6 posts tagged “trawling”
It's the fantasy of many a marine biologist and explorer. To catch a glimpse of the giant squid, alive, and in its natural habitat: The deep ocean. Giant squid have been scientifically documented at a size of up to an incredible 43 feet long based on specimens that have washed ashore. I've seen one such specimen at the Los Angeles County Museum of Natural History. Laying there pickled and motionless in its sterile white display case, it was hard to imagine this animal rocketing about the dark depths, living up to its reputation as a formidable predator. During one of his talks when I first met oceanographer Bob Ballard, he compared trying to find the giant squid from a submersible to trying to find an F-15 jet racing by, on a mountain top, at night, in a driving rainstorm, with a flashlight. Yesterday I had second thoughts about looking for the giant squid when one of its cousins, less than 2% of its size, disabled my sub and aborted my dive as I was descending through 1,300 feet.
In all the years I've been scuba diving, I've never been attacked by a sea creature. This, of course, excludes two unnerving but harmless remoras that simultaneously hitched a ride on my legs, or countless tiny dusky damsel fish that bit at my chest to defend their territory they felt I was invading, or stinging hydroids I accidentally brushed against. Never have I (knowingly) been mistaken for food while exploring the depths -- until now. On almost all of our sub dives here in the Bering Sea, starting at close to 1,000 feet, we've encountered the "squid layer," concentrations of 6-12" squid, Loligo opalescens, which go by the official common name of "Opalescent inshore squid" but are more commonly known on the west coast as "California market squid." My encounters with these mollusks have given me new respect for what I have come to recognize as sleek and skilled predatory missiles whose prey don't stand a chance.
Squid are truly jet-propelled. They swim faster than any other invertebrate by rapidly shooting water out of their mantle cavity into a jet stream nozzle they can steer, like a jet boat. Some squid have been clocked up to nearly 15 miles per hour. Underwater, that's practically light speed. Our subs clock in at about 3 miles per hour. Their blinding speed, coupled with their armament of two powerful tentacles (in addition to their 8 legs), barbed suckers and razor sharp beak, give them quite an edge over their prey, which include small fish, crustaceans, and mollusks, among others. Many of the squid's prey, like lanternfish, are bioluminescent, creating their own flashes of light. Squid are highly tuned to these bright flashes and are powerfully drawn to any source of light…like the lights of a descending submarine.
A massive triangle of light in the middle of the Sea of Japan is so brilliant it's visible from space. The source of light was a mystery until someone realized that the fleets of industrial fishing boats that pursue squid know well about the squid's lust for light. This triangle marks the position of the Japanese squid fishing fleet. Each vessel may have up to 50 lamps of up to 3,500 watts. The entire fleet may be using 200 megawatts to power these lights. That's nearly 20 percent of the generating capacity of Unit #3 of Southern California's San Onofre Nuclear Generating Station, enough electricity for nearly 250,000 homes.
Squid are commercially fished around the world, including in the United States. And squid are also taken from the sea as bycatch, the unintentional catch of one species when fishing for another. This has been a serous problem here in the Bering Sea when fishing boats seeking Alaskan pollock were hauling up far more squid than pollock, necessitating fishing restrictions. The seemingly limitless bounty of squid, as with so many other animals in the sea, has turned out not to be so limitless after all. They are a critical part of the ecosystem, voracious predators themselves, and, in turn, serving as prey for all sorts of fish, porpoises, whales and seals. The fur seals we saw on St. Paul Island are just one of the species that depend on squid.
As I descended into Zhemchug Canyon yesterday past 1,300 feet yesterday, I reported to Mike at the navigation station on Esperanza that I had entered the "squid layer." My external lights were on, as were Michelle's in the other sub about 100 feet below me, so that we could maintain visual contact during the dive, a safety precaution at these depths. But to a squid, my lights meant a meal, and they pursued me with intent to consume. Ink was everywhere, they clung to the lights with their tentacles and attacked with their beaks. They torpedoed in all directions around me, leaving black clouds of ink hanging in their paths. So much ink accumulated it appeared that my lights were smoking. On the front of the sub was tied a mesh bag of styrofoam cups. Under pressure, the air in the styrofoam cups compresses, and the cups shrink to a fraction of their original size. The crew had creatively decorated the cups with clever slogans and artwork…a great souvenir. I noticed the squid were especially attracted to the white, reflective cups and grabbed onto the mesh bag, trying to reach the goodies inside.
