Anchovy School Video from Bowen Island-Great Comeback
- Thread starter Dogbreath
- Start date
Why what effect would they have?
It would likely be a complex interaction - dependent upon the amount and size of the fish species involved - and the timing and location of the competing schools.
For subadult, and larger juvenile piscivorous (fish-eating) salmon like coho and Chinook - more large baitfish - such as anchovies might indeed be beneficial. Their eggs and larvae could also contribute to the diet of the smaller smolts.
For the smaller, early marine entrants of juvenile salmon - either they could be competitors for the same plantonic food - or for the larger anchovies - anchovies could be predators feeding directly on outmigrating juvenile salmon (esp. pink and chum).
Alternatively - anchovies could also provide an alternative food source to small fish predators - taking some of the pressure off outmigrating juvenile salmon schools.
BUT...
Most importantly - anchovies are more of a warmer-water fish - at the Northern end of their range in BC. Their presence indicates warming water with the associated decreases in lipids and nutrients found in the warm-water plankton - that the outmigrating salmon would have available to eat. This generally means reduced survival for particularly pink, chum and sockeye salmon stocks - that are primarily plankton eaters.
See: http://oregonstate.edu/ua/ncs/archi...ies-may-be-key-juvenile-salmon-survival-ocean
http://www.estuarypartnership.org/sites/default/files/resource_files/Daly&Brodeur_CREC2016.pdf
http://www.nrcresearchpress.com/doi/pdf/10.1139/F10-080
http://www.klamathbasincrisis.com/fishermen/management/KRUSE1998SalmonRunFailures1997-1998Ocean Conditions_041308.pdf
TheBigGuy
Well-Known Member
It can't all be about global warming in the case of anchovies because my dad told me Anchovies used to be plentiful on the inside of the strait in the old days. He told me they used to quite plentiful up Indian Arm way back when. He told me they were commercially harvested in the old days, until their numbers dwindled and that was the end of the resident Anchovies. Maybe he was mistaken, but my dads family has lived and fished in this area for over 100 years going back to his father's time. The old timers didn't have computers, but I put pretty good stock in them as a source of information.
Halibut were commercially harvested from Vancouver harbour way back when. The resident population was of course decimated never to return. Sturgeon banks off the mouth of the Fraser obviously was so named, for a reason. Don't think you'll find many Sturgeon there nowadays though. Same with Halibut bank in the Lower Strait. Overfishing just wiped out many of our local stocks.
I'm not denying global warming has many negative impacts on on our local stocks. It's just that global warming generally takes a while to impact a stocks viability. Man is far more devastating to fish stocks in the short term, by simply never knowing when to limit harvesting until it's too late.
Halibut were commercially harvested from Vancouver harbour way back when. The resident population was of course decimated never to return. Sturgeon banks off the mouth of the Fraser obviously was so named, for a reason. Don't think you'll find many Sturgeon there nowadays though. Same with Halibut bank in the Lower Strait. Overfishing just wiped out many of our local stocks.
I'm not denying global warming has many negative impacts on on our local stocks. It's just that global warming generally takes a while to impact a stocks viability. Man is far more devastating to fish stocks in the short term, by simply never knowing when to limit harvesting until it's too late.
Hey TBG - thanks for sharing your Dad's observations. I am sure he was a great source of invaluable information.
In those links I sent - they reference other periodic processes/patterns operating that also cause warmer waters to happen in BC (besides GW/CC) - like the PDO.
In those links I sent - they reference other periodic processes/patterns operating that also cause warmer waters to happen in BC (besides GW/CC) - like the PDO.
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