Seabirds in Strife

Forest and Bird, Volume 21, Issue 4, 1 November 1990, Page 23

Seabirds in Strife

New evidence shows that commercial fishing is responsible for the deaths of hundreds of thousands of New Zealand seabirds a year. However, as Forest and Bird researcher Alan Tennyson writes, such a slaughter is both unnecessary and avoidable.

N= ZEALAND can boast the most outstanding seabird fauna of any country in the world. Being situated in the middle of the southern ocean and having a latitudinal range spanning over 20 degrees, from the sub-tropical Kermadec Islands south to subantarctic Campbell Island, our country offers nesting grounds to a huge diversity of seabird species. About 85 species breed in New Zealand waters, including 10 albatrosses, 35 petrels and shearwaters and more inshore species, such as penguins, gannets, shags, gulls and terns. Forty five percent of our seabirds breed nowhere else in the world. This November/ December, ornithologists are flocking to New Zealand for the world conferences of the International Council for Bird Preservation and the International Ornithological Congress to celebrate our special seabird fauna. Few New Zealanders realise this country’s huge diversity of seabirds. Unfortunately, the

ground-nesting habits of seabirds make them highly vulnerable to predation by introduced cats, stoats and rats and as a consequence, most are now confined to nesting on offshore islands where the public has little chance of seeing them.

Lack of protection

The lack of public awareness of seabirds has resulted in neglect of this magnificent and unique fauna. Fisheries by-catch problems have existed for decades, yet the majority of seabird colonies remain unsurveyed so that there are no measures of population changes. While most New Zealand seabirds enjoy legal protection onshore and within 12 miles of the coast, they are completely unprotected further out to sea. Albatrosses, shearwaters and petrels spend most of their lives in offshore waters where they can be legally killed. As with the conservation of most of our marine animals, the conservation of our seabirds has

been sadly neglected.

The foreign tuna longline fishery

Japanese longline fishing for tuna began in the early 1950s. It has been a major fishery around New Zealand for about 25 years. Daily, the boats set their lines, which are an astonishing 125 km long and have about 3,000 hooks. Each boat sets just one line. In the early 1980s, about 100 foreign longliners operated in our economic zone, but that figure has dropped to about 70 a year. The largest foreign fleet has about 40 boats and fishes for southern bluefin tuna. These boats generally begin the season in southern New Zealand waters in late summer and move, following the tuna, to the East Cape region during winter. Only one spawning ground for bluefin tuna, between northwest Australia and Indonesia, is known. Most bluefin tuna leave New Zealand waters in

spring and presumably travel to this spawning area. A second foreign tuna longline fleet, made up of Korean and Japanese boats, operates in northern New Zealand. It mainly targets albacore tuna but high numbers of big-eye and yellowfin tuna may also be taken.

Fishery in danger of collapse

As with many New Zealand fisheries, tuna have been grossly over-exploited. Between 1980 and 1986 bluefin catch rates fell by 65 percent. In 1988, the drastic situation led New Zealand's Ministry of Agriculture and Fisheries (MAF) scientists and Australian and Japanese experts to suggest that the bluefin fishery be closed until there were clear signs of stock recovery. Only a 50 percent quota reduction occurred. MAF scientists were left to "hope for the right combination of environmental conditions ... to further slow the rate of ... decline". As the southern bluefin catches have declined, other species of tuna (for which there are no quotas) have come under great pressure from longliners and the by-catch rates have increased. The tuna longline fishery may more aptly be described as a shark fishery in some areas. For example, 1200 sharks were taken when 650 tuna (including only 128 target bluefin) were taken by two boats off Poverty Bay. There is no limit to the number of other species such as mako and blue sharks or seabirds taken. Frequently, more seabirds than bluefin tuna are caught on the lines.

Longline mortality of NZ birds

In New Zealand waters, an average of between one and five birds die each time a bluefin tuna longline is set. About 5,000 lines are set annually, thus 5-25,000 birds are likely to be killed by foreign longliners each year. During the early 1980s, more than 10,000 foreign longlines were set annually, which would indicate that twice as many birds would have been drowned in this period. The main species caught in New Zealand waters on foreign longlines are: e Buller’s mollymawk @ White-capped mollymawk e New Zealand black-browed mollymawk @ Grey-headed mollymawk e Wandering albatross © Grey petrel e Westland black petrel There is not enough data to indicate exactly how many of each species are caught in New Zealand waters. New Zealand breeding species reported caught elsewhere include: e Light-mantled sooty albatross e Giant petrel @ White-chinned petrel e Southern skua Worldwide, a yearly average of 107.9 million hooks were set between 1981-86 in the Japanese southern bluefin tuna fishery. Average catch rates for birds range from 0.35 — 1.6 per 1,000 hooks set, thus from 38-173,000 birds die annually. Tasmanian catch rates are among the lowest reported worldwide, but even they indicate that a minimum of 44,000 albatrosses die on longlines in the southern ocean each year. Not all birds die at sea, as

several albatrosses have been found fatally injured by longline hooks at their nests. These figures take no account of the bycatch in other longlining fisheries. For instance, more than 30 boats fish in northern New Zealand's albacore longline fishery. Northern domestic commercial longliners and even amateur fishers probably affect species such as flesh-footed and black petrels, which are strongly attracted to baits on lines.