I noticed something else -- squid parts. Some of the squid ended up as calamari, having taken the unfortunate route to my lights through the sub's thrusters. Suddenly, the thrusters sounded different, more faint. The sub was no longer descending and it began to spin. One of my vertical thrusters was offline. I tried powering the thruster circuit off and on again, reversing direction like you would on an outboard motor to clear debris, but to no avail. The sub did what it was supposed to do…it sacrificed a two dollar fuse to save a $15,000 thruster. I would not make it to the bottom, just another 400 feet below me. The topside team wisely instructed me to terminate my dive and prepare for recovery.
As I slowly made the ascent back to Esperanza, I realized my image of squid had changed forever. How different was my image of these agile, powerful animals from the my first sight of squid, compressed into a frozen block inside a cardboard box my father had pulled from the general store's freezer in Cape May Point, New Jersey as we were heading off to cast our rods into the Delaware Bay. That image of the giant squid laying at the Los Angeles County Museum suddenly had life and gave me pause about the wisdom of maintaining the fantasy of pursuing such a formidable creature in the dark depths. But a moment later, I came to my senses. I'll still take my chances for a fleeting glimpse of that magnificent animal. Later that day, I smiled when I read what one of the crew had written on one of the styrofoam cups: "No pressure, no diamond."
They look strange, out of place…and they are. Because they're not from around here. The odd-shaped stones and boulders that pepper the flat, dark, silty bottom here at nearly 1,800 feet look like meteorites, each surrounded by a wide, shallow crater. They're not from outer space, but many have traveled a vast distance on Earth -- hundreds, perhaps thousands of miles, over millennia. And now my sub is face to face with one of three I'd encounter on our first dive in Zhemchug Canyon yesterday (Saturday) afternoon.
They're called "drop stones" and it's icebergs that do the dropping. As glaciers move across the land, rocks become incorporated into the glacial ice. Once the glaciers find the coast, they "calve" into ice bergs and travel vast distances floating upon the ocean, melting along the way and eventually, releasing their rocky payload.
One might think of a rock, even a hefty one, falling to the bottom of the vast Bering Sea as one of the more inconsequential events in the universe. But if you're tiny, living in a world that's flat and unprotected from the swift Arctic current ripping by, even a tiny pebble can mean the difference between survival or not. Corals, like the sublimely pink Swiftia pacifica we came across yesterday, appear to be growing right out of the brown silt. But a closer look reveals a small rock or pebble beneath the surface providing a holdfast against the current. If you're a tiny critter like a shrimp, your only option is to get down into a hole, if you can find one. But holes don't last forever -- the current will eventually sweep them away. You can also try to get yourself up against the downstream side of an object -- like a rock -- so you're not swept away with the current. Other than that, there aren't many options across the flat, nearly rockless landscape of the bottom of this neighborhood in Zhemchug Canyon.
So if one day a huge rock comes a-plummeting out of the sky, it's like a deluxe condominium suddenly appearing, and the shrimp don't waste a moment moving in. They covered the lee side of the drop stones I encountered, wall-to-wall. The penthouse was reserved for critters like basket stars, corals, anemones, sponges or hydroids that could attach themselves firmly, then grab prey as they float by in the current. Fish like rocks, too, especially, well…rockfish. The brightly orange-colored shortraker rockfish lay against one of the drop stones. A prehistoric-looking Giant grenadier, perhaps 4.5 feet long, with its long, eel-like tail gently waving in the current, nestled by another. And I encountered the aptly-named bigmouth sculpin by the third.
During my last dive at Pribilof Canyon, I noted flatfish depressions and the fact that they were full of shrimp. Same here at Zhemchug. I was even treated to a flatfish hole digging demonstration by a small halibut that I "encountered" (translation: terrified). He was quite upset at being awakened by a noisy metal object with bright lights pointed at his face, so he swam a few body lengths, then flapped his flat body furiously and kicked silt up onto the top of his flatness until he was (or at least thought he was) invisible. That process, repeated millions of times, means sanctuary for a critical part of the food chain, including the many shrimp I spied enjoying their stay in a flatfish hole. Not only does the hole allow them to relax and not have to fight the current, but NOAA scientist Bob Stone points out that little eddies forming as the current runs by cause food particles to drop out of the water column. So if you're a shrimp, you can kick back, not lift a claw, and let the food come to you. The current scours shallow craters around the drop stones, so shrimp living there not only get regular food deliveries, but also a high-rise view. I suppose that's the Bering Sea definition of the good life.
