Fisheries
management is not an exact science.
Although biologists are constantly refining their stock
assessments and population models, there are still many sources of uncertainty.
Some of them fall into the category of “scientific uncertainty.”
Such scientific uncertainty applies to all of the important parameters, such as
stock size and the number of young fish recruited into the stock each year.
Biologists deal with such uncertainty by specifying a “confidence interval,”
stated as a probability that the actual stock size, recruitment figure or other
parameter is included in a particular range of values.
The summer flounder stock assessment provides a good example. Biologists have a lot of good data available to them, and the assessment
is updated each year, as new information becomes available. Even so, the
confidence intervals used in summer flounder management are fairly broad.
Thus, while the Summer Flounder Stock Assessment Update for 2016 estimated the spawning stock biomass
to be 36,240 metric tons (mt), it also recognized the uncertainty in that
estimate, stating that “The 90% confidence interval for [spawning stock
biomass] in 2015 was 32,605 to 44,425 mt,” meaning that there is a 90%
probability that the actual biomass fell somewhere between those two numbers.
Obviously, management measures that are appropriate for a stock
of 36,000 mt are a little more restrictive than they would need to be if the
stock size is closer to 44,000 mt, but not restrictive enough if the stock size
be closer to 32,000 mt. However, such measures would represent a statistically
defensible way to strike a balance between those two extremes.
Because some degree of
scientific uncertainty is inevitable, fisheries managers aren’t permitted to set harvest quotas at the
overfishing limit (OFL), the threshold where overfishing begins.
Instead, the Science and Statistics Committee (SSC) of each regional fishery
management council must address scientific uncertainty by establishing an
allowable biological catch (ABC), an upper limit on landings which represents
the OFL, reduced by a buffer that allows for such uncertainty.
In the case of 2017 summer flounder harvest, such buffer reduced
a 7,600 mt OFL to a 5,125 mt ABC, making it far less likely that overfishing
will occur.
Scientific uncertainty is
only half of the problem that managers face when setting annual catch limits
(ACLs); they must account for management uncertainty as well. Unlike scientific
uncertainty, which must be considered when setting ABCs, management uncertainty need not be considered at all.
Management uncertainty can arise in a number of ways. Harvest
might not be accurately calculated; that’s a particular problem in recreational
fisheries, where harvest is estimated based on a survey, and less of a problem
in commercial fisheries, where landings must be reported. Managers can never be
completely certain that the regulations that they adopt in any given year will
prevent overfishing. Even if the regulations opposed are adequate, there is no
guarantee that all fishermen will obey them.
Thus, management uncertainty can have a real impact on the
success of management measures. However, because accounting for uncertainty
will inevitably reduce ACLs, regional fishery management councils are often
reluctant to do so.
That became a particular problem for the Gulf of Mexico Fishery
Management Council (Gulf Council) a few years ago, which couldn’t keep
recreational fishermen from exceeding their ACL for red snapper.
Anglers caught too many red snapper in every year between 2008 and 2013,
with the exception of 2010, when the catastrophic oil spill that occurred after
BP’s Deepwater Horizon oil well blew up kept fishermen off the water.
The Gulf Council admitted that “management uncertainty was high for the
recreational sector,” but
refused to adopt the 20% buffer recommended by its SSC. It argued that a new
benchmark stock assessment and better methods of gathering recreational data
rendered such a large buffer unnecessary.
A group of commercial fishermen, concerned about the damage that
constant recreational overharvest was doing to the stock, sued NMFS in federal
court, seeking a decision that would compel the agency to hold anglers
accountable for their repeated overages.
The commercial fishermen won the lawsuit.
The court that decided the
case, Guindon v. Pritzker, said that accountability measures (AMs)
“can and should be used to address management uncertainty. NMFS must disapprove
and return for revision any Council proposal that does not contain adequate
AMs.”
It quoted a section of the administrative record which stated
that “Considerable uncertainty exists in projecting season estimates given
variability in average weights, catch per day, and implementation of
incompatible state regulations,” and ultimately found that “NMFS had a
statutory duty to…require whatever accountability measures are necessary to
constrain catch to the quota.”
