Pinfish Primer: A Look at the Important Life History of a Favorite Meal for Many Predators
A Great Blue Heron eats a pinfish in Destin, Florida.
I told the kids that in a few hours, the little baitfish would ride over the migration route that similar fish typically make offshore on their way to maturity. I said that, thanks to federal laws, red snapper, gag grouper, and red grouper populations are rebounding strongly – and that the captain had assured me the pinfish with us today would shortly meet their maker as bait for these predators. Sure enough, the boat limited out quickly on red snapper, and a fair number of red and gag grouper came aboard. The kids were stoked. That trip brought full circle the tremendous importance of pinfish as prey for predators caught inshore, offshore, or both, over a broad geographic range.
The pinfish is important throughout its life, during all stages of what scientists call an ontogenetic migration. That's the pathway in their development that leads to changes in their bodies and/or evolving habitat preferences and food sources.
Pinfish occur in coastal waters from New England south to Cuba, throughout the Gulf of Mexico and in Mexico's Yucatan waters. They're abundant from coastal Virginia southward. And by "coastal," scientists mean essentially any brackish waters out across the reefs to the edge of the continental shelf, where fertile waters give way to a clear blue desert. Where and whenever you find pinfish, at any life stage, they serve as a vital source of nutrition for predators. Once they're big enough to put on a hook without killing them, you can catch just about every piscivorous (fish-eating) predator alive.
One interesting thing about a pinfish is that once it attains a size of about 40 millimeters (1½ inches), changes occur in its teeth and gut tract so that it can effectively digest vegetative matter, beginning with diatoms (phytoplankton), detritus (decaying vegetation), and algae. Later, once it reaches 100 mm (4 inches) or so, the fish can digest seagrass. As a pinfish matures, it hosts symbiotic bacteria that lend the fish the enzymes necessary to obtain energy from the long chain of sugar molecules found in plants, called cellulose. The anaerobic bacteria in the fish's guts use the sugars released during cellulose fermentation, while the fish get the metabolic byproducts of bacterial fermentation, which are various volatile fatty acids—high-octane energy perfect for ripening fish eggs.
This grazing is good for seagrass. A number of studies, albeit more in the manatee and sea turtle literature, have shown that grazed seagrass tends to grow faster and have more nutrition than the old long blades. So grazing contributes to healthier, more robust seagrass meadows, which in turn contribute to more robust fish populations. Fish return the favor again and again by helping to consume excess nutrients. Thus, healthy populations of pinfish are imperative if we are to save the remaining seagrass in polluted ecosystems such as Florida's Indian River Lagoon.
Pinfish play a really important role in relatively healthy ecosystems, too. In naturally nutrient-poor systems, their urine and feces provide fertilizer. Next time you're on a clear flat in a remote area such as the outer islands of The Bahamas or the Cays of Belize, look for the halos of more verdant seagrass next to rocks that have attracted fish. You'll see exactly what I mean.
Sexually mature pinfish spawn offshore from late fall through early spring in large groups called spawning aggregations. For a thorough and fascinating discussion of the dynamics of spawning aggregations of reef predators, please enjoy Dr. Will Heyman's article in Fly & Light Tackle Angler, issue 2.1.
On their way out to spawn, the schools of pinfish are hunted by a great many predators, including snappers, groupers, and amberjacks, as well as bottlenose dolphins. Red drum also spawn offshore about then, and the nutrition provided by plump, ripe pinfish could play a significant role in their reproductive success.
As Dr. Heyman demonstrates with incredible high-definition video, spawning introduces a huge amount of food into the water column. Spawning aggregations of more than 1,000 pinfish have been documented in the northern Gulf of Mexico. And the clouds of eggs can attract a host of predators, with fertilized eggs providing essential energy for larval, juvenile, and adult predators.
In the Gulf of Mexico, scientists found that at certain times of the year, especially spring and early summer, pinfish can be the numerically dominant species, especially in seagrass. This is also true on the Atlantic side, in Florida's Indian River Lagoon complex. That's because young-of-the-year juveniles are transported by currents in their planktonic phase to shallow water habitats—predominantly seagrass meadows but also mangroves, oysters, and manmade structures—through the process called "recruitment."
Think about what else is going on in estuaries this time of the year – when many larger predators are spawning and in need of the precious energy that pinfish provide.
Spotted seatrout (Cynoscion nebulosus)
Male speckled trout are drumming their hearts out around each full and new moon through summer. They attract females, which also must put incredible amounts of energy into reproduction after hunting down the calories to ripen tens of thousands of viable eggs. Click this link to hear what I mean. Though dietary preferences among piscivorous predators can change on seasonal scales and/or geographic scales as small as one water body to the next, seatrout would be hard-pressed to maintain their tremendous fecundity—the fish's stupendous ability to reproduce—without an abundance of pinfish for nutrition.
Snook (Centropomus spp.)
The common snook (Centropomus undecimalus) is another species that occurs from freshwater to relatively deep reefs. Where we live along Florida's East Coast, you can catch a snook an hour inland in Lake Okeechobee or drive to the coast and catch one in estuaries or along the beach. Weather permitting, you can also dive with large schools of adult female snook on wrecks and reefs pretty far offshore. I've seen them in caves offshore that were almost 140 feet deep. They occupy almost all of the wrecks and reefs from emergent nearshore hardbottom to structures in 80 to 90 feet.
Snook feed on pinfish wherever there is the faintest trace of salt in the water, and I don't think there's a more iconic baitfish for snook anglers. Like trout, snook begin spawning around the new and full moons in late spring and continue through the early fall. Where trout, snook and other fish-eating predators co-occur, they all compete aggressively for pinfish and other baitfish—also known as forage species—especially before and after spawning, when they are in dire need of calories.
