Millions of immigrants from Latin America began streaming north to the California coast two years ago. No one knows why they came here. No one knows the impact they will have on the state's economy and the environment. Scientists are on the case, but answers elude them. After all, these aliens do not speak our language and they currently reside miles from shore, more than 100 fathoms down, occasionally rising to the surface when overcome by a feeding frenzy.

Clearly, the giant Humboldt squid (Dosidicus gigas) is not your ordinary migrant. It's a cephalopod that grows to over a hundred pounds, eats voraciously and may possess an intelligence quotient comparable to that of many mammals. Originally named for the Humboldt Current that flows northward along the coast of Chile, the creature's presence in California has baffled local biologists, ecologists and fishermen. Now, just a decade after their discovery in our waters, they have become an expected wintertime phenomenon.

Stanford professor Dr. William Gilly has studied the Humboldt squid for about five years, but it was almost three decades ago that he first heard about the animals. In the 1980s, he traveled up and down the Baja California peninsula seeking out the squid in the Sea of Cortez, but to no avail. Finally, in 1994, he made contact near Santa Rosalia. He discovered on the beach a bustling squid-processing plant, based on a strong localized fishery that had existed for years. He observed fishermen in the middle of the night beaching their small skiffs and weighing in thousands of kilos of the hefty squid.

"There's also a big fishery off Peru and Chile," says Gilly, "and we've identified them as far as 60 degrees north. They're incredibly temperature-tolerant and oxygen-tolerant, so why they're only expanding their range now, I don't know. They've been fishing for them off South America since the 1960s, but where they started before that and where they spread from is unclear."

In spite of their large size, Humboldts live only one to two years. Their growth rate approaches one millimeter per day, a phenomenal pace. In these regards, Gilly likens a Humboldt squid to a human baby that has achieved blue-whale dimensions before its parents have even thought about signing the kid up for preschool. And so Humboldt squid are gluttonous eaters. They eat and eat and eat. They ingest krill, they chomp fish, they attack small sharks, they devour each other and they do not stop, ever.

That, of course, has left fishermen in California wondering: What impact will the squid have on our already struggling fish stocks? Gilly, one of the premier experts on the Humboldt squid, says it is too early to know. No one is even sure yet how many squid are presently out there, how long they will stay or what group of fish they will choose as their staple.

Ink Fest!

Rick Powers, a fishing boat captain in Bodega Bay, believes that the squid have selected rockfish as their dish of choice, and are currently devouring what remains of local populations. Powers' livelihood once thrived on those deepwater fish. He ran boatloads of customers out to Cordell Banks, a region of submarine terrain hundreds of feet underwater off the coast of Northern California. In several hours of fishing, his customers would fill gunny sacks full of the colorful, big-mouthed, spiny-backed rockfish, and every day Powers motored back to the dock and shepherded his clients onto solid ground again, each of them toting an 80-pound sack. Then, in 2003, the Department of Fish and Game put Cordell Banks off limits to rockfishing, and the legendary fishing trips came to a halt.

But the Humboldt squid have spawned a new and profitable fishery, and for a year now Powers has been taking customers out to his old stomping grounds. He began running his first squid trips in the winter of 2005. The results were spectacular. His boat hauled in 10,000 to 20,000 pounds of squid almost on a daily basis, according to web and newspaper fishing reports. The high and consistent scores from Powers' boat gained the captain a following of anglers who began coming from as far away as Nevada to fish under his guidance and enjoy the messy thrill of an "ink fest," a brand-new experience that might find an angler by noon covered in the black emissions of the squid and standing knee-deep in expired specimens.

This past November, as with last year and the year before, the squid showed up abruptly en masse, and Powers' expeditions started again. As a fisherman, I follow the daily reports and confess that I found the prospect of sliming myself in dead squid very appealing. My brother Andrew had also been reading the online fishing reports, dreaming of ink and slime and chaos, and in early February I called Rick Powers to reserve two spaces on his boat, the New Sea Angler.

As dawn broke over the eastern dairy-land hills of Sonoma, the 65-foot-boat steadily filled with fishermen. Each had a pocket full of cash, a heavy-duty fishing rod and images of monster squid dancing in his head. When 30 of the 35 expected fishermen had signed in, our captain called us back to the stern of the vessel to give his morning introductions.

