The half day Delta Smelt "workshop" in Kemper Hall last week was a fascinating look at heroic efforts to save a "vanishing" species. If there are smelt remaining in the Sac-San Joaquin Delta, and a US Fish and Wildlife researcher assured me they are, they are getting harder to locate. That poses a big problem for research, since you can't study what you can't find. Nonetheless, studies are in progress and waiting for smelt. The UC Davis staff in Byron, California is gearing up to provide larger quantities of smelt for research only. Since UC Davis researchers Joan Lindberg and Bradd Baskerville have been nurturing their "refugial population," they estimate they have provided 70,000 fish for research so far. There are no plans to turn their facility into a smelt "hatchery" for restocking the Delta, (and they were quick to add that they don't want to be regulated as a hatchery) however as the Delta smelt become more elusive, there is a distinct possibility that the smelt "refugia" might someday be the last and only refuge for this sensitive species.  A "just-in-case" plan has already been spawned for captive breeding, mostly in terms of how the refuge plans to improve and expand the genetic breeding of their captive population.

Lessons learned about captive species were brought to this forum by Phil Hedrick from Arizona State University. Hedrick was involved in breeding winter run chinook in the Sacrmento River and topminnows from various Arizona springs. Endangered species are known to have frequent inbreeding and less genetic variation than what is desired for ensuring healthy populations. When fish hatcheries began studying their spawing populations, it was discovered that 41% of the product of one hatchery was from a single female ancestor. After developing a protocol for returning spawners, they were able to improve the genetics of their releases, which is important to keeping the population resistant to disease. By the mid-1990s, it was possible to trace the fish back to their parents using genetic markers called "microsatellites." The method uses DNA sequences to verify that  the crosses made in the breeding program were successful.

Before a captive population can be reintroduced, it has to exhibit "genetic fitness." Since captive breeding often reduces fitness, efforts must to be made to preserve wild genetic adaptions and minimize captive adaptions. This is done by starting with a large captive population, minimizing kinship, and keeping replicate populations as a safeguard. It also helps to breed in a simulated environment that is close to their natural habitat. The lower the number of generations that are bred in captivity, the less the population adapts to captivity, and the higher the expected success of reintroduction. If a captive population is released while there is still a wild population, the captives might transfer undesireable traits to the wild fish, further weakening them. So as long there are smelt in the Delta, the captive population of smelt will be swimming in circles.  If the program breeds more fish than needed, they will be allowed to die a natural death, presumably from old age, which for a captive smelt is about two years?

If the worst case scenario for the smelt is realized, who is going the take the blame?  Evidently not the Department of Water Resources, who is bringing in power, back up generators, and major improvements to the facility to shore up the capacity. There are 44 multi-family groups of smelt capable of producing up to 7000 eggs.  These will be transferred to the facility once the improvements are completed. A spawning pedigree is being developed for 2009 and more wild fish will be brought in to augment the genetic fitness if permits can be issued for taking them. (No mention of the cost of these extraordinary efforts, but lawsuits are likely to be costly as well.) The Bureau of Reclamation is partnering with US Fish and Wildlife to study how the export pump screens can be improved to exclude the smelt, which they hope will eliminate the pumps as a possible cause of the smelt's demise. If the smelt are done in by their preference for a species of zooplankton that no longer predominates, the blame falls on the invasive species that transformed this habitat, or whomever failed to take on regulation of shipping bilgewater.  Most likely, there is plenty of blame to go around, beginning with the introducers of non-native fish over a hundred years ago.

If they release captive smelt someday, would they survive? That is the million-dollar question. With limited food due to changes in the Delta ecosystem, the smelt today are smaller than they used to be. You can't release them until they at least learn to feed, and where are they going to hide from predators when the trucks drop them off in Suisun Bay? Once they are released, it might be impossible to track their fate.  A short study of much larger electronically-tagged fish that were released near Stockton last summer, ended with the expensive fish found dead on the river bottom, suspiciously near the waste treatment plant outlet.

If the smelt habitat can be restored, how long might that take? Will it be ten years for the issues with export pumps and water transfers to be resolved, and by then will the smelt be just another shiny aquarium fish waiting to get fed at the same time every day?

And what does this have to do with climate change? Everything, because if the smelt survive the loss of their favorite food and habitat, and manage to avoid getting sucked into the huge export pumps, it may be the heat that finally does them in for good after the investments have been made. They have been referred to the environmental community as an "indicator fish", the canary in the coal mine, a warning system for rapid change. One of the last questions asked in the smelt meeting was, "Could you breed a smelt that could survive higher temperatures?"  Why not ask, "Can you breed a canary that can live in poison gas in a coal mine?" The fish has indicated what it was meant to, the sport fisherman heard the warning and sued for action.  I doubt that breeding a more adaptive indicator is what they were thinking of in terms of action. But in this uncertain world, every solution is worth considering, for at least a moment.

Photo courtesy of US Bureau of Reclamation

 

 

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