Naturat Irensiata: Our Natural Heritage

By Greg Schroer
Special to the Saipan Tribune

Haggan—the Green Sea Turtle

Sea turtles are the ultimate ocean navigators. After birth, female green sea turtles spend 20 to 30 years traveling thousands of miles across the open ocean before finally returning to the beaches where they hatched. And it is here that they attempt to perpetuate the cycle once again.

Female turtles nesting on our beaches today most likely hatched from those same beaches during the late 1970s or early 1980s. And the young hatchlings that scramble from our beaches today will be those that may return in the 2030s. This is a long cycle, and it can be broken if eggs are removed or nests are disturbed or destroyed. According to current estimates, only 1 in 300 juveniles survive to a mature age, and that estimate only applies if their nests are not disturbed.

It is uncertain how haggan locate isolated islands and beaches over thousands of ocean miles. But as with all animals, they have a keen perception of their environment, and are in tune to such factors as scent, temperature and ocean currents. Other characteristics, such as sun and starlight, may also influence their navigation.

Haggan are the most abundant turtles around our islands, and they also are the largest hard-shell sea turtles in the world. They have brownish/olive shells (carapaces), which can be more than 4 feet long, and adults average more than 350 lbs. They are second in size only to the leatherback sea turtle (not found in CNMI’s waters), which can weigh in excess of 1,000 lbs! Adult haggan are herbivores and they frequent shallow reef areas and sea grass beds, where they feed on sea grasses and algae. In contrast, the small juveniles are carnivores that typically feed on invertebrates and fish eggs in open ocean (pelagic) habitats.

Once the female arrives in near-shore waters off of her natal beach (or possibly an alternate beach), she can produce multiple clutches of eggs. With each new clutch, she lifts her massive body from protective waters, crawling inch by inch under the cover of darkness. Laboriously she digs a pit using her back flippers, and deposits 40 to 140 eggs before covering them with sand. Within 50 to 90 days, 2 inch (5 cm) hatchlings will emerge at night. Their instinct guides them toward light, which, in the past, came solely from star and moon light reflecting from coastal waves. Today, artificial lights along coasts can misdirect them inland, where the hatchlings perish.

Haggan populations are threatened by egg theft, disturbance or destruction of nesting habitat (including driving and parking on beaches), and lights along or near nesting beaches. Loss of foraging habitats, such as sea grass/algae beds and coral reefs also can adversely affect the species over time.

Historically, turtle meat, eggs and shells were important to the Chamorro and Carolinian cultures, yet today the declining populations are unable to support those practices. Turtle hunting and egg gathering is banned in the CNMI, but poaching still exists in the area and other parts of the world.

We are fortunate to have this member of our island home with us. This species, as well as the rare hawksbill sea turtle (haggan karai), has been listed by the CNMI and federal governments as threatened in an effort to protect them and allow them to recover. The haggan is an important part of our natural and cultural heritage, and it will require conservation awareness and actions to sustain it for future generations.

Information derived from DFW files and public fact sheets.

(Greg Schroer is a consulting scientist and planner for the Division of Fish and Wildlife, Department of Lands and Natural Resources.)