| | | | | A close encounter The day started off with four friends getting together for a summer’s day of diving in Washington’s Hood Canal. We rendezvoused at the boat launch at Triton Cove, happily setting out for what was expected to be an ordinary day of diving. It was decided to go to a location that we call Flagpole Point due to the fact that a lone flagpole stands on shore marking its location. This site is a popular wall dive known for having an abundance and variety of marine creatures. The decision we made to dive there placed us directly on course for an amazing encounter that we will remember for the rest of our lives! Upon arrival at Flagpole Point, we rolled over the side of the boat and descended together. The visibility was extremely poor (less than 8 to10 feet), so I had left my camera on the boat. Despite that, the dive immediately proved to be a naturalist’s dream as we plummeted down the seemingly endless wall. We encountered hordes of Squat Lobsters poking their tiny heads and claws from virtually every hole, several Spiny Lithode crabs (a rare treat), Pacific Lyre crabs scuttling around the rocky ledges, and a couple of Scaled crabs, the first of that species I had personally ever seen. Clouds of Rock Fish hovered just out of reach and, naturally curious, seemed to follow us as we made our way across the face of the wall. At approximately 120 FSW we encountered a large Giant Pacific Octopus completely out in the open that looked oddly different than it should have. As we slowly approached it, we were stunned to find that all eight of its legs had been bitten off approximately 1 to 2 feet from its body. It was quite literally moving around on eight stumps. I have seen a Ling Cod bite off a leg from an octopus before, but this was a far larger octopus (the head approached three feet across) and all eight legs were missing. I couldn’t imagine what would have done this as we swam across the wall. Within minutes, we encountered a second octopus, every bit as large as the first. To our surprise, it was also missing two of its legs. I hovered briefly over the octopus, eye to eye, vainly seeking an answer to what had happened. Our bottom time had now extended to the point that we were into our planned decompression, so we turned and began our ascent through the murk, our lights the only reliable means of maintaining contact with each other. Almost immediately, we encountered a third octopus, this one moving rapidly towards us as if fleeing something. Puzzled, we turned our lights toward the approaching creature and were absolutely astounded to see that this one too was missing three of its legs. | | | | We were all pretty creeped out at this point as the octopus passed directly through the center of our team, ignoring us as if we weren’t even there. While the rest of us continued to watch the rapidly moving octopus, my buddy, Shawn, turned his light into the gloom from the direction the octopus had come, only to find a 7 to 8 foot Sixgill Shark approaching us. The flashing of Shawn’s light caught our attention, and we turned just in time to find the shark amongst us as it swam leisurely right through the middle of our group with its pale, luminescent green eyes. Fascinated, I reached out and gently placed my hand on its side just behind its gills, feeling the surprising smoothness of its skin. All thoughts of the octopus forgotten, we remained with the shark for approximately 3 to 4 minutes, completely absorbing the experience. When I first saw the shark, we were at 97 FSW and both our plan and my computer were telling me that I had deco stops in the immediate future. When the shark turned and began to descend, we all knew that no matter how much we wanted to follow, physiology demanded that we begin our ascent. Giddy as small boys with a secret, we were virtually dying to surface to talk about what we had just experienced, but the tiny bubbles coursing through our systems kept us on task. Ultimately bursting through the surface and into the sunshine, each of us erupted with whoops and hollers as we celebrated the magical experience we had just shared. Since that extraordinary day, I have sought to dive with and photograph these amazing sharks at every available opportunity and have made it a point to learn as much as I could about Sixgill Sharks. I’ve poured over the available literature and have spoken with marine biologists in the Pacific Northwest knowledgeable of these remarkable creatures. A survivor from the ancient world The Bluntnose Sixgill Shark, Hexanchus griseus, is a member of the Hexanchidae family and a species of shark that has remained virtually unchanged for over 100 million years. Some naturalists have even humorously referred to it as “Jurassic Shark”. To dive with such an animal is to dive with a relic of a bygone age, your mind racing with thoughts of dinosaurs, ancient sea-reptiles, and other species now known only from their fossils. Of all of the sharks dwelling in our oceans today, none resemble their ancient