The Peace River, which flows through the middle of Central Florida’s phosphate mining belt, has lost about a third of the fish species it once had, according to environmental scientist Thomas Fraser.
Also, the types of fish now found in the Peace caused a scientist in 1986 to group it with the Alafia — a smaller river that runs from Polk County through Manatee that has also experienced phosphate mining — and the lower Everglades.
In theory, the Peace should have instead been grouped with several other large rivers in Southwest Florida, Fraser said. But those rivers — the Hillsborough, Withlacoochie and Kissimmee — all have significantly more species of fish than the Peace or Alafia.
Those facts have led Fraser to conclude that phosphate mining is the prime suspect in the loss of species diversity. His comments came during a presentation Friday at the Charlotte Harbor National Estuary Summit in Punta Gorda. The three-day scientific conference concludes today with presentations geared for the general public.
“About a third of the species of fishes in the Peace River appear to be in trouble,” Fraser declared. “This suggests the river is in pretty sad shape.”
Fraser said he researched historical archives at museums in several states to determine that before 1970, at least 44 species of fish had been counted in the Peace River. About 50 could be expected based on the river’s characteristics, he said.
However, in a half-dozen studies by state biologists and industry consultants since then, the average number of species found was 32.
Actually, a total of 39 species were counted. But some studies found species that were not found in the other counts, leading Fraser to conclude that seven of the species were so rare they represented an anomaly.
Fraser said the Peace should be similar to several other rivers that have their start in the Green Swamp of Central Florida, including the Withlacoochie, Hillsborough, Braden and Myakka rivers.
Recent studies show the Hillsborough, Withlacoochie and Kissimmee rivers now support between 42 and 48 species.
The Alafia supports just 28 species, Fraser said.
“The Peace River and the Alafia obviously have the phosphate industry in common,” he said.
One of the fishes missing from the Peace, the Atlantic sturgeon, also disappeared from the Hillsborough River amid a commercial fishing boom, Fraser acknowledged.
Another fish, the redeye chub, is common in runs fed by freshwater springs. It’s found in the Withlacoochie and Alafia, but not in the Peace, Fraser said.
Two other fishes, the black banded darter and the bandit sunfish, are only found in the Withlacoochie, Fraser said.
Another four species are missing in the Peace probably because they require heavy submerged vegetation, which has all but disappeared, Fraser said.
Another of the missing fishes requires “seasonal inundation of the floodplain” to survive, Fraser said. Thousands of acres of floodplain may have been impacted by past mining operations, he said.
Mining company scientists say their operations have no impact on river flow because they capture only the rainfall during peak flow periods. However, Fraser warned the capture of flood waters could reduce the periods of inundation of the flood plain.
“There’s clearly going to be a relationship between the annual inundation of the floodplain and the population of fish we have in the river,” he said.
He recommended more fish sampling in the future to monitor the state of the river.