58
3.5.2 Biological Carrying Capacity – The Whales
Animals perceive tourism as a risk and may respond to interactions in the same way
they would respond to predators (New et al. 2014). This can result in disruptions of
their activity budget, displacement from the area and other sub-lethal effects that
can lead to long-term consequences for the populations (Pirotta et al. 2014).
Methods of boat approach, boat behaviour around the animals and the number of
vessels present have all been shown to change humpback whale behaviour (Corbelli
2006; Stamation et al. 2010).
Avoidance of disturbance is one of the most commonly used behaviour measures
of disturbance, but there are other forms of behavioural responses to disturbance,
for example, increased levels of vigilance, reduction in parental care or amount of
time spent resting, that could potentially affect survival or fecundity (Gill et al.
2001).
Short-term effects of individual interactions between whale-watching boats and
cetaceans are unlikely to result in any long-term effects for the animals, since they
may be able to compensate the effects of the disturbance once it is absent
(Christiansen and Lusseau 2014). The problem is that the effects from whalewatching disturbance may be cumulative when they become more frequent or target
individuals within a population, certain areas, behaviours or age classes more
frequently.
Responding to disturbances has associated energetic consequences. One way to
evaluate the energy cost of human disturbances is to analyse the amount of time the
animals dedicate to different energy-relevant activities, such as swimming, feeding
and resting, in the presence or absence of tourist vessels (Christiansen and Lusseau
2015).
Lusseau (2004) suggests population estimates, structure, reproductive rates and
behaviour budgets should be included in a whale-watching monitoring program. To
assess the carrying capacity of a population to whale-watching the most sensitive
parameter must be determined and its limits assessed to manage the activity within
them.
The most biologically significant impact of whale-watching, when performed in
a breeding ground, is the interruption of reproductive behaviour, including courtship and parental care. Therefore, if disturbance to female and calf pairs is the most
sensitive variable, the number of vessels or time they spend with these groups
should be limited to avoid impacts (Berrow 2003).
Future research should consider how soon whales come to rest after disturbance,
as an additional indication of the strength of avoidance and whether this is likely to
be biologically significant (Kessler et al. 2013).
L. Fernandes and M.R. Rossi-Santos
3.5.2 Biological Carrying Capacity – The Whales
Animals perceive tourism as a risk and may respond to interactions in the same way
they would respond to predators (New et al. 2014). This can result in disruptions of
their activity budget, displacement from the area and other sub-lethal effects that
can lead to long-term consequences for the populations (Pirotta et al. 2014).
Methods of boat approach, boat behaviour around the animals and the number of
vessels present have all been shown to change humpback whale behaviour (Corbelli
2006; Stamation et al. 2010).
Avoidance of disturbance is one of the most commonly used behaviour measures
of disturbance, but there are other forms of behavioural responses to disturbance,
for example, increased levels of vigilance, reduction in parental care or amount of
time spent resting, that could potentially affect survival or fecundity (Gill et al.
2001).
Short-term effects of individual interactions between whale-watching boats and
cetaceans are unlikely to result in any long-term effects for the animals, since they
may be able to compensate the effects of the disturbance once it is absent
(Christiansen and Lusseau 2014). The problem is that the effects from whalewatching disturbance may be cumulative when they become more frequent or target
individuals within a population, certain areas, behaviours or age classes more
frequently.
Responding to disturbances has associated energetic consequences. One way to
evaluate the energy cost of human disturbances is to analyse the amount of time the
animals dedicate to different energy-relevant activities, such as swimming, feeding
and resting, in the presence or absence of tourist vessels (Christiansen and Lusseau
2015).
Lusseau (2004) suggests population estimates, structure, reproductive rates and
behaviour budgets should be included in a whale-watching monitoring program. To
assess the carrying capacity of a population to whale-watching the most sensitive
parameter must be determined and its limits assessed to manage the activity within
them.
The most biologically significant impact of whale-watching, when performed in
a breeding ground, is the interruption of reproductive behaviour, including courtship and parental care. Therefore, if disturbance to female and calf pairs is the most
sensitive variable, the number of vessels or time they spend with these groups
should be limited to avoid impacts (Berrow 2003).
Future research should consider how soon whales come to rest after disturbance,
as an additional indication of the strength of avoidance and whether this is likely to
be biologically significant (Kessler et al. 2013).
L. Fernandes and M.R. Rossi-Santos