Identification: Shortfin Mako are a slender species of mackerel shark, found in most tropical and sub-tropical areas. The species is the smaller of the two Mako species, but what they lack in size they make up for in speed. The shortfin is the fastest species of shark, reaching top speeds of 46 MPH when hunting. This speed has also led to the species being recorded to jump over 9 meters out of the waters surface. Shortfin makos are sexually dimorphic, with females being longer and heavier than males on average. Despite an average weight of 80kg, the largest shortfin ever recorded reached 570kg around the same weight as a small great white.
Shortfin mako are also unique in their ability to adapt their diet dependant on life stage and prey availability. However, different populations appear to have different preferences. Studies of the species found that Atlantic populations predate almost exclusively on bluefish, while Australian populations ate mainly cephalopods. This generalist diet is a distinct advantage for the species and may be a key to its historic success.
Life cycle: As with most sharks the shortfin gives birth to live young with a gestation period of around 18 months. It is typical for a female to produce 4 offspring, giving birth in the early spring. Unlike other species, mako females usually only breed once every three years. This makes the species more vulnerable to population declines as their ability to recover is much lower than other species. They also reach sexual maturity later than other species, with females maturing around 20 years old and having a lifespan of 32 years. This again puts more strain on the species when mature females are killed, with high population abundance not always a good indicator of the species health.
As well as being physically different populations of Mako’s are also segregated by sex and developmental stages, with juveniles spending most of their time in the water near the surface when compared to adults who dive deeper into the water column. Movement patterns between ages also differ with Atlantic populations of juveniles migrating seasonally between offshore wintering grounds and summer feeding grounds.
Species importance: Apex predators like the shortfin mako are a vital part of an ecosystem and help regulate them by ensuring species diversity through predation. Without sharks the numbers of other predatory species would greatly increase, impacting the numerous species that act as prey for them. This type of interaction has been seen around Australia where declines in mako sharks lead to a population boom of groupers fish. This boom lead to a decline in many of the herbivorous fish species that lived in the great barrier reef and lead to a macroalgal bloom that damaged significant areas of the coral reef. It is this type of knock on impact that should be expected in any ecosystem where the top predator is removed.
Conservation status: The shortfin Mako has recently been classified as an endangered species by the IUCN due to a rapid decline in recent years, with population levels dropping by 48% globally since 1986 and in some regions dropping by 97%. As recently as 2017 is was still classified as vulnerable, but at the current rate of catchment it is predicted that the species will be extinct in much of its territory by 2050. A study performed on a single fishery off the coast of Morocco found that there was an annual accidental catch rate of 31,100–46,300 Shortfin mako sharks, with a proportion of one shark per six targeted species, in this case Swordfish. Due to the nature of indiscriminate fishing techniques as well as a number of the species life cycle features, it is likely that without a concentrated conservation effort the species will be fished to extinction.