CURRENT RESEARCH
Alabama Shad Research Has Double Benefits
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Data to help restore species of fish is being used to help determine the impacts of tropical systems on inland fisheries.
In 2005, FishAmerica awarded a $21,900 research grant to the USDA Forest Service's Southern Research Station as part of an ongoing effort to provide a scientific basis for developing actions to restore Alabama shad populations.
Forest Service biologist Susan Adams, Ph.D., and several graduate students from the University of Southern Mississippi, set out to collect data on juvenile and adult shad. The goal was to determine the migration patterns, spawning activity, habitat selection and overall population abundance of Alabama shad in the Pascagoula River drainage in Mississippi. Little did they know that their research prior to Hurricane Katrina would provide critical data needed to assess the impacts of hurricanes and other tropical storms on freshwater fisheries.
On August 29, 2005, the eye of Hurricane Katrina struck just 70 miles west
of the mouth of the Pascagoula River, where the research was being conducted.
While large tropical storms can have dramatic effects on coastal and estuarine
fisheries, it was not as well understood how they might affect freshwater fisheries
further inland. Hurricane Katrina provided an opportunity to examine these effects
in areas where biologists had pre-storm fish community data.
Using pre-storm and post-storm data from the Alabama shad study, biologists determined that the hurricane impacts were most pronounced in the areas closest to the Gulf of Mexico. The long-term impact of the storm to fish habitat will be the addition of rootwads and fallen trees to streams and smaller rivers. Among its many functions, dead wood creates complex habitats such as pools and side channels. In general, fish communities are expected to realize benefits from the storm in both the short and long terms.
Although there were some reported fish kills in the Pascagoula, these mainly resulted from what is known as a “pulse disturbance” – the cause of the impact was of short duration. Within a short period of time, habitat and water quality conditions in the upstream freshwater systems of the Pascagoula quickly returned to within a normal range. Because of the quick return to normal, most of these freshwater fish populations began recovering immediately.
The data showed that in the Pascagoula River drainage, juvenile Alabama shad use habitats that are continuously created and altered by the natural hydrologic and sediment regimes and ongoing inputs of large wood into the rivers. The results also documented shifts in habitat use as the fish grew. The habitat models developed can be used to predict juvenile Alabama shad presence and absence at the habitat scale.
While benefits from this research to sportfish must be viewed in the long term
due to the small size of most remaining
populations of Alabama shad, the results have provided new information about
the habitat needs of the juveniles that can be used to help guide conservation
planning for the freshwater phase of the life cycle.
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Rebuilding the Alabama shad populations could lead to new, seasonal sportfishing opportunities and markets in Southeastern rivers. Furthermore, management of other sportfish may be improved via the maintenance or restoration of the same river processes that appear to be important to Alabama shad recovery.
Alabama shad is an anadromous species that was once abundant in the Gulf of
Mexico and Mississippi River drainage. Alabama shad are close relatives to American
shad and skipjack herring and have great potential as a forage fish to support
other sportfish. Populations in some rivers have been extirpated, while other
populations have declined rapidly over time. Although dams are thought to be
responsible for most declines, the Pascagoula River drainage is the largest
drainage without a major dam or hydrologic alteration in the contiguous United
States, providing the ideal watershed to conduct effective research on the issue.
