I would like to extend a huge thank you to everyone who participated in the 17th Annual Port Stephens Community Dolphin Census on 4th June, 2017. We were faced with challenging weather throughout the morning and I greatly appreciate everyone’s effort and dedication to the event.
67 dolphins were sighted throughout the morning. This included some well known residents such as Smoky and his alliance; a group of three males believed to be well into their twenties. This group was spotted near ‘Wayne’s Bar’ not far from Corrie Island and were in the company of approximately 14 other dolphins, including Ben’s alliance (another older group of three males) and Debby, a female who was also seen during the 2015 and 2016 census. The largest pod encounter; a group of 20 dolphins, was spotted near Yacaaba Headland as they moved offshore. A group of 8 animals was reported from Kingsley Beach; the highest sighting from shore.
Figure 1: Census results from seventeen 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 seventeen years. This year, 73 participants were located across 49 sites around Port Stephens. Most participants were situated in the areas of Hawks Nest/Tea Gardens, Boat Harbour/ Birubi and between Nelson Bay and Soldiers Point. Participation in areas around Karuah/Tiligerry and the western end of the Port was higher than previous census years, however there were still many vacant areas. Hence, most observations from vessels were focused west of Soldiers Point.
The census count of 67 dolphins is lower than the average of 89.2 for the 17 year census period (with a range of 12 dolphins in 2011 to 194 in 2004). Weather conditions during this year’s census were difficult. Many people have commented on heavy rainfalls and fog which reduced visibility at times. This likely affected the final counts. We do not consider the lower than average result of this year’s census to be reflective of any greater trends in population health.
Dolphin distribution is constantly changing; influenced by tidal patterns, time of day and weather events. It is likely that these factors also impacted on sightings within the census period. Weather events, such as the recent series of East Coast Lows can affect salinity and water quality within the Bay, encouraging dolphins to spend time offshore or in areas of the Port where water quality is less influenced by fresh water run out from the rivers and estuary.
This year’s census was run on the slack of the low tide. This is the time when the bay is most effected by water run out from the river systems which can cause water within the Port to become brackish (particularly after heavy rains). As such, it is no surprise that the majority of dolphin sightings occurred offshore or in areas close to the headlands.
Past studies conducted by Macquarie University estimate the Port Stephens dolphin population is comprised of approximately 90 individuals, with many more visiting from other areas around the coast. Additionally, an ongoing population study by the Marine Parks Association using photo identification has observed 275 individuals, with 201 individuals sighted in the last 12 months, 137 individuals are sighted within the Bay on a regular enough basis to place them within a pod structure.
I want to take a moment to reiterate how much I appreciate the support of everyone who participated in the 2017 Port Stephens Community Dolphin Census, particularly those of you who lend your support year after year. We are fortunate to have such a dedicated volunteer base.
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. The value of the census goes beyond the number of dolphins sighted each year as the information collected throughout the day helps shape our understanding of dolphin distribution and their movements throughout the Port. We look forward to working with everyone again during next year’s census event (hopefully we will be treated to better weather).