This past summer, two science papers documented, for the first time, the presence of two species of sharks not known to exist in Puget Sound. These species are commonly called sevengill and soupfin sharks. I am sorry to say that I did not know much about sharks in Puget Sound, and I had never written much about them, although I had been reading reports about sixgill sharks in Elliott Bay. I thought it was about time for a deeper understanding that I could share with readers.

As it turns out, some interesting studies about various Puget Sound shark species had gone largely unreported outside the scientific community. I began interviewing some amazing shark experts, each with a passion for these ancient and highly unusual fish. Their studies and personal accounts developed into a seven-part series published in the Encyclopedia of Puget Sound.

One thing I learned is that average people in our region are not as fearful of sharks as I thought they might be. Experts who make public presentations on the subject report that many people are surprised to find out that we even have sharks among us. Any apprehension — born from movies, television and  other media — quickly gives way to curiosity when people learn about the specific sharks that live here and come to realize that their risk of attack is minimal — even for those who spend significant time in the cold waters of the Sound.

I’m told that some scuba divers spend time looking for large sharks in Puget Sound, going to places where sharks have been seen in the past. Most never find them, because sharks tend to stay away from people. When divers do see a shark, such as a sixgill, the encounter is generally brief, with the shark showing more curiosity than aggression.

Since 1837, only two shark attacks have been reported in Washington state, and both of those were on the coast, according to the International Shark Attack File maintained at the University of Florida. Only Connecticut has had fewer incidents (with just one), although five coastal states have had two attacks. Most of the shark bites involve surfers or divers. The reasons are speculative, but several shark species hunt marine mammals, such as seals and dolphins, so many of the attacks could be a case of mistaken identity.

By far, the most shark attacks in the United States occurred in Florida where lots of people enjoy their ocean waters. Since 1837, 928 attacks have been reported in Florida, followed by Hawaii with 195 and California with 138. See the U.S. map or the world map for information about specific incidents. For details about West Coast shark injuries, check out the various pages on the website of the Shark Research Committee.

Primitive or advanced species?

Sharks are scientifically classified together with other fish that have skeletons of flexible cartilage rather than hard bone. These chondrichthyans include two subclasses. Actual sharks are grouped with rays, skates and sawfish in the subclass Elasmobranchi, while the subclass Holocephali includes spotted ratfish — the most abundant fish in Puget Sound.

One of the impressive statistics about sharks is that these species can be traced back to ancestors living some 450 million years ago. This predates the age of the dinosaurs by some 200 million years. In such discussions about ancient sharks, we are often left with the impression that sharks have remained virtually unchanged through all this time. Some folks have even referred to sharks as “living fossils,” since their skeletons of cartilage are believed to predate skeletons of bone found in most fish species.

But recent fossil discoveries are calling into question these evolutionary assumptions. A precursor species to both sharks and bony fish was found with a skull made of bone, suggesting that shark skeletons may have evolved to bone before evolving back to cartilage. Sorting out these evolutionary changes remains difficult, because cartilage is not typically preserved in the fossil record.

“If sharks had bony skeletons and lost it, it could be an evolutionary adaptation,” said Martin Brazeau, lead author of one study, quoted in Science News. “Sharks don’t have swim bladders, which evolved later in bony fish, but a lighter skeleton would have helped them be more mobile in the water and swim at different depths.” The 2020 study was published in Nature Ecology & Evolution.

Instead of a swim bladder, sharks have evolved with large livers filled with low-density oil to improve their buoyancy. Skeletons of cartilage and other adaptations improve their speed and agility. Unique scales, for example, increase the smooth flow of water over their skin to boost swimming efficiency, and adaptations among the fastest sharks include sleek, streamlined bodies. All these features, along with highly evolved senses, tend to dispel the notion that sharks are primitive, unchanging creatures.

One of the senses enjoyed by sharks but foreign to humans is an ability to detect electrical fields generated by other animals during muscle contraction. When a fish is injured, for example, a shark can detect the discordant electrical pulses and home in on the prey. Sharks also use the Earth’s magnetic field to find their way around the great expanse of the oceans.

Stimulating the electrical sensory system found in some sharks can produce a temporary paralysis or hypnosis, called tonic immobility. Touching and rubbing a shark’s snout may innervate the electrical sensory system and cause the shark to go limp. In some sharks, tonic immobility can be induced by turning the shark upside down and holding it there. After a few minutes without stimulation, the shark will return to normal with no lingering effects.

 Little is understood about the mechanism or reason for this phenomenon. Some say the process of decreasing aggression may be useful during mating. But killer whales that prey on sharks have been known to turn sharks upside tide and hold them in this motionless state until they have too little oxygen passing through their gills, resulting in death. For more about this phenomenon, see the article in Environmental Biology of Fishes, 2023.

 More than meets the eye

Among sharks of Puget Sound, the Pacific spiny dogfish shark is a common resident that many people recognize. But how many people understand that vast numbers of these long-lived sharks migrate to the outer coast each fall and then return in the spring, as I describe in the story about dogfish sharks.

Ever wonder what animals are thinking? I’m accustomed to the notion that killer whales are individuals, highly intelligent, each with a unique personality, socializing with other killer whales. But I never gave much thought to a fish being an individual, perhaps with a distinct behavior and attitude, even if their social connections are not as refined as orcas. As part of my story involving education and conservation, biologist Rachel Easton informed me that her job of feeding nurse sharks at the Point Defiance Zoo and Aquarium allowed her to become acquainted with individual personalities — or what we might call “shark-alities,” she said.

