There’s an ongoing misunderstanding about fisheries
management that often appears in print, when people aver that fisheries are, or legally should be, managed for “maximum sustainable yield.”
You often hear it repeated in the angling press,
particularly from spokesmen
for some of the more aggressive, and less thoughtful, “anglers’ rights”
organizations. They can probably be
forgiven such errors, given that the same mistake has been made by the current
Secretary of Commerce himself.
The term “maximum sustainable yield” isn’t even defined
in the Magnuson-Stevens
Fishery Conservation and Management Act, the law that governs all fishing
in the federal waters of the United States, although the law does employ that
phrase on five occasions (three of those occurring in a single
definition). However, it
is defined in related regulations as
“the largest long-term average catch or yield that can be
taken from a stock or stock complex under prevailing ecological, environmental
conditions and fishery technological characteristics (e.g., gear selectivity), and the distribution of catch among
fleets.”
Maximum sustainable yield thus marks the precipice, the
point where overfishing begins. The
regulations recognize that fact, and state that
“Overfishing occurs whenever a stock or stock complex is subjected
to a level of fishing mortality or total catch that jeopardizes the capacity of
a stock or stock complex to produce MSY on a continuing basis.”
Harvesting every last fish possible to achieve maximum
sustainable yield is a very risky management approach, as any mistake in
calculating either the size of fish stocks or the level of harvest that such
stocks can sustain in the long term could easily lead to a population
decline. And there is always enough
uncertainty in scientific estimates to assure that, sooner or later, such a
mistake will be made.
“The term “optimum,” with respect to
the yield from a fishery, means the amount of fish which—
(A)
will provide the greatest overall benefit to the
Nation, particularly with respect to food production and recreational
opportunities, and taking into account the protection of marine ecosystems;
(B)
is prescribed as such on the basis of maximum
sustainable yield from the fishery, as reduced by any relevant economic,
social, or ecological factor; and
(C) in
the case of an overfished fishery, provides for rebuilding to a level consistent
with producing the maximum sustainable yield from such fishery.”
“The determination of [optimum yield] is a decisional
mechanism for resolving the Magnuson-Stevens Act’s conservation and management
objectives, achieving [a fishery management plan’s] objectives, and balancing
the various interests that comprise the greatest overall benefit to the
Nation. OY is based on MSY as reduced
under paragraphs e(3)(iii)(A) and (B) of this section. The most important limitation on the
specification of OY is that the choice of OY and the conservation and
management measures proposed to achieve it must prevent overfishing. [emphasis added]”
Those definitions open up some interesting possibilities,
and dispel some common misconceptions, particularly when linked with other
existing regulations.
For example, optimum yield is more than just maximum
sustainable yield, possibly reduced to account for a handful of factors. Optimum yield is, first and foremost, a tool
to prevent overfishing.
The regulations don’t say that the most important role
of optimum yield is to maximize harvest, or recreational opportunity, or even
to enhance marine ecosystems. First,
above any other consideration, optimum yield “must prevent overfishing.”
That word “must” takes away all discretion. Overfishing must not occur.
That means that, as a practical matter, optimum yield should
be set at a level somewhat lower than MSY.
In theory, if fishery managers’ calculations were absolutely precise,
and allowed for no error at all, optimum yield could safely equal maximum
sustainable yield. But in the real
world, there is always some level of uncertainty, and that uncertainty means
that optimum yield, if properly set, will always be less than MSY.
Earlier, I used the brink of a precipice as a metaphor for MSY; as is the case with
any precipice, disaster could easily ensue if one slipped over the edge. To extend that metaphor just a bit farter, uncertainty is
fog, that makes it harder to tell when the brink is drawing close.
In the case of some fish stocks, that are
blessed with good data, managers can come fairly close to the edge—to MSY—with
little risk of going beyond; in the case of others, where uncertainties are
rife, they’re proceeding in the densest pea soup imaginible, where the slightest haste or lack of care could lead to serious problems.
Because that risk is very real, Congress has established a
procedure to help the regional fishery management councils negotiate foggy
terrain without falling off the edge of a cliff. Magnuson-Stevens requires that each regional
fishery management council
“develop annual catch limits for all of its managed fisheries
that may not exceed the fishing level recommendations of its scientific and
statistical committee or the peer review process established [elsewhere in the
law].”
