Black Petrel - hanging on, just by Kate Waterhouse

Environmental News Issue 27

An iconic seabird species may vanish in our lifetime – under threat from cats, pigs, rats and dogs in their ridgetop breeding sites, and from a thousands of baited hooks at sea.
 

October 22nd, coming out of Tryphena on the Island Navigator, straight into 60 knots of SW gale and 3m of steep nasty swell. What creature on earth could possibly find conditions like that habitable – Procellaria parkinsoni, our own Black Petrels do. The wind abated to 40-50 knots as we got further across the gulf, and hanging on I watched them, barely moving as they curved and soared above the waves, the slightest adjustment of the 110cm wingspan enough to send them up into another magnificent dark arc.

Black petrels arrive in October from their winter foraging grounds, which stretch from the east coast of Australia to the west coast of South America – the waters of Mexico, Ecuador, the Galapagos islands and Peru. They come home for one thing and one thing only, to mate. Almost all of them are looking to do this on the summits and ridges around Hirakimata/Mt Hobson. For the black petrel, mating is worthy of a soap opera. Males usually claim the same burrow year on year, returning to spruce it up and make a lot of noise waiting for their steady girl to (hopefully) come back and mate with him. This is a noisy process according to Elizabeth Bell (Biz), who has been researching these birds since 1995. If all goes well, pairs leave the island on honeymoon for up to a month, returning in late November when the females lay a single egg. Petrels are a modern family – both male and female share incubation of the egg for about 8 weeks. Eggs can hatch from late January through February but chicks take a further three months to fledge. This may happen from mid-April through to late June, so you may see Black petrels around in the gulf until then. Bell’s data shows in the past about 75% of chicks go on to fledge but in 2011 breeding success fell to 61%.

However, it’s not all a bed of mairehau up there – males will try to attract another female if their mate doesn’t show up, or if there’s been a divorce – which happens to about 12% of pairs annually according to Bell. Some males will even be kicked out of their burrows by a returning son. 

The main colony can be a busy place at night – with about c. 4000-5000 resident birds over summer, including approximately 1300 breeding pairs and 1000 “pre-breeders” looking for mates. You can hear them at dusk, but will almost never see them, as they return to the colony as a distinctive yakyakyakyakyak overhead. They sound similar to a Cook’s petrel, which breed in the hundreds of thousands on Little Barrer/Hauturu.

Adults and chicks migrate to South America for winter to waters off the Ecuador coast. Juveniles will remain at sea in the West Pacific for 3-4 years until they are ready to breed – survival rate is 46% during this time vs 90% for birds over 3 years old. At about 4 years old, ‘pre-breeders’ as they are known, will come back to the colony to find a mate. Advertising by the males is noisy and may take 1-2 seasons to pay off.

Research by Bell and others shows birds forage much closer to the Hauraki Gulf from December to Autumn while incubating an egg and raising a chick – mainly in the Tasman Sea and to the north-east of NZ. Females and males forage separately and in different places – it is not known why this is. They may go a long way for a fish – the longest recorded foraging trip from Great Barrier is 39 days!

A Consistent Decline

Black Petrels were previously found throughout North Island and Northwest Nelson but feral cats and pigs caused their extinction on the mainland from about the 1950s. The population has been declining by at least 1.4% per year since 1995. They are at risk at sea and on land, classed as Nationally Vulnerable by DoC and they are listed on the International Union for Conservation of Nature UCN Red list: Vulnerable.

Threats On Land

Even five years ago if you walked along the Cooper’s Castle track or around Tataweka in Te Paparahi, you could be confident of coming across the smell of seabirds – black petrels love mature forest with roots and rocks that provide good burrow sites, which are crucial for breeding success. Petrels occasionally nest on ridges away from the main colony and one has even nested under a house at Okupu. However Bell suspects that the Coopers Castle and Tataweka colonies have been destroyed by pigs in recent seasons. Pigs dig up burrows and eat eggs and chicks – in one example in 1996 pigs destroyed 8 burrows in one incident (Bell & Sim 1998). Pigs have been sighted on Hirakimata and around Mt Heale in the last year. If they become established this could spell disaster for the black petrel. Feral cats can kill adults on the ground or at the nest as well as chicks. DOC traps cats in the adjacent Whangapoua basin to protect Brown Teal, but until this season there has been no specific protection of the colony. This month DoC has begun trapping cats and is working on an approach to control of pigs in known nesting areas. Kiore and ship rats are less of a concern – kiore cannot eat through a black petrel egg and predation levels are between 1 and 6.5% per annum (Bell et al. 2011). The risk to black petrel survival from a one-off event is significant due to the importance of the single breeding site around Hirakimata – for example from fire, storm damage or cat and pig invasion of the main colony.

