scholarly journals Abundance, survival and temporary emigration of bottlenose dolphins (Tursiops sp.) off Useless Loop in the western gulf of Shark Bay, Western Australia

2012 ◽  
Vol 63 (11) ◽  
pp. 1059 ◽  
Author(s):  
Krista Nicholson ◽  
Lars Bejder ◽  
Simon J. Allen ◽  
Michael Krützen ◽  
Kenneth H. Pollock
Keyword(s):  
Western Australia ◽  
Bottlenose Dolphins ◽  
Early Spring ◽  
Anthropogenic Activity ◽  
Apparent Survival ◽  
Photo Identification ◽  
Temporary Emigration ◽  
Shark Bay ◽  
Abundance Estimates ◽  
Capture Recapture

Capture–recapture models were used to provide estimates of abundance, apparent survival and temporary emigration of Indo-Pacific bottlenose dolphins (Tursiops sp.) in a 226-km2 study area off Useless Loop in the western gulf of Shark Bay, Western Australia. Photo-identification data were collected during boat-based surveys in Austral autumn to early spring (April–September) from 2007 to 2011. Abundance estimates varied from 115 (s.e. 5.2, 95% CI 105–126) individuals in 2008 to 208 (s.e. 17.3, 95% CI 177–245) individuals in 2010. The variability in abundance estimates is likely to be a reflection of how individuals used the study area, rather than fluctuations in true population size. The best fitting capture–recapture model suggested a random temporary emigration pattern and, when coupled with relatively high temporary emigration rates (0.33 (s.e. 0.07) – 0.66 (s.e. 0.05)) indicated that the study area did not cover the entire ranges of the photo-identified dolphins. Apparent survival rate is a product of true survival and permanent emigration and was estimated annually at 0.95 (s.e. 0.02). Since permanent emigration from the study area is unlikely, true survival was estimated to be close to 0.95. This study provides a robust baseline for future comparisons of dolphin demographics, which may be of importance should climate change or increasing anthropogenic activity affect this population.

‘O father: where art thou?’- Paternity assessment in an open fission-fusion society of wild bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia

2004 ◽  
Vol 13 (7) ◽  
pp. 1975-1990 ◽  
Author(s):  
Michael Krützen ◽  
Lynne M. Barré ◽  
Richard C. Connor ◽  
Janet Mann ◽  
William B. Sherwin
Keyword(s):  
Western Australia ◽  
Bottlenose Dolphins ◽  
Shark Bay

Distribution and Abundance of Dugongs, Turtles, Dolphins and other Megafauna in Shark Bay, Ningaloo Reef and Exmouth Gulf, Western Australia

1997 ◽  
Vol 24 (2) ◽  
pp. 185 ◽  
Author(s):  
A. R. Preen ◽  
H. Marsh ◽  
I. R. Lawler ◽  
R. I. T. Prince ◽  
R. Shepherd
Keyword(s):  
Western Australia ◽  
Bottlenose Dolphins ◽  
Large Population ◽  
World Heritage ◽  
Shark Bay ◽  
Ningaloo Reef ◽  
Marine Park ◽  
Whale Sharks ◽  
Exmouth Gulf ◽  
Marine Megafauna

Strip-transect aerial surveys of Shark Bay, Ningaloo Reef and Exmouth Gulf were conducted during the winters of 1989 and 1994. These surveys were designed primarily to estimate the abundance and distribution of dugongs, although they also allowed sea turtles and dolphins, and, to a lesser extent, whales, manta rays and whale sharks to be surveyed. Shark Bay contains a large population of dugongs that is of international significance. Estimates of approximately 10000 dugongs resulted from both surveys. The density of dugongs is the highest recorded in Australia and the Middle East, where these surveys have been conducted. Exmouth Gulf and Ningaloo Reef are also important dugong habitats, each supporting in the order of 1000 dugongs. The estimated number of turtles in Shark Bay is comparable to the number in Exmouth Gulf plus Ningaloo Reef (7000–9000). The density of turtles in Ningaloo Reef and, to a lesser extent, Exmouth Gulf is exceptionally high compared with most other areas that have been surveyed by the same technique. Shark Bay supports a substantial population of bottlenose dolphins (2000–3000 minimum estimate). Exmouth Gulf and Ningaloo Reef were not significant habitats for dolphins during the winter surveys. Substantial numbers of whales (primarily humpbacks) and manta rays occur in northern and western Shark Bay in winter. Ningaloo Reef is an important area for whale sharks and manta rays in autumn and winter. The Shark Bay Marine Park excludes much of the winter habitats of the large vertebrate fauna of Shark Bay. In 1989 and 1994, more than half of all the dugongs were seen outside the Marine Park (57·4 and 50·7%, respectively). Approximately one-third to one-half of turtles and dolphins were seen outside the Marine Park (in 1989 and 1994 respectively: turtles, 43 and 27%; dolphins, 47 and 32%). Almost all the whales and most of the manta rays were seen outside the Marine Park. Expansion of the Shark Bay Marine Park, to bring it into alignment with the marine section of the Shark Bay World Heritage Area, would facilitate the appropriate management of these populations. This would also simplify the State– Commonwealth collaboration necessary to meet the obligations of World Heritage listing. The coastal waters of Western Australia north of the surveyed area (over 6000 km of coastline) are relatively poorly known and surveys of their marine megafauna are required for wise planning and management.

