The Hauraki Gulf has an extraordinary wealth of seabirds, supported by its productive marine area, diverse habitats and numerous predator free islands. Over 80 species have been seen in the region which comprises 20 per cent of the world’s total species. Of these at least 27 species breed in the wider Hauraki Gulf region.
Seabirds spend most of their lives at sea; they only come to land to breed. Although many of the birds travel enormous distances, some to the north and eastern Pacific – to waters off Japan, Hawaii, California and Ecuador – others venturing down to the Polar Front, they return each year to breed in burrows on the Gulf’s islands.
Historically, seabirds would have also bred on New Zealand’s mainland, but the destruction of habitats and predation by introduced animals have left the remnant populations mostly on islands. Where once seabirds brought fertility to soils, adding nutrients through the decomposition of guano and dead eggs, chicks and adults, farmers now spread fertiliser, much of it derived from seabird islands elsewhere in the Pacific.
The Hauraki Gulf’s rich seabird population attracts birders from all over the world. Threats to the seabirds include longline fishing hooks (the birds dive on the bait and get caught on the hooks), predators at breeding sites and lack of food through overfishing and depletion of fish stocks, especially bait fish.
Commercial fishers are adopting seabird friendly fishing methods to avoid seabird bycatch which include setting their lines at night, weighting the lines so they sink quickly and running tori lines over the top of the long line.