It's quite remarkable in nature how little things matter, like where a rock falls or where a flatfish rests. And there are big things in this world that threaten those little things, like taking too many fish from the sea, and global warming, which is already believed to be changing the patterns of the ice pack in this region, along with distant glaciers, and the would-be drop stones they encounter. It's important for us to think about what it takes -- even the seemingly little things -- to make an ecosystem work, especially one as wondrous and important as this one. Because if a rock falls in the Bering Sea, and no one is there to hear it, it's still someone's condo.
Yesterday (Thursday) morning, Michelle Ridgway and I descended in the twin subs for our expedition's penultimate dive on Pribilof Canyon. Michelle's lights shone as tiny pinpoints in the distant green as the light from above slowly vanished and the cold darkness of Pribilof Canyon enveloped us. I had a rare moment amid the descent's harried series of checks and radio transmissions to reflect on where I was, and Michelle's lights reminded me of how tiny we were, trying to comprehend an enormous, complex tapestry in the darkness armed with only a pen light. But on this dive, some of those complexities began to tell a story.
The welcoming committee of squid was there to greet us en masse, larger squid this time, more abundant, and more aggressive. They rocketed through the water faster than anything I've seen, passing millimeters from the front of the light, causing a startling bright flash against their light bodies, before deploying a cloud of brownish ink, spreading their tentacles to reveal a hungry beak, convinced that the light that had drawn them to the sub meant food was near. Some latched on a appeared to try to take a bite. Others gave a menacing dance, another blast of ink, and rocketed into the darkness. Still others appeared in pieces, casualties of my thrusters. It was squid madness, and it was fascinating, even comical to watch. But it also was a vivid reminder of the predatory prowess of these animals -- a small fish wouldn't stand a chance, but at least the end would come in the blink of an eye.
The bottom arrived at 1,052 feet and I landed on what appeared to be some sort of geologic stratification -- unusual layers and grooves of sediment in parallel lines across my path. I then realized I was looking at a trawl "scar," the deep ridges in the bottom made by the wheels of a trawl net dragged across the bottom. A wide swath of bottom appeared as if it had been plowed like a cornfield, overturned sediment neatly piled along the long groove. I remembered that Michelle had told me some of the trawls used in these parts are as wide as a Boeing 737's wingspan.
We began our transect, but shortly thereafter I was told to hold position -- apparently the squid had won the last round against Michelle, causing one of her thrusters to blow a fuse. She surfaced for an early recovery while I continued the dive alone. I was excited to see a number of corals. The bottom was covered with tiny (an inch or two) white sea whips (Halipteris willemoesi), one of the corals we had seen elsewhere in Pribilof Canyon. But the sea whips we had seen elsewhere were much larger, 3 or 4 feet long. I only spied two or three that big in this location.
I moved along in the darkness, saw many snow crabs and flat fish, including the beautiful rex sole and equally dramatic sharp nose skate. I then spied a strange white ridge along the black horizon. As I approached I saw this ridge lay directly in my path, straight as an arrow. A geology professor of mine once gave our class a clue at identifying features in aerial photos by pointing out that straight lines are rare in nature. Sure enough, this was another trawl scar, larger than the first. I radioed to Sasha at the navigation station on the ship and asked that he note this location on his tracking computer. I continued and found many more linear features along my path, more trawling marks, no doubt, perhaps older ones.
As I continued ahead, some of the pieces I had been seeing in the tapestry during the week started to merge and suggest a pattern. Most of the tiny sea whips I had seen were roughly the same size, suggesting that they're roughly the same age and most likely regrowth after a major disturbance, such as one that might be caused by dragging a massive object over the bottom...like a trawl. It's gratifying to see an ecosystem demonstrating resiliency -- little sea whips pushing up and trying to make a go of it. But knowing how important corals are to the health of marine ecosystems, it's troubling to see such widespread impacts.
Continuing the transect, I enjoyed seeing the sole, halibut, skates and other flat fish. I've always been fond of these strange looking creatures and never appreciated the role they played in the tapestry until this dive. Shallow flat-fish-sized depressions cratered the soft bottom. But as I passed over these "flat fish holes," the lights from the sub reflected off of hundreds of tiny eye balls looking back at me. These little depressions were teeming with little shrimp and other critters -- colorful micro ecosystems moving in where a flat fish moved out.
