The Revised Management Procedure (RMP)
At the outset of its discussions on future
management of commercial whaling, following the
moratorium (effective from 1985/86), the Scientific Committee recognised the
need to develop management objectives and procedures
that learnt from its previous difficulties and in particular
recognised the limitations of both the data it had and
the data it was likely to obtain. To put it simply,
there was no point in developing a management procedure
that required estimates of current population size accurate
to the nearest whale when, for example, the best that
might be expected was an estimate that the population
lay somewhere between 10,000 to 20,000.
Computer simulation testing
Clearly it is not acceptable to try out experimental
management procedures in the wild. Apart from the serious
consequences of 'getting it wrong', in long-lived species
such as whales it would take a long time before one
would find out whether or not it really worked. So the
Scientific Committee resorted to computer whales and
simulated population behaviour over a long period (100
years was chosen).
Management objectives
The development process can only take place in the
light of management objectives. These were set by the
Commission and can be summarised as:
- catch limits should be as stable as possible;
- catches should not be allowed on stocks
below 54% of the estimated carrying capacity;
- the highest possible continuing yield should
be obtained from the stock.
The Commission decided that greater priority should
be given to objective 2. The quantitative component
of this was achieved by the Commission choosing among
three options provided to it by the Scientific Committee.
Taking
uncertainty into
account
After several years of intense work, the Committee
developed a procedure for determining safe catch limits
that required knowledge of two essential parameters:
estimates of current abundance taken at regular intervals;
and knowledge of past and present catches. The Committee
during this period carried out intensive testing of
the procedure to numerous assumptions and problems.
Some of these are summarised below:
- Several different population models and associated
assumptions;
- Different starting population levels, ranging
from 5% to 99% of the 'initial' population size;
- Different MSY levels, ranging from 40% to 80%;
- Different MSY rates, ranging from 1% to 7% (including
changes over time);
- Various levels of uncertainty and biases in
population size;
- Changes in carrying capacity (including reduction
by half);
- Errors in historic catch records (including
underestimation by half);
- Catastrophes (irregular episodic events when
the population is halved);
- Various frequencies of surveys;
How are catch
limits set?
A major component of the RMP is the CLA or
Catch
Limit Algorithm - this specifies the way in which catch
limits are calculated from the required information.
Very simply, the CLA recognises that initially the
'true' situation of the stock is poorly known i.e. that
there is a wide range of possible values for the level
of depletion of the stock and its productivity. Similarly
it recognises the two kinds of uncertainty in the estimate
of current population size: that the methodology used
to estimate abundance, although it produces a 'best'
estimate can actually only give a range within which
the population size probably lies; and secondly that
the estimate may be biased.
The CLA is a 'feedback' procedure - as more information
accumulates from sighting surveys (and catches if taken),
then the estimates of necessary parameters are refined.
In this way the procedure constantly monitors itself.
Catch limits are set for periods of five years. This
is one of the ways in which the objective of stability
of catches is met. Catches are also phased out if new
sightings estimates are not obtained at the requisite
intervals. As more information accumulates from new
surveys, the CLA improves its estimates of parameter
values. This in turn will narrow the range of possible
catch limits.
Testing for
real scenarios
The CLA was initially tested on the assumption that
it is applied to known biological stocks. At present,
this has only been carried out for minke whales in the
North Atlantic and Southern Hemisphere. Without such
'implementation trials', catch limits will be zero under
the RMP. Even with such trials, it is clear that for
very many species, such as blue whales in the Southern
Hemisphere, it will be a very long time before catches
would be allowed under the RMP.
The Revised Management Procedure
The CLA plus the rules about, amongst other things,
details of stock boundaries, allocation of catches to
small areas, what to do if many more of one or other
sex are caught, and when complete reviews of all available
information should be carried out, form the RMP.
In addition, the Scientific Committee has developed
guidelines and rules for how sighting surveys should
be conducted and how the data are to be analysed if
the resultant estimates are to be considered to be of
sufficient quality to be used in the CLA. Similar guidelines
and rules have been developed with respect to data requirements,
quality and analysis.
In summary, the culmination of eight years' work
by the Scientific Committee has been the most rigorously
tested management procedure for a natural resource yet
developed. It sets a standard for the management of
all marine and other living resources.
It should be noted that the procedure as developed
is very conservative and certainly more conservative
than anything that has gone before. In some ways this
is intuitively obvious. Any procedure that explicitly
takes into account large levels of uncertainty, and
can cope with the wide range of scenarios tested will
have to be conservative.
In general terms this is illustrated by the fact
that typically, annual catches after only one survey
has been completed will be less than half a percent
of the estimated population size e.g. if the population
is thought to number 10,000 animals, the annual catch
will be less than 50.
The level of conservatism is a reflection of the
relative priorities assigned to the objectives, the
level of uncertainty in the information on abundance,
productivity and stock identity of whale stocks, and
the fact that many years are required before the CLA
refines its estimates of the required parameters.
The Revised
Management Scheme
The Scientific Committee has unanimously recommended
the RMP to the Commission, noting that all the scientific
aspects of the work had been completed. These scientific
aspects were adopted by the Commission in 1994. Its actual
implementation in whale management (at least for those
stocks for which it has been tested), is of course a
political decision. The Commission will not set catch
limits for commercial whaling until it has agreed and
adopted a complete Revised Management Scheme (RMS).
Any RMS will not only include the scientific aspects
such as the RMP, but a number of non-scientific issues,
including inspection and enforcement, perhaps to humaneness
of killing techniques. (For more detailed information
on the RMS click HERE).
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