I recently got the chance to fish a worm swarming on Cape Cod. This is something I wrote about over 20 years ago in my book Saltwater Naturals. (The book is out of print, but you can find used copies on Amazon.)

In short, worm swarmings occur when sexually mature annelid worms—here we’re talking about clamworms of the genera Nereis or Platynereis—leave their burrows to mate, sometimes in very large numbers. When enough spawning worms are present in an area, striped bass will tend to feed on them selectively, so the pattern you fish has to approximate the size, shape, and action of the natural. My friend Harry Graff spends his summers on the Bass River in South Dennis and has fished these swarmings for many years. Understanding the science behind the phenomenon doesn’t hurt, but it’s no match for experience, or for keeping your finger to the pulse of the river.

Harry dropped me an email to tell me the “hatch” was on. In Harry’s experience the swarmings tend to occur in the vicinity of Memorial Day weekend. They tend to begin at twilight—about 7:30 where we were—and end at dark. The bulk of it tends to take place over three consecutive evenings.

I pulled into Harry’s driveway at about seven. The tide was still coming in as we got to the water. The Bass River is a good early-season spot, as the fish tend to arrive here before we see them on the northern side of the Cape. Nearly 30 years ago, in my mid-20s, I caught my first striped bass in this river, in the piece of water below Wilbur Park in Yarmouth. I used a soggy glass Garcia bass rod (my father’s) to fling a 3-inch Lefty’s Deceiver into a subtle current seam. As if on cue, the fish pulled. As I recall, the fish wasn’t very big—certainly no more than 16 inches. I’ve caught a lot of striped bass since then—a few over 40 inches—but I don’t think I’ve ever caught one that thrilled me more than that first one.

There were huge schools of small fish in the river, Harry said; he’d taken one as small as 7 inches. Small fish are a promising sign; the fishery isn’t what it was back in the late ‘90s—no one seems to know why.

Page Rogers’s Cinderworm

As we stepped into the water I saw my first worm. The spawning form of the worm—heteronereid or epitoke, in the scientific literature—is shorter and more stout than the non-spawning adult. This worm was about 2 inches long and maybe a quarter-inch in diameter, reddish in color. During the process of sexual maturation the rearward legs of the worm (parapodia) become modified into tiny scoop like oars–only slightly in some species, but radically in others. Swarming worms are amazingly adept swimmers. Their gyrations at the water’s surface call to mind skywriting airplanes. The flies used during the swarmings are fairly simple. Harry was using Page Rogers’s Cinderworm—a length of red velvet tubing fastened to the hook and sealed at the tail end. (Harry likes this fly, he says, because it’s very durable.) The fly I took from Harry was a 2-inch red bucktail with a body of small orange cactus chenille, well-worn from years of action. It was dressed on a carbon-plated hook about 1/0 in size.

Harry Graff’s Cinderworm

I wanted to satisfy myself that the fish were indeed being selective, so I began by tying on one of my favorite flies, a white Tabory Snake Fly, which I’ve used to catch just about everything everywhere, including false albacore and tarpon. I quickly picked up a 12-inch schoolie with it, but only one. About five minutes later Harry had landed his second fish and had missed probably a half dozen due to short strikes. That was enough to convince me. I switched flies.

I worked the worm fly with a continuous hand-over-hand retrieve at a pace appropriate to the natural—quickly, but only 2 inches at a time. It wasn’t long before my first strike—short, as were many of the strikes Harry was getting. It felt as if the fish grabbed only the tail. Also, I think a 1/0 hook is a bit large for very small fish (my smallest of the evening was about 10 inches). In all, we landed a fair number of fish, but we missed many more than we hooked.

Ten minutes after we arrived, the swarming was in full swing. Up and down the river, as far as you could see, the surface was dimpled with the swirls of feeding striped bass. Harry’s house has been in his family since the 1950s. His father had done most of his fishing with a spinning rod and a Rapala. Harry recalls evenings like this as kid when the river came alive with activity but they couldn’t buy a strike. That’s how it was the first time I experienced a swarming. I knew almost nothing then about saltwater forage, selective feeding, or anything else. I just knew the fish weren’t interested in whatever I was showing them. This evening I only actually saw that single worm, so it’s easy to see how an angler can get stumped by a swarming.

If ever you face a situation like this—the fish are eating, but not what you’re showing them—you’ll do well to look around the water’s edge to see what might be available. I’ve experienced striped bass feeding selectively on grass shrimp just under the surface. In the twilight I could see their sides flash white as they took, and their action bulged the surface not unlike the rise of a nymphing trout. Had I not shined a flashlight along the the shallows I never would have noticed the thousands of grass shrimp flitting about. Only then, after I trimmed my black Deceiver to an inch and worked it in 2-inch strips, could I catch a fish (and I was surprised at how hard they took).

The rule of thumb in selective feeding is to first match the size of the prey and then the action. (One time I took 20 or more bass out of a school busting on silversides using a 6-inch Deceiver while the surfcaster throwing a 12-inch plug from the jetty finally left in frustration.) Some will argue with me, but I don’t consider color of much importance, generally (I’ll change retrieves before I change a fly in which I have confidence). And fish don’t see color at night, so I think black is as good a color as any (my father did well with black Jitterbugs and Hula Poppers at night for largemouth bass).

When night proper fell, the river turned off, as Harry said it would.

I first met Harry through Henry Weston Outfitters in Pembroke, Massachusetts, one of the many fly shops that popped up in the area when the striped bass fishery made a comeback in the early 1990s (and after The Movie caused the fly-fishing industry to explode). This was the first time we had ever fished together. I think I’m going to have to fish with him again (I still have a bit more to show him ;)).

I left Harry’s in time to make it to KKatie’s Burger Bar in Plymouth before the kitchen closed. This isn’t a restaurant review, but after an evening of fishing on the South Shore you could do worse than to sit down to a Hell Burger and an IPA. Piscator non solum piscatur.