Salmon sharks

Photo from Animal Spot

The salmon shark (Lamna ditropis) does not look like a salmon fish. Nor is it pink or red or whatever hues salmon are finding trendy nowadays. Found swimming in the eastern and western North Pacific, it seems like a pretty stable population! Hooray! It's why the IUCN has assessed them as... well, don't want to ruin the whole post for you now. 

First, as you can see from the picture the salmon shark is a torpedo-shaped animal with a short snout and big eyes that is grey on top and paler below; their underbelly can sometimes have dark spots scattered throughout. Sounds similar to the great white shark, huh? Well, don't worry- these are sometimes mistaken for one! Tiny, needle-like teeth allow for these animals to catch their slippery prey (like fish) in nearshore and oceanic environments. Yes, including salmon, hence the name. However, it sometimes eats squid, too!

#Finfact: There is a sex ratio difference in salmon sharks across the North Pacific basin. The western side is male dominated and the eastern side is female dominated, and the dominance increases with latitude (Sano 1962, Nagasawa 1998, Goldman 2002). Larger sharks also seem to be bolder, going farther north than smaller individuals, and most southern catches of these animals tend to be in deeper waters (Nagasawa 1998).  The salmon shark migrates south to breed, too.

Speaking of breeding, a salmon shark pupping and nursery ground may exist north of the transitional domain in oceanic waters. From the IUCN bio: "According to Nakano and Nagasawa (1996), larger juveniles than term (70-110 cm PCL) were caught in waters with SSTs of 14-16°C with adults occurring in colder waters further north. Another pupping and nursery area appears to range from southeast Alaska to northern Baja California, Mexico, in the northeast Pacific (Goldman and Musick in press)."

They are aplacental viviparous and, yes, their pups do eat fertilized eggs and each other (aka they are oophagous). Litter size ranges from three to five pups and litters sex ratio isn't always even. The IUCN has assessed these animals as Least Concern (LC).

WHAT DID YOU LEARN ABOUT THIS ANIMAL?

GLOSSARY

• IUCN: International Union for Conservation of Nature.
• Pup: Give birth to baby sharks, skates, rays or chimaeras (pups).
• Pups: Baby sharks, skates, rays, or chimaeras.​
• Viviparous with yolk-sac: Also known as aplacental viviparous and previously known as ovoviviparous/ovoviviparity; it is the production of eggs that are fertilised and hatch inside the female shark but the embryos lack a placental connection to the oviduct or uterus and so do not feed off the mother.

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