At Baylands yesterday, a watery, marshy nature preserve in Palo Alto, some kids started screaming "Shark!!"
Well, it's not a shark, but what is it?
Swimming upstream against receeding tide
at least 5 miles from bay leading to ocean
note the size of the bird - the fins were at least 3 ft high and 2 feet across. Maybe 8-10 feet long?
At low tide, this area will have about 2 feet depth of water, and parts of the "river" will be with NO water
I'm guessing some kind of ray? But ..but..it's HUGE
Sandy,
Yours are a pair Dorsal Fins belonging to a pair of Porpoises from what I see in your pics. Rays and Mantas have no dorsal fins so you can rule them out. I am not sure about porpoises but the Bottle Nose Dolphins have a feeding habit of coming up fresh water rivers from the ocean in pods of two to twelve during low tide. They work as a group and heard schools of fish into the shallows then one dolphin will swim in a circle around the school with an unusual tail motion, slapping the water and churning up the silt on the bottom of the river creating a muddy ring around the school of fish to corral them inside. Then that dolphin will swim half way back around and turn into the center of the circle at the school. For some reason the fish will not swim thru the the muddy water but jump out and over it and into the mouths of the waiting dolphins that have positioned themselves perfectly. If this is also a habit with porpoises it would explain why they were there. I included a pic I took last year in florida of two dolpins in the shallows of a river real similar to yours.
Based on size and where you shot it, I would hazard a guess it is Bat Ray (Myliobatis californica )Maximum size is just over 200 lbs. and about 5 feet wide. In shallow waters or around bars they are often seen "flying" that is moving the pectoral fins up and down bringing the tips out of the water. They need very little water to navigate.
Have a great weekend.
Sandy,
I said your fins look like they belong to porpoises, my pics are dolphins, I just posted two additional pics in wildlife of them feeding.
The Ray theory would have your two objects moving up and down or in and out of the water in a flapping of the wings motion, did you notice this at all or where they just moving thru the water like a dorsal fin would do?
From your description of how the two "fins" moved, it's a Bat Ray, Myliobatis californica. It's the right habitat, too. I've seen them as far up as the sloughs around Stockton.
I would guess some type of ray, although not a sting ray. I'm not familiar with rays, skates, etc. over on your side of the country, but I would say definitely not a porpoise/dolphin or sting/manta ray.
Discussion
18 repliesWell, it's not a shark, but what is it?
Swimming upstream against receeding tide
at least 5 miles from bay leading to ocean
note the size of the bird - the fins were at least 3 ft high and 2 feet across. Maybe 8-10 feet long?
At low tide, this area will have about 2 feet depth of water, and parts of the "river" will be with NO water
I'm guessing some kind of ray? But ..but..it's HUGE
Ray
Yours are a pair Dorsal Fins belonging to a pair of Porpoises from what I see in your pics. Rays and Mantas have no dorsal fins so you can rule them out. I am not sure about porpoises but the Bottle Nose Dolphins have a feeding habit of coming up fresh water rivers from the ocean in pods of two to twelve during low tide. They work as a group and heard schools of fish into the shallows then one dolphin will swim in a circle around the school with an unusual tail motion, slapping the water and churning up the silt on the bottom of the river creating a muddy ring around the school of fish to corral them inside. Then that dolphin will swim half way back around and turn into the center of the circle at the school. For some reason the fish will not swim thru the the muddy water but jump out and over it and into the mouths of the waiting dolphins that have positioned themselves perfectly. If this is also a habit with porpoises it would explain why they were there. I included a pic I took last year in florida of two dolpins in the shallows of a river real similar to yours.
I'm thinking a ray..
Sandy
Have a great weekend.
I said your fins look like they belong to porpoises, my pics are dolphins, I just posted two additional pics in wildlife of them feeding.
The Ray theory would have your two objects moving up and down or in and out of the water in a flapping of the wings motion, did you notice this at all or where they just moving thru the water like a dorsal fin would do?
Sandy
It's a Bat Ray