Impacts of Vessels on Dolphins

ASSESSING VESSEL IMPACT ON BURRUNAN DOLPHIN BEHAVIOUR IN GIPPSLAND LAKES

The Gippsland Lakes support a resident, maternal-based population of only 63 Burrunan dolphins (Tursiops australis), with an annual wintering influx which temporarily doubles the population size (Charlton-Robb et al. 2015). This small, geographically and genetically isolated population must be protected from stressors, including exposure to boat activity.

Numerous studies on bottlenose dolphin (Tursiops sp.) populations indicate that boat presence can cause a significant change in the animals’ behaviour (Bejder et al. 2006; Constantine et al. 2004; La Manna et al. 2013; Lusseau 2006; Stensland & Berggren 2007). This impact may have serious conservation implications, as a change in behaviour may mean an impact on core biological activities, such as feeding, mating, and resting.

Researchers at MMF have observed a growing interest in the Burrunan dolphins, and have directly observed numerous vessel (specifically boats and jet skis) approaches that breach the current government regulations (Wildlife (Marine Mammal) Regulations 2009). Recreational boats must remain 100m away from dolphins, except if approached, and high impact vessels such as jet skis must remain 300m away from dolphins. As outlined in Charlton-Robb et al. (2015), concerns and impacts of tourism industry expansion and increased vessel usage have been well documented (Bejder et al. 2006; Lundquist et al. 2013).

Our previous research shows a dramatic shift in habitat use in the Gippsland Lakes across seasons, with the resident dolphins almost exclusively using Lake Victoria during summer, whilst winter saw a shift to the almost exclusive use of Lake King and Reeves Channel (Henderson, Charlton-Robb et al). Vessel impact has been hypothesised as a main driver of this shift in habitat use, and could potentially affect core biological activities of the dolphins and create displacement, causing sensitive dolphins to move from areas of high impact to areas of low impact, thus affecting behaviour and condition.

There is currently no research on the frequency, location or character of boat interaction with the Burrunan dolphin in Gippsland Lakes, nor on the population’s natural (undisturbed) behaviour. Investigating vessel impact on these dolphins’ behaviour is an important piece in the puzzle of understanding the Burrunan, and how best to protect them.

 
 
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How is this research conducted?

Aims

In partnership with the Department of Environmental, Land, Water, and Planning, we aim to assess the impact that the vessels operating in the Gippsland Lakes – including speed boats, tour boats, yachts, jet skis and kayaks – have on the behaviour of the Burrunan dolphin. This important research will likely have conservation implications for this endangered species.

Specifically, this project aims to improve our understanding of:

  • The baseline behaviour of the Burrunan dolphin in Gippsland Lakes

  • Locations of significance within Gippsland Lakes for core biological activities of the Burrunan dolphin

  • Behavioural disturbance of the Burrunan dolphin caused by vessel presence and approach

Boat-based observations

Our team will conduct five 10-day boat-based surveys across Gippsland Lakes to collect data on both the Burrunan dolphin behaviour and vessel interaction. The surveys will run from March 2017 to March 2018, covering the full range of seasonal variation and peak and off-peak seasons for the Gippsland Lakes region.

We will record the Burrunan dolphin population’s frequency, sequencing, and geographic distribution of behavioural states (such as traveling, foraging, socialising and resting) and behavioural events (such as leaps, surging, and tail slaps) during times of vessel presence, vessel approach, vessel regulation breach, and vessel absence. Once initial data is collected, we will conduct focal follows; whereby the research vessel will sit a distance and monitor the dolphins behaviour.

Land-based observations

The vantage point at Kalimna offers a unique perspective across The Narrows and Lakes Entrance, acting as the only entry/exit point to Bass Strait for the dolphins, and an area of high vessel traffic. A team of six researchers will conduct land-based observations from the Kalimna Lookout and Bullock Island across the year, representing high vessel times (summer) and the annual dolphin influx (winter). Using photogrammetric and theodolite tracking, we will be able to remotely track through space and time Burrunan dolphins entering and leaving the Lakes system, dolphin demographic parameter assessments, vessel observations and compliance to regulations, and observe dolphin behaviour around vessels.

This combination of both boat and land-based observational methods allows numerous places across the Gippsland Lakes system to be assessed during one survey period.

We’re also using the results from these findings to help with the conservation of Burrunan dolphins, through releasing our Boating with Burrunan campaign, and informing Victorian marine mammal boating regulations.

Presentations

Robb, K., Flynn, A., Puszka, H., Johnson, M. (2019) Drivers of distribution for the endangered Burrunan dolphin (Tursiops australis), anthropogenic or environmental influences? Poster Presentation. World Marine Mammal Conference. Barcelona.

Puszka, H., Shimeta, J., Charlton-Robb,K. (2018) Impacts of vessels on the behaviour and distribution of the endangered Burrunan dolphin (Tursiops australis) in Gippsland Lakes, Australia. Oral presentation. Victorian Biodiversity Conference. Melbourne.

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