White sharks are known to feed primarily on seals and sea lions. But, by analyzing the composition of growth bands in shark vertebraefrom 15 different sharks, the team was able to determine variations in a shark’s diet throughout its lifetime.
“We did find that white shark diets changed with age, as expected, but we were surprised that the patterns and extent of change differed among individuals,” explained Sora Kim, who led the study as a UCSC graduate student.
All of the sharks used in this study were caught along the west coast of the U.S. near California. Sharks from this area feed on seals, sea lions, dolphins, fish and squid.
Co-author Paul Koch, professor of Earth and planetary sciences as USCS explained that not every shark eats the same thing.
“We confirmed that the diets of many individuals observed at seal and sea lion rookeries shift from fish to marine mammals as the sharks mature,” he said. ”In addition, we discovered that different individual sharks may specialize on different types of prey. These two types of flexibility in feeding behavior are difficult to document using traditional methods, but may be very important for understanding how the population is supported by the eastern Pacific ecosystem and how it may respond to changes in that ecosystem.”
To learn more:
- Read the full press release from UCSC here: White shark diets vary with age and among individuals
- Read the full study published on September 28 in the journal PLoS ONE: Ontogenetic and Among-Individual Variation in Foraging Strategies of Northeast Pacific White Sharks Based on Stable Isotope Analysis
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