Turtle in SF Bay?

Hey all, stopped at the observation pier under the bridge on YBI on my way home, and saw this little guy. Pic is kinda lousy, but I watched it swim up to the rocks and climb out. Was maybe 6" or so across the shell.

I didn't realize SF Bay had marine turtles.

Very cool.

Looks kind of like a trash bag. But, assuming it is a turtle, are you sure it is a marine turtle? Maybe it's a freshwater turtle on its lunch hour...

That’s a pond turtle. At least it sure looks like it.

How many points is that worth for AOTY?

When I was a kid fishing muni pier in SF I saw a middle age Asian woman  walk onto the pier and stopped next to where I was fishing.  She rested a cardboard box on the rail and started tossing freshwater turtles into the water.  My friend and I walked over to try and explain those turtles would die in the saltwater but she never even acknowledged us.  Had this serene smile on her face as she dropped about a dozen turtles into the bay.  Since then I've learned that Buddhists sometimes free animals that are destined to be killed(eaten) as a religious practice. 

I wrote this as an explanation of how the turtle in your picture could have gotten there, but then I had this far fetched thought that maybe this turtle was one of the survivors from my high school days.   

That would be so cool.

It definitely could have been a freshwater turtle someone released, but given where it was, I kinda doubt that. The shell kinda looked like a pet store turtle, but I'm definitely no expert. I was maybe 15 ft from it at the closest.  Caught me a bit off guard. How long can a freshwater turtle live in saltwater, and how far can one that size swim?

I looked up CA turtles later, and maybe it was a baby hawksbill? Coloring was about right. No idea if those ever come into the bay tho.

Turtles show up in the strangest places on the coast.  they're super tolerant of a variety of conditions.  I saw a turtlehead repeatdly pop up in the surfline at Corona del Mar once in belly deep water, it was a trip.

I don't think marine turtles can climb out on rocks very easily with their flippers. Freshwater turtles have claws that would allow for slightly better purchase. In Maryland the terrapins live in brackish water. Our only native freshwater turtle is the Western Pond Turtle. But non-native Red Ear Sliders and Painted turtles are more common in most urban ponds and waterways. They get larger and are more aggressive and can out-compete the native ones.

That is a red-eared slider.  A nonnative FW turtle.  Our river systems are full of them.  I counted over 200 at Fox Grove on the Tuolumne River one sunny afternoon last year.  Some were bigger than a dinner plate, some no bigger than a can of chew.  Many of the rivers are making pre-flood releases (10,000cfs) where normal flows range between 100cfs and 500cfs this time of year.  It makes sense to me that numerous FW turtles are taking a ride on the flows and ending up in the Bay. 

Tried to find a prior post where someone described how they caught red ear sliders and gave them away as pets.  Instead, found a old post where a sea turtle was in a river:

I vaguely remember that story. This is not that.....  Flat smooth carapace vs rounded plated carapace. How about those front legs – free dive flippers vs mitten claws.  We are over run with invasives.  But wait, last year ~12,000 Mahi-mahi harvested in southern CA.  that's about 8,000 more than any previous year.  Wait till they start showing in the Bay, we probably wont complain about the lack of salmon any more......

Yup, looks like a red-eared slider.  The most common pet shop turtle in the country and invasive species on the west coast.  They often outcompete our native western pond turtles and cause all sorts of ecological havoc.  I did my masters research on the western pond turtle and freshwater turtles have been known to live in brackish water, but I would be surprised to see them spend too much time in SF bay.