Increasingly, cetaceans (whales & dolphins) around the world are facing modern pressures upon their environment – pollution, accidental capture in fishing nets, and disturbance from vessels, particularly high-speed craft.
Recreational activities in inshore waters have burgeoned recently, and can pose a major threat to whales and dolphins either by direct injury when animals are accidentally rammed or cut by the boat’s propeller, or by interference or stress caused from the noise made by the vessel’s motor or from its propeller when at speed.
There is no reason why boats and cetaceans should not be able to co-exist if care is taken to observe the following rules:
- If you sight cetaceans at a distance, make forward progress maintaining a steady speed, ensuring that you do not exceed ten knots as soon as you are within a kilometre of them
- Do not chase cetaceans, drive a boat directly towards them, or encircle them; wherever possible, let them approach you. If they choose to bow-ride, maintain a steady speed and course
- Do not respond to them by changing course or speed in a sudden or erratic manner; slowing down or stopping suddenly can confuse and alarm animals as much as sudden acceleration
- Allow groups to remain together. Avoid deliberately driving through, or between, groups of cetaceans
- Avoid close approach to individuals with young. You risk disrupting mother-calf bonds and expose inexperienced young to stress and possible boat strikes
- Do not swim with, touch or feed cetaceans, for your safety and theirs. Besides the stress you can cause them, remember that, just as in humans, diseases can be spread by close contact, and they are larger than humans and can cause unwitting injury
- Do not throw rubbish or food near or around cetaceans
- Always allow cetaceans an escape route. Avoid boxing them in between vessels
- Ensure that no more than two vessels are within a kilometre of cetaceans at any one time and no more than one boat within close proximity (i.E. Radius of 100 metres). Refrain from calling other vessels to join you
- If other vessels in the vicinity are interested in watching the cetaceans, limit your presence to 20 minutes. (note: the wildlife and countryside act makes provision for licences to be issued to allow certain activities such as research and survey to take place)
- Move away slowly if you notice signs of disturbance, such as repeated avoidance behaviour, erratic changes in speed and direction, or lengthy periods underwater
- Possible sources of noise disturbance can be avoided by ensuring speeds are never greater than ten knots, and by keeping the engine and propeller well-maintained. On the other hand, care should be taken to avoid collision with dolphins when using sailing boats or boats with a low engine noise as the animals are less likely to hear the vessel until it is close.
- People regularly using vessels in areas where cetaceans are known to occur should consider fitting propeller guards to minimise the risk of injury to them
- Please note that under uk law, it is an offence to intentionally kill or injure cetaceans. It is also an offence to disturb cetaceans and basking sharks. To do so intentionally or recklessly* may result in a prison sentence.* Recklessness is a legal term. A person who is heedless of the consequences of his actions or of danger will be reckless.
Besides the physical threat of collision, remember that whales, dolphins and porpoises use sound as a daily part of their life, for locating and capturing food, locating and communicating with one another, detecting predators, and forming a picture of their underwater environment in often very dim light. Many of the sounds made by craft directly overlap the frequencies used by cetaceans: the lower frequency noise of the engine and those caused by cavitation of the propeller blade, producing broadband, high frequency noise. This causes interference with their daily activities, sometimes excluding them from preferred feeding or nursery areas. It can also lead to undue stress, particularly when mothers are pregnant or with small young. Scientific studies have shown that cetaceans respond negatively to craft moving directly at them, increasing the time they spend underwater and often swimming rapidly away from the sound source.
To guide people on how best to approach a whale, dolphin or porpoise (or group of them), and then once they have done that, how to assess their reaction at the time to the vessel’s approach, the following two graphics have been prepared:
Fig. 1. Vessel Approach diagram (from Würsig & Evans, 2001)
Fig. 2. How to ensure a successful interaction without causing disturbance (from Würsig & Evans, 2001)
(*Receptive means that the animals are in a behavioural state (e.g. socialising, but not trying to feed) to likely cause least disturbance. **Successful Encounter refers to both the animals not being disturbed, and the humans being happy with the situation.)
Aggressive contact is defined as rapid approach by the vessel, or rapid changes in speed and direction. Gentle contact means careful appraisal of the animals, their behavioural state, and how best to approach them, usually slowly and not head-on. Note that even gentle contact can result in unacceptable potential detriment if the animals are not in a receptive mood.
Disturbance can be assessed by observing how animals respond to your vessel: If they repeatedly move away from you, changing their course in response to changes in the course of the vessel, they you are probably disturbing them. Similarly, if they dive on your approach and then re-surface further away, you probably have disturbed them.
This was taken from The Sea Watch Foundation