Photo by Joe Klein

Florida-strain largemouth bass. "We cut this fin off. It doesn't really affect the mobility of the fish."

The gate below the dam at San Vicente Reservoir in Lakeside is closed when I arrive just before 10:00 o'clock on a late-April morning. The lake is closed to recreational fishing today. But I'm here to see fishing of a different kind, involving neither bait nor hook but electricity.

San Diego City lakes biologist Larry Bottroff (at stern) and assistant Matt Dupra. "When the water is colder, it increases the range a little bit, and the shock seems to last longer."

Photo by Joe Klein

To the right of the gate, tucked under a grove of trees, stand the offices of San Diego City Lakes, a division of the city's water department. Offices may be too strong a word for the collection of temporary trailer buildings where I meet Jim Brown, (then) San Diego City Lakes program director. "Why don't you follow me up to the lake," says Brown, a stocky man in his 50s, dressed in blue jeans and a blue-and-white pullover emblazoned with the City Lakes logo. He hops in one of the white pickups parked outside the offices.

The narrow road to the lake climbs and winds up a steep hill to the west of the dam and terminates in an empty football-field-sized parking lot. On the east end of the lot, side-by-side boat-launch ramps slant down into a cove at the southwest corner of the lake. Next to a ramp, a floating dock stretches 100 yards out into the cove. The area is deserted except for a couple of black coots roosting on a nest of tangled reeds next to the dock, and a pair of white geese on the shore honking at Jim and me. Far out on the surface of the lake, just starting to ripple with a late- morning breeze, a strange- looking boat moves toward the ramp where we're standing. "There's Larry in the shock boat," Brown says.

Larry Bottroff is a fisheries biologist for the City of San Diego; he works for City Lakes monitoring the breeding-fish populations. His chief tool on that job is the boat that putters into the cove, powered by an outboard motor, and scrapes to a halt on the ramp in front of us. Bottroff, tall and lean with gray-blond hair flowing from beneath his cap and the tanned face of someone who spends his days outdoors, welcomes us aboard.

The shock boat is a flat-bottomed, rectangular aluminum craft reminiscent of the fan boats used in swamps and bayous, minus the fan. It's 18 to 20 feet long and 5 feet wide. The only seat in the boat is on a raised platform at the rear, behind a steering console. In the middle of the boat, a couple dozen Florida largemouth bass swim in a type of open tank -- about three feet by one foot -- known as a livewell. Another raised platform, surrounded by a metal railing, occupies the front third of the boat. From each of the front corners of the boat a six-foot boom extends out over the water at a 45-degree angle to the center line of the boat. From the end of each boom, six cables hang down toward the water like the tentacles of a jellyfish. And they have a similar purpose -- they are used to shock fish into temporary paralysis. But right now, the chains suspending the booms are pulled up so that the cables are not touching the water.

It's on this forward platform that Matt Dupras, Bottroff's assistant, stands as Bottroff steers the boat out toward the middle of the lake. Once we're in the deep water -- over 150 feet deep -- a couple hundred yards behind the dam, he cuts the engine and leaves the boat to drift. Grabbing a clipboard from the top of the steering console, he moves forward to the livewell tank in the center. The clipboard he hands to Dupras; from a compartment on the side wall of the boat, he pulls a lacquered board with a ruler built into it and sets it across the top of the tank. On the board he lays a rusted pair of wire clippers and a hole punch, then reaches into the tank and pulls out a bass. The fish is green and black on the top and white on the belly. He lays it on the board and calls a measurement -- in millimeters -- to Dupras, who takes it down on the clipboard, "347." Then, holding the fish in his left hand, Bottroff turns it bottom side up and, with the wire clippers, severs the right of two pelvic fins on the bottom of the fish about halfway between tip and tail. "What we do is" -- he holds the fish toward me -- "we cut this fin off. It doesn't really affect the mobility of the fish. And, if you cut it at the origin, it never grows back. This distinguishes that it has been marked and this" -- he punches a hole near the leading edge of the dorsal fin -- "determines the year it was marked. The hole will grow back, but when it does, it will form scar tissue and have a big knot on it. And you can always identify it later on. So we know by the position of the hole what year the fish was marked."

