Polperro Dolphin Swims
13 April 2007
I wish to make a submission regarding the Supplementary Environment Effects Statement (SEES) for the Port Phillip Bay Channel Deepening Project. As an employee of Polperro Dolphin Swims, my main area of concern is the impact the project may have on the welfare of the dolphins in
In reviewing the SEES, I concentrated my attention on reading ‘Chapter 13 – The Bay’ of the main report, and ‘Appendix 56 – Marine Mammals and Penguins’ of the technical appendices.
When reading the section ‘13.8 Effects on dolphins’ in the main report, I was alarmed at how inaccurate certain statements and facts were, which contradict the information in the technical appendix. For example, under section 13.8.1 on pp. 83-84, the main report states the following: ‘Although dolphins occur near shore from time to time and regularly enter
Of cetaceans listed in Figure I.1-2 only bottlenose dolphin is considered likely to depend on the Bay to any significant degree and Port Phillip Bay has a population that may be considered genetically and biogeographically isolated from other populations in the region … Bottlenose dolphin is important for intrinsic reasons but is also an integral part of the Bay’s ecosystem as well as a source of tourism revenue. It is therefore treated in detail in the following sections of this report and represents a key feature of the SEES.
Also, on p. 72:
Genetic studies on the population in Port Phillip Bay are ongoing but preliminary results suggest that they are genetically distinct from other populations in the region … Whatever the outcome of the genetic research, the recommended approach in the context of this study is to accord with the view that Port Phillip Bay bottlenose dolphins are a distinctive feature of the Bay and having evolved in relative isolation for hundreds or thousands of years may be adapted to the local environment — bathymetry, currents, habitats and other features.
Finally, in reporting the results of a population viability analysis by Hale (2002), the technical appendix explains (pp. 78-79):
… in a population where female natal philopatry is exceptionally high [where philopatry is the affinity individuals have with their place of origin. Female T. aduncus are considered to be highly site faithful i.e. they do not disperse to other areas when they reach maturity. The female population in Port Phillip Bay should be regarded as a single closed system], there is little scope for outside recruitment ... Therefore, incremental loss of females in a closed population such as Port Phillip Bay is likely to result in a threat to the population since no other females are available to move in. Given the isolated nature of the female population in
Port Phillip Bay, this is a consideration for any development.
All of the above quotes emphasise the importance of
The fact that the SEES main report claims that Port Phillip Bay is of no ecological significance to the bottlenose dolphins is therefore nothing short of alarming, as such a statement has totally failed to accurately represent the scientific information contained in the technical appendix and other sources of information. The main report also makes no reference to the specific sub-species of bottlenose dolphin in
Given that Port Phillip Bay supports only a small resident population of 80 to 100 bottlenose dolphins that is genetically distinct and must be self-sustaining for its future survival, the loss of a small number of individual dolphins beyond the existing mortality rate can have dire ramifications for the population’s viability (see p. 78 of Technical Appendix 56). This ‘fine line’ regarding the population’s survival must always be considered in the context of the potential impacts of the channel deepening project. While the impacts related to contaminants, dredge plumes, fish stock decline etc. may be assessed as negligible, minor or moderate, there is little margin for error given the existing fragile state of the dolphin population. A larger and more robust population of bottlenose dolphins would be more resilient to sustaining such impacts or tolerating additional losses. Unfortunately, this is simply not the case with the sub-species of bottlenose dolphins in
In the impact assessment contained in Technical Appendix 56, the impacts and consequences of underwater noise from dredging and pile-driving in the project areas Yarra River and Hobson’s Bay (p. 135), North of the Bay (p. 149), and South of the Bay (p. 159) are all assessed as ‘major’ impacts on the bottlenose dolphins, as ‘acute impacts on individual animals [are] possible through injury to hearing. If this affects a small number of females, this could result in a significant impact at the population level’ (p. 159). In other words, given the existing fragile state of the population, the loss of only a small number of females may have disastrous ramifications for the population. As Technical Appendix 56 further explains:
Impacts on bottlenose dolphin population viability however could be significant if it resulted in any injury or lasting impact on a very small number of individual females. Although the duration of pile-driving is relatively small, the consequence could be high if it affected a nearby pod within about 500m for a period greater than about 50 minutes’ (p. 158; also repeated on p. 148 and p. 134).
The impact of noise on bottlenose dolphins has been predicted as potentially major but only if it results in a serious acute impact on individual female bottlenose dolphins that are part of the
Port Phillip Baypopulation. The likelihood of this occurring is already very low. The likelihood of injury can be removed altogether, by ensuring that bottlenose dolphins are exposed to pileâ€driving noise for far less than 50 minutes. This is done by doing piling during daylight hours and stopping piling if animals are observed to approach within a distance … Mitigation measures based on visual observation, whilst ensuring pileâ€driving is done only during daylight hours and in conditions that are not unreasonable to detect a bottlenose dolphin within about 500m, dramatically reduces the likelihood and consequence. The final residual consequence would be considered negligible (p. 178).
Furthermore, on p. 179:
Potentially serious impacts of noise from pileâ€driving on bottlenose dolphins is effectively mitigated by ensuring that this work is not undertaken at night nor in conditions of poor visibility so that observers can search for dolphins and piling is suspended if they approach to within 1000m of operating equipment. This mitigation measure reduces the potential likelihood and the consequence of pileâ€driving impact on dolphin to a negligible level.However, to suggest that the risk of major impacts associated with underwater noise can be removed or reduced to a negligible level based on visual observation without further elaboration, detail or critical appraisal of the protocols involved is a concern. Given that visual observation is proposed as the only means to prevent the major impacts from underwater noise, the public deserves more details about the visual observation protocols before any assurances can be made about the welfare of the dolphins using this technique. For example:
How many observers will be used and where will they be located? Are they able to effectively observe a 360° area around dredging/pile-driving activities?
What are the skill levels of the observers? I ask this question because I know that even experienced marine mammal observers can miss seeing dolphins, especially when the weather conditions are unfavourable (e.g. rough seas, grey skies, wind, rain).
What equipment (e.g. binoculours) will the observers be using to spot the dolphins and will they be able to accurately measure distances by eye of 500-1000 metres to raise the alarm that dolphins are present within the ‘shut down’ zone?
What assurances are there that a multi-million-dollar project will shut down operations when dolphins are in the vicinity, and that they will only operate in conditions where dolphins can be easily observed? Clarification is needed regarding what are deemed as ‘poor visibility’ conditions, combined with the assurance that observers can accurately estimate distances of 1000 metres by eye.
Unfortunately, I find it hard to believe that such expensive dredging activities would stop without hesitation if the weather is wet, windy or there are rough seas (which, let’s face it, are common sea conditions in Port Phillip Bay) that make observing the presence of dolphins difficult. Yet, this is what we are being asked to believe. I also suspect that the visual observation protocols being alluded to in the technical appendix are much more suited to observing whales, which are easier to spot because of their size and slow speed. Dolphins are smaller and faster animals, making their detection by eye far more problematic.
To the Independent Panel’s credit during the original EES process, it recognised that the SEES needed to refine the assessment of impacts and risks to the sub-species of bottlenose dolphin in
Polperro Dolphin Swims