Worm Swarm in Southeast Florida

September 02, 2011 By Florida Sportsman

Anglers and biologists decipher a spectacular snook fishing mystery.

By Brett Fitzgerald

Originally published in May 2010 print edition

There's a connection between a fabled tarpon bite in the Keys and finicky nighttime snook fishing in Lake Worth Lagoon, often centered around dock lights. That connection has to do with a worm.

Night fishing can furnish odd impressions—the water and air become thicker than during the sunlight hours. The bait dances in the lights with an almost playful attitude, even though the predatory fish smack the water with a purpose. It keeps your hairs on end, in constant anticipation of a biblical-size slaughter just under the surface. You try to be ready for anything.

Last May an ordinary night of snook fishing took a decided turn. Our boat routinely slithered across a dead-flat ICW, hoping the snook would be drawn to the same lights we were. I tried to explain the whole idea of snook fishing to my friend Will Conner, who had recently flown in from Australia.

Looking for a simple analogy, I asked, “How much experience do you have with barramundi?”

“I've had it on the barbee, quite tasty.”

Captain Danny Barrow caught the point, and reached for a spinning rod with the instinctual thought, Rube rig—circle hook with live bait. He dropped to an idle and gave Will a quick casting lesson.

I knew Will could work a rod and reel because we had successfully bass fished all morning. But fishing after the kids go to bed is best accomplished when everyone on the boat has a true understanding of each other's strengths and limits. The tutorial was completed at a brisk pace, and the first dock light looked promising. Snook were not only visible, but active.

We kept a good distance away and Will bowled a perfect strike to the glowing monster that had so many hungry mouths.

Nothing.

When I woke the next morning, I had an email from Danny. It was forwarded from his friend Bill Cresswell. It read something like this: “Danny, couldn't get the fish to take artificials last night. They were slurping these weird-looking things like crazy—sometimes right under the boat!” Bill scooped a few with his bait net and attached a photo.

Danny was right—there was a worm swarm in Palm Beach County.

As if fishing the night lights for snook wasn't exciting enough.

Will Conner and Capt. Danny Barrow with one of several of a trip's snook landed on a small jig.

To say I was interested would be like calling Niagara Falls a dribble. I forwarded that photo to every biologist I knew, and several I didn't. Rolling questions over and over in my mind, I might not have slept for a week. Could this actually be a Keys-style palolo swarm? If so, how, and why here? And for how long? … and if not, what the heck is this thing?

Slowly, pieces of the answer started to trickle in.

From Anja Schulze, biologist in Texas: “It is possible palolo were carried up in the Gulf Stream, but your photo more resembles the family nereididae.” Uh… okay.

From Ron Taylor, lead snook biologist at the Florida Fish and Wildlife Research Institute (FWRI): “Looks like you have a new bait to contend with in Palm Beach,” (along with a vague dare to fry them up and eat them).

From Jim Whittington, FWRI's east coast snook point man: “Heard reports of a similar swarm in Jupiter Inlet last year, and snook would only eat the worms!”

Eventually, the evidence supported Dr. Schulze's initial thought—these worms were not palolo. As it turns out, there is another segmented marine worm, or polychaete, that haunts Florida's waters.

The palolo worm belongs to a family of marine worms called eunicidae, which has a bizarre spawn where only the reproductive organs show up to the swarm. That is how Dr. Schulze was able to immediately state that the photo was not a palolo, as Bill's photo shows an entire worm.

Unfortunately, learning that these worms belonged to the family nereididae didn't lead to a direct understanding of what is happening in Palm Beach County, or how it relates to fishing.

There are some 400 species of marine worms in the family, and many of them look very similar. Among fishermen, the common names are used interchangeably—clam worm, rag worm, sand worm, blood worm. Even the scientific names have been affixed to a variety of different worms. For this reason, no biologist with a string of letters would definitively ID Bill's worm. For simplicity's sake, I'll use the term “clam worm” from here on out.

Even without biological specifics, plenty of vital angling information could be pieced together. First off, swarms of these worms are more common farther north in the Atlantic, and there are documented episodes of striped bass feeding on the critters with the same abandon of tarpon in the Keys. Secondly, like the palolo, the spawn is tied to annual lunar cycles. Because the timing for each subgroup of clam worm might vary a smidge, it will be a long time before anybody nails down exactly when the swarm will occur from year to year. But the good news is, these swarms can last three to five days, and it can occur in varying intensities over a two- or three-month period—possibly as early as mid-May to late July.

Since clam worms are widely distributed around the world, it's not shocking that they are found in Florida. But finding them in the Lake Worth Lagoon is somewhat curious. Geologically speaking, the lagoon is a newborn—it was a fresh water lake until the 1870s. Further, pollution and other environmental degradations ravaged most of the lagoon for the past 50-plus years. The light where Bill captured his specimen had for decades been known as “the dead zone” due to a thick layer of oxygen-robbing muck that covered much of the filthy bottom.

