So what happens when a cetacean is disturbed and what is the consequence? Here’s Marine Scotland’s take on it:
How do I know if disturbance of cetaceans occurs?
Although wide scale displacement or abandonment of an area can be relatively easy to detect, other forms of disturbance can be difficult to determine, particularly if animals appear to do nothing or are even attracted to the source of impact. For example, if prey sources are unusually abundant, many cetaceans will tolerate a greater level of noise in order to forage in a particular area (e.g. a harbour entrance). This does not mean that they will tolerate additional pressures or that they are not ‘unharmed’ by that particular impact. In addition, many studies have shown that cetaceans, like humans, are very individual in their behaviour – thresholds for one individual may not be the same for the rest of the species and signs of disturbance can vary. Some examples of the consequences of disturbance are:
- Changes in (direction or speed of) swimming or diving behaviour
- Bunching together or females shielding calves
- Changes in breathing patterns
- Changes in vocalisation
- Aggression, agitation or panic behaviour
- Certain surface behaviours such as tail slashes and trumpet blows
- Moving out of an area previously occupied
The Scottish Marine Wildlife Watching Code (SMWWC) provides additional information on signs of disturbance exhibited by cetaceans, and particularly sensitive times of year.
What disturbance to a cetacean may mean
Changes in behaviour like those described above may not appear to be detrimental in the short-term. The long-term consequences, however, are not yet well understood, but could be significant. Additionally, the effects may be minor in isolation, but may become significant in accumulation. The following are some of the potential problems that may be caused by disturbance:
- Displacement from important feeding areas.
- Disruption of feeding.
- Disruption of communication, migration, breeding, nursing, feeding, resting and other social
behaviours.
- Abandonment of preferred breeding or calving sites.
- Changes to regular migratory pathways to avoid areas of human interaction.
- Increased vulnerability of an individual or population to predators or physical stress.
- Increased risk of injury or mortality.
- Excessive use of energy leading to loss of condition (caused by continual or repeated
avoidance or flight).
STS is not worth it, as we’ve said all along, wrong plan, wrong place!
