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 that there 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 purposes 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, they were quick to state that they don't want to be regulated as a hatchery, however as the Delta smelt become more elusive, there is a possibility that the smelt "refugia" might someday be the last and only home for this sensitive species. A "just-in-case" plan has already been spawned for captive breeding, mostly in terms of how the refugia can improve and expand the genetic breeding of this 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 in the wild. 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 lineage 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 by encouraging captive adaptations, efforts must to be made to preserve the wild adaptions and minimize any new captive adaptions. This is done by starting with a large captive population, minimizing kinship during breeding, and keeping replicate populations as a safeguard. It also helps to breed in a simulated environment that is as close as possible to their natural habitat. The lower the number of generations that are bred in captivity, the less the population can adapt to captivity, and the higher the success of reintroduction. If a captive population is released while there is still a wild population to breed with, 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 will be swimming only in circles (meaning in a tank). 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 to take action? It might be up to the Department of Water Resources, who is bringing in power, back up generators, and major improvements to the smelt breeding facility to shore up the breeding 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 these. (No mention of the cost of these extraordinary efforts.) 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 one of many causes for the smelt's demise. The smelt might be done in by their preference for a species of zooplankton that no longer predominates, overtaken by an invasive species from the release of ship bilgewater.
If they release captive smelt, would they survive? 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 will they know where to hide from predators when the trucks drop them off in Suisun Bay? Once released, it might be impossible to track them and determine their fate. A previous study of larger electronically-tagged fish released near Stockton last summer ended with the expensive fish dead on the river bottom, suspiciously near the waste treatment plant outlet.
If the smelt habitat could be restored, how long might that take? If it takes ten years for the export pumps to retrofit for the smelt, will the smelt become another aquarium species waiting to get fed at the same time every day?
And what does this have to do with climate change? If the smelt survive the loss of their favorite food and habitat, and manage to avoid getting sucked into the export pumps, it may be the heat that finally does them in for good after these 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?" Can you imagine asking, "Can you breed a canary that can live in poison gas in a coal mine?" The fish has already indicated, the sport fisherman have heard the warning and sued for action. Will breeding a more adaptive indicator satisfy the laws protecting this species? In the uncertain Delta, every solution is worth considering, for at least a moment.
Photo courtesy of US Bureau of Reclamation
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