assumes the habitat is constant, supporting the stock at the same level consistently.
Virtually every stock examined over long intervals shows that this not true, as
illustrated above for the eastern Pacific yellowfin tuna. Carmel Finley (2011), has
stated well the overall problem with MSY management: “the emphasis tends to fall on
maximum, not on sustainable”.
(^) However, clear and generally correct idealizations are very valuable and MSY
retains that value. Peter Larkin’s (1977) “Epitaph for the Concept of MSY” is
appropriate for fishery experts, but for the rest of us the idea still has some useful life:
(^) “Here lies the concept MSY,
(^)
It advocated yields too high,
(^)
And didn’t spell out how to slice the pie.
(^)
We bury it with best of wishes,
(^)
Especially on behalf of fishes.
(^)
We don’t know yet what will take its place,
(^)
But we hope it’s as good for the human race.”
(^) Larkin’s last line shows even he thought it had its virtues.
(^) Current management techniques (and/or philosophies) include “virtual population
analysis” (VPA) and “reasonable and prudent alternatives” (RPA) and “ecosystem
based management” (EBM, lately rephrased as “ecosystem approach to
management”, EAM). A suite of techniques for evaluating stock size, condition, and
interaction with fishing, VPA incorporates detailed analyses of size, age, and
reproductive status, and applies year-class estimates to take account of the uneven
recruitment rates among years. At least in the United States, RPA is a legal mandate to
find and apply management schemes that protect stocks, protect other populations
affected by fisheries, and prevent undue harm to marine habitats. Ecosystem-based
managers attempt to consider everything about exploited stocks and their habitat, with
concern for habitat health ranking above concern for yield. The general terms of EBM
are spelled out by Pikitch et al. (2004). It can at least be mandated, if not readily
applied. In all cases, the stated goals are for fisheries to be prudently managed with an
eye to long-term environmental health and stock protection. All such efforts are made
vastly more complex by their interaction with economic and political factors. In the
USA, for example, management is not done by scientists alone, but by regional
management councils composed of stakeholders in the fishery – fishers, packers, and
scientists. Both the councils and the scientific agencies somehow sustain their work
despite recurring interference from the courts, which are brought into play through
suits filed by environmental organizations on behalf of fish and by fishing folk trying