"Welcome to the New Sea Angler," he said. "I'm Rick Powers, and this is my boat." The two young and sleepy deckhands stood sullenly by as the captain detailed the mission plan in a speech they had doubtless heard a hundred times before. "You guys are warriors," Powers said gravely. The harbor was quiet with the soft sounds of a new day, and the captain's voice produced an intense excitement about what would soon take place 20 miles from shore. "I see you laughing over there, but it's true: you are warriors, and today we're going to war. We are going to do battle with giant Humboldt squid."

Powers introduced himself as the man who discovered the Humboldt squid in local waters 10 years ago. At the time, he was donating his services as a captain toward Department of Fish and Game fish counts at Cordell Banks. While fishing for rockfish and lingcod, the biologists on board began to haul up from the depths 20- and 30-pound squid, animals that had scarcely been seen before in local waters.

In subsequent years, the squid showed up in increasing numbers, and Powers began to suspect two things: one, that the squid were eating his rockfish; and, two, that bored fishermen would pay prime cash to pursue the beasts. Powers was right about the fishermen. They zeroed in from all over the state, over freezing mountain ranges and terrible deserts, across valleys and rivers, all the way to Bodega Bay to take part in what Powers calls "the most exciting fishery you'll ever see, hands down."

I See Color

With the sun rising above the harbor, Powers described how a school of squid will follow the hooked individuals toward the surface, how the animals go nuts and begin to eat each other and attack the anglers' lures with accelerating fury.

"And there's no legal limit on these squid. That's the beauty of this fishery. And right now, they're out there devouring our rockfish, and you're actually doing them good by taking these squid."

After explaining the ecological virtues of filling the New Sea Angler with tons—literally tons—of squid, the captain added in a solemn tone that a responsible fisherman never takes more than he or she needs.

"Some people are happy once they've gotten two, others want 22, but the bottom line is, no squid gets left on my boat at the day's end, and you only take what you can utilize."

With that, Capt. Powers promptly disappeared into the wheelhouse, fired the engine and motored the happy lot of us out of the harbor to do some eco-friendly damage at Cordell Banks. The ride there from Bodega Bay would take two solid hours, and my brother and I crammed in beside each other at one of the small wooden tables in the cabin. The men around us (there was only one woman) were of varying sorts. Many were salty veterans of the Cordell Banks squid runs; others were soft-skinned doctors and real estate agents who didn't know a fishing rod from a power drill.

Two old, gray-haired fishermen from the Sacramento suburbs sat across from Andrew and me. They began to tie knots and sharpen fishhooks while discussing their favorite Central Valley hobbies. One evidently poached salmon in the Feather River in season, another shot black bears out of trees, and each used racial slurs as casually as a veterinarian calls a dog a bitch. Andrew asked them about cooking squid. The men growled that they did not care much for the stuff, and that they would be using most of their squid steaks for crab bait.

The boat's motor slowed at about 9am, and the captain began to turn in a wide circle. He must have something on the screen, the fishermen in the cabin mused. We put on our coats, went outside into the fog and began to line the rails and ready our tackle. We each tied an eight-inch-long, missile-shaped squid-jig to the line, a dangerous lure furnished with 42 sharp steel needles that point upward and serve as so many hooks. The boat meandered slowly through the mist for 10 suspenseful minutes before the engine halted and Powers' voice roared through the intercom.

"Giant squid below! Drop the lines, go all the way to the bottom!"

That meant a drop of more than 500 feet. Each fisherman flipped his reel out of gear and let the heavy lure dive for the bottom of the sea. Three minutes later my squid-jig finally hit bottom. I engaged the reel and cranked back several feet of 50-pound line when a great weight halted my efforts and bent the rod over the rail.

I gasped at the power pulling from below. Andrew, fishing beside me, suddenly hooked up as well. I glanced up the rail toward the bow and back toward the stern, and all but two or three anglers were evidently hooked into Humboldt squid. The heavy creatures came up slowly. Periodically they resisted and pulled 10, 20 or 30 feet of hard-earned line off the reel before the angler could resume the long haul up from the depths.

In other types of fishing, the exciting moment comes when the fish first strikes. The angler shouts "Fish on!" and his neighbors all bubble with excitement and lean this way and that to admire the fight. Meanwhile, the deckhand comes running with the net, and a minute later the fish is flopping on the deck. But in the pursuit of giant squid, the strike is hardly dramatic—just a sudden dull resistance—and the fight lasts 15 minutes or more and is relatively boring. In due time, however, the creature from the deep finally appears some 30 feet below the surface as a reddish brown mass, and the fisherman's cry comes as "I see color!"