ancestors more than do the members of the Hexanchidae family. Bluntnose Sixgills are among the most readily identifiable shark species. They have a long, slender body with a single dorsal fin located far to the back of the body, almost to the base of the tail, (see the photos and illustrations). As their name implies, they have six pairs of gill slits, as well as a short, blunt snout. Their eyes are almost mystical; being extremely large and teardrop shaped, and appear to be almost luminescent and green like those of a cat. Their eyes are extremely light sensitive, with a non-contracting iris and only rods with no cones. Camera flashes often send them turning toward the depths for relief. The lateral line is readily visible and has an interesting bump or dip in it just above the lower caudal or tail lobe. The lower caudal lobe itself is relatively short, while the upper caudal lobe, or tail, is quite long - tapering back at a slight upward angle from the body. The Bluntnose Sixgill is one of the few species of shark that regularly grows beyond 12 feet in length. Many sources site their maximum length as 26 feet, although it is now believed that this is the result of a typographical error made while early records were being studied. It is generally accepted that the maximum length attained by this species is between 15 and 16 feet with an average size of 8 to 12 feet. | | A worldwide presence The Bluntnose Sixgill Shark has a confirmed presence off every continent with the exception of Antarctica. Only the Great White Shark approaches the Sixgill in the overall size of its distribution. In the western hemisphere, it has been found from Chile to the Gulf of Alaska on the west coast and from Argentina to Southeastern Canada on the east coast. It is common along the coast of Europe, off southern Iceland, in the Mediterranean, both northern and southern Africa, and off the coasts of Asia, Australia, and New Zealand. Bluntnose Sixgill Sharks have been verified and filmed in deep submersible expeditions to a depth of 8,200 FSW. With most specimens taken or observed in deeper waters, it has been assumed until recent times that the Sixgill shark was a denizen of the abyss, only irregularly and unpredictably approaching the surface. It has been demonstrated in the waters of the Pacific Northwest, however, that this is not true and that shallow water annual migrations can be reasonably predicted and observed. Sixgills can be found over rocky reefs as well as muddy bottoms, both of which abound in the Pacific Northwest. In Washington’s Puget Sound, the link with the muddy bottom has historically been so profound that fishermen have nicknamed it the “Mud-Shark”. Sixgill diet and hunting strategies The Sixgill’s food preferences vary from region to region based on both availability and abundance. Mollusks, crustaceans, hagfish, and other small to medium sized fish head the list in most parts of the world. However, it is in the Pacific Northwest that the menu becomes truly interesting. In the waters of Washington and British Columbia, the species known to be a regular part of the Sixgill diet include Pacific Hagfish, Pacific Salmon, Lingcod, Cabezon, rockfish, Spiny Dogfish sharks, and Harbor Seals. Two things stand out amongst these prey items: most of them are fairly large and all of them but the hagfish can be extraordinarily fast. Watching a Bluntnose Sixgill swimming underwater it will seem slow, even lethargic. Clearly, however, from the prey it eats the Sixgill is capable of bursts of speed. Although observations of Sixgill predation are not common, one current theory is that, similar to the White Shark, the Sixgill approaches prey relying on stealth. It then launches an attack from close-range, striking the victim suddenly and by surprise, leaving it with little time to react. The species has also been observed pinning prey to the bottom with its snout. The Sixgill’s teeth are as unique as the species itself. The upper and lower teeth are astonishingly different from each other (see illustration). The upper teeth are relatively simple: the middle teeth have one cusp, the outer teeth have two cusps, and the corner teeth have three or four cusps. The lower teeth, however, are completely different, having multiple cusps (7 or 8) and are almost trapezoid in shape. The lower teeth are almost comb-like and are likely used to saw chunks of flesh from prey too large to be swallowed whole. Reproduction Research and observation have shown that Bluntnose Sixgill sharks reach sexual maturity at approximately 11 feet in length for males and 14 feet for females. No ironclad, verifiable data yet exists regarding growth-rate or longevity, but most researchers agree that the species is slow growing and probably has a long life span, perhaps over a century. Some researches believe that the species comes into shallower waters to both pup and breed, and in fact newborn Sixgills are often found in shallow waters in the Pacific Northwest in the Summer and early Fall. This corresponds