64
with intrinsic environmental differences, behaviour patterns are quite similar, suggesting these are not sub-populations and that differences in behaviour are due to
the groups that use each area, groups with calves preferring the shallow and protected waters around Abrolhos (Lunardi et al. 2008).
The presence of coral reefs around the Abrolhos archipelago provide greater
protection for calves, different from the straight and narrow continental shelf along
Praia do Forte, where the female and calf groups use more extensive areas along this
coast (Rossi-Santos et al. 2008). Zerbini et al. (2006) showed humpback whales to
be extremely transient, moving around 42 km per day within their breeding grounds
and Wedekin et al. (2010) found whales off the Brazilian coast to travel up to 600 km
within the same breeding season.
As such, it can be anticipated that the pressure from whale-watching observation
on individual groups of females and calves will be less in Praia do Forte than in
Abrolhos, where the activity concentrates around the archipelago.
Another way in which whale-watching disturbance can affect humpback whale
behaviour and reproduction is through acoustic interferences. Rossi-Santos (2016)
observed good compliance by the local operators with the limits imposed by the
Brazilian whale-watching regulations (minimum distance of 100 m and maximum
30 min permanence time with each group). However, he also observed that whalewatching operations produce a frequency range similar to the song of the humpback
whale, which may result in masking of this important breeding display during boat
approach.
The strong growth in the humpback whale population, utilising the waters off
Bahia, including Praia do Forte, however, suggests that any changes to behaviour
resulting from interactions with whale-watching vessels to date have not been biologically significant, i.e. population growth is not inhibited. However, the increasing
popularity of whale-watching means assessment and management of interactions
must be ongoing and responsive to changes.
From a conservation perspective, human disturbances are only of concern if they
affect survival or fertility, consequently decreasing population size (Gill et al. 2001).
As previously mentioned, the Brazilian humpback whale population is demonstrating a consistent growth. Thus, in the absence of evidence of these long-term impacts,
and bearing in mind all the important educational, social and economic benefits of
whale-watching in Praia do Forte, and the important opportunities for scientific
research it offers, the minor short-term levels of disturbance incurred from whalewatching may be considered acceptable (Fig. 3.12). As argued by Gill et al. (2001),
without knowing whether behavioural changes do in fact result in population decline
or distribution changes, there is a risk in limiting human access to wildlife, such as
whale-watching, with all its associated benefits, in order to protect species which
have their behaviour altered by human presence but suffer no other impacts.
L. Fernandes and M.R. Rossi-Santos
with intrinsic environmental differences, behaviour patterns are quite similar, suggesting these are not sub-populations and that differences in behaviour are due to
the groups that use each area, groups with calves preferring the shallow and protected waters around Abrolhos (Lunardi et al. 2008).
The presence of coral reefs around the Abrolhos archipelago provide greater
protection for calves, different from the straight and narrow continental shelf along
Praia do Forte, where the female and calf groups use more extensive areas along this
coast (Rossi-Santos et al. 2008). Zerbini et al. (2006) showed humpback whales to
be extremely transient, moving around 42 km per day within their breeding grounds
and Wedekin et al. (2010) found whales off the Brazilian coast to travel up to 600 km
within the same breeding season.
As such, it can be anticipated that the pressure from whale-watching observation
on individual groups of females and calves will be less in Praia do Forte than in
Abrolhos, where the activity concentrates around the archipelago.
Another way in which whale-watching disturbance can affect humpback whale
behaviour and reproduction is through acoustic interferences. Rossi-Santos (2016)
observed good compliance by the local operators with the limits imposed by the
Brazilian whale-watching regulations (minimum distance of 100 m and maximum
30 min permanence time with each group). However, he also observed that whalewatching operations produce a frequency range similar to the song of the humpback
whale, which may result in masking of this important breeding display during boat
approach.
The strong growth in the humpback whale population, utilising the waters off
Bahia, including Praia do Forte, however, suggests that any changes to behaviour
resulting from interactions with whale-watching vessels to date have not been biologically significant, i.e. population growth is not inhibited. However, the increasing
popularity of whale-watching means assessment and management of interactions
must be ongoing and responsive to changes.
From a conservation perspective, human disturbances are only of concern if they
affect survival or fertility, consequently decreasing population size (Gill et al. 2001).
As previously mentioned, the Brazilian humpback whale population is demonstrating a consistent growth. Thus, in the absence of evidence of these long-term impacts,
and bearing in mind all the important educational, social and economic benefits of
whale-watching in Praia do Forte, and the important opportunities for scientific
research it offers, the minor short-term levels of disturbance incurred from whalewatching may be considered acceptable (Fig. 3.12). As argued by Gill et al. (2001),
without knowing whether behavioural changes do in fact result in population decline
or distribution changes, there is a risk in limiting human access to wildlife, such as
whale-watching, with all its associated benefits, in order to protect species which
have their behaviour altered by human presence but suffer no other impacts.
L. Fernandes and M.R. Rossi-Santos