[3] Council Gets Complicated Message On Toxics
The Northwest Power and Conservation Council heard a sobering analysis of toxic pollutants and their effects on Columbia Basin salmonids at last week's meeting, but federal scientists admitted they have little data that could actually quantify the effects.
In their presentation NOAA Fisheries scientists discussed a wide range of studies from spring and fall chinook, along with field studies and lab work to estimate how much effect toxics might have on migrating salmon.
A month ago, the Council had prepared a series of questions for the scientists to help members deal with the possibility of including toxics issues in the next revision of the basin's fish and wildlife program. The toxic chemicals include pesticide residues from agricultural runoff, hydrocarbons from urban runoff, heavy metals, PCBs and DDT.
NOAA scientists Tracey Collier and Lyndal Johnson told a complicated story to the Council, mixing lab studies that showed detrimental effects on fish from contaminants with field work that showed how juvenile migrants already stressed from the rigors of inriver passage could be adversely affected by spending time in the estuary.
Collier told NW Fishletter they were trying to present a "big picture" of the toxics issue. The scientists estimated that juvenile fish might incur 3 to 11 percent mortality from exposure to toxics, with more ill effects likely to occur to fish that spend a month or more in the estuary.
That lets most young spring chinook off the hook, since they are making a beeline for the ocean. Some fall chinook migrants, however, spend considerable time in the estuary, where most pollutants in salmonids were found at the confluence of the Willamette and Columbia rivers.
The presenters cited a study that found transported fish seemed actually healthier than inriver fish when both groups were presented with a "disease challenge," and another one that suggested juvenile salmonids with lipid contents below 1 percent were more susceptible to mortality from toxic sources, a group that made up about 13 percent of the total number examined.
They pointed out early on, however, that the hydropower system was responsible for only about 5 percent of toxic contaminants found in the Columbia.
Johnson said modeling studies found that the increase in disease-induced mortalities during estuary residence "was pretty similar in fish exposed to chemicals and in fish that were undergoing the stress of dam passage and all the difficulties associated with that, but without this additional chemical exposure. So this study basically shows that the problems with the contaminants may be comparable to the problems with dam passage, at least for this particular endpoint."
She said the studies suggest "if we got better control of the contaminants and reduce the levels, this might give a boost in survival that could actually have some real effects on the recovery of the population."
Council chair Bill Booth questioned how much real inriver data was used in these analyses. Johnson said contaminant concentrations in fish were based on inriver studies and the mortalities were based on lab work.
Johnson said another study on fall chinook in the lower Columbia that modeled potential adverse effects of toxics on the fishes' ocean survival and fecundity showed that such effects could influence abundance and population dynamics throughout the ESU.
Collier's bottom-line message to the Council: "We're pretty sure contaminants in the Columbia are affecting the survival and productivity of some of the listed salmon stocks." He said research in Puget Sound found that contaminants can undermine the effectiveness of physical habitat restoration efforts, "and that certainly indicates the potential to occur with some of the restoration sites and where they are located, in the lower Columbia, especially."
Collier said discussions are underway to work toxics issues "adequately" into salmon recovery modeling, and was "exceedingly complex," noting that the presentation before the Council represented only about 15 percent "of what they had."
Collier said it was quite a challenge to develop enough data to be regionally specific to the different stocks, noting that at present, there is no data about the rates that fish are picking up contaminants in the lower part of the river. -B. R.
The following links were mentioned in this story:
Fish Passage Center, July 14, 2008
Toxic chemical contaminants and salmon in the Columbia River, July 15, 2008
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