Talk:Hector's dolphin

Range map

The range shown in the map seems to be incomplete. Hector's dolphins also live in the Catlins, at the far southeast corner of the South Island. -- Avenue 12:49, 27 March 2006 (UTC)

I've updated the map to include the Catlins in their range. -- Avenue 13:22, 7 June 2006 (UTC)

Hector's Dolphin photo

Hi,

I took a picture of a Hector's dolphin in Akaroa a couple of months back, which shows off their head colourings quite well.

Click to see the picture on my weblog [1]

I would be more than happy for this to be used on the page, if anyone thought it would add anything? (ps I actually don't know how to do this myself).

Thanks, Rich FatRich 01:59, 3 April 2007 (UTC)

Vandalism?

Why is this page being targeted? Was this mentioned on the Colbert Report or something? vlad§inger ^tlk 02:43, 26 July 2007 (UTC)

Maui's dolphin (popoto)

Is it ok to create a new page for Maui's dolphin? As a "subspecies" of Hector's dolphin is the agreement to have species as separate pages and any subspecies contained within them?FionaBlinco 10:23, 27 July 2007 (UTC)

Exactly what I was going to say, either that or this page needs to make it very clear that there are different subspecies of Hector's dolphins and detail them --Nengscoz416 22:05, 2 December 2007 (UTC)

Hector's dolphin

I am very interested in dolphins. My friends and I have a project on dolphins and we were wondering if anyone had pictures of Hector's dolphins? Thanks!! —Preceding unsigned comment added by 24.93.199.82 (talk) 20:33, 28 November 2007 (UTC)

Top photo error

The main photo in the upper right does not look like a hector dolphin. "Hector's dolphin has no discernible beak and a rounded dorsal fin." That dolphin pictured has a pointed dorsal fin and looks suspiciously similar to a dusky dolphin: http://en.wikipedia.org/wiki/Image:Lagenorhynchus_obscurus.jpg —Preceding unsigned comment added by Smilingscar (talk • contribs) 20:22, 10 December 2007 (UTC)

Absolutely correct, it was listed as a Hectors, and the description "the throat and chest are white" matched the image. But the fin does not, clearly very similiar to the dusky dolphin photo. I think this image shows a Hector's, obviously a different animal. I'll fix it up, thanks for pointing it out. XLerate (talk) 00:01, 11 December 2007 (UTC)

suggestions for Hector's dolphin page

I am a Hector’s dolphin researcher at the University of Otago in New Zealand. I recently completed my PhD on Hector’s dolphins and so I am up to date with the most recent literature. I hope that these suggestions are useful for improving the page. Please let me know if you have any questions or queries.

Introduction
1. I am not aware of anyone who uses the name white-headed dolphin, it does not appear in any of the major identification guides and as the species does not have a white-head it seems unusual to include this name.
2. The most recent estimate for Maui’s dolphin abundance is 111 (95% confidence interval = 48-252)[1].
3. Maui’s dolphins may be at risk of injury due to being struck by boats but I am not aware of the evidence. There is evidence for boat strike in Hector’s dolphins, from Akaroa Harbour on the east coast of the South Island, where the deaths of two calves have been attributed to boat strikes[2].
4. I believe the information about length and weight of Maui’s dolphins would be more appropriate in the “Physical description” section.

Physical description
5. The age of Hector’s dolphins has been determined by counting the growth layers in the teeth of bycaught or beachcast animals. The maximum observed ages were 19 years for males and 20 years for females[3]. However, photo-identification of naturally marked dolphins at Banks Peninsula has revealed individuals reach at least 23 years old.
6. Hector’s dolphins typically live in small, fluid groups. They are often encountered as lone individuals[4] or in small groups of 2-8 individuals[5].
7. “When leaping from the sea, individuals will often land on their side, creating a loud splash (their vertical and horizontal jumps are much less noisy).”

Population and distribution
8. The range of Hector’s dolphin extends all the way down the east coast of the South Island and around the south coast as far as Te Waewae Bay. The distribution map needs to be changed to reflect this.
9. Analysis of mitochondrial DNA sequences has shown that the species is divided into four regional population units (North Island, South Island west coast, South Island east coast and South Island south coast) connected by little or no female dispersal[6,7]. These genetic differences are likely to result from individuals having small home ranges and high philopatry[8].
10. Hector’s dolphins are typically seen in waters less than 100m deep. This means they have a strongly coastal distribution, although in shallow areas such as off Banks Peninsula they can be seen up to 18 nautical miles (33 km) from the coast[4]. In some regions there is a distinct seasonal difference in distribution, dolphins being sighted closer to the coast in summer and more spread out in winter[4].
11. As mentioned previously, the most recent estimate for Maui’s dolphin abundance is 111 individuals[1].
12. I don’t think that the information about the ice age and the depth of Cook Strait is really relevant. Hector’s dolphins are found all around the South Island and before fishing impacts had a wider distribution in the North Island. Note that the correct spelling is Hector’s dolphin and Maui’s dolphin.

