DIVE DRY WITH DR. BILL #346: A DIFFERENT KIND OF "JAWS"
I was teaching at Toyon Bay back in the mid 70's while they were filming scenes for some obscure movie about great white sharks near Torqua Springs. When the film came out about a year later, it caused quite a stir. I drove up to see it in Santa Barbara with my marine biology teaching assistant, Barry "Bam Bam" Aires. The film was "Jaws," and I must admit it played on one of my fundamental fears when I moved to Catalina in the late 60's. Having "Bam Bam" introduce me to a surfer who had been attacked by a great white near Pt. Conception didn't help any. The scars that literally engulfed his torso, combined with seeing the movie, made me give up diving for several years. A few years later while working on Cousteau's Project Ocean Search, Jean-Michel came over when he saw me donning a wetsuit again. He said "I thought you had given up diving after you saw 'Jaws.' What happened to get you back in the water?" I replied with a smile on my face "I saw 'Jaws II.'"
In the years since, I've conquered my fear of great white sharks. I've dived with them off Guadalupe Island (admittedly protected... in a flimsy cage) and filmed footage used by Dr. Guy Harvey in his TV episode on "the landlord." I even had one swim past dive buddy Wyland and I while we were filming giant sea bass near the East End Quarry. I've learned they just aren't very interested in divers. I think it has something to do with the hard "shell" or SCUBA tank we carry on our backs, and the bubbles the rig constantly releases. Although sea lions will emit a stream of bubbles when "threatening" a diver, I'm sure the sharks can tell the difference. We just aren't that tasty!
During the winters I spent diving in the Sea of Cortez out of La Paz, I had concerns about another "jaws," the Humboldt or jumbo squid (Dosidicus gigas). These rather large calimari, up to a possible eight feet long and 300 pounds (but possibly much more), had a bad reputation down there with the Mexican fishermen, some of whom claimed they'd pull one of them right out of their pangas. They feared them more than they did the large sharks. I didn't do any night diving the winters I was down there since that was when these squid came into shallower water. Divers who enter the water with these carnivorous cephalopods often wear chain mail shark suits to avoid bites from their powerful beaks, or rips and tears from the hooks around the suction cups on their tentacles.
Over the past decade we've seen Humboldt squid invade the waters of California. They first appeared in numbers here following the 1997-1998 El Nino. I used to wonder if I'd encounter them when I was doing frequent deep dives down to 200 feet in our waters. This species has expanded its northern distribution from northern Baja all the way up to British Columbia, an incredible extension of their range. A number of divers in San Diego have been seeing them regularly on night dives in shallow waters (including Roger Uzun who granted me permission to use several of his images here). Some news reports tried to link their appearance with an offshore earthquake near La Jolla, but several scientists including yours truly expressed serious doubts about any connection. Normally this species frequents deep waters where light fails to penetrate, and they feed on lanternfish and other "delicacies" (at least if you are a squid). There are more than 400 known species of lanternfish, and they are said to be more common than sardines or anchovies.
Since the squid live in deep (about 1,500 feet), cold water, one would not suspect a link to global warming. However, systems work in often intricate and not too obvious ways. Let me explain the current thinking by scientists. One theory proposed by Stanford biologist Dr. William Gilly focuses on the oxygen minimum layer. At these depths, where light vanishes, microbes like bacteria feed on the downward "rain" of phytoplankton and organic matter from shallower waters. Their activity requires oxygen, so they deplete what is present in these deep waters where there is no direct contact with the atmosphere to replenish it. NOAA scientist Steven Bograd has found that deep oxygen levels have declined and the start of the oxygen minimum layer os now shallower than before. The extent of this layer in the waters off Baja has also increased, expanding the habitat for the lanternfish and therefore the squid that eat them. One interesting question is how these squid survive in such oxygen depleted regions.
