Status and assessment, research, and restoration needs for lake ...

Summary of Impediments for Lake Herring in the Great Lakes
Overall the loss of stocks in the Great Lakes was considered the biggest impediment (Table 1, Fig. 2). This
would strongly argue for protection of the existing stocks through reduction of targeted fisheries and by-catch
by commercial and sport fisheries until the size and amount of genetic diversity in existing populations can be
determined. In the event that existing stocks are too small and genetically depleted relative to historic stocks
consideration should be given to restoration.
The impact of non-native biota on lake herring stocks in the Great Lakes represents a large and poorly
understood group of impediments. now facing lake herring stocks in the Great Lakes. The list includes
alewives, rainbow smelt, sea lamprey (Petromyzon marinus), cormorants (Phalacrocorax auritus), dreissenids
(Dreissena polymorpha), round gobies (Neogobius melanostomus), Bythotrephes longimanus, and Cercopagis
pengoi. Although alewives have been in the lakes since the late 1800s, much of the evidence linking them to
declines in lake herring abundance is anecdotal, speculative, and circumstantial. Negative statistical correlations
between the abundance of lake herring and alewives are lacking as are mechanisms that would explain such
correlations. The inability to secure robust qualitative and quantitative data linking the impacts of non-native
species on lake herring will become only more daunting and complex with the increasing pace of invasions in
the Great Lakes. Nevertheless we can neither anticipate nor expect controls on existing or future invasive
species without first producing more tangible evidence of effect than has characterized the record to date.
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