scholarly journals Characterizing the socially transmitted foraging tactic “sponging” by bottlenose dolphins (Tursiopssp.) in the western gulf of Shark Bay, Western Australia

2013 ◽  
Vol 30 (3) ◽  
pp. 847-863 ◽  
Author(s):  
Anna M. Kopps ◽  
Michael Krützen ◽  
Simon J. Allen ◽  
Kathrin Bacher ◽  
William B. Sherwin
Keyword(s):  
Western Australia ◽  
Bottlenose Dolphins ◽  
Shark Bay ◽  
Foraging Tactic

Distribution and abundance estimates of bottlenose dolphins (Tursiops truncatus) around Lampedusa Island (Sicily Channel, Italy): implications for their management

2013 ◽  
Vol 94 (6) ◽  
pp. 1175-1184 ◽  
Author(s):  
Marina Pulcini ◽  
Daniela Silvia Pace ◽  
Gabriella La Manna ◽  
Francesca Triossi ◽  
Caterina Maria Fortuna
Keyword(s):  
Tursiops Truncatus ◽  
Marine Protected Area ◽  
Bottlenose Dolphins ◽  
Future Research ◽  
Photo Identification ◽  
Abundance Estimates ◽  
Core Study ◽  
Future Data ◽  
Special Area ◽  
Baseline Information

This paper represents the first quantitative assessment of the distribution and abundance of bottlenose dolphins (Tursiops truncatus) inhabiting the waters around Lampedusa Island, Italy. Eleven years of photo-identification data, collected from 1996 to 2006 by three different research groups, were brought together, reviewed and analysed to fulfil the following objectives: (i) to obtain baseline information on the abundance and residency of the local bottlenose dolphin putative population; (ii) to review the current Marine Protected Area (MPA) boundaries, especially those referred to waters around Lampedusa Island, with a view to establish a new Special Area of Conservation (SAC); and (iii) to explore the potential and limits of analysing heterogeneous datasets to improve future data collection methods. The most resident dolphins were regularly observed in six specific areas around Lampedusa Island. From a total of 148 photo-identified bottlenose dolphins, 102 were classified as well-marked. The capture histories and the distribution of sightings clearly show a number of dolphins regularly use the study area. Best estimates for the first period within the ‘core study area’ were obtained for 1998 data. The 2005 estimate was significantly larger than the 1998 estimates (z = 2.160;P< 0.05) compared to that of 1998. Implications of our results for the current MPA, for transboundary conservation initiative involving Italy, Malta and Tunisia and for directing future research within and outside the MPA are fully discussed.

A robust baseline for bottlenose dolphin abundance in coastal Moreton Bay: a large carnivore living in a region of escalating anthropogenic impacts

2008 ◽  
Vol 35 (7) ◽  
pp. 593 ◽  
Author(s):  
Vimoksalehi Lukoschek ◽  
B. Louise Chilvers
Keyword(s):  
Bottlenose Dolphin ◽  
Anthropogenic Impacts ◽  
Bottlenose Dolphins ◽  
Estimation Methods ◽  
Line Transect ◽  
Mark Recapture ◽  
Abundance Estimate ◽  
Photo Identification ◽  
Moreton Bay ◽  
Abundance Estimates

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 analysed 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, analysed 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.

Sign in / Sign up

Export Citation Format

Share Document