ANTHROPOGENIC IMPACTS ON THE DEEP SEA
457
the very recent one of Koslow et al. (2000)]. The
life-history characteristics of the species are described
as typical for their deep, cold and energy-poor environment, reflecting mostly extreme K-selection: slow
growth, low natural mortality, late maturity (25 years
in the orange roughy, Hoplostethus atlanticus), high
longevity (>100 years in the same species), large eggs
and low specific fecundity, all resulting in exceptionally
low productivity. Additionally, recruitment seems to
be an episodic process, with many years of low
recruitment to the adult stock and rare ones in which
it is high. Generally, species with these features
are highly vulnerable to exploitation and disturbance.
Nearly all exploited deep-water populations suffer from
overfishing within a few years. According to Clark
(1995), the sustainable yield for orange roughy in New
Zealand waters has been estimated at only 1–2% of the
population, and even this figure may be too high.
Various impacts on fish populations as a result of
fishing activities may be predicted, but life-history
characteristics may hide changes in community structure. Individual sizes in fished populations were found
to decrease (Large et al., 1998) but no alteration of
species composition in the community was observed.
A shift in community structure to a larger proportion
of species or size classes with faster turnover, and the
consumption of smaller prey, had been hypothesized
by Merrett and Haedrich (1997) as results of fishing
and described by Jackson et al. (2001). The few
observations available demonstrate the discrepancy
between the development of deep-water fisheries and
the lack of basic knowledge on the ecology of fish
species, and on the functional relationships of species
in deep-water ecosystems.
Deep-water fisheries impact not only the fish stocks
but also the benthos and their habitat. The depth
range at which fish occur and fishing takes place
includes the zone of the continental slope in which the
coldwater coral Lophelia pertusa builds up its large reef
structures in European waters (Freiwald and Wilson,
1998; Rogers, 1999). Trawling with heavy fishing gear
destroys those reefs upon contact, their communitystructuring functions are lost, and the unique deepwater ecosystem dramatically changes, losing its high
biodiversty. This has been well demonstrated by Probert
et al. (1997), Koslow and Gowlett-Holmes (1998),
Richer de Forges et al. (2000) and Koslow et al. (2001),
who have described fishery impacts on the benthos off
New Zealand and Australia, with decreases of biomass
by 83% and number of species by 59% on the tops of
Tasmanian seamounts. Thus, deep-water trawl fisheries
not only overexploit fish stocks, but also over-disturb
deep-water habitats and the benthos, particularly the
epibenthic species.
Truly sustainable yields for fish species are unknown, and therefore cannot inform discussions on
fishery management. Only precautionary measures can
be emphasized, and catch limits should be regulated
at a level low enough to ensure recovery of fish
stocks, benthos and environment. By such regulations sustainable fishing may become economically
unfeasible. Fisheries for deep-water fish stocks are
virtually guaranteed to be unsustainable if they are
developed without the support of scientific knowledge
and expertise. Fishing News (2000) reported a rush
of trawlers from Namibia, New Zealand and South
Africa to seamounts in the southern Indian Ocean to
fish for orange roughy, and others from Russia and
China were expected to join the fishing fleet. Such an
action will most probably lead to short-term profit for
a few people, but at the same time to the loss of the
fish stocks on isolated seamounts through overfishing.
For seamounts and other deep-water habitats beyond
the national jurisdiction of states no regulations exist
for the conservation of species, species diversity and
habitats (see pp. 459–461).
LEGAL REGULATIONS
Three legal instruments exist for the protection of
the deep sea from environmental harm: the London
Convention, 1972; the Convention for the Prevention
of Pollution from Ships, 1973/1978; and the UN
Convention on the Law of the Sea, 1982 (Sand, 1992).
Their memberships are not identical.
The “Convention on the Prevention of Marine
Pollution by Dumping of Wastes and other Matter”,
the so-called “London Convention” (LC
5 , originally
LDC: London Dumping Convention) was adopted on
29th December 1972. Article 1 gives as the main
objectives to
prevent the pollution of the sea by dumping of waste and
other matter that is liable to create hazards to human health,
to harm living resources and marine life, to damage amenities
or to interfere with other legitimate uses of the sea.