Landings of the Humboldt or jumbo squid off Mexico, Central and South America have increased from less than 200,000 to more than 700,000 metric tons! Scientists believe that in addition to the expansion of the squid's habitat, there are other factors which have contributed to their increase. Stanford researcher Lou Zeidberg suggests that the depletion of sharks, and to a lesser extent tuna, due to severe overfishing of them removed major predators on the squid, allowing them to multiply. This increase may be providing more food for sperm whales which have increased their numbers off the West Coast recently as well. An important question for scientists to address is whether these jumbo squid are completing their life cycles within this expanded range by reproducing. A female with a male's packet of sperm was seen off Monterey, so it is quite possible.
Just last week I received reports from a mainland dive boat captain that Humboldt squid were seen during daylight in the shallow waters off Catalina's West End. I don't want to reveal the exact location to avoid the rush of fishing boats heading out to try to catch them... which happened to sharks after "Jaws" was released. These fish pose a threat to anglers due to their powerful beaks and "toothed" suckers. I also don't want swimmers off the island to panic and fear they will become victims of these colossal calimari. Reports from the divers off San Diego who encountered them suggested they were curious rather than truly aggressive. They would attach to the diver's mask or camera, and do have sufficient force to wrest either away. However, none of the divers were bitten by them So if you do happen to see a squid that would make a plateful of calimari for a hungry man like myself, do exercise caution... but don't panic. Despite all the sensational stories about them in the mass media, Dr. Gilley dismisses the idea of them being a real threat to humans. Others like underwater filmmaker Scott Cassell feel they can pose a danger but are not the "crazed killers" the press has made them out to be.
NOTE: I recently had a conversation with a fishing boat captain from San Diego who reminded me that the Humboldts were up in southern California waters back around 1971, and that squid fishermen from San Diego and San Pedro targeted them at the time. Interesting that none of the reports I've read so far mention this previous incursion. My aging brain seems to remember this event, too.
Image caption: Images of Humboldt squid from MBARI, the Monterey Bay Aquarium Research Institute (upper left) and from Roger Uzun's spectacular video that was circulated on many television stations not only in the States but internationally. Thanks Roger for allowing me to use these!
I was teaching at Toyon Bay back in the mid 70's while they were filming scenes for some obscure movie about great white sharks near Torqua Springs. When the film came out about a year later, it caused quite a stir. I drove up to see it in Santa Barbara with my marine biology teaching assistant, Barry "Bam Bam" Aires. The film was "Jaws," and I must admit it played on one of my fundamental fears when I moved to Catalina in the late 60's. Having "Bam Bam" introduce me to a surfer who had been attacked by a great white near Pt. Conception didn't help any. The scars that literally engulfed his torso, combined with seeing the movie, made me give up diving for several years. A few years later while working on Cousteau's Project Ocean Search, Jean-Michel came over when he saw me donning a wetsuit again. He said "I thought you had given up diving after you saw 'Jaws.' What happened to get you back in the water?" I replied with a smile on my face "I saw 'Jaws II.'"
In the years since, I've conquered my fear of great white sharks. I've dived with them off Guadalupe Island (admittedly protected... in a flimsy cage) and filmed footage used by Dr. Guy Harvey in his TV episode on "the landlord." I even had one swim past dive buddy Wyland and I while we were filming giant sea bass near the East End Quarry. I've learned they just aren't very interested in divers. I think it has something to do with the hard "shell" or SCUBA tank we carry on our backs, and the bubbles the rig constantly releases. Although sea lions will emit a stream of bubbles when "threatening" a diver, I'm sure the sharks can tell the difference. We just aren't that tasty!
During the winters I spent diving in the Sea of Cortez out of La Paz, I had concerns about another "jaws," the Humboldt or jumbo squid (Dosidicus gigas). These rather large calimari, up to a possible eight feet long and 300 pounds (but possibly much more), had a bad reputation down there with the Mexican fishermen, some of whom claimed they'd pull one of them right out of their pangas. They feared them more than they did the large sharks. I didn't do any night diving the winters I was down there since that was when these squid came into shallower water. Divers who enter the water with these carnivorous cephalopods often wear chain mail shark suits to avoid bites from their powerful beaks, or rips and tears from the hooks around the suction cups on their tentacles.
