By Terry Gibson
Mullet and other forage species such as pinfish are obviously a vital food source for the predatory fish we like to catch. They also help maintain important fish habitat critical to the health of the Indian River Lagoon and other Florida waters. Take, for instance, the ways mullet, pinfish, and sea grasses all depend upon one another. As early juveniles, mullet and pinfish go through a life stage where they are carnivorous, feasting on tiny crustaceans and other tiny animals found among the blades of sea grasses and on the algae that cover sea grass blades. These forage species need those sources of protein for a growth spurt that makes them less vulnerable to predators and more likely to make it to sexual maturity.
Then they undergo what’s called an ontogenetic shift where metamorphic changes to their stomachs, intestines, lips, and even teeth (in the case of pinfish) allow them to feed on detritus and algae, including the kinds of algae that attach to sea grass, known as algal epiphytes. Epiphytes occur naturally and provide cover for tiny organisms at low levels of the food webs, such as the crustaceans that really young mullet require. But the epiphytes can smother sea grasses if they are not grazed on by forage species such as adult mullet and pinfish.
In disturbed ecosystems such as the Indian River Lagoon, where we’ve added nitrogen in excess, the grazers become all the more essential to winning the battle against choking algae and ensuring that Florida’s sea grasses receive sufficient sunlight. Meanwhile, these forage species turn nutrients from the epiphytes into the fatty acids that predator fish and birds require in high volumes in order to grow and reproduce.
Therefore, maintaining sufficient abundance, variety, and sizes of mullet and other forage fish species is imperative if we are to restore sea grass beds and maintain strong numbers of snook, tarpon, redfish, speckled trout, and other recreationally important fish species for future generations of anglers.