Dolphins, Porpoises, and Whales - IUCN

then) is a highly precautionary approach to setting catch
limits. A stock must be fully protected when it falls below
54% of its estimated pre-exploitation abundance, and the
eventual objective of the RMP is to maintain exploited
populations at equilibrium levels of approximately 72%
of initial size. The procedure specifically takes account
of the uncertainty surrounding estimates of pxjpulation size
and of vital parameters. Even the effects of a reduction in
carrying capacity during exploitation have been investigated
by simulation, and the RMP has been shown to be
robust to this pxjssibility.
In situations where direct exploitation occurs, it is
important to ensure that struck-but-lost rates are as low as
possible and that the products obtained are procured and
used efficiently. This does not mean that the CSG
endorses sustainable harvesting as a preferred approach to
cetacean conservation. However, it is recognized that in
some situations, especially those involving traditional harvests
for local subsistence, the immediate emphasis needs
to be on ensuring sustainability rather than on imposing
protection. In any sustainable-use regime for cetaceans,
small margins for error are unacceptable. This is true not
only because the variability in population estimates is usually
large, but also because low intrinsic rates of increase
mean long recovery times. Moreover, cataclysmic effects
need to be taken into account. The large die-offs recorded
for some populations of odontocetes in recent years, whatever
their causes, give added force to the argument for
extreme caution in setting catch limits for such species.
Reduction and Management
of Environmental Pollution
Pollution of freshwater and marine systems is recognized
as a serious problem globally. Unfortunately, the
processes of testing and measuring the effects of various
pollutants on wild organisms lag far behind the processes
of manufacturing and releasing these substances into the
environment. Even when damaging effects are known or
strongly suspected to occur, the feared economic consequences
of shutting down or sharply curtailing the activities
of an offending industry often prevent such action.
In too many instances, less developed countries have
become dumping grounds for noxious chemicals banned
in the developed world. Broad and equitable agreements
that contain enforcement provisions are needed to control
global pollution. Concern about impacts on human
health should be adequate incentive for such agreements.
If it is not, then there is little cause for optimism with
regard to limiting the exposure of cetaceans to environmental
contaminants.
16
Development or Reinstatement
of Less Wasteful
Fish-Harvesting Techniques
Less wasteful fish-harvesting techniques are at least as
imperative for the well-being of human communities as
they are for the integrity and survival of stocks of
cetaceans and other top predators (not to mention the prey
populations themselves). Unselective fish-harvesting
techniques are incompatible with principles of conservation.
They have no place in any credible strategy for sustainable
living.
A number of forces are responsible for the deplorable
condition of many of the world's fisheries, quite apart from
the obvious problems of too-intensive direct exploitation
of target species and huge, unselective bycatches.
Burgeoning human populations increase the demand for
sustenance and wealth, putting ever-greater pressure on
all of the earth's resources. The degeneration of terrestrial
environments (from overuse and abuse by humans)
is forcing more people to look toward the sea for commodities
and profits. As they do, these people enter into
competition for stocks that have already been depleted by
local and foreign fleets and environmental degradation.
Countries whose own coastal resources have diminished
send their fleets far and wide in search of new fishing
grounds, often on the high seas or in other nations' exclusive
economic zones. New technology provides the means
for finding and catching fish more effectively, and this
technology is available not only to the large commercial
fleets but, increasingly, to the beneficiaries of foreignassistance
programs in less developed countries. Thus,
artisanal fisheries, many of which may once have been
sustainable or self-correcting, incorporate new techniques
and equipment that provide short-term benefits but lead, in
the long term, to crashes in the fish stocks and to suffering
for those people who depend on them.
The fisheries that take cetaceans as a bycatch involve
various technologies, occur within a large variety of
socio-economic contexts, and affect numerous cetacean
species. In some instances, there has been hope that simple
and inexpensive modifications of equipment or technique
could reduce or eliminate cetacean mortality, while
not seriously affecting the catches of target species. In
spite of research and field trials, however, such
approaches have not proven effective. Any further studies
of gear modification need to incorporate rigorous
experimental designs and procedures to ensure that results
can be evaluated statistically. In the vast majority of
cases, the bycatch problem can only be effectively
addressed through concurrent investigations of alternative
fishing techniques and areal or seasonal closures of fish-