He measures, clips, and tosses a few more fish back into the lake until he holds one up for me to see, gesturing toward the stub of a pelvic fin with the clippers. "See, this fish is from a previous year," he explains while looking for the hole-punch scar in the dorsal fin, "actually last year." He points to a lump of opaque scar tissue on its dorsal fin. "That's what the hole looks like when it heals."

A few fish more and Bottroff pulls up the biggest one so far: "471," he calls to Dupras. It looks like an elongated football. I wonder how much it weighs. "We don't weigh them," he explains, "because we get so many weights [from the fishermen] during the course of the fishing season. But this is probably a four-, four-and-a-half-pound fish."

"Matt's dad," Brown remarks, "caught one of the only three bass over 20 pounds ever caught in San Diego County. That was at Lake Hodges back in the late '70s."

I wonder what a 20-pounder would look like on the measuring board. "It would be about here," says Bottroff, putting his hand near the one-meter mark on the measuring board.

When the last fish is back in the lake, Bottroff returns to the steering wheel. In the quarter hour it took to measure, clip, and release all of the fish, the cool spring wind whipping up over the dam has pushed us northeast up the lake. Bottroff now drives the boat in the same direction for about 20 minutes until we reach a small, shallow cove on the north shore of the lake. Bottroff cuts the outboard and starts a tiny electric outboard to the right of it. Dupras adjusts the boom chains so that the cables hang down into the water. Then he picks up a fishnet mounted on a 12-foot pole. Larry starts a generator that is hidden from view in a cabinet under his seat. "When Matt steps on that pedal on the floor up there," Larry explains, "that will start the current. A beeper will sound when the current is on. When you hear it, don't touch the water. It won't kill you, but you won't like it, either."

With that, Matt steps on the pedal, and while the annoying high-pitched beeper sounds, down in the water around the front of the boat, the white bellies of overturned, paralyzed bass start to appear. Matt lets his foot off the pedal, scoops one up, and reaching the net back, deposits the bass in the livewell. There they float, slowly coming back to consciousness. He repeats this process, sometimes scooping two or three at a time. As Larry guides the boat into the tight nooks and shallows of the cove, Matt hits the pedal again, and a new crop of bass freeze and flip, their white undersides shining in the sunlight.

How close do the fish have to be to the boat?

"It depends on a few factors," Bottroff answers. "When the water is colder, it increases the range a little bit, and the shock seems to last longer. Their size is another factor. The larger fish are more susceptible to the shock because they have larger mass to absorb the electricity. It also depends upon the speed at which they're traveling. The faster they're swimming, particularly if they're swimming away from the boat, the less effect it has on them. Generally, they'll revive within five minutes."

When no more white bellies can be seen in this cove, Larry steers the boat along the shore into the far northeastern corner of the lake, where Barona Creek, which has wound its way through the nearby reservation, spills into the lake. In this area the shocking not only nets largemouth bass, but red-eared sunfish — a round, flat fish so named because of a red spot just behind the eye. Along with the bass, channel and blue catfish, crappie, and seasonally stocked trout, the "red ears," as Bottroff calls them, are one of the game fish anglers hope to hook in San Vicente. They were introduced into the lake five years ago. The Florida largemouth bass were introduced in San Diego city lakes in 1960 and, despite heavy fishing, were last stocked in 1972. "They've done very well here," Brown boasts, "better than in their native Florida."

After working this far corner of the lake for 20 minutes or so, the livewell is packed full of fish, many of whom are fully revived. Now and again, one of them wiggles and sets off a chain reaction of flailing and jumping. Sometimes, a panicked bass clears the top of the tank and lands flopping on the deck. Again, Bottroff steers the boat out into the middle of the lake, where he begins to measure, clip, and release them.

San Diego is the only municipality in the country that owns a shock boat. Brown explains why the city made the unusual investment. "It allows us to capture a sample, mark it, and return it to the lakes. Then, over the [fishing] season, Larry looks for those fish when anglers come in and keeps track of the marked fish he sees compared to those not marked. And from that he can project very accurate population data."

Before we pull back up to the dock around 3:00 in the afternoon, Bottroff and Matt fill and empty the tank three more times. In all they've caught 200 fish today.