5 For a list of acronyms see the appendix on p. 471.
457
the very recent one of Koslow et al. (2000)]. The
life-history characteristics of the species are described
as typical for their deep, cold and energy-poor environment, reflecting mostly extreme K-selection: slow
growth, low natural mortality, late maturity (25 years
in the orange roughy, Hoplostethus atlanticus), high
longevity (>100 years in the same species), large eggs
and low specific fecundity, all resulting in exceptionally
low productivity. Additionally, recruitment seems to
be an episodic process, with many years of low
recruitment to the adult stock and rare ones in which
it is high. Generally, species with these features
are highly vulnerable to exploitation and disturbance.
Nearly all exploited deep-water populations suffer from
overfishing within a few years. According to Clark
(1995), the sustainable yield for orange roughy in New
Zealand waters has been estimated at only 1–2% of the
population, and even this figure may be too high.
Various impacts on fish populations as a result of
fishing activities may be predicted, but life-history
characteristics may hide changes in community structure. Individual sizes in fished populations were found
to decrease (Large et al., 1998) but no alteration of
species composition in the community was observed.
A shift in community structure to a larger proportion
of species or size classes with faster turnover, and the
consumption of smaller prey, had been hypothesized
by Merrett and Haedrich (1997) as results of fishing
and described by Jackson et al. (2001). The few
observations available demonstrate the discrepancy
between the development of deep-water fisheries and
the lack of basic knowledge on the ecology of fish
species, and on the functional relationships of species
in deep-water ecosystems.
Deep-water fisheries impact not only the fish stocks
but also the benthos and their habitat. The depth
range at which fish occur and fishing takes place
includes the zone of the continental slope in which the
coldwater coral Lophelia pertusa builds up its large reef
structures in European waters (Freiwald and Wilson,
1998; Rogers, 1999). Trawling with heavy fishing gear
destroys those reefs upon contact, their communitystructuring functions are lost, and the unique deepwater ecosystem dramatically changes, losing its high
biodiversty. This has been well demonstrated by Probert
et al. (1997), Koslow and Gowlett-Holmes (1998),
Richer de Forges et al. (2000) and Koslow et al. (2001),
who have described fishery impacts on the benthos off
New Zealand and Australia, with decreases of biomass
by 83% and number of species by 59% on the tops of
Tasmanian seamounts. Thus, deep-water trawl fisheries
not only overexploit fish stocks, but also over-disturb
deep-water habitats and the benthos, particularly the
epibenthic species.
Truly sustainable yields for fish species are unknown, and therefore cannot inform discussions on
fishery management. Only precautionary measures can
be emphasized, and catch limits should be regulated
at a level low enough to ensure recovery of fish
stocks, benthos and environment. By such regulations sustainable fishing may become economically
unfeasible. Fisheries for deep-water fish stocks are
virtually guaranteed to be unsustainable if they are
developed without the support of scientific knowledge
and expertise. Fishing News (2000) reported a rush
of trawlers from Namibia, New Zealand and South
Africa to seamounts in the southern Indian Ocean to
fish for orange roughy, and others from Russia and
China were expected to join the fishing fleet. Such an
action will most probably lead to short-term profit for
a few people, but at the same time to the loss of the
fish stocks on isolated seamounts through overfishing.
For seamounts and other deep-water habitats beyond
the national jurisdiction of states no regulations exist
for the conservation of species, species diversity and
habitats (see pp. 459–461).
LEGAL REGULATIONS
Three legal instruments exist for the protection of
the deep sea from environmental harm: the London
Convention, 1972; the Convention for the Prevention
of Pollution from Ships, 1973/1978; and the UN
Convention on the Law of the Sea, 1982 (Sand, 1992).
Their memberships are not identical.
The “Convention on the Prevention of Marine
Pollution by Dumping of Wastes and other Matter”,
the so-called “London Convention” (LC
5 , originally
LDC: London Dumping Convention) was adopted on
29th December 1972. Article 1 gives as the main
objectives to
prevent the pollution of the sea by dumping of waste and
other matter that is liable to create hazards to human health,
to harm living resources and marine life, to damage amenities
or to interfere with other legitimate uses of the sea.
5 For a list of acronyms see the appendix on p. 471.