Concern over seabird decline

Concern over seabird decline

Volume 2 0 / N u m b e r 9 / S e p t e m b e r 1989 Concern Over Seabird Decline The 1989 breeding season appears to have been another very poor one ...

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Volume 2 0 / N u m b e r 9 / S e p t e m b e r 1989

Concern Over Seabird Decline The 1989 breeding season appears to have been another very poor one for several species of bird around Shetland, with the overfishing of the local sandeel fishery being held to blame by many groups. As reported previously (Mar. Pollut. Bull. 19, 502; 20, 4; 20, 54) the Arctic tern first had a poor breeding season in 1984 and has suffered breeding failures every year since. In 1987 the Nature Conservancy Council and the

The Puffin, Shetland's mascot, falls on lean times.

Royal Society for the Protection of Birds funded a research study to investigate the phenomenon. The work confirmed that most chicks were starving to death or so underweight that they were unlikely to fledge. Adult Arctic terns have also been shown to be underweight explaining some cases of breeding failure even before the eggs hatch. Breeding success of the Kittiwake, measured by the proportion of nests occupied towards the end of the breeding season, has fallen from 0.69 chicks fledged per nest in 1986 to 0.09 in 1988, with breeding failing completely in some parts of Shetland. The puffin, a mascot of Shetland and another bird which feeds mainly on sand-eels, is also suffering a similar fate at the Sumburgh and Hermaness colonies situated at the extreme southern and northern ends of Shetland. Studies over recent years have shown that the percentage of sand-eels in the food which puffins feed to their chicks has dropped from between 80-100% in the period 1973-1986 to 19% in 1987 and 36% in 1988. While some species such as gannets have been able to shift their diet, other birds such as fulmars, great skuas, red-throated divers and black guillemots, which are still very much dependent on sand-eels, have also shown signs of lower breeding success. The seabird colonies in Shetland, the largest in the European Community, are regarded as being of international importance. It is not surprising therefore that part of the blame for the recent decline has been apportioned to the rapid development of the industrial fishing









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"That's the umpteenth message-in-a-bottle this week l When are you going to realise that nobody takes a blind bit of r~otice of a bottle on a beach these days?"


Marine Pollution Bulletin

of sand-eels which started in 1974 in Shetland. The fishery peaked in 1982 at 53 000 t and since then has decreased to 4800 t in 1988. Because of the population dynamics of sand-eels, a naturally short-lived fish, it is difficult to prove that the present shortage of sand-eels is caused by commercial fishing. However, some fisheries biologists have warned that the dependence of the fishing on young immature fish makes it very vulnerable to changes in the levels of recruitment and therefore increases the possibility of a large decrease in stock abundance and productivity of the fishery. While other sand-eel fisheries in the North Sea concentrate on older fish the Shetland fishery relies heavily on catches of O-group fish. In the past the Shetland Fishermen's Association has considered a voluntary close season to protect O-group fish and in 1987 they introduced voluntary restrictions on the size of fish that could be landed. After sustained pressure, the Department of Agriculture and Fisheries for Scotland took action on the 28 June this year to ban sand-eel fishing around Shetland for the rest of the season in order to allow stocks to recover. The situation is to be reviewed before a decision is taken on whether to reinstate the fishery next year. The other important sand-eel fishery in Scotland is off the north-west coast in the Minch. This fishery started in 1980 and, as in Shetland, has grown quickly, although the ban imposed by DAFS this year does not extend to this area. Nevertheless the Mallaig and North West Fishermen's Association has expressed strong concern over the threat this year posed to their members by several large pelagic boats turning their attention to the west coast stocks before starting on the fishing of North Sea herring. The larger pelagic boats had been prematurely excluded from working in the Norwegian sector due to overfishing by the Danes. Because of the uncertainties involved in these issues, many scientists have b e e n urging that more studies should be carried out to improve our understanding of and ability to predict when overfishing of sand-eels is occurring so that controlled exploitation of this species can be maintained without detrimentally affecting seabird populations.

Green Light for Red List Pesticide The controversial pesticide Nuvan, used to control sealice infestation in farmed salmon, has now been granted a licence by the veterinary products committee effectively sanctioning its use in the aquatic environment. Experts appointed by the Ministry of Agriculture, Fisheries and Food (MAFF) to research the effects of Nuvan concluded that the active ingredient, dichlorvos, is biodegradable and non-persistent in the environment. While the announcement was welcomed by the Scottish Salmon Growers Fishermen's Association, both the Shellfish Association and Scottish Fishermens Federation remain less than enthusiastic about the indiscriminate use of a pesticide known to be particularly toxic to crustacean larvae (see Mar. Pollut. Bull. 20, 422

102). After the 1987 North Sea Conference the UK Government placed Nuvan on the provisional Red List of dangerous chemicals .whose discharge into waterways should be reduced by 50% by 1995. Many feel that the recent granting of a full product licence for Nuvan is therefore inexplicable. However, MAFF's reasoning is that in granting the licence for one year only, they are allowing time for a more environmentally-sound method for sea-lice control to be developed.

UK Acts on Antarctica The British Government's Antarctic Minerals Bill, intended to regulate mining activities in the so far undeveloped continent, has passed its second reading without division in the UK House of Commons. The bill, while not sanctioning mining operations in the fragile Antarctic environment, does allow prospecting under tightly defined conditions. It has come under criticism from the Labour Opposition, environmental groups, and scientists who feel that, in spite of its 'green' claims, the UK Government is more interested in commercial rather than conservation aspects. The regulation of mineral exploitation in Antarctica is compounded by the number of countries which have sovereign or territorial claims in the area. Britain, Chile, and Argentina have competing claims to sovereignty while Australia, New Zealand, France, and Norway all have territorial claims. The United States, USSR, Japan, and West Germany refuse to recognize any territorial rights in the Antarctic continent which they feel should be a commonly-shared heritage and as such be internationally regulated. The purpose of the UK Antarctic Minerals Bill is to ratify the Antarctic Minerals Convention introduced last year which provides a legal framework for the governing of mineral exploitation (see Mar. Pollut. Bull 20, 8). The Convention was supported by the UK, Argentina, Chile, Norway and New Zealand but both France and Australia have to date refused to sign. Their stance is that Antarctica, as the last great wilderness on Earth, should be preserved in its unspoilt state and be designated a world park area with a permanent moratorium on mineral activity. The recent Exxon oil spill in Alaska and its devastating consequences has served to bring support to this view. However the British Government's opinion is that there is no reason why mining activities in the Antarctic should be any more environmentally damaging than mining elsewhere. A L E X A N D R A DUFF

Move to Outlaw Drift-netting At the annual meeting of the South Pacific Forum national leaders agreed on measures leading to a ban on drift netting in the South Pacific area. Vessels from Japan, Taiwan, and South Korea use the fine nylon nets, which have a mesh size of about 170 mm primarily to catch albacore. However large numbers of other fish species, marine mammals, and seabirds attracted by the struggling fish also become ensnared in the nets which