Mysterious Lifestyles Of Female Great White Sharks Revealed

The results of a two-year study on the migratory patterns of great white sharks has revealed some new insights on previously unknown behavioral patterns of female white sharks in the Pacific Ocean, as well as potential threats from commerical fishing the sharks face on their migration path. 

Up to now, the migratory patterns of Pacific white sharks have been somewhat of a mystery. Researchers have known that the sharks' migratory patterns cover a vast amount of territory, from the coastal locations where the sharks tend to gather all the way into deep ocean far offshore. Males sharks have been tracked undergoing annual round-trip migrations from the coastal mating areas and the deep ocean. But the whereabouts of the female sharks has been unclear, as they were only seen visiting the mating areas one every two years, and previous attempts to monitor them have fallen short due to techinical limitations with long-term tracking. 

Using satellite-linked, long duration radio transmission tags, researchers tracked the movements of four female white sharks tagged at mating site at Guadalupe Island, Mexico, to learn more about the lifestyle of the female white shark.

The study was able to break down the female sharks' two-year migration cycle into four phases. The first is gestation phase where the sharks remain far off shore for most of their 18 month gestation. Next came a pupping phase which where the sharks gave birth along the Mexican coast. Third was transitional phase where the sharks moved from the pupping site back to Guadalupe Island. The final aggregation phase showed fully mature female sharks arriving back at the Guadalupe Island mating site, where they were seen for up to four and a half months before the two-year cycle began again.

The findings shed some light on why the female sharks may stay away from male sharks when not mating as well as potential dangers the sharks face while on the migratory path.

"During the mating phase both males and female sharks are seen with injuries. It's unclear whether males are fighting over food or females or both, but this aggression may be why the females avoid males at other times. Our tracking has also highlighted a previously unknown period of vulnerability when the females are exposed to commercial fishing off the coast of North America," said Michael Domeier part of the team that conducted the study. 

The study was published in the online journal Animal Biotelemetry. 

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