The Auckland Island squid fishery

Since the late 1970s, a major squid fishery has existed around the Auckland Islands, 460 km south of mainland New Zealand. Up to 50 trawlers fish in the area from December to May. Most trawlers are Soviet, with some Korean and Japanese boats, chartered by New Zealand companies such as Independent Fisheries Ltd, Sealord Products Ltd and Fletcher Fishing Ltd (whose deep water interests were recently sold to Sealords). Many of the ships are the size of the Cook Strait ferries and are the same ones that work in other major New Zealand fisheries, such as the hoki and southern blue whiting fisheries. These trawlers have drowned nearly |1,700 fur seals during the last two West Coast hoki seasons. Nearly 1,800 of the threatened Hooker's sea lion may have died due to the Auckland Island squid fishery since 1978, where large numbers of seabirds are also killed.

Trawler mortalities

Disturbingly high numbers of birds are killed by the Soviet Auckland Island squid trawlers. Vast flocks of birds are attracted to food at the trawlers’ sterns as offal is dumped and nets are hauled in. On the Soviet boats, a cable that runs from the boat to the net proves a deadly obstacle. Birds hit the cable, which can catapult through the air like a whip as the tension from the net varies. Those struck by this flexing cable may be killed or injured. The force of a blow from the wire is sometimes enough to sever birds’ wings completely. Many birds become tangled in the wire,.slide into the water and drown. Thousands of white-capped mollymawks and sooty shearwaters may die in the fishery

each year. Up to 14 mollymawks have been reported killed during a single net retrieval. Royal albatrosses have also been killed. Forest and Bird's proposal for a marine mammal sanctuary around the Auckland Islands for the Hooker's sea lion excludes trawlers from within 60 nautical miles of the island's shoreline. Banning trawlers from this area should considerably reduce seabird mortality, but the trawlers still pose a problem to birds in other areas that they fish. The Bounty and Campbell Island albatross populations may also be threatened by the Soviet trawlers which fish for southern blue whiting close to those islands. Japanese boats do not have the offending cable used on Soviet boats and have much lower seabird kill rates. The Soviet trawlers’ obsolete equipment should be replaced with the more modern equipment used by the Japanese boats. The squid trawler bird mortality is but one example from New Zealand waters. We have no detailed information on seabird mortality

in other trawl fisheries around New Zealand or elsewhere in the southern oceans. Casual observers report that seabirds are killed frequently by other trawlers, both foreign and domestic, but few people have any idea how to identify the different species being killed. There is no legal requirement for skippers or observers to record seabird deaths in our economic zone.

Drift netting and set netting

The indiscriminate slaughter of thousands of marine mammals, turtles, birds and non-tar-get fish in drift nets has received huge media attention during the last two years. In July this year, Japanese and Korean fishers agreed to temporarily cease drift netting in the South Pacific and Tasman Sea but the Taiwanese are preparing for one more season in this region. Drift netting continues in the North Pacific and most other oceans. South Pacific drift nets were known to catch some seabird species but there are no details. Species worst

affected were likely to have been those taken on longlines in New Zealand as well as smaller diving species such as shearwaters. Few realise that half the 875,000 seabirds dying in the North Pacific Japanese and Taiwanese squid drift nets each year are species that breed on New Zealand islands. Every winter, the entire New Zealand population of sooty shearwaters, which breed mainly around our southern islands, migrate to the North Pacific where drift nets drown 427,000 of them annually. Flesh-footed and Buller's shearwaters from New Zealand have similar winter migrations and also drown in the nets. Thousands of sooty shearwaters are also drowned in other North Pacific gillnet fisheries, such as the Japanese salmon fishery and the Californian halibut fishery. For many other gillnet fisheries, there is no information on seabird by-catch. Set nets in our coastal waters are well known as a killers of inshore seabird species, including little blue and yellow-eyed penguins,

Hutton’s shearwaters, and pied, Stewart Island and spotted shags.

