Bottlenose dolphins are found in most of the World’s coastal areas.

Of the dolphins, only killer whales (which really are dolphins) have a wider distribution. While bottlenose dolphins can been seen all over Aotearoa-New Zealand, they are most frequently seen in the Bay of Islands, the Hauraki Gulf, Tasman Bay, Golden Bay and Fiordland.

Key Points

  • The Trust, in collaboration with the Department of Conservation, sponsors a long-term research programme on Fiordland bottlenose dolphins
  • The Doubtful Sound population has experiences periods of decline since the study began in 1990
  • Calf survival has been lower than in any other bottlenose dolphin population, including bottlenose dolphins in captivity
  • Potential causes for the very low calf survival include tourism, direct and indirect effects of freshwater input from the Manapouri Power Station, and the long-term, ecological effects of anthropogenic pressures (i.e. fishing and climate change)
  • Dolphin protection zones provide some protection from tourism
  • Tourism guidelines are currently voluntary


New Zealand’s bottlenose dolphins, particularly those in the far south, are among the largest of the species in the world, reaching almost four metres in length, and weighing as much as a medium-sized horse. They are stocky – which is typical of cold water populations.

Bottlenose dolphins reach sexual maturity between 7 and 12 years old. Mature females give birth to a single calf every 2-4 years. Maximum lifespan is at least 40 years. In Fiordland, births are highly seasonal with most births observed between the spring and summer. Our research has shown that the timing of births is important as calves born early or late in the calving season have a much lower chance of survival. Calves are dependent on their mothers for the first six months, and become progressively independent over the next several years.

In Doubtful Sound, our studies have shown that the resident dolphins have a much more stable society than elsewhere. Ties within the group are strong and long-lasting. This is unusual among dolphins, which, except for mothers and calves, typically have more casual social ties. Strong bonds in this community may be due to the habitat. Fiordland is almost as far South as bottlenose dolphins go. It may be that these dolphins need to co-operate more to survive near the limit of their distribution.

It is clear that the cold of Fiordand is an important factor in where the dolphins go. In the coldest months, the dolphins avoid the extremely cold inner regions of the fiord, but are often sighted there in the summer when the inner regions are warmer.

Bottlenose dolphins are incredibly adaptable. Ultimately, that’s why they are so widely distributed – they can modify their behaviour to adapt to almost any circumstance. Whether it is herding fish against the side of a boat, or beating their tail against a muddy bottom to create a visual barrier, these dolphins are capable of extraordinary co-operation to catch elusive prey.

Conservation problems

New Zealand Whale and Dolphin Trust sponsorship has been instrumental in continuing a long-term research programme on the Doubtful Sound dolphins. For over 20 years, researchers have studied their habitat use, ecology, behaviour and population trends and the impact of tourism.

Our work has shown that the population has experienced periods of decline including in the early 2000s. The decline has been attributed to a sudden change in calf survival, which halved in 2002 and has stayed low.


Potential reasons for the extremely low level of calf survival include tourism, ecological impacts of long-term fishing within the fiords and ecological and/or direct impacts of freshwater discharge from the Manapouri power station.


The unique beauty of Fiordland supports a lucrative tourism industry. The dolphins, of course, are a key attraction. Even though the levels of tour boat activity are relatively low, in Doubtful Sound these activities can have impacts on the dolphins’ behaviour. These reactions are most obvious when skippers ignore the rules imposed by the Marine Mammal Protection Regulations, approaching at speed, or head-on. Thankfully, vessel behaviour has improved, and the tourism companies follow a code of practice designed to reduce impacts.

Power Generation:

A local power station takes water from Lake Manapouri, runs it through hydro-electric turbines and then disposes of the water into Doubtful Sound. The height difference between the lake and the fiord makes this a very efficient power station. The problem is, the water can be much colder than the ambient temperature of Doubtful Sound, especially in winter and spring. This is an important time for the local dolphin population. The females go through the final stages of pregnancy in winter and give birth in spring. The young calves have to keep their own bodies warm for the first time, and are at their physiological limits. Cooler water temperatures at this time are a challenge. Add to that potential stress from approaches from tour boats and the relatively low food availability in the fiords, which are still recovering from the impact of past intense fishing pressures. We are not yet sure which of these human impacts are most critical and how the combined effect of several human activities affects the dolphins. This is the focus of our continued research.


