Juvenile White Shark Behavior and Biology

The CSULB Shark Lab has been studying the juvenile white sharks found off southern California for 16 years, in an effort to learn more about their behavior, migration patterns, and biology. We share this information with lifeguards, regulatory agencies, and the general public in an effort to improve safety for people, while also helping to improve management strategies for this species. This work began as a collaboration with Monterey Bay Aquarium with the goal of understanding the behavior and environmental preferences of juvenile white sharks. As the population continues to grow, we are also seeing and tagging more adult white sharks around the offshore islands (Catalina, Northern Channel Islands), Santa Barbara, and San Luis Obispo Counties.

What is a White Shark (aka Great White Shark)

The white shark (Carcharodon carcharias) is a member of the Lamnidae family, a group of sharks known for their streamlined shape that makes sharks in this family highly efficient swimmers. Close relatives of the white shark include the salmon shark (Lamna ditropis), mako sharks (Isurus spp.), and the porbeagle shark (Lamna nasus).

White sharks are a slow-growing species and can live up to 70 years or more. They reach an average length of 14-16 ft. (4.3-4.5 m), with females of the species typically growing larger. Some of the largest white sharks on record have reached approximately 20 ft. (6.1 m) in length. Like all fish, white sharks continuously grow in length over their lifetime, but while growth in length slows down, they tend to increase in girth as they age.

adult white shark
Fig. 1: A white shark seen swimming at the surface. This male was observed at Guadalupe Island off the coast of Baja California, Mexico.

There are genetically distinct populations of white sharks distributed globally in temperate and subtropical waters. These populations spend their time migrating between offshore feeding grounds and coastal-aggregation hotspot areas throughout the year. Juveniles tend to be found nearshore, which suggests that birthing occurs in coastal waters and young white sharks use these areas as nurseries.

White sharks inhabit coastal and oceanic environments, and their movements range in depth. They travel from the surface (dorsal fin breaking the surface) to depths of over 3,280 ft. (1000 m), but have been known to make deeper dives of nearly 4,200 ft. (1280 m) deep. The purpose of these dives is likely for feeding, but little is known about their activity on these dives.

white shark global distribution
Fig. 2: Map of global distribution of white sharks. Areas highlighted in yellow are coastal areas where white sharks are reported to aggregate during certain times of the year. Areas shaded in light blue represent the potential offshore migratory range of white sharks.

White sharks are characterized by having a sharply pointed snout and 5 gill slits on each side of their body. They have a large, stiff, lunate-shaped tail, large pectoral fins, and a triangular dorsal fin that aids with stabilization and maneuverability while swimming.

White sharks have a tapered grouping of muscles and connective tissue near the tail, known as the caudal peduncle, which provides the necessary power for the white shark's lunate (crescent shaped) caudal fin. The caudal peduncle helps propel them efficiently through the water. White sharks also possess one lateral keel that improves the stability of the caudal fin and minimizes drag over the part of the body that drives the caudal fin.

fins and gills of a white shark (Carcharodon carcharias)
Fig. 3: Key external features of a white shark (C. carcharias) with scale bar for size reference.

White sharks are typically dark gray, bluish-gray, or brown on the upper surfaces of their body and white underneath. This pattern of coloration is commonly described as countershading.

Countershading is a form of camouflage that allows the shark to avoid detection by its prey from above or below, and it has evolved in many other animals including fishes, marine mammals, and penguins. Countershading also allows a white shark to sneak up on its prey from below.

 dark on top, light on bottom
Fig. 4: A white shark displaying countershading coloration. The shark is dark grey on the upper parts of its body while the bottoms of its fins and belly are white.

How can you tell if the dorsal fin you're seeing breaking the surface is from a dolphin or a shark? Visit our section on Staying Safe at the Beach to learn more!

White Shark Nurseries in Southern California

In recent years, an increasing number of juvenile white sharks have been observed near many southern California beaches, especially during the summer and fall months. These months typically coincide with an increase in human ocean-recreation, as well. Many of these white sharks are newborns and/or young individuals that use the beaches as nursery habitat (i.e. habitat where the young of a species grow up).

