Nature & Environment
Sharks Have Taste, Change Diet as They Age and Adopt to Ecosystem
Brooke Miller
First Posted: Oct 01, 2012 06:50 AM EDT
The white sharks are the top most predators feeding on mostly seals and sea lions. These white sharks shift from fish to marine mammals as they mature. But a slight deviation was noticed by the researchers at the University of California, Santa Cruz. They noticed a surprising variability in dietary preferences of individual sharks.
The details of the study was published online September 28 in PLoS ONE. The researchers analyzed the composition of growth bands in shark vertebrae to trace variations in diet over a shark's lifetime. Stable isotopes of carbon and nitrogen included into an animal's tissues serve as a natural tracer of dietary inputs.
"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," said Sora Kim, who led the study as a UCSC graduate student and is now at the University of Wyoming.
For the study the researchers analyzed the vertebrae of 15 adult's white sharks caught along the west coast. According to the researchers the sharks in this region consume seals, sea lions, dolphins, fish, and squid.
"But not every shark eats the same mix of prey," said coauthor Paul Koch, professor of Earth and planetary sciences at UCSC.
"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."
The previous group studies have stated that white sharks found along the California coast have a regular migratory pattern, cruising coastal sites from late summer to early winter and moving to offshore areas during the rest of the year. This study highlights on the dietary and behavioral differences among individual sharks.
"Interestingly, we do see a small shift in diet as marine mammal populations increased after the passage of the Marine Mammal Protection Act in 1972," Kim said.
See Now:
NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone
©2024 ScienceWorldReport.com All rights reserved. Do not reproduce without permission. The window to the world of science news.
More on SCIENCEwr
First Posted: Oct 01, 2012 06:50 AM EDT
The white sharks are the top most predators feeding on mostly seals and sea lions. These white sharks shift from fish to marine mammals as they mature. But a slight deviation was noticed by the researchers at the University of California, Santa Cruz. They noticed a surprising variability in dietary preferences of individual sharks.
The details of the study was published online September 28 in PLoS ONE. The researchers analyzed the composition of growth bands in shark vertebrae to trace variations in diet over a shark's lifetime. Stable isotopes of carbon and nitrogen included into an animal's tissues serve as a natural tracer of dietary inputs.
"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," said Sora Kim, who led the study as a UCSC graduate student and is now at the University of Wyoming.
For the study the researchers analyzed the vertebrae of 15 adult's white sharks caught along the west coast. According to the researchers the sharks in this region consume seals, sea lions, dolphins, fish, and squid.
"But not every shark eats the same mix of prey," said coauthor Paul Koch, professor of Earth and planetary sciences at UCSC.
"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."
The previous group studies have stated that white sharks found along the California coast have a regular migratory pattern, cruising coastal sites from late summer to early winter and moving to offshore areas during the rest of the year. This study highlights on the dietary and behavioral differences among individual sharks.
"Interestingly, we do see a small shift in diet as marine mammal populations increased after the passage of the Marine Mammal Protection Act in 1972," Kim said.
See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone