oday we are going to discuss a shark named after a fish (but it’s still a shark!) Salmon Sharks (Lamna ditropis) are fast-moving pelagic, or open water, sharks that are found in varying depths and temperatures throughout the Eastern and Western North Pacific. They have been found as far north as Alaska and south as Mexico. There is also a territory distinction between male and female sharks. There is a higher ratio of male salmon sharks in the Western Pacific, whereas the Eastern Pacific is inhabited by predominantly female populations.
The coloration and shape of this shark has led to misidentification as a juvenile White Shark. However, there are ways to distinguish Salmon Sharks from White Sharks. Salmon Sharks have a darker dorsal (you will remember “dorsal” means the top fin) and white underbelly, which helps with countershading. A prominent characteristic of the Salmon Shark is that of a smaller caudal keel, which is the lateral ridge found in front of the tail fin, located below the primary keel. Salmon sharks can reach up to 10 feet with females reaching maturity at around 10 years old and males just a few years before the females.
This shark was originally largely caught in bycatch in salmon fisheries. According to IUCN Red List of Threatened Species the species is at “least concern” with population levels currently maintaining stability. There are regulations against capture of this species in Alaskan waters but there is little catch data throughout other fisheries in the North Pacific.
To help make sure Salmon Shark populations are continue to thrive, all bycatch in U.S. and Federal waters needs to be documented to help create and improve sustainable management.
Goldman, K., Kohin, S., Cailliet, G.M. & Musick, J.A. 2009. Lamna ditropis. The IUCN Red List of Threatened Species 2009: e.T39342A10210228.http://dx.doi.org/10.2305/IUCN.UK.2009-2.RLTS.T39342A10210228.en . Downloaded on 14 September 2015.
Edited by KC O’Shea
Photography: BBC Natural History Unit courtesy of ARKIVE