Scalloped hammerheads are a migratory species of hammerhead. They receive their name from the scalloped front edge of their head. They are a species with a wide-ranging global habitat, as they are found in warm temperate and tropical waters in the Indian, Atlantic, and Pacific oceans.
Scalloped hammerheads are a critically endangered species. The main contributing factor for their endangered species status is due to shark finning practices. Due to their wide range and migratory patterns, they interact with many potential fishing grounds. This leads to an increase in the need for studies to develop policies that best protect and help rebuild their populations. Currently, most of the studies being done are use the tagging of individual sharks to acquire locational data. This method can be helpful in obtaining data where and when boats can’t necessarily follow, but it also possesses some downsides. The biggest downside is the smaller data pool, as one tag is representative of only one shark, limiting the data. Another other big downside is the lifespan of the tag, as after a while, the tag’s battery can die, or the tag may come off.
In addition to being a migratory species, scalloped hammerheads also use and inhabit a wide range of habitats throughout their lives. Females, especially, have high variability in the habitats they use during their lives. Scalloped Hammerheads have a very complex spatial pattern, as the newborns, juveniles, and adult females and males all typically occupy different habitats.
Juvenile females are often found in coastal estuaries. This is thought to be due to good sources of food and protection from predation. After maturing to full adulthood, female scalloped hammerheads migrate out to oceanic waters where they spend large periods of their life. When females are ready to give birth, they will then make the migration back to the nearshore coastal waters to give birth.
Scalloped hammerheads are viviparous reproducers, meaning they have a live birth. Their birth usually takes place in the nearshore coastal waters. Although the mother can be found in oceanic waters during the 9–12-month gestational period, she normally returns to nearshore coastal waters to give birth to litters of 12-40 pups. The newborn pups then proceed to stay in the coastal waters to avoid predation, as it is high.
Adult male scalloped hammerheads have slightly different lifestyles than their female counterparts. Adult males participate in one of two migratory patterns, depending on the individual. The first migratory pattern is the coastal pattern. These individuals remain in coastal waters their whole life. The reason for this is thought to be to optimize their reproductive abilities as they may come across more females as they enter or depart coastal waters. The second of the two migratory patterns is called pelagic migration, as the male sharks leave the coastal waters and migrate to the pelagic ocean. One advantage of this migration is thought to be the widening of the gene pool, as traveling farther from shore means you’re more apt to spread your genes farther than if you were to stay nearshore in the same small population of sharks.
