Stranded Sticklebacks

Just after low tide on January 20, I wasn’t expecting the explosive blast of a gasoline-started campfire and I wasn’t expecting to find sticklebacks on the beach sand. The sticklebacks, several of them, were stranded in the drift line from the previous high tide.

They were three-spined sticklebacks, one of the common fishes in streams that drain into the ocean or onto the outer shores beaches. I’m interested in how they ended up on the beach, why they were in the surf zone and if I’m going to find sticklebacks are important surfperch prey.

I guess the first thing to consider is whether the fish were alive or dead when they arrived on the beach. Check out the image above. You can see the impression in the sand of where the fish was and where the fish landed after its last flip. Thus, these fish were alive and they either got washed or purposely moved from their home streams into the ocean or directly onto the beach. For live fish, a washout would require a pretty big rain event. Below I show the rainfall for the week prior to my observations:

The only noticeable rainfall was a quarter inch on the night of January 14 and a quarter inch isn’t much on theoutershores. If the sticklebacks reached the surf zone in the week or so before I found them, I’m guessing they made it on their own and they must have arrived via one of the larger streams or rivers with open passage to the surf. Once in the surf, well…the surf zone is a rough place.  A west swell of 8′ with 2’wind waves is a piece of cake for a surfperch, but sticklebacks aren’t designed for life in the surf. I’m not surprised they got dumped.

That’s my thinking about how they got deposited on the beach. What I really want to know is why were they in the surf zone in the first place. If you have a hypothesis, I’d like to hear it.

Note: I updated the photos and lightly edited the text on October 21, 2017.