A fatal attraction

The bird species worst affected by trawl and longline fishery by-catch are those most strongly attracted to offal and rubbish from boats. Seasoned mariners are well aware of this attraction — in the vastness of the open ocean, albatrosses often seem to appear from nowhere and will follow ships for days on end waiting for a morsel to be cast overboard. Albatrosses can cover huge distances in a few days, so are vulnerable to being killed in fisheries thousands of kilometres from their nesting islands. The tuna longliners’ baits, which are usually 30cm squid or fish, are an ideal size for an albatross to swallow. Smaller birds are less likely to be able to swallow the bait before it sinks. Vast flocks of birds often follow trawlers. In one instance, 3,000 white-capped mollymawks were reported following the Auckland Island squid trawler fleet. With such large flocks of birds around these boats, it is easy to see how some are hit by a cable swinging through the middle of them. Overseas, huge numbers of migrating birds are killed by flying into pylon wires at night. In both instances, the birds are unable to see the cables in time to avoid them.

Lack of population information

There is a serious lack of information on the sizes of our seabird colonies. The Department of Conservation must urgently start. regular monitoring of all populations. Population falls overseas and estimated seabird fisheries by-catch numbers clearly warrant detailed breeding colony surveys — especially of albatrosses, such as the white-capped mollymawk, Buller’s mollymawk and wan-

dering albatross. The French and British have been intensively monitoring albatross populations in the Indian Ocean and at South Georgia for 20 — 30 years. New Zealand is a long way behind in its responsibilities to monitor its internationally important seabird fauna. There is no Government scheme to map seabirds at sea, where their numbers should also be monitored.

The increasing threat

As human populations grow and fishing technology improves, seabirds come under increasing threat from fisheries. The more fishing vessels in the oceans, the greater the by-catch problem and pressure on bird’s food supplies. In Britain, overfishing of sandeels has lead to catastrophic failure in seabird breeding. Puffins, kittiwakes, arctic skuas and terns are unable to feed their young because of depleted fish stocks. Tens of thousands of

arctic terns may only produce one hundred young in a season as a result. Local populations face rapid extinction. In New Zealand, MAF commercial quotas take no account of secondary effects of fishing. They are based purely on the sustainability of the target fish population. A bird population's entire food supply could be harvested under current regulations. The intricacy of marine ecosystems needs to be recognised in the quotas. MAF is charged with the conservation of fishery resources, which includes "fish habitat and aquatic life," but specifically excludes birds. Our seabirds face a bleak future unless the marine ecosystem is considered as a whole. Information on fisheries seabird by-catch is scant. We need compulsory reporting by skippers onboard vessels within our economic zone. In August 1990 Forest and Bird pressed the Minister of Conservation to institute compulsory reporting. DoC is now considering

two options: whether to ask skippers to include seabird by-catch figures with their monthly fish returns; or simply to require skippers to advise DoC of all seabird deaths.

Solutions to the problem

Three fishing methods are wrecking havoc on seabirds: driftnetting, trawling and longlining. Drift netting has been described as an ecological disaster; nations practising it are being forced out of the South Pacific, but they continue to plunder other oceans, especially the North Pacific. The only solution is a worldwide ban on this destructive fishing method. Trawling, while more selective, is also damaging to seabirds. Soviet boats, identified as the major cause of bird deaths, must be made to upgrade their antiquated equipment. Nigel Brothers, a seabird expert working for the Tasmanian Department of Parks, Wildlife and Heritage, says several simple measures could drastically reduce the seabird longline

kill. He points out that birds drown when they grab baits as the longlines are passed into the water and sink. The longer baits remain on the surface, the higher the risk of catching birds. The measures suggested by Brothers reduce the amount of time the baits are accessible to birds. He suggests: e Skippers should place a pole at the rear of

the boat. To this a line 150m long with several streamers is attached. The streamers dangle above the area where baits are thrown and frighten birds away. In tests, Brothers found that this method can reduce the number of baits taken by birds by up to 69 percent. ¢ Baits could be made to sink faster by increasing the weight on the lines. This

method has been used to lessen longline bird kills in the Indian Ocean. e Fishers should ensure baits are properly thawed as they then sink faster. @ Baits should be thrown further from the ship when the line is being set. This way they sink faster, away from the turbulence of the ship's wake. e Offal or rubbish which attracts birds should not be thrown overboard. e Longlines should be set at night as seabirds mainly feed by day. Such measures make sense: it has been estimated that losing bait to birds costs the bluefin tuna industry $7.2 million a year. Japanese longliners off Australia have already taken steps to reduce bait loss to birds.

Acknowledgements

Many thanks to Nigel Brothers, the Department of Conservation and MAF Fisherles staff for supplying information for this article.

Key References

Brothers, N. 1990. Approaches to reducing albatross mortality and associated bait loss in the Japanese longline fishery. Biological Conservation. Murray, T.; Edwards, M. 1988. Southern bluefin stock at risk. Catch 15:3-4. Report of the secretary of commerce to the congress of the United States. 1989. Nature, extent and effects of driftnet fishing in waters of the North Pacific Ocean. Weimerskirch, H.; Jouventin, PR 1987. Population dynamics of the wandering albatross, Diomedia exulans, of the Crozet Islands: causes and consequences of the population decline. Oikos 49:315-322. #F