“There were 10 nurse sharks there at the time,” said Rachel, now education director for Harbor WildWatch in Gig Harbor. “We had to distinguish each one so they could get the right vitamins. You get to know them as individuals and realize that they don’t just swim and kill. They have complete lives. Sometimes they rest; sometimes they flirt; sometimes they are interested in what the humans are doing. They crave mental stimulation, just like humans.”

Studies have shown that some sharks cooperate in a group when hunting larger species, something like the hunting style of orcas.

I recently visited the Tropical Reef Aquarium at Point Defiance, where my granddaughter, Emma Jeffries, entered the water in a wetsuit to meet with sharks “eye to eye.” Emma was protected within an underwater cage, where she watched as several sharks circled in the water, some passing quite close to the enclosure. It was an interesting experience for her — more immersive, you might say, than the view we get through the aquarium glass.

Divers who go out looking for sharks in Puget Sound had some success several years ago, when sixgill sharks were observed in relatively large numbers in specific locations such as Seattle’s Elliott Bay, as I describe in the story about sixgills. (See also video.)  It appears, based on research, that this bump in the local population of sixgills may be related to an unusual number of females coming in from the ocean to give birth. Researchers suspect that newborn sixgills live in Puget Sound for a few years before migrating to the ocean, making Puget Sound a natural nursery for this and perhaps other shark species.

To create a list of Puget Sound shark species, I consulted with several shark experts. The list in the first part of this series labels some species as “rare,” meaning they are almost never caught by fishermen or found along the shore. Many of these species considered rare to Puget Sound are fairly common along the Washington Coast, where tropical species may be seen during periods of warming waters with some possibly coming into the Sound.

One species almost never seen is the thresher shark, known to reach up to 21 feet long in the ocean. The only verified report in Puget Sound seems to be a 12-foot shark caught with a hook and line in 1972 off Sucia Island in the northern reaches of the San Juan Islands. The shark was stuffed and hung by wires in the Shrimp Shack restaurant in Bellingham. The shark was moved when the restaurant changed locations. But when the dining spot closed in 2014, the stuffed shark seemed to disappear.

 I did some checking and located the shark hanging in the home of David James, the last person to own the Shrimp Shack before it closed. David kept the shark to remember his longtime friend who had owned the restaurant before he died. Now, David says, it may be time for him to part with the shark and return his living room to a more traditional appearance. Similar shark “replicas” sell for around $5,000, he said, adding that he would take an offer of $8,000 for this rare shark.

I was able to find one other description of a thresher shark in Puget Sound, as reported in a Kitsap Sun article of Oct. 8, 1994. Sherman Perrault, a Kitsap County resident, found the shark in some weeds along the shore at the Southworth Ferry Dock. The shark was barely alive and could not be saved. Perrault dragged it up on the beach and took it to a friend’s house, according to the article, which states that an officer with the Washington Department of Fish and Wildlife confirmed the species.

If any reader would like to share a story about sharks in Puget Sound, please do so in the comments section below.

Shark fishing and the future

A shark fisherman, Connor Seifert, who had been catching sevengill and soupfin sharks in South Puget Sound, triggered the latest scientific investigations when researchers learned that he was catching sharks not known to exist anywhere in Puget Sound, let alone the southern extent of the waterway. Connor told me about his personal experiences fishing for sharks, which I described in part 1 of this series.

Looking into state fishing regulations, I learned that the season on sharks is fairly wide  open, despite concerns about the impact that fishing might have on shark populations. The lack of scientific information makes it difficult to justify stricter fishing rules or to better manage shark populations.

Concerns revolve around the reproductive capacity of many shark species. Female sharks may live for years before they reach reproductive age. Most species have long gestation periods, which means they rarely give birth. And when they do have offspring, their litters are relatively small. This makes for a low level of productivity with risks of a population crash.

Under current sport fishing rules, sharks are classified as “bottom fish” and lumped together with cod, sole, flounder, rockfish, hake, lingcod, sculpins, ratfish, skates, wolf eels and others. In general, anglers may take up to 15 bottom fish per day in Puget Sound.

Although it is illegal to target sixgill, sevengill and thresher sharks, it is not illegal to fish for soupfins — even though this latter species is under federal review as a potential endangered species. Anglers can say they are fishing for soupfin sharks, or dogfish sharks, or any other shark, and they are violating no laws if they release any of the three prohibited species they might catch.

Officials within the Department of Fish and Wildlife have been discussing what, if any, further steps should be taken to protect sharks, particularly the soupfin.

Some folks say it is well past time to remove sharks from the general classification as bottom fish and give them their own designation with special rules for protecting most shark species. One exception could be the spiny dogfish, which I am told is not currently at risk of over-fishing. But that could change if more shark fishing catches on.  If sharks were given their own classification, the daily catch limit of 15 could be more easily adjusted or even set at different levels for different species.

How much evidence is needed to justify increased protections for various shark species is certainly open to debate. Sharks are difficult to study, and they don’t get much attention, which means uncertainty remains high for most populations. Research on salmon and other commercial fish still consumes the majority of funding, but that could change with increased scrutiny about the ecosystem as a whole. Perhaps new findings about how sharks help maintain a balance in food webs will bring additional funding to fill in the blanks about the sharks of Puget Sound.