Over the past decade or so, Palm Beach County Environmental Resource Management (PBC ERM) and other groups have tackled the daunting task of turning the lagoon around, and Bill was fishing adjacent to the highly successful Snook Islands restoration project. I can't prove the newly improved habitat is responsible for bringing these worms in, but there might be something to that. Let's put it this way: For all the names I found for these marine worms, I didn't find any references to them being called “muck worms.” Finding specific habitat requirements for the clam worms has been almost impossible (since nobody can usually identify exactly what the worm is), but other information about the lifecycle of clam worms suggest that quality habitat is critical. They are omnivores, feeding on algae and other invertebrates. They are commonly found around healthy intertidal sand or mud flats, oyster bars or pilings—a fair amount of which can now be found locally at the aforementioned Snook Islands.

Harvey Rudolph, who conducted benthic surveys for ERM at the location of Snook Islands for years, was quick to credit the worm's presence to the environmental enhancement. “I sampled that very location for years, and there was no sign of polychaete worms, nor any indication of suitable habitat to support a colony.” He explained that his work included surveying the lagoon, recording environmental conditions and any life forms. In lay terms, he described the area as a barren wasteland. With very little oxygen in the water, especially in the deeper areas, combined with a thick layer of silty muck covering the bottom, Harvey described an environment that couldn't support many life forms. Without suitable habitats or prey choices, polychaete worms didn't have a chance. He summed his thoughts: “I have no doubt there is a direct relationship between your worms and Snook Islands.”

After all is said and done, there are probably more questions than answers. But I personally feel confident that the presence, at least in numbers noted over the past couple of years, is related to improvements in habitat. With surprising personal observations of trout and redfish, as well as increased numbers of sheepshead and other inshore fish, it is clear that the complexity of the local marine biomass is directly improved and increased when the habitat is restored.

Maybe more significant is the relationship that this points out between habitat and fisheries management. Unfortunately, fishery policies don't currently make this critical connection. The Florida Fish and Wildlife Conservation Commission (FWC) bases seasons, slots and take limits on how many fish have been pulled from the water versus spawning potential ratio numbers. But a fish population will never grow unless the habitat supports an increased biomass. The point is, healthy habitat, where diverse species can thrive, can directly impact the number of fish in the water. Therefore, habitat needs to be a consideration when managing a fishery.

With several restoration projects under construction and more being planned (check ‘em out at www.co.palm-beach.fl.us/erm/lakes/estuarine/lake-worth-lagoon), there are reasons to feel optimistic that more fishing mysteries will tantalize the anglers of South Florida in the near future.

Fishing a Swarm

Before you can fish a swarm, you have to be there when it happens. May 2, 2009 was the first day after the first quarter of the moon. I can't say whether that was the only night in May, or the event lasted a few nights. I can tell you that Bill Cresswell observed the highest worm activity right at high tide on that night. Further, he returned a month later and found a swarm (of seemingly smaller magnitude) at the same spot.

Danny Barrow also returned and found the worms near the light. The consensus was that they seemed to be attracted to the light. Occasionally they were observed to linger in the shadows, briefly darting into the bright light before zipping back into the shadows. They were also seen swimming in a straight line, moving both with and against the current.

With a limited sample to work with, it appears the best approach to fishing these would be either a small jig, with a darker reddish head and a lighter pink or red body, or even better a “clam worm fly.” There are plenty of traditional worm fly patterns on the web, but until this particular swarm is better understood it makes sense to show up with a variety of impressionistic variations, with a few different sizes, weights, and hues.

Last year, Danny had the best luck swimming a jig straight and steady, about half way down the water column, fan casting through the glow of the light. If that doesn't work, letting the jig fall and rise sharply should be the second option. If you are throwing a fly, you might weight your hook with lead wraps instead of dumbbell eyes, since these worms don't have large eyes.

It's worth noting that the devastating cold kill that occurred at the beginning of this year didn't appear to have much of an impact on the snook population in the southern half of the lagoon, so the worm swarm should draw quite a bite. Now the challenge is being there when it happens.

Palolo Worms

Periodic “hatches” of the small worms trigger an unbelievable bite for tarpon.

The palolo worm has been a tarpon angler's dream or nightmare for decades. Guides and flyrodding enthusiasts have spent years trying to decipher the exact timing of the annual swarm. In the tropical Pacific, humans have scooped the spawning critters from the shallow moonlight waters and have been eating them for centuries. The swarm triggered a celebration that might last for days.

Unfortunately, the Atlantic palolo does not follow the exact timing pattern of its Pacific cousin. The Florida Keys anglers that happen onto the right place and time are rewarded with some of the most remarkable fishing on the planet – thousands of tarpon literally getting “drunk” feasting on the worms. The palolos do their thing on days of the full and new moon during May and June, “if they feel like it,” one veteran angler offered as a disclaimer.

As mentioned earlier, it isn't the entire worm they are feeding on. During a palolo swarm, only the gonads are present. The reproductive organs, called epitokes, break off the main body of the worm, which stays in its coral home. These epitokes, guided by rudimentary eyes that allow them to follow light, are either male or female and at a designated time they all explode. Again, exactly when this happens is still a mystery. Find ten anglers who think they understand, and you will hear ten different variations.

One thing everyone will agree on is that being at a swarm is an amazing experience. For just a couple of hours, the Boca Grande fishery takes a back seat. Armed with the correct fly or lure, tarpon fanatics can hook more big tarpon in one evening than most do in a year. Then, as abruptly as it starts, it's over.

Should you luck into a palolo swarm, take note of every variable possible and when you crack the code, lock that secret somewhere safe (but call me first).