Figure 1.
Study areas and sighting locations of bottlenose dolphins in Moreton Bay.
Map of Moreton Bay showing sighting locations of bottlenose dolphin schools (black dots) within the current ∼1,300 km2 study area (dashed lines) compared to study area covered by previous mark-recapture abundance estimates in 1997/98 (dotted lines) (Chilvers 2001; Lukoschek & Chilvers 2008). Shaded areas indicate shallow water/sandbanks.
Figure 2.
Survey effort across four field seasons in Moreton Bay.
GPS track records of boat survey effort in Moreton Bay during four field seasons: A) July–September 2008, B) January–March 2009, C) July–September 2009, D) January–March 2010.
Figure 3.
Assignment of individual bottlenose dolphins to sub-populations based on sighting density.
Maps of sighting density of bottlenose dolphin sub-populations, A) North and B) South, in Moreton Bay, as predicted by generalised linear modelling (see Ansmann 2011). Individuals that could not be assigned genetically were assigned based on whether their mean sighting location fell north or south of the black diagonal line.
Figure 4.
Survey effort and identification curves for bottlenose dolphin sub-populations in Moreton Bay.
Cumulative number of identified individual bottlenose dolphins over four field seasons (July-September 2008, January-March 2009, July-September 2009, January-March 2010) in Moreton Bay (MB; dotted black line), and North (grey line) and South (black line) sub-populations, as well as survey effort (hours; grey bars).
Figure 5.
Sighting rate of individual bottlenose dolphins.
Total number of individual bottlenose dolphins that were sighted on between one and ten occasions over 2008–2010 in Moreton Bay.
Table 1.
Results of goodness-of-fit tests for homogeneity of capture, transience and trap response for sighting history data of identified bottlenose dolphins over the entire Moreton Bay (MB) as well as for each sub-population (South and North) separately.
Table 2.
Abundance estimates from the four Jolly-Seber models fitted to mark-recapture data for the entire Moreton Bay (MB) as well as for each sub-population (South and North) over all field seasons.
Table 3.
Abundance estimates of bottlenose dolphins in Moreton Bay (MB) and sub-populations (South and North) derived from fully time-dependent Jolly-Seber models by field season.
Table 4.
Estimates of effective population sizes (Ne) based on linkage disequilibrium, calculated using biopsy samples collected across the whole of Moreton Bay (MB), only samples strongly assigned to either of two sub-populations (South and North) or all samples assigned to each sub-population regardless of assignment strength.
Figure 6.
Required surveys to detect abundance trends.
Number of annual surveys required to detect different rates of abundance trends at highest and lowest levels of precision (CV) obtained for mark-recapture abundance estimates of bottlenose dolphin sub-populations (North and South) in Moreton Bay. The probabilities of Type I and Type II errors were set at 0.05.