On 8 April 2018, David Ellis conveyed the following observation sent to him by Grant Scott of the Hornby Island Conservancy:
Fifteen years ago when the sea lion population started to greatly expand around Hornby we thought it was mostly young male Steller sea lions. Female Stellers and California sea lions started to show up more recently. This year there were hundreds of both species which tend to stay apart--Steller on Norris Rocks and California on Flora Island. There are also mostly Californias in Baynes sound. This year there were a great number, like in the low hundreds of Steller females and nursing pups, but not Californias. We were wondering whether Norris is becoming a rookery as the young are definitely small and nursing. There was what looked like an afterbirth. We asked Dr John Ford from UBC why they are now here? As in many such questions there is no one simple answer. Obviously they are here for the herring but they arrive starting arriving in November and the spawn doesn’t happen until March so obviously they are feeding on something else as well. Sardines? Hake? I think I read that hake are the largest biomass of fish in the Salish Sea. I’m not sure if that is true. There is obviously a good food source here as they look and act healthy.
Secondly, climate change both the cyclical El Niño and El Niña event and global warming has changed the traditional sea lion food source elsewhere.
Thirdly commercial fishing, both overfishing and changes in fishing patterns, in Alaska and off the coast of California.
It is probably a combination of all three. Please note that I am no expert but have been a keen observer and questioner for many years.
David Ellis replied on 8 April 2018:
Grant, this is valuable observational local knowledge that the scientific community will want too. I will send a map of where DFO notes where the hake, the major sea lion food, spawn in winter. Deep in the middle of the Salish Sea. So wonderful it would be to be a sea lion, and to travel to such depths. And then come up for some herring for dessert.
Grant Scott replied on 8 April 2018:
Thanks. I'd like to see the hake map. I know there are also gray cod and sablefish in deep water around Hornby. I’ve caught both dropping a line down to 300 feet. Maybe sea lions feast on these fish as well. Apparently they can dive to 600 feet.
David Ellis replied to Grant Scott:
...you should apply for an experimental troll fishery for [hake] and for pollock too... Black cod [hake] to be delivered alive. Any size. Live sea urchin coming into Stevenson now. Smaller ones...
Herring biomass could be assessed by DFO in this way too (see below). In the summer so we could see the real extent of the "resident" herring. And protect and rebuild them as each community adopted a local population. And also enhanced it when it's spawning location was found.
Pacific hake aggregate to spawn in the deep basins of the Strait of Georgia from late .... ( CompuGrid, Langford 1996) for mapping and spatial and statistical analysis software (S- Plus)
http://publications.gc.ca/collections/collection_2015/mpo-dfo/Fs70-1-1999-15-eng.pdf
David Ellis started this conversation with the following question and observation:
Why are so many "singles" [California] sea lion males coming up [to Canada's Pacific] - is it sardine or hake overfish[ing]? Or another reason?
"Global warming" and "herring/sardine abundance cycles" do not [explain] it if heavy overfishing down [in California] coincides completely with this huge sea lion migration. A hundred very hungry sea lions on a single seine "set" for herring has got to tell us all something.
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Observations From Members