By then, large segments of the female snook populations have moved from riverine areas out toward inlets and passes, where the spawning aggregations typically form, though they use nearshore reefs as well. Between spawning events, anglers often encounter big females on the flats just inside inlets, where you often find some of the thickest, healthiest seagrass meadows. Tragically, that is mostly no longer the case along Indian River Lagoon, with the exception of the meadows near the Fort Pierce Inlet. Environmental conditions have declined too much for grass to grow.
Many of us are worried that this massive die-off of seagrass will have cascading impacts on marine food webs. Seagrasses just inside iconic snook-fishing destinations, such as Florida's Jupiter Inlet, St. Lucie Inlet, and Sebastian Inlet, barely exist anymore. Because of the flats' proximity to inlets, these are the presumptive first flats to recruit juvenile pinfish as they move inshore in the springtime, right on time to give snook a nearby source of some or even much of the energy they will need to reproduce. And pinfish are also right on time to give year-old snook, trout, tarpon, and many other rock stars the energy boost that they need for a big growth spurt. The quicker and bigger young predators grow, the more likely they are to make it past the "bait" stage themselves.
Tarpon (Megalops atlanticus)
Get this: The sexual fecundity of a 2-meter (79-inch) tarpon is about 12 million eggs. These fish typically spawn in May, June, and July, though there's some evidence that they can spawn year-round. Juvenile tarpon begin feeding on fish larger than mosquitofish and killifish as soon as they're large enough to leave the shallow creeks and ditches that they settle in as post-larval organisms.
Because it is a large, migratory fish with a high level of reproductive capacity, a tarpon must consume an enormous amount of calories. And throughout most of the tarpon's life, along most of its migratory routes, pinfish are important forage for the silver king. Meanwhile, tarpon are competing in grass flats and other pinfish habitats with dozens of other predators, many of which are also in spawning mode. There is more urgency and feeding intensity in all these ripening animals, hence more competition. During the pre-spawn and spawning periods, their survival as a species is at stake. That's why we need healthy populations of essential forage, including pinfish.
Gag grouper (Mycteroperca microlepis)
As anglers, we have an unhelpful but natural tendency to place fish in somewhat arbitrary divisions. I cringe a little when I hear gag grouper called a reef fish or a grass grouper, as I've heard them called many times in the Tampa Bay area, which produces most of the gags in the Gulf of Mexico. In reality, the life history of this species paints a picture of one ecosystem, its parts joined and related by the migrations that these animals make throughout their lives. The gag grouper, like most of the snapper/grouper species that Will Heyman has helped to protect in Belize and Mexico, start as fertilized eggs far out on a high reef toward the edge of a continental shelf. The groupers pass some time adrift as larval organisms and then the few survivors recruit to desirable habitats, ideally seagrass, which provides cover and baby food in the form of tiny crustaceans. When they are large enough, they can tackle larger finfish, including pinfish. There's not a better bait for gag grouper than pinfish. That's because pinfish are so available to these predators everywhere that they live. These habitats include seagrass meadows, mangrove forests, reefs of various descriptions and depths, and the all-important spawning aggregation sites.
Threats to pinfish conservation
The alarming rate of seagrass die-offs poses the gravest threat to pinfish populations – as well as to pigfish and other forage species that also provide vital linkages in Florida's marine food webs.
Fishing is another threat. According to the Florida Fish and Wildlife Research Institute (FWRI), most landings of pinfish in Florida are made by the recreational fishery; in 2009, approximately 98 percent of the 3.09 million pounds of pinfish landed in Florida were landed by recreational anglers. Ninety-two percent of this total was landed on the Gulf Coast.
To my knowledge, there's never been a formal pinfish stock assessment in Florida, but the FWRI has noted that commercial landings have trended upward while recreational landings remain fairly stable and large. Many of us are concerned that we are playing with fire by harvesting pinfish so intensively as habitat productivity declines sharply in many water bodies, such as the Indian River Lagoon complex and the Caloosahatchee Watershed, including Pine Island Sound.
New commercial fisheries are at least possible. A 1978 study on the western Atlantic from the U.N. Food and Agriculture Organization suggested pinfish as a potential source of fish meal, and another study published in 1938 out of North Carolina noted that the species yielded a high grade of oil. Meanwhile, aquaculture is exploding and the harvest in the U.S. Atlantic of menhaden, the fish primarily reduced into high-grade oil, had to be reduced by 25 percent to protect the species from continued overfishing.
Obviously, we need to restore the conditions that allow seagrass to thrive. Meanwhile, we need to manage pinfish and other forage species so that we leave enough fish to graze the grass and provide enough calories for our rock star predator fishes and fish-eating birds. Merganser ducks, cormorants, and ospreys eat a lot of finfish and play important roles as apex predators by eliminating the sick and weak from the gene pool.
The humble pinfish offers us a picture of how diverse coastal habitats are joined and related. That's a good way to start thinking about ecosystem-based fisheries management.
If you want to catch pinfish, remember that you should avoid places where the populations are stressed due to problems with their habitat. Instead, look for healthy pinfish habitat and then break out the cane pole with a gold hook tipped with shrimp. Just drop a chumbag overboard on a grassflat and start picking them. If you can get them schooled up, throw the castnet and you'll quickly have enough and then some. You can buy pinfish traps costing $25 to $50 in most major sporting good outlets and in a lot of local bait and tackle shops. Be sure to release the baits that you don't use in habitats similar to where you caught them.
About the author: Terry Gibson is co-founder and senior editor of Fly & Light Tackle Angler magazine. He also serves as a recreational fishing outreach consultant for The Pew Charitable Trusts in Florida. This article was published in Fly and Light Tackle Angler.