Leopard Sharks in Tomales Bay and Drakes Estero

Leopard Shark. Photo by Kambiz Kamrani. 2005

The easily identified Leopard Shark is often encountered in our waters near Point Reyes, often when paddling near them in our kayaks on tomales Bay and Drakes Estero. But it is in the turbid estuarine environment where this attractive little hunter really shines. Paddling around in June and July we often see the water roiling about with tails and fins as these beautiful fish find mates and give birth.

Leopard Sharks do not rule these murky waters uncontested. They share estuaries with, among other, Shovelnose Guitarfish, Bat Rays, and the Brown Smoothhound Shark. The Leopard Shark and Brown Smoothhound are closely related and would be expected to be competing for the same resources. A study looking at the feeding habits of the Leopard Shark and the Brown Smoothhound in San Francisco Bay found that both species feed predominantly on shrimps, crabs, and fishes, but that Brown Smoothhounds hunt predominantly in rocky intertidal areas while the Leopard Shark tends to feed more in muddy areas of estuarine waters.

Leopard Shark at Point Dume. Photo by Heal the Bay. 2008

Leopard Sharks have a richly varied diet and employ several predatory tricks to secure their meals. Some Leopard Sharks feed heavily on Fat Inn-Keeper Worms, which are forcefully sucked from their U-shaped burrows. Others mutilate burrowing clams by nipping off their fleshy siphons (breathing tubes which stick out of the mud), completely ignoring the rest of the critter. When feeding on circling, densely packed schools of anchovies, Leopard Sharks have been reported to circle in the opposite direction with their jaws open, snatching up the small fish that crash right into their mouths. Their adaptable feeding behavior and appetite for several different species, undoubtedly contribute to their success.

"Jaws" Leopard Shark. Photo by Kambiz Kamrani. 2005

The Facts:

Size: At birth, Leopard Sharks are 7-8 inches. At maturity males are 28-47 inches, females are larger, 43-51 inches. The maximum recorded length is 71 inches.

Reproduction: Males mature at 7years, females at 10 years. They are ovoviviparous, meaning that they give birth to live young that have hatched from eggs within the body. The gestation period is around 12 months, at which point they give birth to 4-30 pups alternate years.

Diet: Juveniles mainly eat shore crabs. While adults have learned a scattered diet of small fish, rock crab, worms, clam siphons, and fish eggs.

Habitat: Leopard sharks are found in and around estuaries, sand bars, rocky reefs, kelp forests and especially like pliable muddy bottoms where food can be found and pried out easily.

Depth: Intertidal, literally inches deep, to about 300 feet.

Bat Rays in Drakes Estero and Tomales Bay

Bat Ray. Photo by Linda Thomas. 2005

Bat rays are commonly seen in our shallow waters of Tomales Bay and Drakes Estero. Kayaking along, often you will see the tips of their grayish-brown fins flapping just above the surface of the water as they meander through the eelgrass beds. The Bat Rays we find in Tomales Bay are a type of Eagle Ray and you may have heard someone refer to a “bat ray” as an “eagle ray”. Bat rays are sometimes sought after by fisherman for there edible meat. In some areas around the world rays have been overharvested and beaches filled with their remains lie as a daunting reminder to any species fragility.

 Ray Skeletons, Baja California Sur, Mexico. Photo by Tressa Bronner. 2007

Bat rays were eating oysters being farmed in the bay for human consumption, but they weren't the only marine animal looking for a meal.  There was a push by farmers to reduce the predation of their farmed oysters by the rays. With the reduction of bat rays and continued predation of their oysters it was discovered that the rays were actually feeding on crabs that were feeding on their oysters. 

These creatures are fun to watch and it is magical when they swim underneath your kayak.

Kayaking Drakes Estero. Photo by Tressa Bronner. 2009

The Facts:

Size: At birth, these rays are around 8 inches across and are born with their tail wrapped around themselves to protect the mother from the barb on their tail while giving birth. Rays grow steadily until hitting maturity, at which time growing slows. Females are larger than males, ranging 40-70 inches across at maturity. Males range from 23-40 inches across at maturity.

Diet: Bat Rays use ther "wings" to hunt for food. Flapping their pectoral fins in the sand, they expose buried prey, such as clams. Rays also use their lobelike snouts to dig prey from sandy bottoms.

Bat Ray Photo by Linda Thomas. 2005

Reproduction: Males typically live up to six years. Females live longer, up to 25 years of age. In May-July, 2-10 pups are live born after a ten to twelve month gestation period. During mating season, June and July, the rays can be seen in Drakes Estero and near the oyster beds north of Hog Island in Tomales Bay. The rays move into the estero for birthing just as the harbor seals are wrapping up their birthing season.

Range: Bat rays move into open coastal waters as water temperatures drop below 50 degrees F and head for warmer water. They are often seen schooling with smoothhound sharks and leopard sharks as they travel.

Predators: Bat rays are eaten by Great White Sharks, Seven gill sharks, and occasionally by sea lions and humans.

Stay tuned for our next blog about creatures we have been seeing while on the water, leopard sharks.

*Linda Thomas has more photos available for viewing . Check out her ac4it's Flickr page.