This was an area of high current -- maneuvering the sub was difficult -- and I saw that these depressions offered the shrimp refuge out of the current on a silty bottom that was virtually devoid of rocks or other relief. I realized my flat fish friends were ecosystem engineers. The simple act of burying themselves in the silt and leaving a depression behind meant habitat for countless other creatures. NOAA scientist Bob Stone, aboard Esperanza for this expedition, smiled when I later mentioned this to him -- he's published a paper on the topic. I've seen a similar pattern in the Gulf of Mexico, where grouper dig enormous swimming pool-sized holes in the soft bottom sediment, exposing hard substrate for corals and sponges to grow and attracting many fish and invertebrates. So it's troubling to me when we think of fish essentially as crops that we can simply harvest from the sea. Such a perspective ignores the critical point that fish themselves are part of the ecosystem and have important, often critical roles, in maintaining the health of the ecosystem. Removing fish from the ecosystem changes the ecosystem.
The call from Sasha came too soon, as it always does, "DeepWorker 6, at this time prepare the cabin for recovery." As I ascended through the darkness, alone this time, I turned my lights off to gaze upon Pribilof Canyon in its true state and pondered how much of our planet's life lives in complete darkness. My tiny sub had illuminated but a few new corners of this vast place. There lies so much more to see and discover, but with each tantalizing glimpse come new insights and a little more of the story the tapestry tells.
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Earlier in this blog I've confessed my darkest secret as a marine scientist: I get seasick. So my biggest fear of the Bering Sea is what the Bering Sea is fond of doing often -- getting rough with the boats that dare to ply its waters. Yesterday, things got a bit rough for the Esperanza. A major front pushed through and seas kicked up from nearly flat to a confused sea state -- wind-driven waves 4-5 feet heading one direction, a much larger swell, Penny the boatswain noting swells up to 12 feet, heading at a 45 degree angle. The result made for a rough ride. Awakened at 4am, I dashed up to my hideout, the video editing room, to make sure that our precious data stored inside several hard drives, were secured. I added some bungee to keep things from sliding. I tried to return to sleep, but it was fitful.
At breakfast, I ate light and looked forward to a productive day of catch up on this blog, web site, data analysis, etc. since dives of any kind were out of the question. Esperanza headed in to St. George Island to pick up Andy Malavansky, head of the St. George Ecological Office, along with fur seal ecologist, Steve Insley. I felt remarkably well given the rockin' and rollin', but as the day wore on, I felt more and more exhausted, as did my peers. The constant movement of the ship makes simple tasks much more difficult. For me, working on the computer was especially tough, here in my windowless station, and trying to drop files into the right folder with the mouse became an exercise in eye-hand coordination like playing a video game. Ultimately it took its toll, and I started to feel a bit green. I then had a choice: Take a pill and endure the side-effect of sleepiness, or do nothing and probably lose my lunch.
I had added a new medication to my arsenal of Dramamine and Bonine: Stugeron, recommended by many aboard Esperanza. The directions said to take two initially then one every 8 hours. I took one pill. Initially, I felt great and got back to work. A bit later, I couldn't keep my eyes open. Nap number one. I awoke for a few hours, stumbled around a bit, then took nap number two. I was so out of it that Timo had to awaken me when I was 30 minutes late to dinner.
After dinner we gave a brief presentation to the crew of our findings so far -- eyes were riveted on the monitor. Ken Lowyck, Greenpeace Action Unit Coordinator in Toronto and I showed a number of clips from our tandem dive to 1,071 feet the previous day where we landed in a beautiful, rich coral habitat. Afterwards I stumbled back into my cabin, and for the first time on the expedition, was in my bunk before my bunkmate, Ruud, who has the 4am-8pm shift. When I awoke for pre-dive this morning, so much sleep made me euphoric, especially with much calmer seas to greet me.
Still photographer Todd Warshaw and I donned our drysuits, along with Dive Master (and fellow sub pilot) Ken Lowyck to capture the deepworker launch from in the water -- I'd be shooting HD video. The dive went reasonably well, though my weight belt was somewhat uncooperative, so I left it behind and filmed from the surface. I remembered all my zippers and my dive was comfortable, warm and dry!
As I write this, John and Michelle at about 1,000 feet -- I hear the echo of the sonar tracking system from the bridge deck above. I heard John's voice over the in-water comms indicate he's made some good collections. And I'm back in my little video editing hole, feeling good, alert, and hungry. But, more bad weather expected on Friday. Not sure if I'll choose the little white pill again this time...
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When I used to teach marine science at Seacamp, a wonderful marine science camp in the Florida Keys, I always tried to impress upon my students (especially the ones reluctant to get into the water) that I always saw something new every time I went diving or snorkeling. This axiom has held true my entire life, but with a submarine and the deep waters it reaches, it seems that I see something new every 5 minutes.