Research funded by the NZ Whale and Dolphin Trust has been crucial in the development of the current protection measures. Our research has raised the profile of these dolphins’ conservation problems, both nationally and internationally, to help them get the protection they need.

bottlenose-solution01Dolphin Protection Zones have recently been created, in areas that our research showed to be most frequently used by the dolphins. These are a step in the right direction. The protection zones extend 200m from the shoreline, in the areas indicated in red on the map below. Boats are allowed to enter these areas for fishing, diving, anchoring etc. Voluntary guidelines request that boats travel at a slower speed (5 knots) than elsewhere in the fiord, and do not enter Dolphin Protection Zones if dolphins are seen.

Protection of the Doubtful Sound dolphins could be improved by further reducing the effects of tourism and other human impacts. For example, by increasing the size of the Dolphin Protection Zones and turning the voluntary guidelines into regulations. The amount of freshwater input into Doubtful Sound could be reduced, especially in late winter and early spring which are critical times for dolphins in the final stages of pregnancy and newborn calves. Young calves are especially vulnerable to human impact. We are interested in determining how effective these measures are.

Research Papers

Bottlenose dolphins

Bennington, S., M. Guerra, D. Johnston, R. Currey, T. Brough, C. Corne, D. Johnson, S. Henderson, E. Slooten, S. Dawson, W. Rayment. 2022. Decadal stability in the distribution of bottlenose dolphins in Dusky Sound/Tamatea, New Zealand. New Zealand Journal of Marine and Freshwater Research. doi: 10.1080/00288330.2022.2038214

Bennington, S., W. Rayment, and S. Dawson. 2020. Putting prey into the picture: improvements to species distribution models for bottlenose dolphins in Doubtful Sound, New Zealand. Marine Ecology Progress Series 653:191-204. doi: 10.3354/meps13492

Bennington, S., W. Rayment, R. Currey, L. Oldridge, S. Henderson, M. Guerra, T. Brough, D. Johnston, C. Corne, D. Johnson, E. Slooten, and S. Dawson. 2020. Long‐term stability in core habitat of an endangered population of bottlenose dolphins (Tursiops truncatus): Implications for spatial management. Aquatic Conservation: Marine and Freshwater Ecosystems 31:665-676. doi: 10.1002/aqc.3460

Johnston, D. R., W. Rayment, E. Slooten, and S. M. Dawson. 2017. A time-based method for defining associations using photo-identification. Behaviour 154:1029-1050. doi: 10.1163/1568539x-00003455

Brough, T. E., S. Henderson, M. Guerra and S. M. Dawson. 2016. Factors influencing heterogeneity in female reproductive success in a Critically Endangered population of bottlenose dolphins. Endangered Species Research 29:255-270. doi: 10.3354/esr00715

Guerra, M., and S. M. Dawson. 2016. Boat-based tourism and bottlenose dolphins in Doubtful Sound, New Zealand: The role of management in decreasing dolphin-boat interactions. Tourism Management 57:3-9. doi: 10.1016/j.tourman.2016.05.010

Brough, T. E., M. Guerra, and S. M. Dawson. 2015. Photo-identification of bottlenose dolphins in the far south of New Zealand indicates a ‘new’, previously unstudied population. New Zealand Journal of Marine and Freshwater Research 49:150-158. doi: 10.1080/00288330.2014.984728

Guerra, M., S. M. Dawson, T. E. Brough, and W. J. Rayment. 2014. Effects of boats on the surface and acoustic behaviour of an endangered population of bottlenose dolphins. Endangered Species Research 24:221-236. doi: 10.3354/esr00598

Henderson, S. D., S. M. Dawson, W. Rayment, and R. J. C. Currey. 2013. Are the ‘resident’ dolphins of Doubtful Sound becoming less resident? Endangered Species Research 20:99-107. doi: 10.3354/esr00484

Elliott, R.G. Dawson, S.M. and Henderson, S.D. 2011. Acoustic monitoring of habitat use by bottlenose dolphins in Doubtful Sound, New Zealand. New Zealand Journal Marine and Freshwater Research.

Currey, R.J.C., Dawson, S.M., Schneider, K., Lusseau, D., Boisseau, O.J., Haase, P. Slooten, E. 2010. Inferring trends and causal factors for a declining population of bottlenose dolphins via temporal symmetry capture-recapture modelling. Marine Mammal Science.

Elliott, R.G., Dawson, S.M. and Rayment, W. J. 2011. Optimising T-POD settings and testing range of detection for bottlenose dolphins of Doubtful Sound, New Zealand. Journal of the Marine Biological Association, UK. doi:10.1017/S002531541100035X.