For these young white sharks, southern California beaches provide the ideal nursery habitat for various reasons:

  • Beaches have warmer water
  • Plenty of easy to capture food (stingrays, fish, squid)
  • Safety from predators like adult white sharks, large mako sharks and orca
Juvenile white shark nurseries requirements and technology u
Fig. 5: Nursery habitats are areas where the young of a species can thrive with protection from predators and access to abundant easy to capture prey. Additionally, these habitats are often warmer which allows these juveniles to grow faster, assuming there is plenty to eat. To study juvenile white shark nurseries we use multiple tools and technology such as: eDNA, Drones, Acoustic tracking, autonomous underwater vehicle (AUV).

Female white sharks give birth to live young, and when white sharks are first born, they are 4-5 ft. (1.5 m) in length and are called the young of the year (YOY - so less than 1 year old). The mother does not provide any parental care, and the newborns are fully independent the moment they are born. While no one has ever seen a white shark giving birth, and we do not know where birthing actually occurs, it is suspected that birthing occurs in deeper water, and the newborns move towards the shallower shoreline waters seeking protection and warmth.

Size comparison between female adult white shark and its pup
Fig. 6: Size comparison of an adult female white shark (top) and her offspring (bottom). Newborn white sharks are typically 4-5 ft. (1.5 m) in length while the female is typically 16 ft. (4.5 m) long.

While it is difficult to determine how fast young white sharks can grow, captive studies at Monterey Bay Aquarium and recapture of juvenile sharks in the field, suggests that young individuals can grow about 12" (25 cm) per year for their first 5-6 years. Some researchers group young white sharks into these size categories - neonate, YOY, and juvenile. A white shark between 6-10 ft. (less than 3.0 m) in length is considered a juvenile white shark (JWS). These size classes (neonate, YOY, and juvenile) will utilize a nursery habitat until they are big enough to transition to their adult diet and habitat.

 newborn, juvenile, and adult shark sizes
Fig. 7: Size comparison of the different white shark life stages. A newborn white sharks is 4-5 ft (1.5-2 m), a juvenile 6-9 ft (2-3 m), and a adult white shark (3-6 m).

Two nursery areas have been identified for white sharks in the Eastern North Pacific Ocean: southern California and Vizcaino Bay, Baja CA, Mexico.

juvenile white shark nursey habitats from Santa Barbara to V
Fig. 8: Location of known white shark nurseries in southern California and Baja Mexico. Tagged individuals have been shown to migrate between the two sites.

Depending on water temperature, YOY and JWS are most common along southern California beaches from April-October, and in the late fall, YOY sharks migrate south to Vizcaino Bay, Baja CA, Mexico. The next spring, some individuals will migrate north to SoCal nursery areas.

Within the nursery habitat, there are seasonal hotspots where YOY and JWS are most commonly found. These hot spots can vary from year-to-year, and they may frequent nursery hot spots for several years before eventually moving to adult aggregation sites (e.g., Monterey Bay, Ano Nuevo, Northern Channel Islands, Guadalupe Island).

Sharks detection data from 2009 to 2014. Sharks seem to chan
Fig. 9: Many tagged sharks were detected by acoustic receivers near Will Rogers in 2009-2011, but then shifted to El Segundo/Manhattan Beach in 2012-2014. The reason for these shifts are still not understood.

We do not yet fully understand what makes a good hot spot area for YOY and JWS and how this changes over time, but the CSULB Shark Lab has several projects underway to further investigate habitat preferences, feeding behavior, and migration patterns.

Techonolgy used to study juvenile white shark nursery areas
Fig. 10: Juvenile white shark nurseries can be studied in a number of ways including sampling for environmental DNA (eDNA) from seawater, aerial surveys by drones, tracking movements using acoustic tag technology and satellite tags (PAT tag), and 3D mapping of shark nursery habitat by autonomous underwater vehicles (AUV).

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