Māui Dolphin: New Zealand's Critically Endangered Endemic

The Māui dolphin (Cephalorhynchus hectori maui) is a subspecies of Hector's dolphin found only off the west coast of New Zealand's North Island. With ~54 individuals estimated (2021), it's the world's rarest marine dolphin—and a national conservation crisis.

Biology & Identification

• Size: 1.2-1.7m, 40-60kg — smallest dolphin globally
• Appearance: Grey back, white belly, distinctive black "cape" across blowhole to flippers, rounded dorsal fin (Mickey Mouse ear), short blunt rostrum
• Social: Pods of 2-10; fission-fusion society
• Diet: Small fish (ahuru, red cod), squid, crustaceans — benthic foraging
• Reproduction: Slow: females calve 2-4 years; maturity 7-9 years; lifespan ~20 years

Range & Habitat

• Current: West Coast North Island, Maunganui Bluff to Whanganui (mostly <20m depth)
• Historical: Extended further south/north; range contracted 90%+
• Overlap: Southern edge overlaps with South Island Hector's dolphin (C. h. hectori)

Threats (Ranked by Impact)

1. Fisheries bycatch: Set nets (gillnets) and trawling — #1 killer; ~5 deaths/year = unsustainable for population of 54
2. Habitat degradation: Sedimentation, pollution, seabed disturbance from coastal development
3. Disease: Toxoplasmosis (cat feces → runoff → marine); brucellosis
4. Climate change: Prey distribution shifts, harmful algal blooms
5. Vessel strike: Low speed but high vulnerability in shallow habitat
6. Seismic surveys: Acoustic disturbance

Protection Measures

• Marine Mammal Sanctuary (2008, expanded 2020): Set net bans 0-4nm (extended to 7nm in parts); trawl restrictions
• West Coast North Island Marine Mammal Sanctuary: Overlaps; seismic survey controls
• Threat Management Plan (2020): Bycatch reduction, disease research, toxoplasmosis mitigation
• Monitoring: Aerial surveys, photo-ID, acoustic monitoring, genetic sampling

Why It's Not Working (Yet)

• Sanctuary boundaries don't cover full range (dolphins forage further offshore)
• Compliance/enforcement gaps in recreational/commercial fishing
• Toxoplasmosis requires land-based cat management — not addressed
• Population too small for demographic resilience — Allee effects, inbreeding

What's Needed

• Full habitat protection to 100m depth / 20nm offshore
• Eliminate set nets in range — transition fishers
• Cat management (feral + owned) in catchment
• Genetic rescue? (Controversial: translocate Hector's dolphins?)
• Political will matching ecological urgency

The Māui dolphin is New Zealand's kakapo of the sea — a unique evolutionary lineage on the knife-edge. Saving it requires treating the entire west coast North Island ecosystem as its critical habitat. Half-measures have failed for 20 years.