Noticing Nature

Indigenous to the Gulf Coast, mullet thrives in both saltwater and freshwater, often abundant in the brackish water of Florida’s estuaries, and often find their way into rivers. Mullet are euryhaline and eurythermal marine fish, meaning that mullet can live in areas with both a great range of temperature as well as salinity. Although mullet are present all year round, the drop in temperature associated with cold fronts signals to these fish that it’s time to reproduce. They spawn most of the year, but the peak is between October and December. Spawning takes place in the open Gulf of Mexico, sometimes far offshore.
Because of their abilities to live in both fresh and salt water, in a wide temperature range, the distribution range of the mullet is quite large. Mullet live off of both Florida coasts, as well as both coasts of the United States.
Mullet primarily feed on detritus and by doing this, they sometimes ingest sand or silt. It is believed that this is the way that they clean and oxygenate their gills in stagnant, warm, low oxygen waters. Traveling in schools and feeding off the bottom, their diet consists of bacteria and single-celled algae found attached to plants. Due to its bottom-feeder status, if the mullet is ingesting mud from a polluted source like the recent toxic red tide bloom on Gasparilla Island, death from brevetoxin exposure is immediate; however, death can also occur after long-term exposure to toxins.
Months of consistent red tide sampling and reports from CHNEP Water Atlas confirm that runoff from recent storms has significantly contributed to fish kills in our area. Because mullet forage for phytoplankton, they are one of the first to come in contact with Karenia Brevis. Mullet aggregate into very large schools as they head out the passes to spawn. Florida anglers often notice schooling mullet apparently “gulping air,” but they are actually feeding on tiny phytoplankton from the neuston layer, which is the top few centimeters of water.
The mullet spawn or lay their eggs at sea, and utilize estuaries as their nursery areas. It has been theorized that mullet fish jump during the spawning season to break open their egg sacks, in preparation for the spawn. However, mullet primarily jump out of the water to access more oxygen through a specialized organ in their throat that allows them to survive in low oxygen level areas. This behavior is most often observed when the water is warm or has reduced oxygen content.

Dead mullet on the beach.

Because the elements and barometric pressure are ideal for their run, mullets swim right into red tide. Not only are the fish that spawn caught up in the red tide, the hatch from the spawn may also die from the red tide. This poses great danger to all marine life by the red tide organism, which produces brevetoxins that are ingested, inhaled and consumed by species that eat the toxic prey. These toxins can exist for over six months in aquatic vegetation which is consumed by marine animals like sea turtles and manatees.
Bird species who rely on fish as their food source can experience secondhand poisoning. This affliction is known as brevetoxicosis and can affect these animals in numerous ways; including an inability to fly, lethargy, balance issues, and inability to perform natural behaviors such as preening and hunting. Seabirds can easily be spotted and appear intoxicated on the beach, unable to walk or fly straight. When left untreated, red tide poisoning results in mortality.
Playing an incredible and vital role in the ecosystem, the turkey vulture, with its unsavory eating habits, greatly reduces the risk of diseases spreading from the decaying flesh of red tide fish kill. Turkey vultures have the most sophisticated olfactory sense of any bird in the world and are able to spot and smell carrion from heights of up to 200 feet. As a carrion feeder, turkey vultures thrive on red tide incidents, feeding on the washed-up mullet carcasses. Quite a predicament and unfortunate, untimely demise for the mullet, considered to be Florida’s most ecologically and culturally important fish.
The mullet’s unique adaptability allows it to thrive in diverse environments, but this same trait makes it particularly vulnerable to ecological disruptions like red tide. As these fish play a crucial role in the marine food web, their decline due to toxic blooms has a ripple effect on other species, from seabirds to sea turtles. While nature has its own way of managing the aftermath—through scavengers like turkey vultures—the ongoing impact of pollution and climate-related changes underscores the importance of protecting Florida’s delicate coastal ecosystems.

Story and photo Tonya Bramlage