This prompts the deckhand. He appears in a hurry, clad in yellow slickers with a 10-foot-long gaff in his hand. The squid grows larger in the clear water as the angler gains line. The deckhand stands by as the fisherman struggles to gain the last 10 feet. The squid approaches the surface, as alien and dangerous to it as the bottom of the sea would be to a person. The gaff goes down and meets the four-foot animal. The deckhand sinks the giant hook into the base of the head and black ink jets 12 feet into the air, splattering the boat and several occupants.

The 20-pound squid comes over the rail and hits the deck with a dull plop as another shout for the gaff comes from the other side of the boat. Then comes another cry from the stern, another from the bow, then a chorus of cries from all around the rail, and just like that the poor deckhands enter a four-hour squid-gaffing marathon: "I see color!"

A fishing session at Cordell Banks lasts generally from 9am until about 2pm. By 1 o'clock, my brother and I had nearly 200 pounds of Humboldt squid. My arms and back ached with the strain of reeling them to the surface. The animals lay strewn over the deck less than ankle-deep—a relatively slow day so far. Yet my bothersome conscience loaded my shoulders with guilt as I contemplated the killing. I generally approve of dispatching an animal if one intends to eat it, but I wasn't sure that I wanted so much squid.

I recalled an occasion in Baja California when I found a large Humboldt dying on a remote beach north of Mulege. I chased away the gulls that had liberated the three-foot long squid of its eyeballs, and I proceeded to kill and butcher it with my knife. I went away with a two-pound hunk and cooked it over a fire. I ate most of the meat, then vomited in the bushes and experienced stomach difficulties for two days.

"Andrew," I said in a mild state of epiphany, "we're going to have to eat all this stuff."

I set my rod down for a moment to make an exact count and an estimation of the slimy biomass we would soon be cramming into my brother's car. A deckhand saw my idleness and hurried over to ask why I was not attempting to catch another squid.

"I'm done. We can't take any more," I said. "We're driving a Honda Civic."

"Drop your line," he commanded. And then to the whole starboard side of the boat: "Drop your lines back down, everybody!" And then came Powers' voice on the intercom: "Keep fishing! Don't lose 'em! Keep the squid at the surface! Get your lines in the water! You're fishing like a bunch of grandmas!"

Under the watchful eyes of deckhand and skipper, I reluctantly dropped my squid-jig again. Powers announced that the school was holding at about 250 feet, so I dropped only 70 feet before engaging the reel again and hanging my lure in barren waters. I figured I would be safe there, but lo and behold, Powers' excited voice roared through the intercom again.

"The squid are coming up! I see 'em at 225 feet, and they're rising. Two hundred! Oh, 180! There's 90! Squid at 90 feet!" I began to reel up frantically lest I wind up hooked into another 20-pound piece of meat. "Sixty feet!" Powers shouted. "They're right under the boat. They're charging the boat! Man your battle stations, put your helmets on! Let's get some squiiiiiiiiid!"

I could not keep my lure from the rising school, and at about 40 feet, my rod bent over and pulled me against the rail. My brother, too, reeled his lure up as fast as he could. His white squid-jig came into sight below. A big Humboldt followed in hot pursuit, however, and then another appeared. Each scooted forward with eager tentacles reaching for the tempting little trinket. "No, no, no!" cried Andrew as he cranked away, but 10 feet from the surface the foremost squid slipped its tentacles around the jig—and its fate was sealed.

The deckhand saw us each hooked up again and said, "Nice, nice!" Andrew's squid remained just under the boat. We watched it struggle 20 feet down. As it tired, one of its own mates sensed a disadvantage. It charged, tackled and took a bite from the doomed squid's meaty mantle.

Meanwhile, every other fisherman was engaged in a battle of his own. Bright red squid splashed at the surface all along our side of the vessel. They waved their alien tentacles in the air and spewed ink in large arcs that rained down on the fishermen as they shouted for the gaff. The deck of the boat grew thicker with dead squid, and through the intercom, Powers told his customers to use caution as they moved about the slimy deck—and to keep on fishing.

This killing frenzy reminded me of the old days of whaling and passenger pigeons and bison. It reminded me of men who killed for fun, killed for days, killed for blood, killed by the thousands. What was the point of all this? Would all these animals really be eaten?

I was tired of the ink fest, and I was not alone. Several fishermen had already sneaked away to the cabin, yet the deckhands remained busy. They raced around the boat. Sweat beaded on their foreheads and ran down their cheeks in black streams as they hauled more and more squid onto the New Sea Angler. "Don't let 'em get away!" ordered Powers from the comfort of the wheelhouse. The animals swarmed beneath the vessel. We watched them attack lures and cannibalize each other. "I see color!" anglers cried, and the frenzy went on for another hour.

