Size in Square Kilometres
Qualifying Species and Criteria
Bryde’s whale – Balaenoptera edeni
Criterion B (2); C (2)
False killer whale –Pseudorca crassidens
Criterion C (2)
Pygmy blue whale – Balaenoptera musculus brevicauda
Criterion A; C (2)
Marine Mammal Diversity
Criterion D (2)
Orcinus orca, Pseudorca crassidens, Delphinus delphis, Globicephala melas, Ziphius cavirostris, Mesoplodon grayi, Berardius arnuxii, Balaenoptera borealis, Megaptera novaeangliae, Balaenoptera bonaerensis, Physeter macrocephalus, Eubalaena australis, Hydrurga leptonyx, Arctocephalus forsteri
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The Hauraki Gulf – Tīkapa Moana – Te Moanaui-ā-Toi covers the inshore and offshore waters off the Auckland region. It is New Zealand’s only marine national park (Hauraki Gulf Marine Park Act 2000) but very few areas have protection from exploitation. The productive warm-temperate, wind-mixed waters are influenced by cooler upwellings from the continental shelf and, in summer, the warm East Auckland Current increases sea temperature. There are year-round populations of Bryde’s whales, common bottlenose dolphins and common dolphins with regular sightings of killer whales (Kozmian-Ledward 2015, Hupman et al. 2015, Dwyer et al. 2016, Colbert 2019, Stephenson et al. 2020). In the summer and autumn (January – May) there are frequent sightings of false killer whales, pilot whales and pelagic bottlenose dolphins, sometimes foraging together (Zaeschmar et al. 2013). Humpback and pygmy blue whales are seen regularly; minke and southern right whales are observed occasionally, and there is at least one resident sei whale (R. Constantine unpub. data). Pygmy right whales, sperm whales and beaked whales (e.g., Gray’s, Arnoux’s and Cuvier’s) are observed occasionally but are unlikely to use this area much except when stranding (Thompson et al. 2013). For Gray’s beaked whales the strandings may involve females coming inshore during the summer-autumn with calves (Thompson et al. 2013). There is a resident leopard seal with increasing reported sightings of this species in the region (Hupman et al. 2020).
The Hauraki Gulf forms an integral part of the home range of the species that occur regularly throughout the year (Bryde’s whales, bottlenose dolphins and common dolphins) even though some individuals range outside the IMMA (e.g., bottlenose dolphins, Berghan et al. 2008). There is niche separation between the three main species feeding on zooplankton, fishes and squids (Kozmian-Ledward 2015, Carroll et al. 2019). The Bryde’s whales and common dolphins appear to shift habitat slightly offshore during warm-water events, but killer whales and bottlenose dolphins do not change their distribution (Colbert 2019). Bryde’s whales were threatened with unsustainable levels of ship-strike mortality but this has been resolved with voluntary speed reductions by the shipping industry (Constantine et al. 2015, Ebdon et al. 2020). Whether this has led to an increase in population size is yet to be determined. An estimated 135 (95% CI = 100-183) Bryde’s whales use the Gulf, with some individuals year-round residents and others transient (Tezanos-Pinto et al. 2017). The estimate of 171 (95% CI = 162-180) bottlenose dolphins is negatively biased as the research behind it covered only part of the population (Great Barrier Island) (Dwyer et al. 2014). There is an estimate of 2,478 (95% CI = 1598-3615) common dolphins for the whole Gulf generated using aerial survey distance sampling methods (Hamilton et al. 2017), but a photo-identification study estimated up to 8,632 (95% CI = 7,738-9,630) common dolphins (Hupman et al. 2018).
Description of Qualifying Criteria
Criterion A – Species or Population Vulnerability
Pygmy blue whales, listed as Endangered on the IUCN Red List, use the Gulf for foraging in the summer months (Olson et al. 2015; Barlow et al. 2018). Whilst not listed as endangered by the IUCN, the Gulf is an important year-round habitat for a small, resident population of Bryde’s whales and frequently used by killer whales ranging more widely throughout New Zealand waters – both species are listed in New Zealand as nationally critical (Baker et al. 2019).
Criterion B: Distribution and Abundance
Sub-criterion B2: Aggregations
The Hauraki Gulf forms an integral part of the home range of Bryde’s whales, even though some individuals range outside the IMMA. There is niche separation between the three main species feeding on zooplankton, fishes and squids (Kozmian-Ledward 2015, Carroll et al. 2019). The Bryde’s whales appear to shift habitat slightly offshore during warm-water events (Colbert 2019). An estimated 135 (95% CI = 100-183) Bryde’s whales use the Gulf, with some individuals year-round residents and others transient (Tezanos-Pinto et al. 2017). Bryde’s whales were threatened with unsustainable levels of ship-strike mortality but this has been resolved with voluntary speed reductions by the shipping industry (Constantine et al. 2015, Ebdon et al. 2020). Whether this has led to an increase in population size is yet to be determined.
Criterion C: Key Life Cycle Activities
Sub-criterion C2: Feeding Areas
There are increasingly regular summer-autumn aggregations of pygmy blue whales over the past decade (Olson et al. 2015; Barlow et al. 2018). These whales are feeding on zooplankton (Barlow et al. 2018), most likely krill that are a preferred prey of Bryde’s whales in the Gulf (Carroll et al., 2019). In summer-autumn, two primary groups of false killer whales regularly use the outer Gulf waters for feeding, often in association with pelagic bottlenose dolphins (Zaeschmar et al. 2014).
Criterion D: Special Attributes
Sub-criterion D2: Diversity
The area is a key area for cetaceans in New Zealand (Stephenson et al. 2020) with 17 species recorded in the Gulf including Balaenoptera musculus brevicauda, Tursiops truncatus, Orcinus orca, Pseudorca crassidens, Delphinus delphis, Globicephala melas, Ziphius cavirostris, Mesoplodon grayi, Bearadius arnuxuii, Balaenoptera borealis, Megaptera novaeangliae, Balaenoptera bonaerensis, Physeter macrocephalus, Eubalaena australis, Hydrurga leptonyx, Arctocephalus forsteri. There are migratory species such as humpback whales and southern right whales that are infrequently sighted but likely to increase in number as populations recover from whaling (Cranswick et al. 2022). Reports of live beaked whales are infrequent, although mother-calf pairs of Gray’s beaked whales may come closer inshore during the summer months to feed in the outer parts of the Gulf (Thompson et al. 2013). There is a wide diversity of large and small cetaceans as well as native and vagrant species of pinnipeds including leopard seals. New Zealand fur seals are increasing in number, although this is not an established breeding area as it was historically (MacDiarmid et al. 2016).
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