Scientists have been studying the fish population at Silver Springs for decades. The most recent study completed by the Howard T. Odum Florida Springs Institute (FSI) reveals a troubling trend. Blue tilapia, an exotic fish, has exploded at Silver Springs over the last two years to 88% of the total fish population. “This is a troubling trend because blue tilapia compete with native mullet and gizzard shad for food and bass and sunfish for nesting areas. They disrupt the aquatic habitat,” explains Dr. Robert Knight, executive director of FSI. “Breaching the Rodman/Kirkpatrick Dam would bring back large, predatory fish such as the striped bass and channel catfish which would compete with tilapia and potentially help control their population,” he added.
The tilapia explosion is not the only changing fish story at Silver Springs. Native fish species have not fully recovered and still only comprise about 41% of the fish population seen prior to the completion of the Rodman/Kirkpatrick Dam in 1968. Fish populations collapsed after dam construction, decreasing by 78% in 1979 and by 92% in 2004. Largemouth bass and sunfish declined by 67% between 1950s and 2004. These two species are still down by 48% compared to pre-dam data.
The catfish that were historically the stars of the glass-bottomed boat rides dropped by 91% from 1954 to recent studies. Striped mullet, which are one of the few species that eat the algae coating the once bright green eel grass in the springs, diminished by 77% since 1954.
Although total biomass or fish weight in the study area is now on the rise, the increase recorded this year is predominantly by non-native and invasive tilapia. “The only way to fully restore the ecosystem at Silver Springs and bring back our native fish population is to restore the historic fish migration route and natural flow from Silver Springs to the Atlantic by breaching the Rodman/Kirkpatrick Dam near Palatka,” concluded Knight.