Today Island Adventures posted a blog describing sightings of common dolphins in Port Angeles Harbor, which was picked up and pushed back out on the Feiro Marine Life Center Facebook page. First off, were these really Common Dolphins (Delphinus delphis)? I really have no idea, and I would presume and hope that the folks on the Island Adventures boat would know quite a better than I would. There is apparently some confusion about this species on the west coast, with at least one source saying they don't occur on the west coast, but others saying that there is. I suppose they also might be Pacific White-sided Dolphins, which would be rare but not unheard of, at least in this general area? Regardless, I am going to assume that these were common dolphins...in the end it doesn't really matter for my purposes.
Common Dolphins are typically associated with slightly warmer water than we are accustomed to here, and so these photos caught my attention, since just last week I was discussing elevated seawater temperatures with my colleague Eric Grossman, who was mentioning how warm the water was up near his home in Bellingham Bay. This led me to remember that a few years back, when I was working on a climate change impacts assessment for the Olympic Coast National Marine Sanctuary, I put together some Matlab scripts to automate the download and analysis of temperature data collected at NOAA tide stations. So I decided to run my old scripts again.
So this script downloads the entire available record of hourly temperature measurements from a NOAA tide guage (see the photo above of the P.T. gauge, located on the ferry dock in Port Townsend). In most cases temperature is recorded a few feet below the surface. In some cases the record is incomplete or short, but for some of our stations in our area the record typically goes back to the mid-to-late 1990's and can be fairly complete (i.e. no major gaps). Lets look at a selection of those, starting with Seattle:
So, circling back. Common Dolphins in Port Angeles Harbor? Are these dolphins taking advantage of these warm conditions to move into new space in the Salish Sea?