with the time frame in which divers regularly find adults in shallow depths in both Washington and British Columbia waters. Females are also often observed during this time bearing scars similar to other shark species in which amorous males nip at the gill area, pectoral fins, and sides of prospective mates prior to mating. Virtually nothing is known regarding the gestation period for this species, but the assumption is at least 12 months and possibly up to two years. Being ovoviviparous, the Sixgills give birth to live young, which, when born, are approximately 27 to 28 inches in length. The Sixgill is one of the most fecund of shark species, second only to the Blue shark in terms of the potential size of its litters. In fact, one female has been documented as having 108 embryos in her uterus. | A Pacific Northwest oddity: An annual trip to shallow water It is well documented that Sixgill sharks in the Pacific Northwest migrate into shallower waters and remain there during the summer and early fall months, probably to drop their litters and mate. This annual migration into shallower waters is not known to occur anywhere else within the Sixgills range. It is believed that this is partially due to the surface and bottom waters of the Pacific Northwest being well mixed and uniformly cold. Another supportive reason is that plankton levels dramatically increase during the summer months, allowing these light-sensitive sharks to enter shallow water without the extreme discomfort higher levels of light associated with shallower depths would cause. Further, during this time frame major salmon runs are normally taking place in the Pacific Northwest in both the U.S. and Canada. Photographing the Sixgill Towards the end of summer 2003 my dive buddy, John “Sparky” Campbell, and I traveled north to British Columbia’s Barkley Sound on the western coast of Vancouver Island. Our goal was to find and photograph Sixgill sharks during their seasonal migration into shallower waters. Unlike Puget Sound and Hood Canal in Washington, the visibility in Barkley Sound generally remains outstanding at depth despite the heavy layer of plankton at the surface, so the opportunities for successfully photographing these sharks would be far greater. Also, a major salmon run was underway within the Sound. Orcas, Sea Lions, Bald Eagles, and Bears were all arriving for the feast, along with, hopefully, large numbers of Sixgill sharks. We dived with our Canadian friends, Dave and Renate Christie of Rendezvous Dive Ventures. After several frustrating days of beautiful dives and outstanding photography, we had seen no sharks at all. Dave decided to take us to dive the “spot.” He has fondly named this particular site “Shark Alley”, telling me that “It isn’t good for much else, John, but there’s usually a few big old sharks down there. Don’t know why, but that’s just the way it is”. Dropping down the anchor line at the “spot” into the rich, green depths, the contours of the bottom became focused. The cold water caused my face to tingle until numbness set in. As we approached 80 FSW, I couldn’t believe my eyes! There, not 30 feet away was a huge, barrel-shaped female Sixgill slowly cruising by the upper edge of the rock wall, almost begging to be filmed. Sparky and I swam toward her and as we swam abreast of the shark we were able to judge her length at approximately 10 feet. I felt detached from the scene as I looked at everything through my viewfinder. Happily, I fired off two or three shots once I saw both Sparky and the Sixgill in my frame. The flash appeared to visibly annoy her, however, and it was not long before she turned and began to head down the wall toward deeper water. Desperately trying to get as many shots as I could before she was gone, we plunged down the wall after her, only to find that she was moving far faster than she appeared to be. My final shots were of a long, slender tail disappearing into the inky blackness below. Ascending the wall, we reached the upper ledges. Flashing beams of light signaled us that something else was going on. We hurriedly kicked in that direction and found our Canadian friends swimming with three smaller Sixgills, all of them females. Once again I found myself swimming with my eye glued to the viewfinder and happily clicking away. The camera flash again apparently bothering their light-sensitive eyes, this group of sharks also soon headed for deeper water. We quickly found ourselves alone, grinning like absolute fools, and began our ascent. Upon surfacing, the first thing I saw was Dave Christie’s broad grin and heard a loud shout delivered in a Scottish brogue, “Well, John, I didn’t lie to ya, did I? That’s why we call her Shark Alley.” I would like to thank Dave and Renate Christie of Rendezvous Dive Ventures for their skill, hospitality, and friendship. They can be reached at http://www.rendezvousdiveventures.com. Special thanks also to Marine Biologists Cindy Tribuzio and Jeff Christiansen for their kind advice and assistance. | | | | | |
