258
A. NELSON-SMITH
brane structure in some families, e.g. the Umbelliferae, which are very
resistant to oils (see also Baker, 1969).
B. Eflects on marine communities
A very large number of sea-birds die as a result of oil pollution;
chronic pollution probably kills each year as many as die in a single
catastrophic spill. Tanis and Morzer Bruijns (1968) calculated that
total annual losses due to oil in the North Sea and North Atlantic
amount to 150-450 thousand birds. Amongst losses quoted for specific
areas, Lemmetyinen (1966) estimated an annual 10 000-40 000 (mostly
long-tailed duck) in the Baltic, 1952-62; along the Dutch coast, about
11 000 (Tanis and Morzer Bruijns, 1962) and on British coasts, somewhere between 50 000 and 250 000 (Barclay-Smith, 1958, reporting the
results of a nationwide survey in 1951-52). Further annual surveys,
utilizing many observers, have been organized for British shores since
1966-67 (see Bourne and Devlin, 1969). Estimates can never be more
than very approximate, especially where numbers collected over a mile
or two of coast are multiplied by several hundreds to give a " total "
for a lengthy seaboard (see Tuck, 1959; Gillespie, 1968; Cowell, 1968).
Furthermore, it is clear that the corpses stranded on shore represent a
fraction of the total mortality at sea, variously assumed to lie between
5% and 15%; it factor of 10 is probably the most reliable estimate
(Tanis and Morzer Bruijns, 1968; Clark, 1968). As examples of mortality following a major tanker spill, the wreck of the " Frank H.
Buck " in San Francisco Bay in 1937 killed 10 000 or more birds, of
which 6 600 were guillemots (Aldrich, 1938; Moffitt and Orr, 1938);
the collision of the " Fort Mercer " and " Pendleton " off Chatham,
Mass., in 1952 reduced the wintering population of eiders from 500 000 to
150 000 (Burnett and Snyder, 1954) and the stranding of the " Gerd
Maersk " in the Elbe estuary in 1955 affected 250 000-500 000 birds,
mainly common scoter (Goethe, 1968).
From a humanitarian point of view, each of these mortalities is very
regrettable; from that of a zoologist, the significance of the figures
depends entirely on the bird species concerned. The gulls (Larus spp.),
cormorants (Phalacrocorax spp. ), gannets (Sula bassana) and petrels
(fulmars Pulmarus glacialis (L.) ; Manx shearwaters Pufinus pufinus
(Briinnich) ; storm-petrels Hydrobates pelagicus (L.) and others,
although often oiled, are increasing in numbers. Divers (Gavia spp.)
form only a small percentage in lists of oiled birds, but the total world
population is small and their reproductive rate is low, so any additional
losses may be serious. Populations of sea ducks are already showing a
downward trend ; the Baltic is the major wintering-ground for the long-
A. NELSON-SMITH
brane structure in some families, e.g. the Umbelliferae, which are very
resistant to oils (see also Baker, 1969).
B. Eflects on marine communities
A very large number of sea-birds die as a result of oil pollution;
chronic pollution probably kills each year as many as die in a single
catastrophic spill. Tanis and Morzer Bruijns (1968) calculated that
total annual losses due to oil in the North Sea and North Atlantic
amount to 150-450 thousand birds. Amongst losses quoted for specific
areas, Lemmetyinen (1966) estimated an annual 10 000-40 000 (mostly
long-tailed duck) in the Baltic, 1952-62; along the Dutch coast, about
11 000 (Tanis and Morzer Bruijns, 1962) and on British coasts, somewhere between 50 000 and 250 000 (Barclay-Smith, 1958, reporting the
results of a nationwide survey in 1951-52). Further annual surveys,
utilizing many observers, have been organized for British shores since
1966-67 (see Bourne and Devlin, 1969). Estimates can never be more
than very approximate, especially where numbers collected over a mile
or two of coast are multiplied by several hundreds to give a " total "
for a lengthy seaboard (see Tuck, 1959; Gillespie, 1968; Cowell, 1968).
Furthermore, it is clear that the corpses stranded on shore represent a
fraction of the total mortality at sea, variously assumed to lie between
5% and 15%; it factor of 10 is probably the most reliable estimate
(Tanis and Morzer Bruijns, 1968; Clark, 1968). As examples of mortality following a major tanker spill, the wreck of the " Frank H.
Buck " in San Francisco Bay in 1937 killed 10 000 or more birds, of
which 6 600 were guillemots (Aldrich, 1938; Moffitt and Orr, 1938);
the collision of the " Fort Mercer " and " Pendleton " off Chatham,
Mass., in 1952 reduced the wintering population of eiders from 500 000 to
150 000 (Burnett and Snyder, 1954) and the stranding of the " Gerd
Maersk " in the Elbe estuary in 1955 affected 250 000-500 000 birds,
mainly common scoter (Goethe, 1968).
From a humanitarian point of view, each of these mortalities is very
regrettable; from that of a zoologist, the significance of the figures
depends entirely on the bird species concerned. The gulls (Larus spp.),
cormorants (Phalacrocorax spp. ), gannets (Sula bassana) and petrels
(fulmars Pulmarus glacialis (L.) ; Manx shearwaters Pufinus pufinus
(Briinnich) ; storm-petrels Hydrobates pelagicus (L.) and others,
although often oiled, are increasing in numbers. Divers (Gavia spp.)
form only a small percentage in lists of oiled birds, but the total world
population is small and their reproductive rate is low, so any additional
losses may be serious. Populations of sea ducks are already showing a
downward trend ; the Baltic is the major wintering-ground for the long-