Cephalorhynchus hectori ssp. maui
|Scientific Name:||Cephalorhynchus hectori ssp. maui Baker, Smith & Pichler, 2002|
Cephalorhynchus hectori (van Beneden, 1881) ssp. (North Island subpopulation)
|Taxonomic Notes:||This is a subpopulation of Hector’s Dolphin, Cephalorhynchus hectori, recently recognized as a subspecies, C. h. maui (Baker et al. 2002). This subspecies is referred to as the North Island Hector's Dolphin or Maui’s Dolphin (not Maui's Hector’s Dolphin).|
|Red List Category & Criteria:||Critically Endangered A4cd; C2a(ii) ver 3.1|
|Assessor(s):||Reeves, R.R., Dawson, S.M., Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K.|
|Reviewer(s):||Brownell Jr., R.L. & Cooke, J.|
The North Island Hector’s dolphin subspecies is considered to be Critically Endangered A4cd and C2a(ii) due to an ongoing and projected decline of greater than 80% over 3 generations (approx. 39 years, Slooten et al. 2000) considering both the past and the future, and there are clearly fewer than 250 mature individuals remaining. For criterion A4cd, the estimated rate of decline over the three generations from 1970 to 2009 is 93% (Slooten 2007; also see Burkhart and Slooten 2003; Martien et al. 1999). Generation length was estimated at 13 years for Hector’s dolphin on the basis of an age-structured model (Slooten et al. 2000). The principal cause of the decline (bycatch in fisheries) has not ceased. The subspecies also meets criterion C2a(ii) for CR, as the single subpopulation contains fewer than 250 mature individuals, and a continuing decline is inferred based on the fact that gillnet use continues in areas occupied (currently and formerly) by the subspecies (e.g., harbours and the southern part of the range) and trawling continues throughout the subspecies’ range. The distribution of the subspecies is highly fragmented and approximately 90% of the individuals are found in a small part of the range – a 22 nautical mile stretch of coastline between Manukau Harbour and Port Waikato, in the centre of the subspecies’ range. There is also evidence for a decline in geographic range, but further information is needed to quantify this threat. The population size is estimated at 111 individuals (95% CI 48-252; Slooten et al. 2005) and the proportion of mature individuals is estimated at 50% (Slooten et al. 2000; Taylor et al. 2007). Given these figures, the subspecies is also very close to meeting criterion D for CR.
|Previously published Red List assessments:|
|Range Description:||Hector's dolphin (C. hectori) is endemic to New Zealand waters (Dawson and Slooten 1988). The North Island subpopulation (C. h. maui) is currently restricted to the west coast of the North Island of New Zealand, between Taranaki and Ninety Mile Beach (Russell 1999; Baker et al. 2002; Slooten et al. 2005, 2006). The range of the subspecies has undergone a marked reduction (Dawson et al. 2001; Slooten et al. 2005). Previous sightings off the east coast of the North Island (e.g., Russell 1999) suggest either that there used to be a much larger contiguous population or that a separate subpopulation on the North Island has already become extinct.|
The map shows where the species may occur based on oceanography. The species has not been recorded for all the states within the hypothetical range as shown on the map. States for which confirmed records of the species exist are included in the list of native range states.
Native:New Zealand (North Is.)
|FAO Marine Fishing Areas:|
Pacific – southwest
|Range Map:||Click here to open the map viewer and explore range.|
mitochondrial and nuclear DNA show that North Island Hector's dolphins are
genetically distinct from any of the
show that the South Island Hector’s dolphin populations collectively number
about 7,270 individuals (CV=15.8%; Dawson et
al. 2004), while the
model (Slooten et al. 2000) indicates
that approximately 50% of Hector’s dolphins are mature individuals. If about half of the estimated 111
Population viability analyses using current abundance together with entanglement rates and historical and current fishing effort indicated a high risk of decline, and that gillnet entanglement had caused a decline since 1970 in the North Island subspecies population (Martien et al. 1999; Slooten 2007). Estimated abundance in the late 1990s was around 25% of the 1970 estimate of 437 individuals (Martien et al. 1999), and the most recent estimate of depletion is that about 7% of the 1970 population remains (Slooten 2007).
|Current Population Trend:||Decreasing|
|Habitat and Ecology:|
The habits and
biology of Hector's dolphins in the South Island have been well studied in the
last couple of decades (Dawson 2002) and there has been increasing research
There is little
information on the feeding ecology of
Like the species as a whole, Maui’s dolphin faces serious pressures from human activities. The main threat is entanglement in gillnets (Dawson et al. 2001; Slooten 2005; Slooten et al. 2006b). Of 14 stranded dolphins in which cause of death could be determined, seven had clear net markings, and an additional four had injuries suggestive of removal from nets (Dawson et al. 2001). Recreational gillnet fishing may be a more serious problem than commercial gillnet fishing, due to the proximity of Auckland, New Zealand’s largest city. Bycatches in trawl nets also have been reported. Additional potential threats include those listed for Hector’s dolphin, i.e. pollution, disease, vessel traffic and habitat modification (Stone and Yoshinaga 2000) although there is no direct evidence that pollution or disease is affecting this subspecies.
The species is listed in Appendix II of CITES.
is restricted to waters of
The New Zealand Government has created a protected area for C. h. maui where gillnetting is prohibited along 390 km of coastline, but the area does not extend far enough south to cover the range of recent sightings and falls well short of covering the historic range. The latter has clear implications for the prospects of recovery. Gillnetting continues inside harbors, trawling is not restricted, and there are no observer programs to estimate the number of dolphins taken (Slooten et al. 2005, 2006b).
between the New Zealand Ministry of Fisheries and Department of Conservation
are currently (early 2008) underway to develop a comprehensive management plan
for Hector’s dolphin (including
|Citation:||Reeves, R.R., Dawson, S.M., Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K. 2013. Cephalorhynchus hectori ssp. maui. The IUCN Red List of Threatened Species 2013: e.T39427A44200192.Downloaded on 16 December 2017.|