NMFS responded by implementing the 20% buffer that the Gulf
Council had previously rejected, in order to avoid further recreational
overfishing.
Now, management uncertainty may be undermining the effort to
manage summer flounder.
Everyone admits that there
is a serious management uncertainty issue in the recreational summer flounder
fishery. The issue was well-described in a letter sent by James Gilmore, Director of the New York State
Department of Environmental Conservation’s Marine Division, to the Chair of the
Atlantic States Marine Fisheries Commission’s Summer Flounder, Scup and Black
Sea Bass Management Board (Management Board):
“There seems to
be a poor relationship between the recreational measures (derived from
calculations based on the [Marine Recreational Information Program]) and the
performance (as estimated by [such program]). Regional summer flounder
recreational management has been in place for the last 3 years (2014-2016).
During this period regulations adopted by each region have not changed with the
exception of NJ’s portion of Delaware Bay…Under consistent measures there are
numerous factors that may influence recreational harvest in a state, with
weather and fish availability to anglers among the most important. Harvest
estimates are in turn influenced by the actual magnitude of the harvest and the
variability inherent in a survey…Under 3 years of consistent regulations from
2014-2016, coastwide harvest estimates in numbers of fish have ranged from
1.6-2.5 million fish, varying as much as 50% between years. When we consider a
smaller geographic scale, this variability increases to 66% between years in
the CT-NJ region, and an average of 139% at the individual state level. It is
difficult to say how much of this variability is due to estimation vs. actual
harvest magnitude.”
Given such a high degree of management uncertainty, and
considering the court’s decision in Guindon v. Pritzker, one might expect NMFS
to establish a recreational ACL somewhat lower than the ABC, in order to create
a buffer against such uncertainty.
However, in materials provided to the Mid-Atlantic Fishery Management Council (MAFMC) and Management Board, the
MAFMC’s Summer Flounder, Scup and Black Sea Bass Monitoring Committee advised
that “The Monitoring Committee recommends no reduction from the commercial ACLs
to the [Annual Catch Targets] in 2017-2018 to address management
uncertainty…The Committee also recommends no reduction from the recreational
ACLs to the recreational [Annual Catch Targets] for 2017-2018…”
The lack of a buffer for
management uncertainty helped anglers in 2016. Because angling effort was
probably underestimated in 2015,harvest estimates for that year were surprisingly low, which allowed managers to keep regulations unchanged in 2016, even
though the ACL was reduced by 29%.
However, when effort returned to normal levels in 2016, such regulations did
not adequately constrain recreational landings. As a result,anglers overfished, and so will be forced to reduce landings by 40% in 2017, even though the ACL will only decline by 30%.
Such a large one-year reduction has caused a lot of anger in the recreational fishing community,
hostility that might have been avoided had managers been willing to admit that
the 2015 harvest estimates were probably too low, and incorporated a buffer for
management uncertainty into the 2016 regulations.
On the other hand, had such a buffer been adopted for 2016, many
members of the recreational fishing community probably would have protested
that…
That’s why it’s difficult to properly account for management
uncertainty. Fishery managers know that it exists, at some level, in every
recreational fishery; they also know that, eventually, it will probably result
in anglers overfishing their ACL.
However, because accounting for management uncertainty leads to
smaller recreational ACLs, which in turn leads to unhappy recreational
fishermen, managers are reluctant to put such constraints on landings even
when, as was true with red snapper, anglers regularly overfish their ACLs.
A court decision, such as Guindon v. Pritzker, can force
managers’ hands, but managers shouldn’t have to be forced to take needed
actions. By incorporating a buffer for management uncertainty into each year’s
ACLs, fishery managers better assure that regulations will be consistent from
year to year.
Consistent regulations, even if they result in somewhat smaller
ACLs, tend to strengthen anglers’ faith in fisheries management, while
regulations that change every year, without seeming cause or direction, lead
anglers to question managers’ decisions.
Since fishermen are far more likely to obey regulations that
they believe in, properly accounting for management uncertainty is an
important, yet too often ignored, part of the management process.
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This essay first appeared in “From the Waterfront,” the blog
of the Marine Fish Conservation Network, which can be found at
http://conservefish.org/blog/
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