Scientific Literature: Searchable Database

A draft of this report was given to Port Phillip Bay dolphin tour industry as well as researchers prior to being finalised. Useful suggestions were made by both groups at the outset of the study and in response to the draft report. These suggestions were greatly appreciated and many have been incorporated into the final report. The main finding of the report is that proximity of all kinds of vessel to dolphins must be further restricted in order that adverse impacts on the dolphin population can be minimised. The report presents a number of recommendations as to how this can be best achieved while allowing for a sustainable industry. The dolphins that inhabit Port Phillip Bay and are the object of the dolphin swim and sightseeing tour industry are inshore bottlenose dolphins (Tursiops aduncus). They are a small population resident to the southern part of the bay near its mouth. The current population is probably smaller than prior to European settlement, and prior to intensive development and loss of fisheries habitat in the last 40 years. This review addresses the issue of sustainability in regard to tour, other commercial, and private boat interactions with dolphins. NRE advises that other processes and actions are being undertaken currently to protect the Port Phillip Bay environment and as a consequence to protect dolphin habitat. The dolphins use their home range for all aspects of their ecology, including their main activities, foraging and feeding, as well as socialising, resting, and the protection and rearing of young. The population of bottlenose dolphins in Port Phillip Bay is vulnerable to extinction due to its size, female natal philopatry, restricted home range and the human activities within the home range that are likely to be having an adverse impact on the dolphins. Data from several years of research on the Port Phillip Bay dolphins and vessel proximity to them, carried out by the Dolphin Research Institute and Carol Scarpaci et al., was analysed for this report. The research by both groups is generally sound and uses methods HALE - REPORT TO NRE ON VESSEL INTERACTIONS WITH DOLPHINS 6 that are well recognised in this field (eg, Martin & Bateson 1993). The data has limitations but provides a solid basis for making decisions to improve management for sustainability. Many types of vessel use the dolphins’ habitat; high and low-speed recreational vessels, commercial shipping, passenger ferries, dolphin swim-tours and dolphin sightseeing tours. Their use of the habitat is increasing, as will their interactions with dolphins. Of these dolphin swim-tours present the largest potential impact due to their sustained interaction with (proximity to) the dolphins, especially during daylight hours in the summer months, November to May. Breaches of the Wildlife (whales) Regulations (Victoria) (Anon. 1998) by all types of vessel are evident. Adverse impacts from vessel traffic, both lethal and non-lethal, could lead to a reduction in recruitment of females into the breeding population, in which case the population is likely to die out in the foreseeable future. The number of dolphins that swim-tour vessels attempt to interact with on a regular basis is most likely no more than 50, although the size of the population is probably about 80. Increasing levels of interaction by swim-tour vessels and to lesser extent recreational vessels, often in contravention of existing regulations, have been associated with an increase in avoidance of swim-tour vessels by dolphins. This avoidance behaviour is seen as indicative of disturbance that constitutes a threatening process. Regulations contravened include approach distances, number of tour vessels in proximity to dolphins at the one time and swim with foetal-fold (newborn) calves The Victorian regulations governing swim-tour operations and other vessel traffic are comprehensive and in accord with national guidelines. Approach distances to dolphins are less than those recommended (but not as yet regulated) for dolphin and other Odontocete cetacean sightseeing operations in North America, where experience with the cetacean-watch industry spans more than 20 years and is on a larger scale. HALE - REPORT TO NRE ON VESSEL INTERACTIONS WITH DOLPHINS 7 It is apparent from the data that tour operators, other commercial vessels and recreational vessels are not only breaching the letter but also the intent of the Wildlife (whales) Regulations (Victoria), those of relevance having been formulated to allow for vessel interactions at the same time as attempting to minimise any impact on dolphins. After analysis of available data on parameters for the population and the impact of vessel traffic on the Port Phillip Bay dolphins, and consideration of the results of studies overseas, recommendations below (see also Table 5) aim to further protect dolphins as well as give tour operators the opportunity to improve compliance to regulations and recognise the intent of regulations to protect this small and fragile