One fish per species was tested per day (one session was run
during the morning, another during the afternoon, with a randomization
between the two species, completing all experiments between
10:00 and 16:30 local time) in order to prevent any possible effect due
to noise exposure from testing of neighbouring fish. The order of the
two boat stimuli was randomized across subjects. Due to enforced
restrictions within the naturally protected areas (Ciriaco et al., 1998),
we avoided physically handling animals and/or marking the nest for
multiple testing of the same specimen. Therefore the age/length and
sex of each tested fish was not sampled and just one replicate per
animal was possible.