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Ecology and salmon related articles

Estimating Fish Benefits from
Habitat Actions may Take Decades

by Bill Rudolph
NW Fishletter, January 19, 2012

Scientists from the ISRP, the panel that weighs the scientific merit of proposals in the BPA-funded fish and wildlife program, said last week that it could take up to 20 years to figure out how much good all that habitat spending in the Columbia Basin is doing. Or maybe even longer, they said in a presentation before the Northwest Power and Conservation Council about their 2011 retrospective report.

The ISRP reminded Council members what they had originally called for when they commissioned the review, in their executive summary. "The Council will not conclude this review without being comfortable that the monitoring and evaluation protocols and analytical methods are in place to give us a reasonable chance of knowing--in 5, 10, 20 years--whether the region's huge investment in an evolving suite of habitat actions is contributing significantly to the recovery and rebuilding of fish species important to the region."

The panel said the question implied that that a "thoughtful, efficient approach" will provide an answer in 5, 10, or 20 years--and "seems to be at the heart of uncertainty currently being articulated, including in BiOp rulings, over whether or not the huge investment in habitat restoration will achieve intended outcomes." NOAA Fisheries has pegged definite survival improvements from BiOp tributary and estuary restoration actions, and the plaintiffs in the extensive litigation over the salmon plan are holding the feds' to their promises.

The ISRP said some actions, like removing Hemlock Dam from a tributary of southern Washington's Wind River, would show quick results, but other projects like instream structure modifications or reconnecting floodplain habitat, could take years before benefits are realized. And other complicated actions, like riparian forest protection and restoration, "require decades for their full benefits to be expressed."

"In fact," said the ISRP report, "most projects aimed at restoring natural watershed processes fall into the category of projects requiring many years to achieve objectives." The panel recommended long-term monitoring for a suite of projects falling into the different categories, since the time needed to estimate benefits varied widely between them.

And then, comes an even larger problem--measuring the effects on fish populations. The ISRP said that will take even more time. "A high level of variation in abundance caused by a mix of natural and anthropogenic factors requires that considerable time, sometimes on the order of decades, is needed both before and after implementing restoration projects (ital. theirs) to measure the effects of actions on target populations with a reasonable level of certainty."

They said more monitoring of "adults in" and "smolts out" is needed to track effectiveness, but they weren't keen on a standardized approach to monitoring habitat effectiveness, which they said "is not achievable or desirable." In their report, the ISRP said some approaches will become obsolete over time, and protocols should be open to new, more efficient techniques.

But many projects don't have the time or resources to develop a statistically sound evaluation of success, and very few can compare results with an unimproved reference site, which is required to accurately identify the responses to habitat actions. For this reason, they generally support the use of Intensively Monitored Watersheds (IMWs) that call for a planned, experimental approach to evaluating restoration effectiveness at watershed scales.

"The main point here, however, is that the expectation of definitive answers to the question 'Is it working?' may, in many instances, not be achievable in a 5-20 year window. The ISRP therefore suggests that additional dialogue is needed among habitat managers so that realistic timeframes can be established, and appropriate schedules agreed upon, to monitor and evaluate different types of restoration actions, and to establish a suite of control and treatment streams, appropriately monitored over reasonable time frames to evaluate success."

The ISRP's report also called for more research to look at effects of hatchery mini-jacks on adult return rates, since nearly half of some smolt releases are made up of them, young fish that never leave the freshwater habitat before they return to the hatchery.

The panel said more work is needed to look at effects of PIT-tags on fish as well, since some studies have shown reduced return rates for PIT-tagged fish relative to runs at large, sometimes as much as 25 percent lower.

The report also recommended that supplementation projects receive more scrutiny to see if they actually produce more wild fish. So far, empirical evidence is lacking to prove a conservation benefit other than preventing extinction, the ISRP said.

They said supplementation projects that put high proportions of hatchery fish from hatchery broodstock on natural spawning grounds "are likely compromising the long-term viability of the wild populations" (see following story).

Supplementation efforts also need to be better integrated with habitat restoration efforts, "because rebuilding natural populations will ultimately depend of improving habitat quality and quantity. Recruits per spawner ratios must exceed 1 on a consistent basis in naturally-spawning stocks to achieve the ultimate goal of self-sustaining wild populations. Until this happens, supplementation is only a life support system."

More work also needs to be done related to monitoring dam passage as well, said the panel, and installing PIT-tag detectors at dam spillways is a high priority. They pointed to the value of early life history studies for Snake fall chinook to determine whether or not too many hatchery fish are competing with wild fish as the stock rebuilds.

The ISRP also suggested that the region should find out which salmonid stocks are most vulnerable to all predators, which means developing large scale life-cycle models that include predation on adults by seals and sea lions, as well as by birds on juvenile migrants.

Bill Rudolph
Estimating Fish Benefits from Habitat Actions may Take Decades
NW Fishletter, January 19, 2012

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