Tope, Galeorhinus galeus

Tope, Galeorhinus galeus. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, September 2013. Length: 69 cm (2 feet 3 inches).

Tope, Galeorhinus galeus, Female. Fish caught at night from the beach, Encinitas, California, November 2016. Length: 1.75 m (5 feet 9 inches). Catch, photograph, and identification courtesy of Ben Cantrell, Peoria, Illinois.

Tope, Galeorhinus galeus, Female. Fish caught at night from the beach, Solana Beach, California, May 2019. Length: 1.85 m (6 feet 1 inch). Catch, photograph, and identification courtesy of Ben Cantrell, San Diego, California.

The Tope, Galeorhinus galeus, is a member of the Hound Shark or Triakidae Family, that is also known as the School Shark and the Soupfin Shark and in Mexico as  tiburón aceitoso. Globally, this is only species in the genus Galeorhinus, and it  is found in Mexican waters of the Pacific Ocean.

The Tope has an elongated slender body and a long snout. They are gray or brown on their backs and sides transitioning to white ventrally. The underside of their snout tip is translucent. Their fins have no distinguishing marks with the exception of their pectoral fins, which have pale edges. Some fish have scattered pale spots on their flanks. Their head has a rounded mouth, very small front nasal flaps, and horizontal oval eyes. They have small teeth of equal size on both jaws; these are broadly triangular with serrations on 1 side. Their anal fin is the same size as the second dorsal fin and its origin is behind the origin of the second dorsal fin; their caudal fin is strongly asymmetrical with a long upper lobe and a well-developed lower lobe (a key to identification); and, their first dorsal fin is much larger than the second dorsal fin and is inserted well behind the pectoral fins. They have 5 gill slits with the last 2 being over the pectoral fins.

The Tope is a coastal schooling pelagic species found demersal over the continental shelf at depths up to 470 m (1,545 feet). They reach a maximum of 2.0 m (6 feet 6 inches) in length, with females being slightly larger than males, making them the largest member of the Hound Shark family. As of January 1, 2024, the International Game Fish Association world record stood at 33 kg (72 lbs 12 oz) with the fish caught in coastal waters off New Zealand in December 1986. They feed on crabs, fish, isopods, shrimp, squid, and polychaetes worms. In turn they are preyed upon by larger predatory bony fish including the Great White Shark, Carcharadon carcharias, the Sevengill Shark, Notorynchus cepedianus, and large marine mammals. They are a highly migratory species having both winter and summer grounds and can travel up to 2,500 km between sites. Reproduction is via aplacental viviparity with embryos being nourished by yolk-sac placenta. Litters range from 20 to 25 pups that are born live and are 26 cm (10 inches) to 40 cm (16 inches) in length. They have lifespans of up to sixty years.  The Tope is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

The Tope is a resident of all Mexican waters of the Pacific Ocean with the exception that they are absent from Mazatlán, Sinaloa, southward along the coast of the mainland south to Guatemala.

The Tope cannot be confused with any other species due to the shape of its tail.

From a conservation perspective the Tope is currently considered to be of Least Concern in Mexican waters but Vulnerable globally with decreasing populations although they have a wide global distribution in temperate waters. Major factors affecting their long-term survival include unregulated targeted fishing with gillnets and longlines, habitat destruction in nursery areas, and a very low reproduction rate due to females requiring 10 years to reach sexual maturity. They have known pupping areas in shallow protected bays and estuaries which makes them easy targets for commercial fishermen. They are an important recreational species in some parts of the world. In the Eastern Pacific they were a focused species between 1936 and 1944 as a source of Vitamin A but with the production of synthetic Vitamin A, that demand has been eliminated. Globally a modest demand still exists for their liver oil, meat, and fins. In general, their meat is considered of marginal quality and not of economic significance. Recently all sharks have become protected species in Mexico. The Tope is considered to be harmless to humans.