It's easy for an economist to sympathize with fisheries scientists who argue, as Carl Walters and Steven Martell do in their new textbook, Fisheries Ecology and Management, that fisheries science is about choice and trade-offs:
Texts on fisheries and ecosystem management typically begin with discussions about the objectives of management. It is easy to say that the objectives of modern fisheries management should be to ensure sustainable harvests, viable fishing communities, and healthy ecosystems, i.e., to sustain a mix of production, economic, and ecological values. Unfortunately, such platitudes are of little value in guiding either management or science, because there can be conflicts among the component objectives.
A more useful statement of objectives for scientists and managers would be to say that the central objective of modern fisheries science should be to clearly expose trade-offs among conflicting objectives, and the central objective of modern fisheries management should be to develop effective ways to decide where to operate along the trade-offs, and how to operate successfully..."
They elaborate on four trade-offs: harvest now versus harvest later, ecosystem diversity versus ecosystem productivity, efficiency versus jobs, and the allocation of fishery management resources among different activities.
Their discussion of the ecosystem tradeoff is especially interesting:
...It is foolish to pretend that there is some ecosystem principle stating that ecosystems are most productive of harvestable surpluses when they are maintained in the most natural and diverse possible state. An aquatic ecosystem in its natural state, in fact, exhibits no net production at all; the various organisms that prosper in this state have already appropriated all surplus production, otherwise they would be growing in abundance and/or would likely have already been subject to invasions by other species that could use them as resources. Further, long-term data sets on places such as the North Sea do not even support the reasonable proposition that the simplification of ecosystems through fishing might cause increased variability, vulnerability to invasion by exotic species, or even "dynamic instability" among the abundances of interacting species...
...If we set up multiple fisheries in ecosystem models, then search for an "optimum" mix of fishing efforts to maximize some simple economic objective like total profit from the ecosystem...we find that this optimum mix often involves an ecosystem-scale "farming" strategy...That is, the optimization tells us to use some of the fisheries to deliberately overexploit (control/cull) the competitors/predators of a few most valued species, so as to direct as much ecosystem production as possible through these species. This is, of course, exactly what people do in modern farming, through cultivation and pest-control practices. Almost every fisheries scientist who has seen such results has reacted with disgust and has turned to alternative objective functions that represent both broader values (existence as well as catch values) and also the "risk-spreading" value of maintaining a diversified "portfolio" of productive populations. But the simple fact is that we do not have strong, objective evidence from past fisheries experience to demonstrate that it would ultimately be destructive to engage in ecosystem-scale farming, i.e., to move a long ways along a trade-off relationship between natural diversity and the total economic value of fish production.
Terry Anderson and Peter Hill (in their new book on property rights in the 19th Century American West, The Not So Wild, Wild West: Property Rights on the Frontier ) suggest that this is what happened in the American West, when cattle replaced buffalo.
Buffalo were treated as a common property resource in the Old West, and hunted almost to extinction. They remained common property - unlike cattle - because the transactions costs of creating property rights were too high:
The fourth and perhaps most important reason that property rights to buffalo did not evolve was that bison were difficult to control and manage. Ownership and control required either that an owner control a sufficiently large amount of land over which bison could freely range or that he be able to fence them. U.S. land policy was directed toward settled agriculture with small-scale farms, and this made it difficult to establish ownership and control of large land areas...Homestead policy during the hunting era established 160 acres as the maximum size that a settler could claim. Some settlers were able to control more access through multiple claims and fraud, but rarely were property rights secure enough to establish claims to the several thousand acres needed for a viable buffalo herd. To fence buffalo in a smaller area was improbable because barbed wire was not patented and produced in commercial quantities until 1873 and because federal land laws prohibited fencing of the open range. In other words, artificially high transactions costs made it almost impossible for anyone think of establishing ownership of a buffalo herd...
With buffalo being undomesticated, they were not suitable for any sort of settled agriculture. The buffalo were difficult to handle, particularly in stressful situations, and could not be herded or driven to market like cattle...
...Basically, buffalo and cattle consumed grass of the Great Plains and converted it to products in demand in the East and Europe. Hence the entrepreneur had to ask what was th most profitable way to convert the grass into marketable products. The fact that cattle could easily be trailed to a rail head or even to market meant that cattle were valuable for their meat and hides, while the intractable buffalo were valuable only for their hides. In the 1880s, a buffalo hide was worth $3.00, while a cow was worth $20 to $25...
All in all, perhaps the history of the American bison was close to economically optimal. They were magnificent animals that populated much of the Great Plains, and they formed an economic resource that supported Indians and early settlers. They were exploited rapidly by both the robe trade and the hide (leather) trade, perhaps more rapidly than private rights would have allowed. Nevertheless, it is likely that, given the low economic value of buffalo and the fact that they were primarily valuable as an amenity resource, the appropriate degree of preservation occurred.
The buffalo resource collapsed in the early 1880s. As a sidenote - the collapse was very sudden. Anderson and Hill quote John Hanner:
The extirpation of the buffalo was so rapid that it even caught the hunters by surprise. Curiously enough, not even the buffalo hunters themselves were at the time aware of the fact that the end of the hunting season of 1882-83 was also the end of the buffalo, at least as an inhabitant of the plains and as a source of revenue. In the autumn of 1883, they nearly all outfitted as usual, often at the expense of many hundreds of dollars, and blithely sought "the range" that up to that time had been so prolific in robes. The end was in nearly every case the same - total failure and bankruptcy. it was indeed hard to believe that not only the millions, but also the thousands, had actually gone, and forever.
I wonder why the collapse was so unexpected? Walters and Martell point out that with many species of fish, catch per unit of effort can remain high, while the overall population is declining. The remaining fish group together within ever smaller geographical areas, and the fishermen target on these, rather than continuing to search empty water. As a result, catch-per-unit-of-effort may stay high until close to the end, and be a poor indicator of a declining stock. Did something like this happen to the buffalo?