The threat at sea: New Zealand’s most at-risk seabird

This year the Ministry of Fisheries commissioned Dragonfly to develop a Seabird Risk Assessment (Richard et al 2011). The results were horrifying for the Black Petrel. The risk assessment compares the total number of birds potentially killed (via a calculation) against the Potential Biological Removal (PBR) index – that is, the amount of human-induced mortality the species can sustain without heading towards extinction. The Black Petrel was the most at risk of 64 species studied. The report estimates that between 725 and 1524 birds may have been killed each year in the period 2003 to 2009. This number far exceeds what the population could sustain and doesn’t take into account captures outside the EEZ, such as in the Eastern Pacific.

Bottom Longline fishing for snapper and bluenose is how most black petrels are killed. However, there is virtually no monitoring or enforcement of the use of mitigation techniques in these inshore fisheries around the north east of the North Island. This is a key foraging area for Black Petrel from December to May when eggs are being incubated and chicks are hatched and need to be fed.

How black petrels are killed by fishing

Birds will aggressively follow charters and fishing boats and may dive up to 20m below the surface after baits. A longliner will let out or ‘set’ 500 or more hooks at a time. If a bird is caught on a set hook it will be dragged under and drown. Birds caught on the ‘haul’ as hooks are pulled in, have a greater chance of being brought aboard alive and then released. It is not known how many birds are killed in each instance. Discharging waste while stationary attracts more birds, since the more bait and offal are in the water the more birds want to feed. Black petrels predominately feed at night but can feed during the day, unlike albatrosses which do not feed at night, so night setting is unlikely to prevent deaths.

Reported deaths by fishers are low and likely to be under-reported – since 1996, there have been only 38 birds reported caught and killed by local commercial fishers, mainly in domestic tuna long-line and snapper fisheries. The level of deaths in fisheries outside NZ waters is unknown. Mapping of foraging patterns against fishing activity in NZ waters is currently underway. Data loggers have been attached to birds to yield maps of at sea range as we featured in our Spring Environmental News.

There are anecdotal reports of captures from recreational fishers especially in the outer Gulf, but the impact of recreational fishing is also unknown. Leigh charter operator and ex-commercial fisherman Geordie Murman has reported seeing 30-40 black petrels round his boat following baits when close to Great and Little Barrier during the breeding season. Observers have reported instances of very aggressive feeding behaviour in the same area.

If one of a pair of breeding birds is killed while foraging, chances are the egg or chick will also die – taking out 2 from the population in one hit. Biz Bell once observed a female sitting on an egg for 23 days waiting for her mate to return, before she had to leave to feed or die of starvation herself. Bell has removed hooks from birds in burrows and has found birds killed because fishers have left long traces on hooks which then become tangled in trees trapping the bird until it dies.

Mitigation methods to avoid killing birds while fishing are well known in the fishing industry.
For bottom long line (BLL) fishing mitigation is chiefly:

1. Tori lines: these are 20m long sets of streamers attached to poles at the back of the boat. They distract birds and keep them away from the setting hooks while the baits are near the surface. Twin tori lines can ensure coverage of the danger area if strong winds are present.
2. Weighted lines: Weights are attached to each hook to ensure they sink quickly and are too deep for birds to reach by the time the hooks leave the area protected by the streamers.

Ministry of Fisheries regulations for BLL fishing are that vessels over 7 m must use a streamer or tori line and night setting, or use weighted lines if during the day; and that offal/discards are not to be discharged during setting, and only from the opposite side of the vessel during hauling. In the key inshore fisheries, smaller vessels may be operating, night setting will not protect black petrels, and less than 0.5% of boats in the two highest risk fisheries have carried observers in any one year. There have been instances of observers not being able to board boats because they have left early or “decided” not to go out that day. Many boats in the Gulf reportedly do not carry tori lines and there is limited use of weighted hooks.

