Something weird is going on in the water

Tom Stienstra

October 28, 2007

(10-27) 18:44 PDT -- Sometimes in nature, nobody has a clue what's really going on out there. Now is one of those times.

There's a mystery that spans the Pacific Ocean . It touches San Francisco Bay . It extends up the rivers. Even at Shasta Lake , the state of affairs can be nonsensical.

Whether you fish or not, the information should at least be puzzling, if not alarming. In the past few weeks, I've roamed around the Bay Area, the Sierra foothills and fished the bay and several north state lakes. The entire time, I'm wondering what will come next. Every week brings a surprise. And here's why:

-- Bay Area coast: For the second straight summer and fall, the Farallon Islands National Marine Sanctuary has been a wildlife paradise. In the past 30 years, there have never been so many humpback whales and dolphins, feeding and playing. There have been colossal schools of baby sardines, like nothing I've ever seen. At the Farallones, there have been so many murres, puffins and gulls, along with occasional arrivals of pelicans, shearwaters, albatross and others, that I've seen the birds shoulder-to-shoulder for acres on flanks of the south island. The sea is so full of life off the Bay Area coast that it is one of the richest marine regions in the world right now.

And yet: Where are the salmon? They seem to have disappeared the past two years. Last year, the Department of Fish and Game's salmon forecast, a reliable indicator for years, predicted a banner year. This year, the forecast was for more of an average season. Instead, the flow of fish was reduced to a trickle, and the big schools vanished. This makes no sense, since ocean upwelling, sea temperatures and abundant food have allowed other marine life to flourish.

I've asked several biologists for their theories, and as they come in, I'll print them. If you have an opinion, please e-mail it to me.

-- Halibut in the bay: You hear a lot of doomsday-type stuff by environmentalists about the bay, but the number of halibut in the bay this summer was the highest most have ever seen. The number of juvenile fish, which portends the future, was off the charts. High numbers of anchovies, shiners and smelt drew the fish in from the ocean. With all the food, all the usual suspects at the docks - the sea lions, pelicans, cormorants and gulls - have had field days.

And yet: For the first time in history, the striped bass did not migrate down from the Delta to the bay and ocean for the summer. Instead, they stayed in the Delta. Anglers who found the stripers in the Delta, and realized they were biting during the last three hours of the incoming tide, were catching and releasing 30 and 40 stripers apiece (you may remember the story).

Why did the stripers choose not to head to saltwater? Nobody knows. A few schools of small fish, 14- to 22-inchers, finally arrived in late September to southern San Pablo Bay, but this was a ghost run, not the standard en masse migration.

-- Rivers: With the cold-water releases from Shasta Dam, the Sacramento River ran high and cold this summer below Redding, typically about 15,000 cubic feet per second. In other words, conditions were ideal to attract salmon up river.

And yet: No salmon. I know of river guides who have not caught a single salmon this season, that is, from August to now. It doesn't make sense since hatchery releases of salmon on all the major rivers in the Sacramento and San Joaquin valleys have been solid for the past six years and river flows stable. This isn't limited to the Sacramento River , the usual top spot, but also the Feather, American and, on the north coast, the Smith.

-- Lakes for trout: We fished several lakes this month and had limits of trout at remote mountain lakes in Siskiyou County . The lakes were already very cold, with surface temperatures of 47, 48 degrees. Then we fished Shasta Lake this week, and it was the weirdest thing you've ever seen: The trout appeared to be scattered vertically, anywhere from the surface on down 100 feet, and the minnows (threadfin shad), were on the sloped bottom, 100 to 150 feet deep, according to the depth finder.

This makes no sense. With four inches of rain a week ago, surface waters cooling, the trout and minnows should all be in the top 25 feet of water.

And yet: At sunset, on the wind-sheltered side of extended lake points, we kept seeing swirls on the surface from bass, as if it were spring time. So we switched over to bass gear, rigged grubs on quarter-ounce lead dartheads and caught 4 largemouth bass in 20 minutes. The bass were 5 to 10 feet deep, in the rocks, and we hooked them by sliding the darthead grub along the sloped reservoir bottom.

This, of course, makes no sense for late October. The bass always chase the minnows. Since the shad were on the bottom, that's where the bass should have been. In fact, some years in late summer, I admit (because a bass pro would never do this) that we've deep-water trolled for bass with downriggers and caught scads of them.

Where are the salmon? Why did the striped bass not migrate to the bay and ocean this summer? Why are the shad minnows on the bottom at Shasta while the bass act like it's April and stay in the shallows?

As with so many things in nature, nobody really knows why, or what will happen next. Nature is one of the world's greatest mysteries.

E-mail Tom Stienstra at tstienstra@sfchronicle.com.

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Source:  http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/10/28/SPKLT0LNK.DTL