Thursday, August 14, 2008
It is one of the best kept secrets of Mother Nature. When you think of green sea turtles, visions of tropical Islands comes to mind. To folks in the Los Angeles/Orange County area of California, these warm water wanderers are thought to be in far off, exotic locales. And yet in an urban river near the Long Beach/Orange County border, an improbable group of sea turtles inconspicuously resides.
The San Gabriel River runs from the San Gabriel Mountains to its outlet between Seal Beach and Alamitos Bay. About two miles from the ocean, Electrical Power Plants flush warm water into the river raising the temperature way above the normal ocean temperature. And it is in this area that a little known colony of sea turtles reside.
The Aquarium of the Pacific’s Veterinarian, Dr. Lance Adams, and NOAA are getting ready to begin a study of these San Gabriel River sea turtles on August 1, 2008. Dr. Adams, Aquarium of the Pacific Vet Tech Colleen, Aquarist Amy, my wife Pam and I, in a preliminary field survey, watched from banks of the river for these sea turtles. My job that day was to document the presence of the sea turtles in the river photographically. We did see a few sea turtles, but because of the lighting condition, I couldn’t get a decent shot of the turtles. So my wife and I came back on Sunday, August 3 to again try to get images of the turtles and to start recording field notes on them.
In this week’s blog, I’d like to share some of our field notes and images.
Field notes on the San Gabriel River Sea Turtles for 08/03/08:
7:30 – 9:30 a.m.
Conditions: Overcast/Marine Layer, water surface “glassy/very smooth”
During this time, we observed approximately two (2) large, three (3) medium, and two (2) small turtles at various locations along the river. Based on the photos taken, and to the best of our skills/abilities, we have come to the conclusion that the turtles seen were green sea turtles.
During the lower tide (AM observations), most of the turtles stayed farther, about 60-70 yards (at least half way) from the east bank. The turtles usually surfaced very briefly, just showing their heads. One exception was one or both of the large turtles. They actually formed a “surfacing pattern.” The large turtles would surface for two (2) quick sets of three (3) breaths at which time their heads were visible above the surface of the water. The turtles continued to move as they breathed. When the turtles completed a series of breaths, they stayed under for 15–20 minutes. When they did not complete the series, they usually surfaced in 10–12 minutes. The medium/small turtles were very quick to surface and go back under, and did not tend to follow any kind of surfacing pattern. Four turtles were often seen at one time.
11:00 a.m. – 1:30 p.m.
Conditions: clear & sunny, water had slight ripple at surface, and turbulence from all outlets
Based on location of turtle sightings, we now estimated eight (8) turtles in the area (one more large one). Turtles were more active and surfaced more frequently, began to stay at the surface a bit longer, and were closer to the riverbank. The two larger turtles followed the AM “surfacing pattern”, and medium-size turtles would surface in a single series of 2–3 breaths. Two larger turtles spent the whole time surfacing in the same general small area; covering a distance of about 1/8 of a mile. The turtles submerged for about 10–12 minutes (shorter than the AM sightings). The 3rd large turtle was spotted surfacing mid-river, in the turbulence from the first discharge outlet. The medium-sized turtles came to the same area but would also surface closer to the bridge, and further from shore (helf way out or a little further). The small turtles usually surfaced in the “lighter” turbulence near the “water outlet discharge”, but more than half way from the riverbank.
Note: Large, adult California sea lion swam up river (during the AM sighting) and foraged near the power station outflow. Numerous large and small fish were seen leaping from the water throughout both observation periods. Some small fish leaped just as a turtle would surface.
Other incidental sightings along the river included an osprey, coyote, Snowy Egrets, Double Crested Cormorants and Brown Pelicans.
STAY TUNED FOR MORE ON THE SEA TURTLES OF THE SAN GABRIEL RIVER AS THE FORMAL RESEARCH OF THESE CRITTERS, COORDINATED BY THE AQUARIUM OF THE PACIFIC, BEGINS IN THE COMING MONTHS.
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