Such fishing level recommendations are set in accord with
the concept of “acceptable biological catch,” which is defined in the
regulations as
“a level of a stock or stock complex’s annual catch, which is
based on an ABC control rule that accounts for the scientific uncertainty in
the estimates of [the overfishing limit, which is effectively equivalent to
MSY], any other scientific uncertainty, and the Council’s risk policy.”
Thus, annual catch limits will almost certainly be set some
way below MSY even before the “economic, social, and ecological factors” used
to finally establish optimum yield are considered.
When those factors are considered, things begin to get even more interesting, particularly for recreational fishermen.
Fishery managers have long emphasized yield, effectively
working to maximize the number of dead fish that can be piled up on the
dock. Some people
have argued that is essentially a commercial management measure, and not
appropriate for recreational fisheries.
In the case of those latter species, managing
for lower harvest levels, and greater abundance, makes more sense than managing
merely for yield. Such an approach
is thoroughly embraced by the concept of optimum yield, where the
regulations recognize that taking home fish is part of the recreational
experience, but also recognize that
“The benefits of recreational opportunities reflect the
quality of both the recreational fishing experience and non-consumptive fishery
uses such as ecotourism, fish watching, and recreational diving.”
Leaving a bare minimum number of fish in the water, that is, a biomass equal to Bmsy, isn't likely to provide such benefits.
So when you hear someone say that management is all about
yield, and that abundance and similar concepts have no solid foundation in
fisheries law, you can feel free to ignore them. Reducing landings in order to enhance the
recreational experience is very much contemplated by the current regulations.
Things become even more interesting when one looks at what
may be included under the broad heading of social, economic, or ecological
factors relevant to a decision to further separate optimum yield from MSY.
“prudent consideration of the risk of overharvesting when a
stock size or reproductive potential is uncertain, satisfaction of consumer and
recreational needs,…the decrease in cost per unit of catch afforded by an
increase in stock size, [and] the attendant increase in catch per unit of
effort…,”
which are all factors that favor managing for building a larger
biomass, rather than merely concentrating on landings.
Striped bass are not a federally-managed fish, but given a
recent Southwick Associates study, which shows how participation in the striped
bass fishery fell off as striped bass became less abundant, it wouldn’t be
unreasonable to believe that, at least in the case of species targeted primarily
for recreation, higher abundance leads to greater levels of angler
participation, which in turn generate greater economic benefits, and thus justify
lowering optimum yield for such species on economic considerations alone.
Establishing optimum yield at a lower level for primarily
recreational species would also be supported by social
considerations, most particularly, as noted in the regulations, the
“enjoyment gained from recreational fishing”
when there are enough fish in the water to provide for
frequent hookups, even for relatively unexperienced anglers or anglers who must
wait until fish come within range of a pier or of shore before they can catch
them.
But setting optimum yield isn’t just about establishing harvest
levels that suit participants in a fishery; fishing’s impact on the entire ecosystem
needs to be taken into account. Thus,
the regulations inform us,
“…Species interactions that have not explicitly been taken
into account when calculating MSY should be considered as relevant factors for setting
OY below MSY. In addition, consideration
should be given to managing forage stocks for higher biomass than Bmsy to
enhance and protect the marine ecosystem.
Also important are ecological or environmental conditions that stress
marine organisms or their habitat, such as natural or manmade changes in
wetlands or nursery grounds, and effects of pollutants on habitat and stocks.”
That language makes it clear that, when fishermen wish to escape responsibility, in
the form of reduced landings, for a declining stock, and seek to put the blame
for decreasing abundance on inshore pollution, wetlands development or the
impacts of warming waters, they are unintentionally undercutting their own
position, and making a case for reducing optimum yield, and probably
increasing catch restrictions, on the basis of relevant ecological factors.
Clearly, the concept of optimum yield is a powerful and
far-reaching fishery management tool.
Although regional fishery management councils have not yet realized
the full potential that the concept of optimum yield provides, they have
already made a slow start in that direction.
While it’s very easy to argue that such councils need to do a lot more
to fully and explicitly integrate the concept of optimum yield in their fishery
management plans, one thing is already clear.
Managing for optimum yield is very
different from managing for MSY.
And it is precisely what federal fisheries law requires.
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