Bottlenose dolphin abundance in coastal Moreton Bay 2000

University of California, Irvine

Dataset credit

Vimoksalehi Lukoschek, University of California, Irvine


Primary contact Vimoksalehi Lukoschek University of California, Irvine
Data entry Ei Fujioka Duke University



Marine megafauna populations in coastal waters are increasingly threatened by anthropogenic impacts. Moreton Bay, a large embayment in south-east Queensland, lies adjacent to one of the fastest growing regions in Australia and has a resident population of bottlenose dolphins, Tursiops aduncus. Evaluation of the effectiveness of any proposed management strategy requires robust population abundance estimates.

We estimated abundances of bottlenose dolphins in central eastern Moreton Bay (350 km2) using two commonly used abundance estimation methods for cetaceans: photo-identification mark-recapture and line-transect surveys. Mark-recapture data were analyzed in CAPTURE using a model that allowed capture probabilities to vary between sampling events and between individuals. Based on an estimated 76% of the population identifiable photographically, total abundance estimates were 673 ± 130 s.e. (1997) and 818 ± 152 s.e. (1998). Line-transect data, analyzed using DISTANCE, gave an abundance estimate of 407 ± 113.5 s.e. (2000). These abundance estimates are large compared with many other coastal bottlenose dolphin populations. The line-transect surveys comprised a pilot study, and the lower line-transect abundance estimate is probably best attributable to methodological issues. In particular, smaller mean group size was estimated for the line-transects surveys (2.85 ± 0.29 s.e.) than the mark-recapture surveys (4.87 ± 0.39 s.e., 1997; 5.78 ± 0.73 s.e., 1998), and line-transect group sizes were probably underestimated. In addition, the line-transect detection probability (g(o)) was assumed to be one but was almost certainly less than one. However, the possibility of an actual decline in population size cannot be ruled out. Coefficients of variation (CV) were lower for mark-recapture than for line-transect surveys, however, CVs of line-transect estimates could be lowered through improved survey design. We evaluated the power of these surveys to detect trends in potential population declines for bottlenose dolphins in Moreton Bay and make recommendations for ongoing monitoring strategies.



Supplemental information

Effort data do not include date/time.


Lukoschek, V. and B.L. Chilvers. 2008. A robust baseline for bottlenose dolphin abundance in coastal Moreton Bay: A large carnivore living in a region of escalating anthropogenic impacts. Wildlife Research. 35(7):593-605.



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Attributes described below represent those in the original dataset provided by the provider.
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Attributes in dataset

Attribute (table column)Description
obs_timeTime. Seconds are not proviced.
sight_idTotal sights
obs_countGroup size, combining adult, juvenile and calf.
adultNumber of adult
juvNumber of juveline
calfNumber of calf
sp_obsSpecies observed
sp_tsnITIS taxonomic serial number. This field added by OBIS-SEAMAP
behaviourBehavior of the animals
oidUnique ID number (generated by SEAMAP)
Marine mammals48
Sea turtles0
Rays and sharks0
Other species0
Non spatial0
Non species0
Date, Begin2000-01-08
Date, End2000-11-08
Temporal prec.111110
Latitude-27.58 - -27.16
Longitude153.26 - 153.55
Coord. prec.6 decimal digits
Data typeAnimal sighting
EffortYES (ID: 495)
Traveled (km)179
Effort hours0
Contr. through
Sharing policy CC-BY-NC (Minimum)
Shared with OBIS
GBIF (via DOI)
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