Do Mako Sharks Lay Eggs?

Have you ever wondered, "Do Mako sharks lay eggs?" You're not alone. These fascinating apex predators, known for their speed and agility, have indeed captured our imagination. However, their reproductive habits are less known to the public. So, let's delve into the world of mako sharks and find out whether they are oviparous or viviparous.

Mako sharks, scientifically known as Isurus oxyrinchus, are part of the Lamnidae family, which also includes great whites and shortfin makos. Before diving into their reproduction, it's crucial to understand that makos are viviparous, meaning they give birth to live young, unlike some other sharks that lay eggs.

Mako Shark Reproduction

Mako sharks reach sexual maturity between 7 to 8 years, with females maturing later than males. This lifespan, coupled with their late maturity, contributes to their slow population growth and subsequently, lower resilience to fishing pressure.

Reproduction in mako sharks involves a peculiar behavior known as "mating balls." During this process, males form groups around a single female, competing to mate with her. These intense interactions, which can be quite violent, serve as a fascinating example of sexual selection in the animal kingdom.

Pregnancy and Gestation Period

After mating, the fertilized eggs develop into tiny embryos, a process that makes mako sharks viviparous. Mako sharks have a placental system called a yolk sac placenta. This structure provides nutrition to the developing embryos directly from the mother's bloodstream, ensuring they grow strong and healthy.

The gestation period for mako sharks varies slightly, but it generally lasts around 12 to 15 months. This long period allows the embryos to grow significantly. Once ready, the mother mako gives birth to fully-developed pups, a process known as viviparity.

Pupping and Post-partum

After giving birth, female mako sharks usually produce a clutch of 4 to 25 pups, with an average litter size of around 12. When born, these pups are already quite sizeable, measuring around 40 to 55 cm in length. This large size at birth gives them a better chance of survival in their harsh marine environment.

Postpartum, the mother mako does not nurse her young. Instead, the pups are fully independent from birth, swimming off and fending for themselves. This lack of parental care is typical among shark species and contributes to their high early mortality rates.

Difference Between Mako Sharks and Other Egg-laying Sharks

Since we've established that mako sharks do not lay eggs, it's essential to understand how they differ from other sharks like the dogfish sharks (order Squaliformes) and skates and rays (superorder Elasmobranchii), which do produce eggs.

Sharks like the spiny dogfish lay eggs encased in a horny case or capsule, often attached to vegetation or other submerged structures. These "mermaid's purses" protect the developing embryos until they hatch. In contrast, mako sharks, as discussed, give birth to live young.

Conservation and Threats

The International Union for Conservation of Nature (IUCN) lists mako sharks as Endangered on their Red List of Threatened Species. Overfishing, particularly in tuna purse-seine fisheries, coupled with their slow growth and late maturity, has put mako sharks on a path to extinction if not properly managed.

Their delayed reproduction and low productivity make this species highly susceptible to overexploitation. Therefore, conservation efforts focused on reducing bycatch and promoting sustainable fishing practices are crucial for their recovery and continued survival.

Mako sharks are an incredibly fascinating species, and understanding their reproduction, from the absence of egg-laying to their unique mating behaviors, helps us appreciate the complexity and uniqueness of life in our oceans. As responsible stewards of the environment, learning about and protecting these remarkable sharks should be a priority.