Tiger sharks (Galeocerdo cuvier) are a migratory species found in coastal and open-ocean waters. The International Union for Conservation of Nature considers them to be ‘near threatened’, highlighting the need to know more about tiger sharks. A study recently published on PLoS ONE provides fresh insight into movement patterns and habitat use of tiger sharks in the Gulf of Mexico. Sex-based differences and quantifiable information on movement patterns were some of the important findings in the study. Between 2010 and 2018, lead researcher Matthew J. Ajemian and colleagues collected 56 tiger sharks from northern Gulf of Mexico, documented their sex and maturity, and tagged them using satellite transmitter tags, which transmit data every time a tagged fin broke surface.
The data revealed that life stage, sex, and season greatly determined sharks’ movement patterns. Mature sharks swam faster and deeper, probably due to improved swimming abilities. Larger sharks (both young and mature) were more likely to migrate seasonally and utilize different food sources in the open oceans, such as sea turtles. Female sharks were associated with higher movements than their male counterparts, and they occupy the Flower Garden Banks National Marine Sanctuary region near the Louisiana-Texas coast more frequently and in larger groups than male sharks. The study also revealed that over 2500 oil and gas platforms serve as core habitats, especially for younger sharks.
However unintended, oil and gas platforms now serve as man-made habitats for younger sharks. And exposing early-age sharks to petroleum-based pollutants and potential oil spills (such as the catastrophic Deepwater Horizon spill, which is still causing isssues today) threatens the reproductive cycle of this species. Knowing their migratory patterns and the extent of their vulnerability will help scientists not only protect this species but also be able to predict the fatal consequences of future oil spills on tiger shark populations.
Matthew J. Ajemian is Assistant Research Professor at the Florida Atlantic University, Harbor Branch Oceanographic Institute.
Managing Correspondent: Rhea Grover
Press Article: Movements of tiger sharks at varying life stages tracked in Gulf of Mexico on Phys.org
Original Science Article: Movement patterns and habitat use of tiger sharks (Galeocerdo cuvier) across ontogeny in the Gulf of Mexico on PLOS ONE
Image Credits: Wikimedia Common