Rowe, L.E., Currey, J.C., Dawson, S.M. and Johnson, D. 2010. Assessment of epidermal condition and calf size of Fiordland bottlenose dolphin populations Tursiops truncatus using dorsal fin photographs and photogrammetry. Endangered Species Research. 11:83-89.

Currey, R.J.C., Dawson, S.M. and Slooten, E. 2009. Conducting a regional threat assessment under IUCN Red List criteria: the Fiordland bottlenose dolphins are critically endangered. Biological Conservation 142:1570-1579.

Rowe, L.E. and Dawson, S.M. 2009. Determining the gender of bottlenose dolphins (Tursiops sp.) using dorsal fin photographs. Marine Mammal Science 25(1):19-34.

Currey, RJ.C., Dawson, S.M., Slooten, E., Lusseau, D.L., Boisseau, O., Schneider, K. Haase, P., and Williams, J.A. 2009. Survival rates for a declining population of bottlenose dolphins in Doubtful Sound, New Zealand: an information theoretic approach to assessing the role of human impacts. Aquatic Conservation 19:658-670

Currey, R.J.C., Rowe, L.E., Dawson, S.M., Slooten, E. 2008. Abundance and demography of bottlenose dolphins in Dusky Sound, New Zealand, inferred from dorsal fin photographs. New Zealand Journal of Marine and Freshwater Research 42:439-449.

Rowe, L. E. and Dawson, S.M. 2008. Sexual dimorphism in dorsal fin size in a population of bottlenose dolphins from Fiordland, New Zealand. Australian Journal of Zoology 56:239-248.

Currey, R.J.C., Dawson, S.M. and Slooten, E. 2007. New abundance estimates suggest Doubtful Sound bottlenose dolphins are declining. Pacific Conservation Biology. 13:265-273.

Lusseau, D., Slooten, E. and Currey, R.J.C. 2006. Unsustainable dolphin-watching tourism in Fiordland, New Zealand. Tourism in Marine Environments 3:173-178.

Boisseau, O. 2005. Quantifying the acoustic repertoire of a population: the vocalizations of free-ranging bottlenose dolphins in Fiordland, New Zealand. Journal of the Acoustical Society of America 117:2318-2329.

Lusseau D. 2004. The hidden cost of tourism: Effects of interactions with tour boats on the behavioural budget of two populations of bottlenose dolphins in Fiordland, New Zealand. Ecology and Society 9(1):2

Higham J.E.S. & Lusseau D. 2004. Ecological impacts and management of tourist engagements with marine mammals. In: Environmental Impacts of Ecotourism (R. Buckley ed.), pp. 173-188. CAB International Publishing: Wallingford.

Lusseau D. 2003. The emergent properties of a dolphin social network. Proceedings of the Royal Society of London B 270 S1:S186-S188.

Lusseau D., Schneider K., Boisseau O.J., Haase P., Slooten E. & Dawson S.M. 2003. The bottlenose dolphin community of Doubtful Sound features a large proportion of longlasting associations. Behavioral Ecology and Sociobiology 54:396-405.

Lusseau D. 2003. The effects of tour boats on the behavior of bottlenose dolphins: Using Markov chains to model anthropogenic impacts. Conservation Biology 17:1785-1793.

Lusseau D. & Higham J.E.S. 2003. Managing the impacts of dolphin-based tourism through the definition of critical habitats. Tourism Management 25:657-667.

Lusseau D. 2003. Male and female bottlenose dolphins have different strategies to avoid interactions with tour boats in Doubtful Sound, New Zealand. Marine Ecology Progress Series 257:267-274.

Haase, P.A. and Schneider, K. 2001. Birth demographics of bottlenose dolphins, Tursiops truncatus, in Doubtful Sound, New Zealand preliminary findings. NZ Journal or Marine and Freshwater Research 35:675-680.

Schneider, K., Baird, R.B., Dawson, S.M., Visser, I. and Childerhouse, S.J. 1998. Reactions of bottlenose dolphins to tagging attempts using a remotely-deployed suction-cup tag. Marine Mammal Science.14:316-324.

Williams, J.A., Dawson, S.M. and Slooten, E. 1993. Abundance and distribution of bottlenose dolphins (Tursiops truncatus) in Doubtful Sound, New Zealand. Canadian Journal of Zoology 71:2080-2088.