Petition to List Lynn Canal Pacific Herring under the Endangered ...

Sockeye Salmon, Waples et al. (1991) explained the application of a precautionary
approach in the context of the ESA.
The Biological Review Team thus faced a difficult problem: a decision whether
the sockeye salmon petition is warranted is required by law by April 1991, but
there is insufficient information for a definitive determination of the first key
question in the first key question in the process. After a lengthy discussion, the
team reached a strong consensus that, because we cannot conclude with any
certainty that the original sockeye salmon gene poll is extinct, as stewards of the
resource we are obliged to make a conservative decision in this circumstance.
The team was not unmindful of the implications of this decision, and we do not
suggest that a lack of information should always result in a conservative decision
in ESA evaluations. However, a factor that weighed heavily in these
considerations was the irreversibility of the likely consequence of taking the
alternative course. That is, if we were to assume that a recent anadromous O.
nerka in Redfish Lake were derived from kokanee and this assumption proved
wrong, the original sockeye salmon gene pool could easily become extinct before
the mistake was realized.
(Waples et al. 1991: 13)(emphasis added). Therefore, any analysis of Lynn Canal
Herring genetics should acknowledge the role of uncertainty and the precautionary
principle.
Lastly, because the available genetic evidence is scant, any determination of local
population structure using genetic data should be tempered by the limitations of
molecular genetics techniques. As explained by Carvalho and Hauser (1994), failing to
detect population separation using genetic data alone could mean that other methods are
necessary to discern population structure.
A lack of genetically detectable stock separation may arise from five sources: (i)
sufficient gene flow to maintain panmixia; (ii) occasional ‘sweepstake’ events
such as sporadic recruitment from distant, non-neighboring areas which could
produce the appearance of panmixia; (iii) stabilizing selection arising from
exposure to similar environments; (iv) recent genetic divergence of the compared
populations; or (v) failure to detect genetic variants due either to the technique
employed or to insufficient sample sizes. With the exception of (v), it may be
impossible to distinguish between the various possibilities using molecular
genetics alone and it becomes especially important to consider data from other
methods.
If the samples being compared are truly panmictic, then treating the fishery as a
unit stock would have no consequences in terms of recruitment from overfished
locales. If, however, some undetected reproductive isolation exists, the unit stock
hypothesis may result in local overexploitation, diminishing the overall fishery
yield. Furthermore, undetected stocks may become eliminated, with a
corresponding reduction in inter-population genetic variance. Thus the lack of
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