Beyond Sunlight

On the ride back to port, Andrew and I again claimed a table. With inky hands, we each opened a beer and drank to the day. We estimated that we and our fellow fishermen on the New Sea Angler landed about 10 squid each—a total catch of 350 to 400. Yet Captain Powers would later report on www.usafishing.com a precise catch of 625 squid, the largest weighing exactly 46 pounds. Yet no squid count or weigh-in ever took place. But what the hell. Powers knows that these tremendous numbers attract customers who will almost certainly go home at the day's end with all the squid they can manage. Nobody counts his catch, another inflated report goes on the web, more hungry fishermen reserve spots on the New Sea Angler, and the cycle goes on.

The prevailing aspect of the squid fishery is its grotesqueness: the ink, the slime, the squid writhing on the gaff, the sheer mass of dead creatures, and the fact that fishermen happily pay 80 bucks apiece to produce such pulpy carnage. They say that squid harbor first-rate intelligence within their squishy heads. It bothers me to think that they knew what we were doing to them, that they comprehended their fate as they came over the rail spewing the last of their ink and fluttering their fins.

Dr. Gilly feels for the animals, too. "I'll admit that it gets pretty sad to see them hacked up and thrown all around a fishing boat," he says.

But Gilly himself fishes for Humboldt squid now and then. He even eats his subjects on occasion and reports that squid from colder waters taste better than varietals in the lower latitudes. Primarily, though, Gilly catches, tags and releases squid. Commercial and recreational fishermen recover some of these tags while other tags correspond with satellite signals, and Gilly has documented Dosidicus gigas traveling 100 miles in as little as three days.

His tagging studies have also enabled him to make educated guesses at the number of Humboldts swarming in the Pacific. For example, in a region of just several square miles in the central Sea of Cortez, Gilly estimates that there live over 4 million Humboldt squid.

But where was the stronghold of Dosidicus gigas before the great migration began? While the squid have been a routine presence in the Sea of Cortez for as long as most living people can remember, Gilly believes that they came from elsewhere still. He cites the 1940 sea voyage of John Steinbeck and Ed Ricketts. The pair traveled with a small crew from Monterey south around Cabo San Lucas and northward far into the Sea of Cortez. Their voyage was exploratory, and the men made observations of sea creatures in both tide pools and offshore waters. In 2004, Gilly and several biologists replicated the journey. They compared notes to the journals of Steinbeck to see what changes had occurred in the Cortez over the decades. They visited the same places on a similar boat.

"We went everywhere they did," says Gilly. "We saw squid every night, but Steinbeck never reported squid. Maybe 1940 was an anomaly, but no evidence suggests that it was an El Niño year."

Gilly suspects that sometime since 1940 Dosidicus gigas invaded the Cortez. Does that make the species today non-native to Mexican waters? And what about Northern California, where it has thrived for less than a decade? Is it an invader? Does it belong here? Rick Powers wavers on the issue, enjoying a highly successful new squid-fishing business while simultaneously condemning them as destructive intruders.

But Gilly gives the matter more thought. "Dosidicus is an incredibly devastating predator," he says, "but they're also prey for lots of bigger predators. They're destructive on one side and incredibly beneficial on the other side. People should understand that these things in ecology aren't always good or bad. They're a double-edged sword."

I agree with Gilly. The world changes. Species come, others go. Remember the dinosaurs? Mammals took over the world. The woolly mammoths? We killed them all. All those strange birds endemic to Hawaii? Replaced last century by mongooses and exotic snakes. It's sad in some respects, very interesting in others. The Humboldt squid expansion may bring disaster to fish populations, but we are currently observing an unexplained phenomenon in the eastern Pacific Ocean's ecosystem.

Well, sort of. The squid dwell beyond sunlight and beyond the eyes of science. The details of their private lives and habits remain largely unknown, and these fascinating mysteries will likely persist for some time. As 20-pound slabs of meat, Humboldt squid are quite easily hauled up from the depths—it just takes a little muscle—but as reliable pieces of informative data, Humboldt squid remain in the dark. About all we can say for certain is that along the West Coast of the New World, at 100 to 400 fathoms, Dosidicus gigas swarms.

Meanwhile, hapless rockfish perish over the deep reefs, Dr. Gilly speculates at Stanford University and out at Cordell Banks, on the deck of the New Sea Angler, the cry for the gaff comes again and again: "I see color!"

Send a letter to the editor about this story.