Whale Shark Monitoring

The Western Australian Department of Environment and Conservation together with the Ningaloo whale shark tourism industry have been closely involved with monitoring whale sharks at Ningaloo Marine Park since 1995. The following monitoring is being carried out: - Whale shark tourism industry logbooks - Spotter plane logbooks and GPS track and waypoint data collection - Aerial behavioural observations Data from tour operator logbooks has proven useful in gaining an understanding of trends in the whale shark industry. Based on logbook data, the total number of whale shark interactions during the paying season (1st April to 31st May) has reduced by around 36% from 1996 to 2007. This figure needs to be taken with caution as analysis of spotter plane data indicates a shifting peak of whale shark observations to outside the paying season into the months of June and July. Full season data in logbooks was only collected from 2004 onwards. Whale shark interaction success rate for tours has declined slightly, averaging approximately 80%. Sex ratio ranged from 2:1 to 4:1 males:females. Analysis of observed length estimates indicates a 1.5m reduction in mean length. Whale sharks observed showed a trend for direction of travel along the north-south gradient with a greater northward bound favour. Anecdotal reports that whale shark numbers are declining are not supported by an analysis of the aerial spotter plane data. Aerial behavioural observation work was initiated in 2007 as an alternative method of collecting behavioural response to interactions other than the industry logbooks.