On Saturday, thanks to my uncharacteristic good luck in a random drawing with my fellow pilots, my name came out of the coffee mug first, meaning I had the honor of piloting the first dive of the expedition. I later found out from my peers that this also meant being the first human being to descend in a sub into Pribilof Canyon.
I was surprised to still see light above as I descended past 600 feet…a beautiful disc of deep aqua floating high above the dark blue. Shortly thereafter, it was completely dark, my HMI lights providing the sole illumination for the journey. I anticipated bottom at 1,150 feet, but as I descended past 900 feet, I suddenly saw what appeared to be a thick cloud of brown sediment at eye level. Thinking I was kicking up sediment from the approaching bottom, I quickly slowed my descent, but the bottom didn't come. I then realized I was not seeing bottom sediment at all. Hundreds of pencil-sized squid were inking me! Attracted by the light, these squid would rocket toward the lights, pause for a moment, appear to freak out, then squirt their ink and dash away into the black. The ink appears reddish brown under the bright lights.
I touched down at 1,003 feet, excited to be glimpsing a tiny portion of this huge underwater canyon. I encountered numerous cod, perch, along with small sole, halibut and skates as I proceeded with my transect. As a scientist who has spent most of his years in the subtropics and tropics of the Gulf of Mexico and Caribbean, my worst enemy was the microphone hanging below my mouth, into which I
was supposed to utter brilliant annotation to go with the video we were shooting. I knew some local species, but many others were a mystery to me, so I resorted to comedy. The beautiful and enormous anenome Liponema brevicornis appears on my recording as the Hostess Snowball. NOAA scientist Bob Stone was forgiving. He encouraged such names as long as we were consistent. And so I was. Like with the "mystery pink thing," etc.
I returned to Esperanza elated to have brought back our first glimpses of this magnificent canyon and lost track of the number of new things I saw on that dive. I feel like I'm at Seacamp again…seeing things I've never seen before, learning things I've never known before, and feeling young…like a wide-eyed child.
At 5:15 am, the rear suspension of the taxi to Washington, DC's National Airport groaned alarmingly under the weight of my five heavy pieces of luggage: A duffel of dive gear, a pelican case with an underwater video housing, a duffel of warm clothing, a backpack of video and camera gear, and a roll-aboard full of hard disks, cables and other geeky accessories. Alaska Airlines Flight #1 took me west across the country to Seattle, then north to Anchorage. As we pierced the clouds on our descent, the youngster seated behind me shrieked to his parents, "It looks like a big park!" Alaska was as I had remembered it: Big, wild, and beyond beautiful.
I made my way to the Peninsula Airways departures and rendezvoused with expedition photographer Todd Warshaw, who was traveling from San Diego. We later ran into Michelle Ridgway, an Alaskan marine ecological consultant and fellow sub pilot, along with Bob Stone, a NOAA scientist specializing in the cold water corals we hoped to study on the expedition. But we weren't supposed to see Michelle and Bob -- they were supposed to be in Dutch Harbor already. Their earlier flight had been cancelled, due to the notorious thick fog that occurs this time of year in Dutch Harbor. The earliest flight for which they could be confirmed was August 1 -- more than a week away. They discussed the possibility of missing the first week of the expedition and rendezvousing with us in St. George in the Pribilof islands, certainly less than an ideal situation.
Thankfully, Michelle returned from the podium with a grin -- they were on our flight…which was now delayed…and delayed… Finally, we were called and on our way. A three-hour flight along the Aleutian Island chain in a small Saab propeller plane, with a stop for fuel at aptly-named Cold Bay. We arrived at last to Dutch Harbor, met by Timo Marshall, retrieved (thankfully) all our bags, and drove a mile or so to the triple-parked M/V Esperanza. You couldn't have designed a more bizarre obstacle course for those carrying luggage. First, cross the gangway to the large barge, walk through the TV room where one of the crew was oblivious to our delegation, out the back door of the barge, down an external corridor, up a ladder, and around a huge dry dock structure, more twists, turns, chutes and ladders. Finally, Esperanza's gang way was in sight, only angled down to the deck from the dry dock structure with a sign indicating "Only One Person at a Time." Our heavy bags were roped and hauled up to the deck. My first hour in Dutch Harbor and I was overheated, sweaty and out of breath.
A nice reunion with the captain, crew, fellow sub pilots, and the incredible Nuytco crew who oversee all sub operations, and my 16 hours of travel had finally come to an end. Another 16 hours of travel from Dutch Harbor to Pribilof Canyon would begin the next day, but I'd sleep through most of it.