Preventing extinction requires action by the Ministry of Fisheries

In Auckland Council’s 30 Year Plan, there is a Biosecurity target of no extinctions. At current rates of decline and taking into account the Seabird Risk Assessment, it is highly likely that the Black Petrel will be extinct sooner than 30 years, if we do not act to protect it now. Land-based protection is in hand, provided it continues to be funded by DoC in future seasons. The sea-based methods to protect black petrels are largely known, but not being implemented by the majority of commercial fishers in the high-risk inshore BLL snapper and bluenose fisheries. Worse, the Ministry of Fisheries does not enforce its own regulations, which require mitigation to be used.

The Black Petrel Action Group

As a result of the high level of concern about black petrels raised by the Ministry of Fisheries’ own Seabird Risk Assessment the Black Petrel Action Group was formed on 16 September. GBICT, Hauturu/Little Barrier Trust, Ngati Rehua/Ngati Wai ki Aotea, Birdlife International, Forest & Bird, WWF-New Zealand, and leading seabird scientists from the Auckland Council and Wildlife Management International Limited have joined forces to promote awareness of the bird’s status to take action to protect it. What we consider particularly unacceptable is that mitigation measures exist which, if used, will prevent black petrel being killed in highest-risk inshore fisheries. We have written to the Ministers of Fisheries and Conservation requesting action to:

1. Increase observer coverage of the inshore bottom longline and trawl snapper and bluenose fisheries, and/or install cameras on boats as is being trialled in Australia
2. Enforce existing regulations for the use of mitigation
3. Improve the effectiveness of regulated mitigations, especially around night setting
4. Trial an exclusion area around Black Petrel feeding grounds during breeding and chick rearing
5. Implement a revised National Plan of Action for Seabirds: Between 22,500 and 40,000 seabirds may be killed annually in New Zealand fisheries, despite New Zealand’s commitment to the Agreement on the Conservation of Albatrosses and Petrels (ACAP) and other international agreements, and our claim to operate the most sustainable fisheries management system in the world.

What you can do

• Write to the Minister of Fisheries and of Conservation asking for action to protect the Black Petrel and other seabirds (go to our website for a copy of the letter the Black Petrel Action Group sent in October 2011)
• Write to or contact your MP, GBI Local Board or councillor (Mike Lee and Christine Fletcher for Auckland Central and Gulf Islands) and ask what they plan to do to protect the Black Petrel.
• Find the Black Petrel Action Group site on facebook and “like” it.
• Report any dead black petrels you see to Amelia Geary at DOC on Great Barrier – take photographs and record the location or take the bird to DOC in Port FitzROy
• Encourage any fishers you know to be responsible around seabirds, and especially black petrels, especially between December and May.
• Please see our website for guidance on how to remove hooks form birds. Do NOT leave a long trace if hooks cannot be removed.

Black Petrel Essentials

•All black except for pale sections on bill

•Medium-sized (about 700 g) with wingspan of up to 110cm

•Often seen in outer Hauraki Gulf, from October to May

•Range from east coast of Australia to west coast of Ecuador

•Breeds only on Great Barrier (c. 4000 birds) and Little Barrier Islands (c. 250 birds)

•Total population unknown but likely between 10-15,000 including c. 6000 juveniles at sea

•Oldest bird recorded is 27 years

•Classed as Nationally Vulnerable (DoC) and on IUCN Red list: Vulnerable

•Declining by at least 1.4% per year since 1995.

REFERENCES & ACKNOWLEDGEMENTS
We wish to thank Biz Bell for her generosity with her time, knowledge and image library in the preparation of this article. A full list of references can be found on our website appended to the document Black Petrel Essentials, which summarises and fully references the information included in this article. In particular the work of Biz Bell, Jo Sim,
P. Scofield, C. Francis, E.R. Abraham, D. Filippi, Y. Richard and M.J. Imber is acknowledged.