CNMI sea turtles: A shared resource

Why do we need to conserve turtles when we see so many in the waters surrounding our islands? This question is one of the most commonly asked of the DNLR-DFW Sea Turtle Program staff from within the CNMI community. Fortunately, with the assistance of the National Oceanic and Atmospheric Administrations Pacific Islands Regional Office, Pacific Islands Fisheries Science Center, and the Southwest Fisheries Science Center Marine Turtle Genetics Lab, we are just beginning to formulate an answer to that question.

Scientific tools that help turtle researchers find clues to these answers include satellite telemetry and DNA analysis. This past nesting season, three adult female green turtles were satellite tagged and tracked after they finished laying their eggs on Saipan beaches.

What we learned from this experiment was that our turtle named Kumiko swam to Tagum Bay, the Philippines, another named Magas traveled to Miyakojima, Japan, and the third turtle Limwamway laid a total of nine nests before her tag stopped transmitting signals shortly after departing Saipan’s near-shore waters. Saipan’s sea turtles traveled distances of 1,485 to 1,516 miles in under two months time!

After five years of collecting skin tissue samples for DNA analysis from juvenile green and hawksbill turtles hand-captured in CNMI near-shore waters, preliminary lab results are showing that CNMI immature turtles are related to nesting populations found in the Marshall Islands and Yap State, Federated States of Micronesia, meaning that turtles found in CNMI waters appear to be part of a regional stock that uses waters in these Pacific Islands to forage. Genetically speaking, so far Saipan’s nesting turtles (the ones you see on our beaches or mating along our shores) are related to populations in Guam, Palau, Federated States of Micronesia, Melanesia, Taiwan, and Australia. However, some of these evolutionary relations may go back thousands of years.

Another common questions we’re asked is: How old is that turtle? Because turtles have long life spans (upward of 85 years) it takes them until they are 20-35 years old (or 31 inches in shell length) to mature and begin reproducing. The average immature turtle that you may see eating, swimming, or resting around the CNMI islands, based on growth studies performed in Hawaii, is anywhere from 7 to 17 years in age depending on its size. The average length of green and hawksbill turtles captured and tagged in CNMI waters by DLNR-DFW is 20 inches long. Thus if we do the math, the turtles that we see floating around Saipan, Tinian, and Rota all need another 13 to 28 years to grow and mature before they then navigate back to the beaches where they were born to mate and nest. And according to DNA samples taken thus far, this is not on Saipan but the Marshall Islands or Yap State, FSM.

In addition, according to preliminary satellite tag transmission results, our nesting turtles are spending their inter-nesting periods (every 2-5 years) foraging (feeding) in Philippine and Japan near-shore waters.

Basically, the answer to the first question is: because the CNMI sea turtle population is a shared natural resource. Simply put, the teenage turtles we see foraging on our reefs do not nest on CNMI beaches and the adult turtles we see nesting on our beaches do not stay on our reefs. Therefore, we not only need to protect and conserve turtles here in the CNMI if we want our children to be able to enjoy them in the future, but we also must depend on fellow Pacific Islanders to do the same with the turtles we share with them for a part of their long and well-traveled life histories.  

Report sea turtle poaching activities by calling the CNMI DFW Enforcement hotline at 670 888-4917, the NOAA Enforcement hotline at 671-472-7200, the Crime Stoppers hotline at 323-PARA, or 911.