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:
First, Seattle (above). So what you are seeing here is the average monthly seawater temperature in blue, and then in red the anomaly from the monthly average. In this case I've specifically defined the anomaly as being the deviation from the monthly average for the period from 1999-2008, for consistency with the "Marine Water Condition Index" used in Puget Sound. Focus on the red line. What this tells us is that seawater temperatures have been hovering around 1C above average since late 2014 (when the "blob" came ashore), after you account for and remove our "usual" annual signal (i.e. warm in summer, cold in winter).
And its not just a Seattle thing. The record above is from Port Townsend, Washington, where you see much the same signal. Note how very warm the last two winters were in particular!
The signal is quite a bit more muted in Port Angeles (above; i.e. the anomalies are as large, but not as unprecedented in the record) and on the outer coast (Toke Point, shown below). My take is that this is a reflection of just a great degree of water temperature variability as you move out of the Strait to the outer coast:
Above is a different way of looking at these data, shown here for Port Angeles - every hourly measurement available plotted together on an annualized axis. I've bolded the temps from this year to show where they sit in the "usual" pattern. Last year is also highlighted with the heavier blue line...also very warm. So whats clear here is that the last two years in Port Angeles have been pretty warm when you put the whole record into context. The real winner, though, in looking at these water temperature data though is up in Cherry Point, near the Canadian border:
The anomalies suggested here are so huge as to be unbelievable. Is this true? It certainly is consistent with Eric saying that "its warm"...but this is quite something. Below are this year and last year's hourly data plotted together...really gives you a sense for how dramatically warm it is compared to the last 20 years, at least during the non-summer months:
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?