The most important fish in Florida: mullet, we owe you gratitude.
It is not uncommon for the serious fisherman visiting from the northern latitudes to be startled by a mullet hurtling its body into the air, breaking the solitude of an otherwise calm morning. What is that fish? Why is it jumping like that?
The answer to the first question is easy. It must be the striped mullet. Even though we have six species of mullet in Florida, the only one that readily takes to the air for no apparent reason is the striped mullet, Mugil cephalus, often called black mullet. In the Western Atlantic, the striped mullet is a warm temperate species absent from the tropical Caribbean, while all the other Florida mullet species occur throughout the Caribbean Sea.
Since the striped mullet occurs around the world I was curious to see if the populations that occur in the Galapagos Islands jumped like the Florida striped mullet. I saw schools of striped mullet there when on expeditions in 1995 and 1998, but they did not spontaneously leap into the air like Florida striped mullet. Since all mullet species have parasites, need to rid their gills of sandy debris and suffer mortality from predators chasing them, these can't be the reasons striped mullet jump, since other species don't jump. I believe the jumping behavior may have something to do with communication in turbid estuarine and riverine waters of the southeastern United States, the prime habitat for southeastern U.S. striped mullet. To our knowledge, mullet do not produce sound other than the splash of an aerial reentry. This splash may be a signal to other mullet, or a system for diverting predator attention from a single fish. The other mullet species that do not spontaneously leave the water may be able to stay in visual contact in clear Caribbean waters and may not need to produce sound, a splash, for communication or to confuse predators.
Mullet, no matter what species, are considered to be one of the most important fish in Florida. Why? Every predator in our bays, lagoons, rivers, creeks, lakes connected to the sea, canals and coastal ocean captures and eats mullet. This includes ospreys, bald eagles, pelicans, sharks, bottlenose dolphin and humans. Mullet feed all major aquatic predators in our coastal ecosystems. They are eaten by the thousands each year as they swim from rivers, lagoons and bays out inlets and passes to offshore spawning sites October through December. Years ago thousands of striped mullet were routinely locked through the C-44 Canal gates leading to Lake Okeechobee in spring, and back to the Atlantic Ocean during fall spawning migrations.
What makes them even more valuable is that they are responsible for the greatest transport of organic material, living wet weight (biomass), from coastal ecosystems: freshwater streams, grass marshes and mangrove forests, to the open estuary and ocean. Quantitative research has shown that striped mullet contributed more wet weight per unit area than any other transient fish in mangrove forests, even more than snook and tarpon. They are analogous to the buffalo of the Great Plains that fed predators, including native Americans. Mullet do not graze on grass, but scrape and suck off microscopic plants/bacteria growing on sand/mud substrates, microcrustaceans and dead plant and animal matter (we call detritus) and the rich layer of microscopic organisms on the water's surface (neuston). Have you ever observed a tight school of mullet sucking the neuston layer? It looks like they are sucking air, but they are feeding.
Striped mullet can also reach a substantial size. The largest striped mullet I have examined weighed 15.8 pounds with a 22-inch girth. That mullet could knock out a wading fly fisherman with a single strategic leap. A mullet this size could feed a family. I grew up eating smoked mullet and mullet roe. It is a bit hard to find these days.
Growing up in Sarasota I can remember schools of mullet that were literally several miles long and hundreds of yards wide. Fishermen swore that the same school that was at Big Pass was also passing through Sarasota Bay and could be seen at New Pass three miles away. Those large schools of mullet appear to be gone now along with the mullet roe and smoked mullet vendors that I knew as a child. Diseased and dying striped mullet from the St. Lucie River were the first troubled fish to come to my attention 30 years ago. Since then, the incidence of diseased mullet has increased with water quality declines in freshwater tributaries, such as the St. Lucie and St. Johns rivers of east Florida.
As we clean up our inshore waters I believe the striped mullet will return in abundance, but we might want to augment their return with mullet hatcheries dedicated to this all important fish. We must keep high water quality standards if we want mullet schools to increase. Mullet will feed the snook, tarpon and host of other predators and at the same time transport tons of organic material from our bays to the ocean and Gulf.
By R. Grant Gilmore, Ph.D.