50
Fig. 2.6. Illustration of optimum sustainable yield
x
Effort
Effort
o
x
m
Effort
x
0'
Total Benefit=$umofO+O' +cY+0 3 +0 4 •.. On
P.R. Burbridge
x = Point of maximum
sustainable yield
m = Point of marginal
return
0= Point of optimal
sustainable yield
Fig. 2.7. Optimal sustainable yield from integrated, multiple uses of coastal resources
The same logic can be applied to the production of a series of resources generated by a
coastal ecosystem where the exploitation of one resource will have a corresponding effect
on the production of other resources and on potential users of those resources. If it is considered economically and socially desirable to maintain production of the mix of resources,
then a level of exploitation of individual resources will have to be found which will minimize adverse effects on the production of other resources. This level of exploitation can
be termed the Optimal level of Sustainable Yield COSY). This is illustrated in Fig. 2.6. It is
interesting to note that in theory the total area under the production curve at OSY for a
speCific resource may not be a great deal less than that for the point "m" at which increasingly marginal returns on investment or effort. However, this must be worked out in practice and the calculation of the economic interactions among different multiple uses will
require sophisticated economic modelling. It may be possible to build upon the economic
models developed for multiple species fisheries to better represent the potential interactions among different economic activities sustained by one or more coastal ecosystems.
Figure 2.7 illustrates a series of uses of different resources generated by a coastal
ecosystem where Optimum Sustainable Yields are maintained. Note that the sum of the
benefits is equal to the sum of the individual levels of OSY for all direct uses of resources. To this can be added a multiplier resulting from secondary economic activities sustained by the direct resource uses.
To actually achieve the total benefits illustrated in Fig. 2.7 will require a very good
information base on the maximum sustainable yield of individual resources and how
Fig. 2.6. Illustration of optimum sustainable yield
x
Effort
Effort
o
x
m
Effort
x
0'
Total Benefit=$umofO+O' +cY+0 3 +0 4 •.. On
P.R. Burbridge
x = Point of maximum
sustainable yield
m = Point of marginal
return
0= Point of optimal
sustainable yield
Fig. 2.7. Optimal sustainable yield from integrated, multiple uses of coastal resources
The same logic can be applied to the production of a series of resources generated by a
coastal ecosystem where the exploitation of one resource will have a corresponding effect
on the production of other resources and on potential users of those resources. If it is considered economically and socially desirable to maintain production of the mix of resources,
then a level of exploitation of individual resources will have to be found which will minimize adverse effects on the production of other resources. This level of exploitation can
be termed the Optimal level of Sustainable Yield COSY). This is illustrated in Fig. 2.6. It is
interesting to note that in theory the total area under the production curve at OSY for a
speCific resource may not be a great deal less than that for the point "m" at which increasingly marginal returns on investment or effort. However, this must be worked out in practice and the calculation of the economic interactions among different multiple uses will
require sophisticated economic modelling. It may be possible to build upon the economic
models developed for multiple species fisheries to better represent the potential interactions among different economic activities sustained by one or more coastal ecosystems.
Figure 2.7 illustrates a series of uses of different resources generated by a coastal
ecosystem where Optimum Sustainable Yields are maintained. Note that the sum of the
benefits is equal to the sum of the individual levels of OSY for all direct uses of resources. To this can be added a multiplier resulting from secondary economic activities sustained by the direct resource uses.
To actually achieve the total benefits illustrated in Fig. 2.7 will require a very good
information base on the maximum sustainable yield of individual resources and how