Thank you to all who braved the weather on 19th June to help make the 16th Annual Port Stephens Community Dolphin Census a success. Mother Nature tested us this year and we really appreciate everybody’s patience, flexibility, understanding and most of all, dedication throughout the process.
86 dolphins were sighted throughout the morning, included a few well knowns. Favourite (A female estimated to be in her 20’s) was spotted near Fly Point with her juvenile (PS057) and 2 year old calf, Brett. Our largest male alliance (9 Dolphins) was seen by vessels, socializing near the jet ski area outside Nelson Bay Marina. The group were socializing with ‘Feathers’ and her pod; a pod which is regularly sighted surfing at Newcastle and Merewether Beaches! This encounter (13 Dolphins) was the largest pod encounter. The highest shore sightings were recorded off Fisherman’s Bay (10) and Barnes Rocks (9).
Figure 1: Census results from sixteen Port Stephens community dolphin surveys showing the number of dolphins sighted (blue columns) and the number of annual participants (red line).
Figure 1 provides an overview of dolphin sightings and community participation over the past 16 years. This year, 54 participants were located across 41 sites around Port Stephens, marginally less than last year. Four less dolphins were recorded this year than in 2015. The 2016 result is marginally lower than the yearly average (90.6) from the 16 year census period, with a range of 12 dolphins in 2011 to 194 in 2004. This year’s result can be attributed to clustered and lower participant numbers resulting in less shore coverage as well as weather conditions, with winds and rainfall increasing throughout this year’s census, reducing visibility.
Past studies conducted by Macquarie University estimate the Port Stephens dolphin population is approximately 90 individuals, with perhaps 100-200 dolphins visiting from other areas around the coast. Additionally, a 2 year population study by the Marine Parks Association using photo identification has observed 251 individuals throughout the study, with 193 individuals within the last 12 months. 137 individuals are sighted within the Bay on a regular enough basis to place them within a pod structure.
We cannot expect to sight every dolphin occurring in Port Stephens during the census period, which was completed in one hour of one day and is sensitive to a number of variables. The number of observation points around the Port affects the number of dolphins sighted. This year we had 7 boats on the water, including commercial operators and Marine Rescue. These boats patrolled known dolphin ‘hot spots’ within the Bay as well as offshore areas and contributed many of the dolphin sightings. Most land participants were clustered around certain areas of the Bay, such as Hawks Nest/Tea Gardens and Tomaree Head, meaning that if one site (eg. At Tomaree) did not see any dolphins, it was unlikely the nearby sites did either. Likewise, if one site did see dolphins, many of the nearby sights encountered the same dolphins. These clusters also meant that certain areas of the Bay were not as well monitored for dolphin activity.
Dolphin distribution and movements within the Port are constantly changing; influenced by tidal patterns, time of day and weather events. This year’s census was run during the same time frame as last year’s census and on a run out tide. A majority of sightings observed dolphins tracking East, likely following the tide.
Recent weather events including severe storms and heavy rainfalls also impact on the movements of dolphins within the Port. These weather events can affect the salinity and water quality within the Bay, encouraging dolphins to spend time offshore or in other areas of the Port. Variations in dolphin distribution resulting from weather and other external factors can cause census sightings to increase or decrease dramatically.
The voluntary census is invaluable because it is the longest running community dolphin count in Australia and directly supports dolphin conservation and studies conducted by research institutes.
If you have any questions or would like to provide feedback, please email Lisa Skelton of the Marine Parks Association firstname.lastname@example.org. Thanks again to all who participated in this year's census, we hope to see you again in 2017.