphins due to a lack of understanding, this is not considered a common problem in Trinidad and Tobago. However, if we are not careful, the increase in boat traffic, including large commercial vessels, can increase the possibility of unintentional vessel harassment.
CCARO is not aware of any reports of vessel strikes locally but increased vessel traffic may raise potential of boat related damage to cetaceans.
Habitat damage from local vessels is a concern, especially with the large number and types of vessels using our waters. This needs to be looked into in more detail to assess the level of threat.