Over the past decade we've seen Humboldt squid invade the waters of California. They first appeared in numbers here following the 1997-1998 El Nino. I used to wonder if I'd encounter them when I was doing frequent deep dives down to 200 feet in our waters. This species has expanded its northern distribution from northern Baja all the way up to British Columbia, an incredible extension of their range. A number of divers in San Diego have been seeing them regularly on night dives in shallow waters (including Roger Uzun who granted me permission to use several of his images here). Some news reports tried to link their appearance with an offshore earthquake near La Jolla, but several scientists including yours truly expressed serious doubts about any connection. Normally this species frequents deep waters where light fails to penetrate, and they feed on lanternfish and other "delicacies" (at least if you are a squid). There are more than 400 known species of lanternfish, and they are said to be more common than sardines or anchovies.
Since the squid live in deep (about 1,500 feet), cold water, one would not suspect a link to global warming. However, systems work in often intricate and not too obvious ways. Let me explain the current thinking by scientists. One theory proposed by Stanford biologist Dr. William Gilly focuses on the oxygen minimum layer. At these depths, where light vanishes, microbes like bacteria feed on the downward "rain" of phytoplankton and organic matter from shallower waters. Their activity requires oxygen, so they deplete what is present in these deep waters where there is no direct contact with the atmosphere to replenish it. NOAA scientist Steven Bograd has found that deep oxygen levels have declined and the start of the oxygen minimum layer os now shallower than before. The extent of this layer in the waters off Baja has also increased, expanding the habitat for the lanternfish and therefore the squid that eat them. One interesting question is how these squid survive in such oxygen depleted regions.
Landings of the Humboldt or jumbo squid off Mexico, Central and South America have increased from less than 200,000 to more than 700,000 metric tons! Scientists believe that in addition to the expansion of the squid's habitat, there are other factors which have contributed to their increase. Stanford researcher Lou Zeidberg suggests that the depletion of sharks, and to a lesser extent tuna, due to severe overfishing of them removed major predators on the squid, allowing them to multiply. This increase may be providing more food for sperm whales which have increased their numbers off the West Coast recently as well. An important question for scientists to address is whether these jumbo squid are completing their life cycles within this expanded range by reproducing. A female with a male's packet of sperm was seen off Monterey, so it is quite possible.
Just last week I received reports from a mainland dive boat captain that Humboldt squid were seen during daylight in the shallow waters off Catalina's West End. I don't want to reveal the exact location to avoid the rush of fishing boats heading out to try to catch them... which happened to sharks after "Jaws" was released. These fish pose a threat to anglers due to their powerful beaks and "toothed" suckers. I also don't want swimmers off the island to panic and fear they will become victims of these colossal calimari. Reports from the divers off San Diego who encountered them suggested they were curious rather than truly aggressive. They would attach to the diver's mask or camera, and do have sufficient force to wrest either away. However, none of the divers were bitten by them So if you do happen to see a squid that would make a plateful of calimari for a hungry man like myself, do exercise caution... but don't panic. Despite all the sensational stories about them in the mass media, Dr. Gilley dismisses the idea of them being a real threat to humans. Others like underwater filmmaker Scott Cassell feel they can pose a danger but are not the "crazed killers" the press has made them out to be.
NOTE: I recently had a conversation with a fishing boat captain from San Diego who reminded me that the Humboldts were up in southern California waters back around 1971, and that squid fishermen from San Diego and San Pedro targeted them at the time. Interesting that none of the reports I've read so far mention this previous incursion. My aging brain seems to remember this event, too.
Image caption: Images of Humboldt squid from MBARI, the Monterey Bay Aquarium Research Institute (upper left) and from Roger Uzun's spectacular video that was circulated on many television stations not only in the States but internationally. Thanks Roger for allowing me to use these!
