If you, like me, read fly-fishing blogs, it is predicted there that 2016 will be a banner year for California anglers. It must be true. I read it on the Internet.
These blog writers (many of whom are entwined with the fishing-industrial complex) must be serious students of Aristotle. In The History of Animals, Aristotle wrote: “it is quite proved that certain fishes come spontaneously into existence, not being derived from eggs or from copulation. Such fish are neither oviparous or viviparous and arise all from one of two sources, from mud or sand, and from decayed matter that rises thence as a scum.”
Although spontaneous generation has deep roots in the legends of fish and fishing lore, to anyone born this side of Louis Pasteur, it would seem rather remarkable that formerly dry streams will spontaneously erupt in a riot of trout. The El Niño rains must have produced an abundance of mud, sand, and scum.
It’s true that as rain and snow have fallen across our watersheds, in a welcome departure from the past four years, California streams are flowing once again, and lakes are filling to capacity. But it is often wrongly assumed that our Mediterranean climate has honed aquatic species to recover rapidly from long periods of drought. Extended drought such as we’ve just experienced has extirpated regional populations of biota (think of any dried lake) and even threatened the existence of entire species (the Delta smelt).
Humans can alter drought outcomes by exacerbating low flows via pumps and diversions or by artificially preserving and releasing water from behind dams. Aquatic animals respond to drought with one of two strategies: resistance or resilience.
Resistant animals are those that can survive drought by lying low in spores, eggs, or pupae that are resistant or immune to desiccation. Fairy shrimp not only lay desiccation-resistant eggs, but require a dry period in their life cycle to survive. Another resistant strategy is to burrow below the riverbed to access habitat damp enough to survive. Some stoneflies and small fishes can burrow deep enough to end up in well water.
Resilient creatures include insects that can occupy a pocket of habitat, then move back to the mainstream to lay eggs after a drought. Dragonflies, backswimmers, and beetles are first-order colonizers. Other pioneer species include midges and Baetis mayflies, which experience multiple life cycles per year. That allows them to fill changing environments quickly. Aquatic ecologists know these insects as “disturbance-adaptive” species.
Spring creeks that have gone dry are the slowest water body to recover. Doctors Don and Nancy Erman spent the later half of the 1950s studying drought recovery on upper Sagehen and Berry Creeks, north of Truckee. It took six years for the creeks to return to predrought populations. Even during severe drought, most rivers will have a tributary or two that holds remnant populations of macroinvertebrates to inoculate the river via drift. Spring creeks, which originate right out of the ground, have no such tributaries and are dependent on the arrival of egg-laden winged insects. Creatures such as fish, worms, scuds, and crayfish obviously must work their way against the drift to reinhabit previously dry spring creeks.
Humans, particularly Americans, are not patient animals. We want our fisheries restored, and we want them restored yesterday. Planting hatchery-reared trout would seem the obvious solution toward shortcutting the nature of things. But like love, you can’t hurry nature.
When the upper Sacramento River was devastated by a derailed train carrying toxic metam sodium, there was a strong contingent of anglers and fishery managers who wanted to fast-track repopulation through hatchery plants. Cooler heads prevailed, but biologists had to explain again and again to an ignorant (and sometimes unwilling-to-listen) public that fish need to eat, and it would take years for the food chain to build itself to the point where a burden of fish could be introduced back in the water. As Mike Berry, a senior environmental scientist with what at the time was the Department of Fish and Game said, “It would be like running off all the wildlife from the African plains and putting the lions back before the zebras.”
Even if the California Department of Fish and Wildlife now could magically create a food base for surrogate trout, they have precious few trout with which to work. The drought not only crashed wild stocks of fish, but also wreaked havoc with the hatcheries. Low, warm flows and silt scoured from nearly dry upstream reservoirs decimated the American River hatchery production of 2015.
There are things that can be done, but there are no quick fixes. Consider the efforts to restore Lahontan cutthroats to the Truckee River drainage.
The U.S. Fish and Wildlife Service operations were not quite as severely affected as the DFW’s. Through years of trial and error, they have refined the hatching and rearing of the Pilot Peak strain of Lahontan cutthroats. The Pilot Peak strain is of course the race of Pyramid Lake and Truckee River cutthroats that John C. Fremont and Kit Carson stumbled upon in 1844. Fremont was so enthralled with the massive size and wonderful flavor of the fish that he named the Truckee the “Salmon Trout River.” In less than a hundred years after its discovery, the Pyramid and Tahoe race of the Lahontan cutthroat was extirpated by dams, diversions, sawmill pollution, and competition from introduced trout and their diseases. In 1943, 99 years after its discovery, the salmon trout was declared extinct.
In the 1970s, an isolated population of cutthroat trout was discovered in a small creek on the flanks of Pilot Peak on the Nevada-Utah border. Though Dr. Robert Behnke surmised that these might be Pyramid Lake ancestors, it wasn’t until 20 years later that Professor Mary Peacock of the University of Nevada at Reno began experimenting with a method of genetic analysis that could recover DNA from fish specimens preserved in formaldehyde. She compared the DNA of the Pilot Peak fish with museum specimens and trophy fish mounts. The Pilot Peak trout were not only a perfect match with ancient Pyramid Lake fish, but also a close match to mounts of Lake Tahoe and other upper Truckee cutthroats. According to Lisa Hecki of the USFWS office in Reno, in fact, the only water body of the Truckee drainage that didn’t share Pilot Peak ancestry was Independence Lake. Apparently the Independence race was cut off from the Truckee River fish and evolved into their own unique strain by spawning in the creek feeding the lake.
Over the past four years, Pilot Peak fish have been successfully reintroduced into Fallen Leaf Lake, immediately upstream of Lake Tahoe. This year, the Gardnerville Hatchery has 1.2 million Pilot Peak–strain fish ready for planting. Though plans have not been finalized between the USFWS and the DFW, it’s hope that the progeny of the Truckee River’s indigenous ancestors eventually can be reintroduced into the system as drought conditions relax and as the food chain reestablishes itself. In fact, in terms of native cutthroat reintroduction efforts, the drought may have been a blessing in disguise by eradicating a large percentage of the nonnative rainbow trout population, which frequently hybridizes and competes directly with cutthroat.
Planting an extinct fish into barren home waters would be as close to recreating spontaneous generation as the world has ever seen. But mud, sand, and scum are not involved — just a long and slow natural process, supported by a lot of work by a lot of good people.
