Sportfishers are taking a greater toll on the sea than previously thought, according to a study published in 2004 in the prestigious journal, Science.

This study scrutinized a 22-year record of fishing data and showed that recreational anglers off California, Washington and Oregon catch about 59 percent of total landings of several depleted coastal stocks—including lingcod, bocaccio and six other species of rockfish. California Sea Grant is supporting research to help anglers, scientists and resource managers work together to minimize the impacts of recreational activities on coastal life.

Addressing a critical question for sportfishing, marine biology professors Chris Lowe and Kevin Kelley of California State University, Long Beach (CSULB), examined the physiological effects of catch-and-release practices on California sheephead, a popular sport and commercial fish. A major focus of the research was to gauge stress levels in fish by measuring hormonal changes that regulate growth, metabolism and tissue repair. Specifically, they examined the levels of the stress hormone cortisol and insulin-like growth factor. They also tagged fish to study the mortality rates of released fish and to monitor behavioral changes that might reduce an animal’s long-term chances of survival.

The researchers learned that...

• Post-release mortality rates of sheephead are very low as long as the fish’s swim bladder is deflated before release.

• Being caught on hook-and-line stresses fish more than being caught in a trap. Regardless of gear type, however, the stress of being caught and handled has longer-lasting physiological effects than previously thought.

• The secondary effects of stress may slow fish growth and delay sexual maturity.

More details about this work are available in California Sea Grant’s Biennial Report 2003 & 2004 [BiennialBook.pdf - 1.4 MB] available online at http://www.csgc.ucsd.edu/PUBLICATIONS/ElecPub.html

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