California drought has pushed winter-run chinook salmon on the verge of extinction, authorities have announced.
It’s the second year in a row that spawning has been disastrous, and this is terrible news for the winter-run native fish species which is already endangered.
It appears that the population of young fish swimming downstream through San Francisco Bay from their breeding grounds in the Sacramento River is greatly reduced even in comparison with last year’s migration.
Back then, unusually high water temperatures have wreaked havoc among winter-run Chinook salmon juveniles, because of a shortage of cold water being released from Shasta Dam.
Eventually, just 5% of the young fish managed to migrate to the sea, and it appears now the situation is even gloomier, even though authorities have tried to distribute cold water from the dam across the Sacramento River in ratios.
Due to severe drought which has been prevalent in the last 4 years, coupled with lack of snow, the quantity of cold water available in the Shasta Reservoir was greatly diminished.
Also, the issue was worsened by miscalculations made by the U.S. Bureau of Reclamation, the federal agency overseeing water resource management.
More reserves were mistakenly alloted to agricultural businesses, which required it for irrigating rice plantations, and although they were eventually supportive in redistributing some of the deliveries the damage had already been done.
Therefore, according to biologist Jon Rosenfield of the Bay Institute, the water shortage was actually “entirely avoidable”.
In an attempt to allow stocks to last through fall, smaller quantities of cold water had to be released by the Shasta Dam during the summer, and river temperature, which should’ve been at 56 degrees, was eventually too high to ensure egg incubation.
As a result, few juveniles have survived, mortality rates among the chinook eggs and hatchlings exceeding 95%., according to the National Marine Fisheries Service.
All in all, the number of young fish reported swimming at Red Bluff Diversion Dam is approximately 22% lower than in 2014, although around 20% more adult fish had laid eggs.
For now, according to representatives of the National Oceanic and Atmospheric Administration (NOAA), the only salvation would be a major boost in migration. This could be caused by projected rainfall and increased snowpack due to El Niño in the following months, which might push the young fish below Shasta Dam.
“These numbers would have to improve very dramatically not to have a high level of concern”, cautions Maria Rea, assistant regional administrator for NOAA Fisheries.
This puts immense pressure on next year’s spawning season as well, given that king salmon fish have an average life cycle of 3 years.
In the event of another disastrous season, the viable only measure which might rescue the previously ubiquitous winter-run Chinook fish from extinction would be relying on hatchery-bred salmon.
These captive fish at the base of Shasta Reservoir might delay irreversible declines in population, but this will only be a momentary solution.
Also, NOAA is currently working on a new monitoring system, meant to assess more precisely the cold water stock available at Shasta Dam.
Another recently implemented strategy was installing fiber-optic cables, which theoretically should help keep track of temperature data more accurately and effectively the following year.
Stricter limitations on commercial and recreational fishing, and water cuts for the agricultural sector may also be introduced, to boost conservation efforts even further.
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