Objectives for managing harvestable resources

If we treat the Garrod and Jones example as typical, then we might conclude that the biologist proposes - but the manager disposes. This is therefore an appropriate point at which to reconsider not only the objectives of harvesting programs, but also the criteria by which successful management should be judged and the role of ecologists in management overall. As Hilborn and Walters (1992) have pointed out, there are three alternative attitudes that ecologists can take, each of which has been popular but only one of which is sensible. Indeed, these are increasingly important considerations that apply not just to fisheries management but to every entry of ecologists into the public arena.

The first is to claim that ecological interactions are too complex, and our understanding and our data too poor, for pronouncements of any kind to be made (for fear of being wrong). The problem with this is that if ecologists choose to remain silent because of some heightened sensitivity to the difficulties, there will always be some other, probably less qualified 'expert' ready to step in with straightforward, not to say glib, answers to probably inappropriate questions.

The second possibility is for ecologists to concentrate exclusively on ecology and arrive at a recommendation designed to satisfy purely ecological criteria. Any modification by managers or politicians of this recommendation is then ascribed to ignorance, inhumanity, political corruption or some other sin or human foible. The problem with this attitude is that it is simply unrealistic in any human activity to ignore social and economic factors.

The third alternative, then, is for ecologists to make ecological assessments that are as accurate and realistic as possible, but to assume that these will be incorporated with a broader range of factors when management decisions are made. Moreover, these assessments should themselves take account of the fact that the ecological interactions they address include humans as one of the interacting species, and humans are subject to social and economic forces. Finally, since ecological, economic and social criteria must be set alongside one another, choosing a single, 'best' option is likely to be seen by some involved in the decision as an opinion based on the proponent's particular set of values. It follows that a single recommendation is, in practice, far less useful in this discourse than laying out a series of possible plans of action with their associated consequences.

In the present context, therefore, we develop this third alternative by first looking beyond MSY to criteria that incorporate risk, economics, social consequences, and so on (Hilborn & Waters, 1992). We then briefly examine the means by which crucial parameters and variables are estimated in natural populations,since these, by determining the quality of available information, determine the degree of confidence with which recommendations can be made.

to 400

ra o

Fishing intensity

Fishing intensity

130 mm

5 10 15

Mesh sizes 160 mm

145 mm

130 mm

to 400

160 mm

33%

■>/ \ N

/'/ V

\\

145 mm

///

"30 mm'

I

i i

T, /fi

45%

V /'/

V>\

160 mm

-

__145 mm

i

130 mm'"-, i i

Years of this regime

5 10 15 20

Years of this regime

Figure 15.14 Garrod and Jones' (1974) predictions for the Arctic cod stock under three fishing intensities and with three different mesh sizes. (After Pitcher & Hart, 1982.)

... but these may still be ignored

three attitudes for ecologists towards managers in the real world ...

... but only one of them is sensible

Figure 15.15 The economically optimum yield (EOY), that which maximizes 'profit', is obtained to the left of the peak of the yield-against-effort curve, where the difference between gross yield and total cost (fixed costs plus variable costs) is greatest. At this point, the gross yield and total cost lines have the same slope. (After Hilborn & Walters, 1992.)

Figure 15.15 The economically optimum yield (EOY), that which maximizes 'profit', is obtained to the left of the peak of the yield-against-effort curve, where the difference between gross yield and total cost (fixed costs plus variable costs) is greatest. At this point, the gross yield and total cost lines have the same slope. (After Hilborn & Walters, 1992.)

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