Green Sea Turtles Channel a Habitat

By: 
Steve Propes

A lingering mystery, unlikely to be solved anytime soon. What forces caused sea turtles to show up at the most southerly part of the San Gabriel River. It amounts to the northern most population of green sea turtles, and though science is able to determine a lot about various examples of sea life, the habits and movement of these turtles, which can weigh well over 100 pounds have largely not been established.

Their normal habitat is the tropical coast of Mexico, and generally, these turtles tend to show up in similarly warm to hot environments. The San Gabriel River, actually the mouth of a flood control channel separating Long Beach from Seal Beach is hardly such an environment, but these hardy creatures seem to be thriving.

They do not swim further up the channel, as there is a sharp drop-off point where the channel passes the CSULB campus. With a host of urban activity in the vicinity such as an adjacent massive power plant, freeway access and the flotsam and jetsam expected in such an area, the turtles don’t appear to be affected. The drop off barrier between the river and brackish waters near CSULB can contain shopping carts, baby rays and juvenile fish, said Aquarium of the Pacific Volunteer Cassandra Davis, who also serves as the aquarium’s sea turtle expert.

According to Davis, there have been one to three sightings of mature turtles of reproductive age in the river. Large sized, weighing as much as 200 pounds, they are generally four to five feet long and have the head size of a soccer ball. Life expectancy is from 25 to 50 years. They have more blubber, which makes them bigger than freshwater turtles. The juvenile turtle before sexual maturity is about 12 inches long with a baseball-sized head.

In the past, they were caught by fishermen, which now use TEDs (turtle exclusion devices), generally enforced by regulations. However, outside of U.S. waters, the turtles are still at risk.

In fact, it’s often fishermen who provide insights into the habits of sea turtles and can provide information about tracking these elusive creatures. “They are very difficult to track,” said Davis. “In fifty years of study, a lot of what we know came from fishermen. We do know the population is improving.”

On the east coast, sea turtles are largely found in the Gulf Of Mexico, existing in a circular pattern. Some which escape from the gulf find themselves migrating north, some ending up in the very cold Cape Cod area. There they are captured in a similar rotation to the gulf, eventually beaching. That is when volunteer rescuers scour the beach, looking for near-dead sea turtles, which they deliver to a recovery center. At least one large batch of recovered sea turtles were taken over land to the warm waters off the coast of Georgia and allowed to return to the ocean.

In years past, they were caught and used for tortoise shells, belt buckles, pens and decorative items. More recently, they are a protected species, in the Long Beach area, signs are posted to help or support sea turtles.

It all begins when female sea turtles migrate to lay eggs in Mexico. This process does not occur locally. The migration of juvenile and fully developed turtles is still mysterious. Some speculate they populate the San Gabriel River because of the heating used by the nearby power plants, but others contend they were here centuries before our current population.

The existence of these sea turtles was largely little known until locals began using the banks of the riverbed for recreation. As users of recently installed bike paths began appearing, so did sightings of sea turtles. Thus the need to create a protective zone.

As the river is the outlet for assorted debris, from Styrofoam cups, plastics of all sorts and other unidentifiable objects. The turtles consume whatever is nearby. There have been cited examples of turtles gnawing and apparently digesting a variety of non-food items, but it would seem other sea-life would be on the main menu.

Estimated numbers of sea turtles in the river vary from 20 to around 100. They are difficult to enumerate, as they must surface to be counted. That being the case, the mere appearance of a turtle head doesn’t mean that very turtle hasn’t already been accounted for at least once, or perhaps several times. In other words, they are tough to distinguish, so if one turtle surfaces ten times, does that count for one or ten?

None of this activity goes far in solving the mysteries of the green sea turtles, which, with current methods, may continue for an extended period. With any luck the turtles may continue to thrive, largely unnoticed, in our area for some time to come.

steve@beachcomber.news

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Comments

Enjoyed the Sea Turtle article, I can confirm that they are recent visitors, probably found their way here in the mid-1980s, not here for centuries like somebody speculated. The reason I know is because I was an avid water skier and that channel was my secret ski spot in the early 80s. (No boating signs or speed limits were posted). I never saw another boat go up that channel, partly because there was a fairly large wave break at the mouth; we had to time the waves going in and coming out. If there were turtles, we would certainly have seen them. We stayed up the channel for hours in the warm water, enjoying the unchopped wake from other boats.

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