Even efforts to plant salmon seem to be doomed

Salmon can be fragile creatures. Around 75,000 Chinook salmon smolts being trucked to San Pablo Bay near Vallejo died on the trip, according to a report from Redding Record Searchlight. The U.S. Fish and Wildlife Service in Sacramento told the newspaper it would try to find out what happened.
This is just more bad news for the salmon fishery, which was devastated this year when only around 90,000 fish returned to Northern California rivers to spawn. Everyone has a pet theory about why the fish didn’t return — from a lack of food in the Pacific to pollution in the Sacramento-San Joaquin Delta to predation on the tributary rivers like the Tuolumne and Stanislaus where they spawn — but no one is calling the numbers anything less than catastrophic.
Losing 40 percent of the 180,000 planter smolts doesn’t help.
It shouldn’t take long to find out what caused the dieoff. Valley temperatures exceeded 100 degrees Monday, and salmon don’t like anything above 65; most would die in acceptable bathwater. If the water in the tank truck got warm, it would kill the smolts. Still, a smaller truck carrying juvenile salmon (about six inches long) survived the trip, according to the Record Searchlight. So even when they’re swimming in a tank truck, the deaths of salmon can be downright mysterious.