GVI
Posted: February 22, 2023
Lemon Sharks are the third largest species in the Carcharhinidae family of sharks. Notorious for their bold behavior, lemon sharks are prominent in coastal ecosystems all around the globe, living in estuaries, and shallow inshore waters close to the coasts of North, Central, and South America. With a bold presence and gracefulness that captures the eye of many, this distinctive species of shark is nothing short of remarkable. In this article, we’ll delve into the anatomy and physiology, habits and habitats, social dynamics, evolutionary history, interaction between humans and lemon sharks, impact of human activity on lemon shark populations, and conservation strategies for lemon sharks.
The average adult lemon shark is typically around 2.5 to 3.2 metres in length and can weigh close to 160 kgs. They have a robust and stout body shape, with a sparse scattered pattern across the dorsal side that extends through to the underside of the pectoral fins. The first two dorsal fins are small to moderate in size and the trailing edges are not pointed. The tail has a lower end that is larger than the upper end and has a distinct black marking along the trailing edge.
Lemon sharks possess an impressive sensory system that allows them to detect changes in their environment. Electro-perception is one of the shark’s main tools for hunting and may help them detect the electrical fields of prey beneath the ocean surface. In addition, lemon sharks have an array of sensory organs including eyes, nostrils, lateral line organs, photophores and ampullae of Lorenzini, allowing them to detect prey not just in darkness, but also in murky waters.
Lemon sharks primarily inhabit shallow sheltered coastal areas around coasts worldwide. During winter they migrate offshore to deeper waters and return again around spring. They feed mostly on bony fish, crustaceans, mollusks and even small cetaceans in some areas. While they mostly prey on small prey, they are also capable of taking down large animals if they team up with other lemon sharks.
Lemon sharks generally keep close to the seabed during the day, preferring overhangs or caves for refuge. They become more active at night and can swim up to 550 metres from their resting area. Lemon sharks are comparatively placid species and do not readily attack divers or boats.
Social behaviors among lemon sharks are still largely unknown due to limited observed interactions between individuals. Lemon sharks exhibit sexual dimorphism in overall body size with the females being larger than the males. While sexual dimorphism often suggests that there are distinct differences in social behaviors from one sex to the other, it is still unknown if this is true with lemon sharks.
While most of their social behaviors remain unrecorded, what is known is that lemon sharks generally avoid each other outside of mating season; as individual feeding territories are maintained year-round. Groups can form periodically during mating season when a female is ready for mating. During this period males will compete for her attention by swimming alongside her or even swimming beneath her and forming leks.
The lemon shark is believed to have evolved some 75 to 95 million years ago during the Cretaceous period. As part of the Carcharhinidae family they are more closely related to hammerheads and bulls than other species such as great whites or tiger sharks. This lineage has undergone significant evolution enabling them to grow up to 3.2 metres long and to inhabit tropical waters worldwide.
Genetic studies suggest that early ancestors of lemon sharks were likely fished out of shallow waters like estuaries on what today is the Peruvian coast although they are now found on both sides of the Atlantic Ocean.
Humans have had interaction with lemon sharks since ancient times however, most of it has been less than favorable for this species. As far back as 300 BC it is recorded that humans in Peru were catching many different species of shark including lemon sharks, from Lima Bay and selling them in markets. As years went on these unsustainable practices and non-selective fishing methods continued, leading to a sharp decrease in lemon shark populations.
In recent years, due to increased human contact lemon sharks have been presented with more risks such as bycatch and gear entanglement as well as impacts from coastal development and climate change. In some areas where lemon shark populations have declined severely some local governments have taken action such as providing protection to areas where this species is found as well as establishing sustainable fisheries with regulations in place concerning sizes and limits.
In many parts of the world, human activity has led to significant losses in resident lemon shark populations due to overfishing, habitat destruction and pollution. Despite significant research conducted during recent years on juvenile lemon shark survival rates and growth rates, population levels have continued to decline at an alarming rate.
In addition, it has been discovered that some forms of fishing bait used by recreational anglers has caused accidental capture of young lemon sharks which lead to their death due to improper handling methods. With uncontrolled urban development occurring close to certain habitats that are utilised by this species, further developments have caused more disruptions to lemon shark migration patterns.
Given the current status of declining populations for this species, a variety of measures have been initiated worldwide focusing on the conservation of lemon sharks. These strategies involve voluntary catch-and-release tactics from recreational anglers, implementing sustainable fisheries management plans with quotas and assessing local fishing practices that encourage population growth.
Local governments have also taken it upon themselves to place bans on commercial fishing methods within certain jurisdictions as well as restrictions on targeting particular sizes for specific species including lemon sharks. Public awareness initiatives about sustainable practices and threats have been made available in many locations with an incentive for people to become involved in their conservation efforts.
Did you know that GVI offers an exciting volunteer opportunity in Seychelles to support lemon shark research? As a volunteer, you’ll work closely with marine biologists to collect data, gain valuable field experience, and help protect these magnificent creatures.
Discover the inspiring stories of endangered species that have recovered from the brink of extinction. Learn how you can get involved in conservation efforts.
Petrina Darrah
Posted: May 20, 2023