Conservation
13. Hector’s dolphin is classified as “endangered” by the IUCN, while the Maui’s dolphin sub-species is classified as “critically endangered”. The current abundance is estimated to be 27% of the population size in 1970[9]. There is also genetic evidence of population decline at both regional and local levels[7].
14. Bycatch in bottom set gillnets has been responsible for the majority of human induced mortality of Hector’s dolphins[10]. Before new regulations were introduced in 2008, the estimated level of bycatch in commercial gillnets was 110-150 Hector’s dolphins per year[11] which is far in excess of the level which is considered to be sustainable[12]. Hector’s dolphins are also threatened by bycatch in inshore trawl fisheries, mortality from boat strikes, bioaccumulation of pollutants and loss of habitat due to development in the coastal zone.
15. The Banks Peninsula Marine Mammal Sanctuary (on the east coast of the South Island) was established in 1988 by the Department of Conservation, in response to the unsustainable level of bycatch in the local gillnet fishery[13]. It was not strictly a marine reserve as some forms of fishing were still allowed, but use of commercial gillnets was effectively banned and recreational gillnetting was subject to seasonal restrictions. A second Marine Protected Area, with fishing restrictions aimed at conservation of Maui’s dolphin, was designated on the west coast of the North Island in 2003.
16. Despite this protection, the Hector’s dolphin population was predicted to continue declining[9]. New measures were introduced by the Ministry of Fisheries in 2008 effectively banning gillnetting within 4 nautical miles (7.4 km) of the majority of the South Island’s east and south coasts, regulating gillnetting on the South Island’s west coast out to 2 nautical miles (3.7 km) offshore and extending the gillnet ban on the North Island’s west coast to 7 nautical miles (13 km) offshore[14]. There are also restrictions on trawling in some of these areas[14].

References
1. Slooten, E., Dawson, S., Rayment, W. and Childerhouse, S. 2006. A new abundance estimate for Maui’s dolphin: What does it mean for managing this critically endangered species? Biological Conservation 128: 576-581.
2. Stone, G.S. and Yoshinaga, A. 2000. Hector’s dolphin Cephalorhynchus hectori calf mortalities may indicate new risks from boat traffic and habituation. Pacific Conservation Biology 6: 162-170.
3. Slooten, E. 1991. Age, growth and reproduction in Hector’s dolphins. Canadian Journal of Zoology 69: 1689-1700.
4. Rayment, W., Dawson, S. and Slooten, E. In press. Seasonal changes in distribution of Hector’s dolphin at Banks Peninsula, New Zealand: implications for protected area design. Aquatic Conservation: Marine and Freshwater Ecosystems. DOI: 10.1002/aqc.1049.
5. Slooten, E. and Dawson, S.M. 1994. Hector’s dolphin Cephalorhynchus hectori [van Beneden 1881]. p. 311-333 in Ridgway S.H. and Harrison R. [eds]. Handbook of Marine Mammals. Volume V. Academic Press, New York, USA.
6. Pichler, F.B., Dawson, S.M., Slooten, E. and Baker, C.S. 1998. Geographic isolation of Hector’s dolphin populations described by mitochondrial DNA sequences. Conservation Biology 12: 676-682.
7. Pichler, F.B. 2002. Genetic assessment of population boundaries and genetic exchange in Hector’s dolphin. DoC Science Internal Series 44. Department of Conservation, Wellington. 37 p.
8. Rayment, W., Dawson, S., Slooten, E., Brager, S., DuFresne, S. and Webster, T. 2009. Kernel density estimates of alongshore home range of Hector’s dolphins at Banks Peninsula, New Zealand. Marine Mammal Science 25: 537-556.
9. Slooten, E. 2007. Conservation management in the face of uncertainty: effectiveness of four options for managing Hector’s dolphin bycatch. Endangered Species Research 3: 169-179.
10. Dawson, S.M. and Slooten, E. 2005. Management of gillnet bycatch of cetaceans in New Zealand. Journal of Cetacean Research and Management 7: 59-64.
11. Davies NM, Bian R, Starr P, Lallemand P, Gilbert D, McKenzie J. Risk analysis for Hector’s dolphin and Maui’s dolphin subpopulations to commercial set net fishing using a temporal-spatial age-structured model. Ministry of Fisheries, Wellington, New Zealand 2008; Available from: http://www.fish.govt.nz/NR/rdonlyres/B034115D-247A-42E5-B08F-F5D267046C59/0/HectorNIWAriskanalysis.pdf
12. Slooten, E. and Dawson, S.M. 2008. Sustainable levels of human impact for Hector’s dolphin. The Open Conservation Biology Journal 2: 37-43.
13. Dawson, S.M. and Slooten, E. 1993. Conservation of Hector’s dolphins: The case and process which led to the establishment of the Banks Peninsula Marine Mammal Sanctuary. Aquatic Conservation: Marine and Freshwater Ecosystems 3: 207-221.
14. http://www.fish.govt.nz/en-nz/Environmental/Hectors+Dolphins/default.htm?WBCMODE=PresentationUnpublished++%23MainContentAnchor%23MainContentAnchor

Will Rayment (talk) 00:50, 24 November 2009 (UTC)

Thanks for the extensive information, please be bold and expand / update the details and references directly into the article. XLerate (talk) 07:47, 24 November 2009 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Hector's dolphin/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

I found this article confusing and irrelevant as it appears there is a confusion in differentiating between the Maui dolphin and the Hector's dolphin, Maui is one of a number of subspecies of Hector's. This was not clear enough, nor does the article discuss the other subspecies of Hecotr's dolphins which are found in other areas of New Zealand. Much work needs to be done for this article to make any sense at all.

Last edited at 23:33, 15 February 2010 (UTC). Substituted at 17:32, 29 April 2016 (UTC)

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