The season's hurricanes may be responsible for a tiny bit of good news discovered in the saltwater marshes of Florida's east coast.
Jon Shenker, director of the Sportfish Research Institute in Melbourne, was dragging a finely-meshed net through the shallows of the Indian River's Mosquito Lagoon in early November when he and his biology students found a bunch of 1-inch to 3 inch-long tarpon.
It wasn't unusual to find juvenile tarpon in the murky shallows, says Shenker, a biology professor at the Florida Institute of Technology.
Years ago, local mosquito control experts figured they could stop mosquitoes from growing in the wet mud of the marshes if they built dykes around them and flooded them, Shenker tells me.
Those mosquito control impoundments are now great nursery areas for juvenile fish, provided they are equipped with culverts to allow water to flow in and out, Shenker says. If Shenker were a betting man, he'd bet that his area produces some of the big tarpon we catch here in the Keys.
What was unique about the fish Shenker and his students discovered in the Mosquito Lagoon Impoundment was their size. "This is the first time I've ever found tarpon down to 1 inch long," Shenker says. He's been sampling the area regularly for about 10 years. Best of all, he found lots of the little fish.
Shenker's hypothesis is that the tidal surges from the hurricanes swept the tarpon into the shallows earlier than normal in their life cycles. These tarpon will have a better chance of survival in the shallows than in the open sea, where they presumably could be gobbled up by birds and other fish.
If this is correct, 2004 could go down as a banner year for the Florida tarpon population.
"Put yourself in the position of this little, half-inch-long fish trying to get to shore. There's nothing like a hurricane to give you a push," he says.
Scientists believe tarpon hatch from eggs offshore and begin life as ribbon-like larvae. At some point, the larvae make the transition into the small fish that are found in Florida's murky estuaries and marshes. Few predators can survive in this murky water but tarpon cope by gulping air at the surface and gleaning oxygen inside their rudimentary lungs, or air bladders.
Shenker says you can literally watch the tiny fish dimple the surface. "They'll spend about the first year of life in these marshes, until they're about 12 inches long," he says.
Shenker knows lots of places like that in his area, but he's hoping kayakers, birders or backcountry anglers in the Keys will contact him if they find similar places here. He plans to take DNA samples for genetic profiling, and also study the chemistry of the ear bones, or otoliths. The otoliths are chemically different based on where the fish live.
Shenker has asked the conservation group Bonefish & Tarpon Unlimited to put out the word to its members, and the group has obliged.
"We have some juvenile nurseries/sampling sites identified in the Everglades and [Southwest] Florida, but are looking for more sites," Shenker writes.
In another interesting twist, Shenker has lined up 50 anglers to take tarpon DNA samples from the tarpon they catch. So far, Shenker has gathered DNA from tarpon up to 150 pounds. "We're hoping to put together the whole tarpon family tree for the Indian River," he says.
By comparing the DNA to that of tarpon in other regions, perhaps including the Keys, Shenker ought to be able to tell how widely the fish in his area are distributed.
The anglers will gather the samples by trimming about a half inch off the long spike that trails from the back of tarpon dorsal fins.
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