population. The proposed changes to regulations represent a shift away from the current focus on regulating the number of swimmers to regulating the proximity of vessels to dolphins. It seems reasonable to trial any proposed changes to the regulations, but to be worthwhile the trials must be monitored by independent observers who are trained in the collection of behavioural data in the field. In addition to recommended changes to regulations outlined below and in Table 5, it is proposed that: • The proximity of vessels to dolphins continues to be monitored, as well as the responses of dolphins to vessels. • There continue for the present to be no limit on the overall number of swim tours per vessel per season or per day, an aspect of operation that may need to be addressed if dolphin avoidance of vessels and vessel disruption of normal dolphin behaviours, including foraging and feeding, continues to increase. • The number of dolphin swim permits be maintained at 4 while not at this stage limiting the number of dolphin sightseeing permits, with the consequences for overall vessel proximity to dolphins, and regulations aiming to reduce proximity, being assessed before there is any decision to increase the number of sightseeing permits beyond the present two. • The use of the Ticonderoga Bay Dolphin Sanctuary Zone and adjacent areas to the west and north by dolphins be investigated with a view to extending the area westwards, northwards or both in order to provide additional area where dolphins HALE - REPORT TO NRE ON VESSEL INTERACTIONS WITH DOLPHINS 8 may not be approached by tour vessels closer than 200m, and where approach distances by other commercial and recreational vessels is restricted to 200m. To regulate the impact of vessels on dolphins: • Limit to three per tour the maximum number of approaches closer than 100m to dolphins by swim-tour vessels, per tour. • Limit to 7 minutes the time a swim-tour vessel can be within 100m of a dolphin on each approach. • Limit to one per tour the number of approaches closer than 100m to dolphins by sightseeing tour vessels. • Limit to 7 minutes the time a sightseeing tour vessel can be within 100m of a dolphin on each tour. • Prohibit approaches within 100m to dolphin groups containing foetal-fold calves. • Increase to 300m the minimum distance that a tour vessel can approach another tour vessel if that tour vessel is within 100m of a dolphin. • Increase minimum approach distances in the Ticonderoga Bay Sanctuary Zone to 200m for all motorised vessels. • Consider prohibiting dolphin swims in areas where vessel navigation is restricted. • Allocate the existing number of swim-tour permits for 2002/2003 and 2003/2004 seasons but not grant any additional permits. • Consider effectiveness of regulations and issue of permits after 2003/2004 season on the basis of dolphin behaviour monitoring and compliance to regulations by permit holders. To monitor short-term impacts on dolphins: • Continue to monitor dolphin responses to approaches from swim-tour, sightseeing tour and recreational vessels. Determine background level of avoidance behaviour through monitoring behaviour in the absence of vessels, and analysis of data. • Continue to monitor compliance to regulations over 2002/2003 and 2003/2004 seasons, from both shore-based and boat-based (including swim-tour) stations. HALE - REPORT TO NRE ON VESSEL INTERACTIONS WITH DOLPHINS 9 • Monitor and analyse data on dolphin and vessel use of Ticonderoga Bay Sanctuary Zone. To inform the industry and public: • Conduct training workshops to inform swim-tour operators of existing and new regulations and the reasons for them, and train them to recognise calves. • Inform the swim-tour and sightseeing industry of results of monitoring operator compliance and dolphin responses to approaches and interactions, on a regular basis. • Include questions on marine mammal regulations in the test for recreational boating license. • Conduct extension activities (eg pamphlets, signage, boat-based surveillance) to inform recreational boaters of existing and new regulations and the reasons for them. Further research for impact assessment and management: • Continue to collect demographic information on dolphins to enable variables such as population size, age at first breeding, calving rate and calf and adult survivorship to be determined with greater precision. Carcase recovery and postmortem to be a priority. • Conduct population genetic analysis to help identify sex of individual dolphins, size of female breeding population and the geographic range of the population. • Conduct population modelling, using collected data and data sourced from other populations, to establish confidence levels for population persistence under different parameter values. • Investigate dolphin use of the Ticonderoga Bay Dolphin Sanctuary Zone and surrounding waters to determine whether an extension to the zone would be effective in providing further sanctuary for dolphins. Other: • Remove the limit on the number of swimmers per tour and per day.