Taxonomy

Rarity

Abundance rates how many are in suitable habitat. Find difficulty rates how hard it is to locate one on a daylight snorkel or freedive through 50 ft. A higher find score means a harder search. The rarity category also reflects the kind of encounter; it is not an average of the 2 scores.

Seasonality

Location

Soupfin sharks live in cold to warm temperate waters worldwide, and on this coast they run from Southern California north to northern British Columbia. Records reach about 3,600 feet, with most fish between 7 and 1,550 feet. The historic fishery is the best available map of where they actually concentrate: it worked within 100 miles of shore, usually in about 150 feet of water, and catch statistics indicated the species does not range far out to sea. They are seasonal in any one place, common at some times and absent at others, and a female tagged 6 miles south of Ventura in July 1943 was recovered at Nootka Sound on Vancouver Island in September 1945, which is the clearest single piece of evidence that these are coastwise travelers.

The most interesting thing about where soupfin sharks are is that it depends on sex and age, in a pattern documented in unusual detail because a fishery once measured it. Catches in northern California were predominantly male. Central California and Santa Barbara ran roughly even, though females predominated at Santa Barbara in water under 180 feet. The San Pedro catch was 97.8 percent female. Young soupfin were abundant in Southern California, and adult females were taken there in greater numbers, at larger sizes, and more often mature than anywhere else in the state. The reading at the time, and it still stands, is that Southern California holds a nursery area. Farther north, San Francisco and Tomales bays held nurseries too, and those are the ones the fishery hit hardest.

Deep Dive

The soupfin shark is one of the plainer sharks on this coast: grey above, pale below, a long pointed snout, a large mouth, small blade-like teeth, and a maximum length of about 6.4 feet. It is also a fish that lives a long time. The maximum recorded age is 55 years, maturity comes at about 4.7 feet, and a female carries a litter for a full year. Reproduction is ovoviviparous, meaning eggs develop and hatch inside the mother with no placental connection and the pups live on yolk. The eggs grow to about the size of a golf ball. Litters counted from Santa Catalina samples ran 16 to 54, averaging 35 for females around 5.75 feet, and the count climbs with the size of the female, so the biggest, oldest females do most of the producing.

Diet is opportunistic, and it shows that the shark works the whole water column. California stomach contents held sardines, midshipman, rockfish, squid, flatfish, herring, mackerel, sculpin, smelt and ratfish. Rockfish, midshipman and flatfish live on the bottom. Squid and sardines do not. A shark eating both is not specialized on anything except availability.

The name is a warning about what happened to it. The gelatinous rays in its fins have long been prized for shark fin soup, and that is where the word soupfin comes from. But the fins are not what nearly finished the species in California. The liver was.

In January 1937 a market opened in Monterey and San Francisco for shark liver oil. In 1938 came the discovery that soupfin liver was unusually rich in vitamin A. Then the war cut off vitamin A imports, and the price of a commodity that had been worthless went vertical. Liver went from about $50 a ton in 1937 to $2,000 a ton in 1941. Total shark landings rose more than 8-fold between 1937 and 1938. By 1939, 600 vessels were fishing sharks along the California coast, using gill nets, otter trawls, or whatever worked.

It did not last 10 years. California soupfin landings fell from 2,172 tonnes in 1941 to 287 tonnes in 1944. The federal review of the fishery published in 1957 put it flatly: effort increased greatly during the war, and despite that increased effort the catches fell off drastically throughout the range, showing a decline in abundance. That is the sentence that matters. More boats, more gear, more money, and less shark. The same pattern ran north. Oregon liver landings peaked at 270,000 pounds in 1943 and were down to 134 pounds by 1951, by which point no Oregon boat was known to be fishing for them at all. Washington peaked at 415,300 pounds in 1943 and landed 1,229 pounds in 1955.

What ended the fishery is the part worth remembering. It was not a catch limit, a closure, a season or any other regulation. Chemists learned to make vitamin A synthetically, at a quality comparable to what came out of a shark, and liver imports rose at the same time. The price collapsed, and the boats went and fished something else. The soupfin shark was saved by being made commercially worthless, roughly a decade after being made commercially valuable, and nothing in between was a decision anyone made about the shark.

The population never really came back. The nursery bays are described as having not fully recovered to this day, and the global assessment 80 years later is Critically Endangered. Federally the species is managed on this coast under the Pacific Coast Groundfish plan as an Ecosystem Component Species, which is a category for monitoring rather than for setting a harvest. California allows 1 per person per day. For a shark that takes decades to grow, breeds once a year, and has already been through this once, that number is doing a lot of work.

Where to Find Them

Researched habitat and range candidates

These locations have suitable habitat within the species range. An assignment is a possible encounter, not a confirmed sighting at every beach. Season, depth, and local conditions still matter. Historical habitat without present-day evidence is excluded.