Cold weather causes fish dieoffs in Florida
KEY WEST, Fla. -- It's not paradise lost.
However, the lasting impact of Mother Nature's cold shoulder won't be known for some time.
Unusually frigid conditions socked Florida in early January and lingered for up to two weeks in some locales, setting the stage for fish kills and wildlife stresses not seen in years. From Jacksonville to Miami and even into the Keys, reports and photos have surfaced in past months of a variety of fish -- including prized inshore game fish -- floating lifeless near shore and littered on beaches.
As you would expect, the negative effects weren't isolated to fish, and scads of other wildlife literally were left out in the cold. The extreme conditions wreaked havoc on the manatee population. Fifty-six manatee deaths were attributed to cold stress last year, which was a record, but there already have been 183 manatee deaths attributed to cold stress this year, according to Florida Fish and Wildlife Conservation Commission (FWC) data.
More than 4,000 cold-stunned sea turtles, mostly green turtles, have been rescued up and down the coast, and most -- at least 80 percent -- are expected to survive after being cared for and released.
One silver lining has been the impact on invasive species of all varieties, including pythons in the Everglades and fish such as oscars, cichlids and tilapia in fresh water that compete with native species for habitat and forage. The cold weather forced the large snakes that have taken over the vast aquatic ecosystem in south Florida into new areas where they could be trapped or eradicated, or they simply succumbed to the elements. Freshwater kills of game fish have not been on the scale of those in saltwater, but the impact on peacock bass was big and the tropical dwellers deliberately introduced have died off from various habitats including canals and drainage areas.
Lee Schlesinger, marine fisheries management spokesman for the FWC, said the cold stress was a significant statewide event. But he pointed to other killing freezes, and noted that they are not an unusual occurrence in Florida's history.
Tropical fish species are most affected by chilly temperatures, which only have to cool water down past the 60-degree mark in some cases to be lethal. The most well-known and most-sought tropical species by sportsmen in Florida is the snook, which also was one of the species hardest-hit by the cold conditions since it's at the height of its northern range. The worst snook die-offs due to cold stress came in 1977 when approximately 1 million were killed during a winter storm, and in 1989 when upwards of 500,000 died during freeze conditions in the Sunshine State.
Schlesinger noted that any kind of reliable kill counts will take biologists and wildlife officials months to calculate, but there already have been reports and photos of large snook -- many above 30 inches -- that were scooped up by anglers and biologists in the aftermath. In one such photo, four men each are hoisting a deceased snook measuring between 30 and 40 inches while the bottom of their bay boat is completely covered with many more of the dead fish.
While snook bore the brunt among game fish in Florida, guides and researchers up and down the coast have been surprised at the number of bonefish and tarpon that were killed. Schlesinger noted that most of the territorial game fish were able to move off into deeper water, but he said some species -- especially those that live on the flats and mangrove locales -- didn't react fast enough before being stunned by the cold.
In response to the fish kills, the FWC extended closed harvest seasons for snook through Aug. 31. The agency also issued executive orders to close the harvest of bonefish and tarpon through March 31. These moves don't restrict catch-and-release angling for these species, though most fly anglers and conventional sport fishermen don't keep bonefish and tarpon anyway.
The biggest aspect biologists will be monitoring, especially for snook, is the effect on spawning-age fish, and a big hit on that population is what could slow future recovery.
The Texas coast also faced frigid conditions this winter, and game fish including speckled trout were killed. However, the result was nothing like freezes in 1983, 1984 and 1989, said Kyle Spiller, the Upper Laguna Madre ecosystem leader for the Texas Parks and Wildlife Department.
"In '84 it essentially wiped us clean," he said. "From December '83 to January '84, we lost about 14 million fish coastwide, including about 600,000 trout and 104,000 redfish. What we did following the freeze was increase the minimum size limit and decrease the bag limit [for trout]. That helped us recover from overfishing, too."
Spiller said the harvest in the next two years was almost nonexistent but that the overall fishery recovered to previous levels in 1988 and 1989. However, the next freeze events occurred in 1989, dealing another big blow up and down the coast and forcing another increase in size limits.
"In 1989 we lost 17.5 million fish coastwide," he said. "The water temperature got down and stayed freezing in those bad freezes. Anything much below 48 to 49 degrees is lethal to trout if it stays that way for an extended period. Redfish typically are in the gulf when freeze events happen, so they're not as affected."
Spiller noted that the underwater geography in many places mirrors the flats and shallow water locales of Florida, making it tough in lasting winter storms.
"Because the water is shallow in the Laguna, when these arctic fronts hit they cool shallow water off quickly and the winds will push that off into deeper water. In these particular fronts there is no refuge for them. That's true especially in places like the Landcut where it spreads that cool water almost like a river."
As in the previous fish-killing freezes, it took time to bounce back, but Spiller noted that the fishery began recovering in early 1992 and exceeded previous levels in the late '90s. He said that the 13-pound, 11-ounce previous state record speck caught by Jim Wallace in 1996 in Baffin Bay was 6 years old, and that fish would have spawned the year after the freezes.
Schlesinger and Spiller pointed to the rate of temperature change as being the main culprit in wildlife-killing events rather than the actual reading in the air, but Spiller summed up the cold-weather scare in Texas best.
"We dodged a big bullet," he said.
Here's hoping for Florida anglers and those who flock to the fishing paradise that the impact was just a glancing shot.
Will Leschper's e-mail address is leschperw@yahoo.com.
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