Mako Sharks: eggs for breakfast, jumbo squid for dinner

Shortfin mako shark

Shortfin mako shark

Thanks to Jaws, sharks have received a bad rap that’s really not fair. It’s annoying to even feel the need to mention Jaws, but I wanted to get it over with. Yes, Jaws was a very scary take on the Great White Shark. Not all Great Whites attack humans and not all sharks are Great Whites.

But just in case anyone is suffering from sharkphobia out there and doesn’t even dare put their big toe in the water, let’s take a moment to gain some perspective and put shark attacks in context of the larger picture. According to The Encyclopedia of Sharks, you the swimmer are “1,000 times more likely to drown than be attacked by a shark.” So if you do anything before swimming put on a life vest and just worry about having fun!

In the South Bay, an occasional near-shore visitor is the Shortfin Mako Shark or Isurus oxyrinchus, a sleek deep blue shark with a large dorsal (back) fin and equally large pectoral fins on the side. Now it’s worth noting that mako sharks belong to the family Lamnidae, the same family as the Great White Shark. But it’s not even close to being as ferocious as its white cousin. Plus, mako sharks are pelagic, meaning their preferred habitat is the deep ocean, which perfectly matches their deep blue coloring.

To be safe though, I asked shark expert Dr. Chugey Sepulveda, senior research biologist with the Pfleger Institute of Environmental Research. Here is what he had to say about mako sharks in Southern California:

“Typically off the coast of Southern California people encounter juveniles and these smaller sharks are preying on small prey. Mako sharks that weigh up to 1,000 pounds predominately have an offshore distribution,” said Sepulveda. “It is actually quite rare to encounter a full-size adult along the shoreline, unlike like the great whites who can hang closer to shore. The mako shark is a very blue water shark.”

And to ease your fears even more, according to Probably More Than You Want to Know About the Fishes of the Pacific Coast by Milton Love, there are few reports of Shortfin Makos attacking humans. But treat a mako shark like any other wild animal with teeth, leave it alone and keep your distance, that’s just common courtesy and best manners as an uninvited guest in their home.

Shortfin Mako sharks can grow up to 12 feet. According to Love, a three-foot mako is one to two years old and a five-footer is four to six years old. Mako sharks reach sexual maturity once they grow to six to nine feet and are seven to eight years old. For a fish, sharks live longer than average and the oldest mako found near Southern California was 17 years old.

Most sharks are ovoviviparous and this includes the mako shark. Now what does this mean you ask? Ovoviviparous? This is the awesome word for female animals who instead of laying eggs, actually keep the eggs in the womb until they hatch.

Now of course these are not hard-shelled eggs because that would not only be impractical, but extremely painful. Instead the eggs have very soft shells made from a flimsy membrane material, but the other characteristics of egg birth remain the same. There is a yolk sac supplying food and once this runs out, it’s time to hatch within the uterus.

But mako sharks take the practice of being ovoviviparous one step further. After the baby mako sharks are hatched, they hang out in the womb for awhile and of course start to get hungry, what with the yolk cornucopia gone and all. Hhmm, what to eat, what to eat?

What happens next depends on what books you read and who you talk to. However, after talking to two shark experts and reading a very thorough scientific paper titled “Reproductive biology of the female shortfin mako, Isurus oxyrinchus Rafinesque 1810, with comments on the embryonic development of lamnoids,” I have concluded that mako shark babies practice oophagy. This is another awesome word that means “eating eggs.”

Once mako sharks are born they eat other eggs in the womb. But don’t get the wrong idea; they are not eating their unborn brothers and sisters. Instead they munch on “nutritive eggs” or unfertilized eggs that are in the womb providing extra nutrition for budding baby mako sharks.

After mako sharks are born in litters that vary from four to 25, they hit the open ocean, their version of the open road. Dr. Suzanne Kohin, leader of the Large Pelagics Lab for the NOAA Southwest Fisheries Science Center in La Jolla, has tagged and tracked mako sharks to figure out what happens when they travel the open sea.

“Based on the tagging we have done in Southern California, most mako sharks born in this area stay in Northeast Pacific waters, but we have had a couple turn up near Japan,” said Kohin. “They travel up and down the coast along the California current which seems important to them. Southern California is thought to be a nursery and we hypothesize that females come nearby and drop pups in this area.”

Kohin explained that the majority of mako sharks researchers come into contact with are smaller, but that could be a bias towards the gear they are using from which larger sharks can escape. Another recent phenomenon Kohin and her colleagues have discovered is a change in diet for makos.

“Mako sharks have taken a liking to jumbo squid and we are wondering if that’s linked to the expansion of the jumbo squid habitat,” said Kohin. “Near Baja California, they’ve had that opportunity before to go after jumbo squid but it didn’t seem to be as common off California. But they do seem to be opportunistic; we are now finding a lot more jumbo squid in their stomachs up and down the coast.”

According to Kohin, the best time to see mako sharks in Southern California is during the summer. Typically makos arrive in late May and June and leave around October or November.

As far as the mako shark’s status, there seems to be a slight declining trend in California waters that could be associated with fishing. Mako sharks are one of the fastest sharks and put up a challenging fight when caught, performing high acrobatic leaps, making them an exciting catch. But trends in the catch rates could also be linked to environmental conditions Kohin said.

“Overall it’s good to be concerned about mako sharks because they live a long time, are slow to reproduce and have live young which makes them more similar to mammals,” said Kohin. “This longer life cycle makes them more vulnerable to fishing impacts and in general it’s good to be cautious, even though we don’t know enough about their status to give a concrete answer.”

Yes, it’s good to be cautious in more ways than one when it comes to the mako shark. Remember to be on your best behavior around any and all wild animals with teeth. And removing such awe-inspiring top predators from the ocean should be done with caution. Mako sharks have an important role to play, so let’s make sure there are enough to continue acting in the unfolding drama beneath the sea.

Comments

  1. J Napoli says

    There should be no further doubt that Carolyn Kraft goes the extra mile for getting the most interesting information and interviews–she found an article from 1810 with a title that has more letters than would be allowed in a tweet! More cool info about a cool subject, those (nutritive) egg-eating mako sharks! (I still don’t like the fact that Great Whites stay closer to shore!)

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