How many giant Pacific octopuses live in Puget Sound? It’s a question we hear frequently at the Seattle Aquarium’s Life of a Drifter exhibit. And in 2000, we set out to try and answer this common query with a survey and have continued every year since.
In addition to counting octopuses, Aquarium staff and local volunteer divers also make note of the depth where they are found, their den type, the habitat, their size, and if any eggs are present. They conducted the survey in January for the first 16 years; starting in 2016, the survey was moved to October since weather conditions are generally better that time of year.
Also in 2016, Aquarium staff began diving at three specific sites in octopus-protected areas and three in nonprotected areas, with the hope of monitoring the population and better understanding any changes over time. If significant changes are noticed over several years, the information can be shared with government agencies and potentially lead to increased protections for these animals in the wild.
So what have we learned? From 2000 to 2015, the population count ranged from nine at the lowest one year to 49 in another, but the methodology used then doesn’t allow us to draw any conclusions about the population over time. Since 2016, when the survey methodology became more consistent, the numbers have ranged from 41 giant Pacific octopuses at the top end to 20 at the lowest.
For example, here’s the breakdown for 2019:
- 58: divers who participated in the survey
- 39: reports submitted
- 16: different sites visited
- 20: giant Pacific octopuses sighted
The overall conclusion is that the population appears to be relatively stable since the survey was begun in 2000.