• Sharks and Tuna
• Monitoring the Mako
• In the Beginning
• Shark Tracks

Sepulveda fondly remembers these same waters as a childhood setting for many family fishing expeditions. A native of Orange, California, the skills and interests Sepulveda developed in those formative years eventually led to studies at California State University, Fullerton. There he earned a master's degree studying tuna and mackerel swimming energetics (the study of how an animal partitions its metabolic fuel).

His master's thesis advisor, Kathy Dickson, was Graham's first graduate student at Scripps. This link eventually led to Sepulveda's arrival at Scripps, in 2000, where he first volunteered on a project headed by Diego Bernal, a recent Ph.D. graduate of Graham's laboratory.

During this time, the seeds of Sepulveda's research were sown. It also was a time when many changes were occurring in the way sharks and other marine life were fished in California waters. Regulations were put into place to protect leatherback turtle populations by ending gill netting off California north of Point Conception, north of Santa Barbara. This has led to increased gill net activity in southern California waters. Also, in an effort to protect marine mammals swimming near the ocean's surface, gill nets are required to be set at levels deeper than 11 meters (36 feet).

Mako sharks are not the primary target of the California gill net fishery, which is aimed at catching swordfish and thresher sharks. However, makos (predominantly juveniles) make up a significant component of the gill net catch. Mako and thresher sharks are important catches for the commercial sportfishing industry and recreational anglers in southern California.

"Our society is so technologically advanced now that our fishing methods are incredibly productive. We are very, very efficient at removing organisms from the ocean," Sepulveda said.

Little information is known about how these sharks move and spend their time in the Southern California Bight, which extends from Point Conception into Baja California, and is one of the few documented nursery habitats in the North Pacific Ocean for makos.

With all of that in mind, Sepulveda began to put together his first tracking excursion.

"Understanding mako physiology and how it relates to their movements in the wild may provide information that can lead to better management strategies," Sepulveda said.