NOTE: The Birch Aquarium at Scripps Institution of Oceanography, along with the Discovery Channel and TimeWarner Cable, will present "Shark Week" at the Birch Aquarium, Sunday, July 30, through Saturday, August 5. For more information about "Shark Week" activities, visit aquarium.ucsd.edu.
As some of the fiercest predators on the planet, sharks have been cast in the public eye with a mix of fascination, fear and awe. Steven Spielberg's "Jaws" thrilled movie-goers in the mid-1970s and furthered the shark's notorious public profile.
Dan Cartamil helps harness a threasher shark that will became part of a research study.
Scientists at Scripps Institution of Oceanography at the University of California, San Diego, and their colleagues have launched an effort to coordinate resources for a better understanding of sharks off Southern California and to elevate public awareness for protecting and conserving them.
The new organization focuses on sharks and rays, animals called elasmobranchs, in the Southern California Bight, an area extending 450 miles along the Pacific Ocean coast from Point Conception near Santa Barbara south to Cabo Colonet in Baja California, Mexico.
"The past century has seen marked reductions in shark populations in the Southern California Bight due to the impacts of commercial and recreational fisheries and changes to critical shark nursery habitats," said Jeffrey Graham, a research physiologist and marine biologist at Scripps. "There is a great need for information to properly manage shark and ray resources, which are vital to the economic and ecological health of the region."
The Southern California Bight Elasmobranch Consortium, which will be headquartered in Graham's laboratory at Scripps, was conceived by Graham not only as a way to link scientific resources, but to engage the public in issues important for shark and ray conservation. According to Graham, at least 40 species of elasmobranchs live within the area. Some large sharks may inhabit the Southern California Bight during seasonal migrations, while others may permanently reside in the area, and many smaller sharks and rays are permanent residents of the coastal areas.
"Part of the idea of the consortium is to raise the level of awareness of elasmobranchs through research and outreach activities," said Dan Cartamil, a graduate student in Graham's laboratory. "Most people are vaguely aware of why it's important not to kill lots of sharks but they are not very well educated about the subject. We'd like to increase public concern of what's going on with sharks and rays in the Southern California Bight and worldwide."
Cartamil indicated that under routine circumstances, fisheries managers, scientists and public officials mostly work independently and information slowly trickles among them.
"This whole consortium idea really facilitates the flow of information and the partnerships among the different groups, which in the long run makes us all more effective at what we do," said Cartamil.
Outreach and education efforts for the consortium will be coordinated through the Birch Aquarium at Scripps. In addition to assembling a large group of science organizations and other research, management, public outreach and political groups in the United States, Graham and Cartamil say it is imperative for their efforts to involve Mexican representatives. Mexican fisheries personnel are especially vital for collecting data that will enable U.S. researchers and coordinators to manage shark fisheries from a "binational perspective" in order to adequately investigate the health of sharks in the entire Southern California Bight ecosystem, they say.
According to Graham and Cartamil, this information is key because commercial and recreational fisheries are catching sharks at increasing rates.
"Recreational fisheries used to be minute, but now, particularly off San Diego in the summer, we see hordes of boats taking thresher, mako and blue sharks," said Cartamil. "We don't know what the impact of that is on the overall population."
Through the consortium, Graham and his colleagues have begun partnering with the National Marine Fisheries Service and Mexico's CICESE (Centro de Investigación Científica y de Educación Superior de Ensenada). Future plans include collaborative investigations on the Pacific side of Baja California to probe the catch rates of thresher sharks in Mexican waters and how those numbers impact U.S. fisheries.
Graham and his students are working with U.S. fisheries managers, including those that oversee the use of gill nets to catch swordfish, but also take blue, mako and thresher sharks, along with a range of other species. In the future, consortium coordinators will develop a web site synthesizing shark catch statistics and other data for academic and public use.
Other factors impacting shark populations include regulatory restrictions for fishery activity north of Point Conception, which has pushed seasonal fishing activity into the Southern California Bight, an area that serves as a nursery ground for juvenile sharks.
Graham and his student researchers also are investigating the activities of juvenile sharks and the locations of nursery grounds, areas critical for the health of shark populations. Juvenile and newborn mako and thresher sharks, for example, typically occupy areas closer to shore, distinct from adult sharks.
"The removal of a large number of juveniles from a population jeopardizes that population's future reproductive potential and may lead to reduced numbers in the future," said Cartamil. "The juveniles are a reservoir, in essence, because they are the future of the fishery... But we don't yet know where those nursery grounds are and how they are impacted by fisheries and habitat degradation. These are the kinds of biological questions that are really important for fisheries management and that we are attempting to answer."
For years, research in Graham's laboratory has focused on sharks from physiological and biological perspectives, including investigations of swimming and cardiovascular mechanics. But with declining populations and increasing fishing activity in the region, the focus of his research group began to widen a few years ago to include shark ecology and habitat studies.
Members of Graham's laboratory recently completed projects in which adult thresher sharks were briefly captured and fixed with acoustic and archival monitoring tags. The data from the devices allowed the researchers to study the sharks' movements and learn about their habitats and population distributions along the bight.