On the West coast of North America, the commercial shark fishery started around 1915 and hit its first peak in 1939, when over 9.3 million pounds of shark were landed. The primary target was the soupfin shark, which earned its name from its fins being used to make shark fin soup. The sharks’ liver oil was used to make vitamin A until scientists found a way to produce it synthetically. Between 1936 and 1944, over 24 million pounds of soupfin shark were landed in America. The fishery collapsed in 1945 because soupfins had basically been wiped out. To this day, the population has not recovered. This pattern is commonly referred to as the boom and bust cycle, which is typically when a few fishermen begin to exploit one species of shark, and as soon as it becomes lucrative, a boom follows. Because of the slow reproductive rate of sharks and the lack of regulations for new fisheries, the fishery quickly goes into a bust cycle of precipitous decline. You can see this cycle repeat itself on Figure 1.

From 1950 to 1976, commercial shark landings averaged below 1 million pounds each year until the commercial shark fishery hit its second peak in 1979, when 11.6 million pounds of shark were landed on the west coast of America. This time, the primary target was the spiny dogfish (actually a shark). The meat was used to make fish and chips. In 1979, 9.4 million pounds of spiny dogfish were landed on the West coast of America. Due to intense fishing pressure, spiny dogfish are now on the IUCN Red List as globally vulnerable to extinction.

The commercial thresher shark fishery peaked in 1982, when over 2.3 million pounds were landed on the west coast (see Figure 2). Landings decreased shortly therafter largely due to gillnet fishery restrictions. All three species of thresher sharks have recently been added to the International Union for the Conservation of Nature (IUCN) Red List as vulnerable to extinction.

Like many other sharks, threshers are very slow to reproduce. They take five to six years to become sexually mature and after a nine to ten-month gestation period only yield one or two pups. They do not spawn hundreds of eggs as some other fish do. We have no idea how long it will take or if thresher populations can recover from the intense fishing pressure they were under in the early 1980's, yet they continue to be targetted. In 2008, 73,400 pounds of thresher shark were landed in the Santa Barbara area (see figure 3), higher than any other area on the West coast of America.

Drift gillnets are the method of choice when it comes to commercially fishing sharks, a method that has been responsible for a high number of marine mammal injuries and casualties as result of bycatch. (Bycatch is a term used to refer to any species caught accidentally while fishing for another species.) Fortunately, electronic pingers have greatly reduced marine mammal interactions.

Bycatch is a huge threat to sharks. According to the Food and Agriculture Organization (FAO), there are few fisheries that don’t catch sharks as bycatch, and some fisheries actually catch more sharks than the targeted species. Estimates suggest tens of millions of sharks are caught as bycatch each year. Longlining, trawling and gillnetting are responsible for most shark bycatch. Mexico and Japan have a joint commercial swordfish effort that is unregulated. The landing reports from these fisheries are inaccurate, so the extent of the bycatch is unknown. Longlines and gillnets are used to target swordfish off Baja, California but a lot of threshers and other sharks end up as bycatch.

Baja, California is also home to an artisanal gillnet fishery that targets sharks. This fishery catches thresher, blue, hammerhead, white and Pacific angel sharks. The thresher sharks caught in this fishery can be found at any of your local grocery stores. Thresher sharks are a highly migratory species, meaning they migrate very long distances, often across several borders. The threshers off of the coast of Santa Barbara are the same group of threshers being caught in Mexico. It is impossible to get an accurate population assesment of threshers without knowing how many are being caught in Mexico, making the fishery very difficult to properly manage.

Shark Free Santa Barbara wants to collaborate with local commercial fishermen to establish long-term goals that will benefit both the fishermen and the future of our ocean by focusing on utilizing more sustainable resources and using more selective gear. Please contact us for more information.