Dive Dry with Dr. Bill

036: Soupfin or Tope Shark

On September 28, 2001, I had the pleasure of diving with about twenty of these awesome animals in Lover's Cove just off Abalone Point on Catalina thanks to a permit from the Avalon Harbor Department. I positioned myself at an opening in the kelp forest at 40 feet depth and videotaped them as they made passes within a few feet to check me out. Unfortunately the bubbles from my SCUBA regulator caused them to execute rapid 180 degree turns, so I had to hold my breath as I filmed them passing overhead, in front of, and beneath me.

The following is based on information in my Cousteau and UCSB colleague Dr. Milton Love's book Probably More than You Want to Know about the Fishes of the Pacific Coast. The appearance of soupfin sharks in the waters of Lover's Cove and elsewhere along the leeward coast of Catalina that year was somewhat unusual, although they had been seen elsewhere around the island in previous years. They are found worldwide (including Australia, South America, Europe and Africa) and on the North American coast from British Columbia to central Baja California. They are considered a cold to temperate rather than a warm water shark. They may be found in very shallow water to depths of 1,350 feet.

Scientifically the soupfin (or top as it is called elsewhere) shark is known as Galeorhinus galeus which translates as "a kind of shark like a weasel." Males reach lengths of six feet and females a half foot longer. They have elongated, somewhat pointed snouts similar to blue sharks but their bodies are grey or bluish on top with white bellies. The most distinguishing feature is the caudal (tail) fin which has a large upper lobe. Females give live birth to 6-52 young sharks about 14" long each season.

Soupfins have an interesting distribution off the West Coast. North of Pt. Arena most soupfins are males. From Pt. Arena to Pt. Buchon males and females are about equal in number. South of Pt. Buchon most of the fish are females and the young are often found in the shallow waters of southern California.

Soupfins eat fish (not humans) including sardines, rockfish, mackerel, surf perches, barracuda, white sea bass as well as squid. Given this, it was interesting to watch a small school of jack mackerel swimming just above one soupfin's back, occasionally scratching their sides on the shark's rough skin. This behavior may have been to rub off parasites. I have also seen jack mackerel do this with black sea bass in the same waters.

Initially soupfins were taken for export to the Asian market for making shark fin soup. In 1937 it was determined their livers were one of the richest natural sources of vitamin A. During World War II soupfins were especially valuable as a source of this necessary vitamin. Prices skyrocketed and and soupfin populations declined dramatically. Following World War II, the synthesis of vitamin A in laboratories reduced the fishing pressure on soupfins and they started to recover. Today soupfins are caught commercially and sold as fillets or steaks.

According to the International Shark Attack File (ISAF), from 1580 to 2000 AD there was only one recorded attack (non-fatal) on a human by a soupfin shark. Of course these sharks are wild animals, and if provoked they will defend themselves. Given that, if you encounter them do not try to touch them, grab their tails or fins, etc. Given the number of "attacks" by humans on these sharks, it is pretty obvious which species should be feared more!

© 2003 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.

Image caption: Soupfin sharks in Lover's Cove outside Avalon, Santa Catalina Island, CA

This document maintained by Dr. Bill Bushing.
Material © 2003 Star Thrower Educational Multimedia