CSUMB’s “Great White Sharks of California” Talk
Dr. Sylvia Earle said, “Sharks are beautiful animals, and if you’re lucky enough to see lots of them, that means that you’re in a healthy ocean. You should be afraid if you are in the ocean and don’t see sharks.” Sharks are fascinating animals. They have been around for about 540 million years, but only in the past 100 years have we been gathering information about them. On January 30, great white shark researchers Dr. Barbara Block, Dr. Chris Lowe, and Dr. Salvador Jorgensen gathered at California State University Monterey Bay (CSUMB) to share their observations and research on these animals.
Great white sharks are a warm-blooded species. They live in coastal temperate water and live around 30 years. Great whites’ senses are sight, smell, hearing, touch, taste, electroreception, and lateral lines. Sharks have conical snouts and can smell things up to three miles away. Their eyes have reflecting layers called the tapetum lucidum behind the retinae. Unlike some other sharks, they don’t have a nictitating membrane, or third eyelid. Great whites, like other fish, have a lateral line that runs through their body. The lateral line can pick up the vibrations in water from up to 800 feet away. They have pores on their snouts filled with electroreceptors called the ampullae of lorenzini. This allows them to sense the power and direction of currents, sensing the electrical field through electroreception. These sharks have 300 teeth and communicate through open mouth gaping. They have 5 to 7 gills, and since they have no true bone, they have no gill covers. Since great whites are endothermic, they pull large surface areas of sensitive gill tissue.
Dr. Chris Lowe is currently based out of California State University Long Beach and directs their shark lab. He studies shark migrations amongst many other topics through acoustic and satellite telemetry. Lowe uses Smart Position and Temperature (SPOT) tags, which send transmissions to satellites and track the shark’s location. He also uses Pop-Up Archival Tags (PATs) satellite tagging, which sends satellites transmissions from low-volume data summaries.
Dr. Jorgensen studies great whites in the broad ocean at the Farallon Islands, Año Nuevo, and Point Reyes. He works out of the Monterey Bay Aquarium, and studies the shark’s migration patterns and feeding habits; he also studies sharks that have been hunted through long lining. Jorgensen has noticed that Monterey Bay’s great white shark population has increased due to climate change. For the past 18 years he has accumulated data on 100 different great whites through electronic tags.
Stanford Woods Institute for the Environment’s Dr. Barbara Block is a professor of Marine Science and Biology. Her main focus is to learn about shark behavior and migrations. Block gets her data through acoustic tags that send signals to buoys, satellite tags, onboard computers, and shark observers. More recently, she has been working to get the resources necessary to protect great whites from Japanese fishing and long lining. Block has tagged around 400 sharks, some of which have been tagged multiple times.
The biologists worked together to answer the questions of the audience, which was full of students, professors, and others who were looking to learn more about these animals. The scientists gave more information on the devices they use. There is no bait used in the process of tagging the sharks, and some of the tags clamp onto the dorsal fin. Underwater robot torpedos are used to collect data; they are programmed to move near the sharks and swim away if the shark gets too close. The robots build algorithms and look for patterns in the sharks. Peter Benchley, author of Jaws, said, “We provoke a shark every time we enter the water where sharks happen to be, for we forget: The ocean is not our territory–it’s theirs.” While it is important that we learn about sharks, it is also important that we protect them and give them the space that they need, because the ocean is their habitat. Lowe said that they have been using drones and underwater cameras to get footage of great whites. The sharks are very curious about the cameras, and oftentimes swim up to them.
Great whites are only in the Monterey Bay for four months out of the year. Biologists have realized that the sharks are returning to the same birth areas every year. Jorgensen’s data shows that there are increased amounts of sharks in Monterey Bay because of climate change, as they are traveling to the colder water. Lowe mentioned that there are potentially untagged sharks in Southern California that aren’t traveling to the Farallon Islands and Guadalupe. The number of juveniles has increased in Southern California, possibly due to the climate. Juveniles are responsive to temperature, and curious and good at detecting what they are looking at. Young sharks are more perceptive about what they are eating, but Jorgensen mentioned that one issue is that sometimes juveniles confuse otters, who insulate themselves by trapping air in their fur. The rate of otters eaten has increased, which is because kelp covers have decreased, so there is less kelp cover for the otters to live in. Block added that the California female sharks in particular have been traveling to Hawaii during gestation periods, due to the offshore open ocean. Jorgensen said that he wants to wait a few years before making conclusions about new trends, but the human incident rates have increased by 90% due to increased human interaction such as scuba divers, surfers, and swimmers, amongst many water activities.
There are many things that we have discovered about great whites, but there is always more to be learned. When asked what new technology she would like to see, Block mentioned that she would like to create chips on the sharks to prevent poaching. The offshore gill netting has decreased by 85% in the past decade, and Mexico is reenacting protection for great whites. Mexico regulates the ocean over the summer, but the fishers keep their gear in the water and the sharks often get stuck in the gillnets. She added that the Mexicans leave the shark carcasses in the deserts, which provide records at the sites, helping scientists figure out how many sharks are getting caught in these fisheries.
Brian Skerry, an underwater photographer, said, “Remove the predators, and the whole ecosystem begins to crash like a house of cards. As the sharks disappear, the predator-prey balance dramatically shifts, and the health of our oceans declines.” Sharks are essential to our ecosystem. Great Whites aren’t the monsters that they are portrayed to be on television. They are interested in us, just like we are interested in them.