Snake River Hatcheries
by Bill Rudolph
The latest hatchery review by the science panel that judges the merit of F&W projects may have provided some cover for lower Columbia tribes who are defending their fish supplementation efforts, but it still found plenty of room for improvement.
The tribes were recently successful in postponing a review of the draft F&W program by the Independent Scientific Advisory Board, which for years has gone on record with well-known concerns about the value of supplementation, and still call it an experiment.
The tribes are calling for a change to draft language in the latest revision on the region's BPA-funded F&W program. They say it is too prescriptive and could lead to reductions in their hatchery operations.
Last year, the ISAB had said the current F&W program should contain guidelines developed by the intense 2009 Hatchery Scientific Review Group (HSRG) review, which actually quantified the numbers of hatchery fish that should be allowed on particular wild spawning grounds.
Language developed by Northwest Power and Conservation Council members in the new draft program calls for using those HSRG recommendations, but notes that final hatchery plans must be consistent with tribal treaty and other legal obligations.
The June 18 summary review by the Independent Scientific Review Panel, which includes some scientists who also serve on the ISAB, said hatchery programs on the lower Snake -- including facilities run by the tribes -- "are largely consistent with the scientific foundation, artificial production strategy, and artificial production principles contained in the [NPCC] Fish and Wildlife Program."
The ISRP originally reviewed the lower Snake spring Chinook programs in 2011, the steelhead programs in 2012, and fall Chinook programs last April. Taken together, the programs are known as the Lower Snake River Compensation Plan, and were originally developed to boost fish harvests after the lower Snake hydro projects were built. After some Snake runs were listed for protection under the ESA, the LSRCP mandate included boosting listed populations.
The review also said high survival rates for fall Chinook, steelhead and spring Chinook programs "are indicative of well-run hatchery programs. Goals for smolt size at release have been set, and with some exceptions, the hatchery programs have met these objectives."
The ISRP noted that "the effects of supplementation on adult abundance and productivity of natural populations are also being investigated, but results have been mixed." The panel said spring Chinook supplementation programs have increased total spawner abundance (hatchery plus wild) in rivers, but have not produced more natural-origin adults.
"Fall Chinook supplementation has likely contributed to the recent increases in natural-origin fish abundance in the Snake River Basin, but the productivity of the natural-spawning population remains very low," said the report.
The latest ISRP summary review said there is "clear evidence" that density dependence has shown up in spring Chinook supplemented populations, which means that limited habitat and competition for food is putting a damper on increasing numbers. But the review also noted a "marked increase" in supplemented fall Chinook in the Snake.
However, the panel pointed out that more research is needed to sort out the genetic and environmental factors, including habitat restoration, that are responsible for the increases, and that the lower Snake supplementation programs offer important opportunities for such investigation.
The hatchery review noted high mini-jack counts in some spring and fall Chinook programs, which reduces the number of fish raised to adulthood for harvest or spawning, since the precocious male mini-jacks don't even reach the ocean before they head back to the hatchery of their origin. NOAA Fisheries' researchers have estimated that 52 percent of the spring Chinook smolts released from Idaho's Lookingglass Hatchery have returned as mini-jacks, a point that is disputed by hatchery managers, according to the ISRP review.
A recent peer-reviewed paper (Harstad et al., 2014) that looked at the mini-jack issue said, "The differences in reproductive success between the hatchery and natural environments were largely due to low reproductive success of mini-jacks in the natural environment, and such programs may be violating the requirement that calls for supplementation programs to minimize alterations to the genetic and phenotypic characteristics of these natural populations."
An earlier ISRP retrospective report (2011) said there was evidence that rapid salmon growth in the hatcheries, especially during summer, increased the mini-jack rate (Larsen et al., 2010a).
"However," the report noted, "growth experiments in which hatchery smolts were equal in size to wild spring Chinook salmon still revealed a four-fold increase in mini-jack rates among the hatchery fish, indicating that some factor(s) other than growth contribute to mini-jack rates.
"Some emerging evidence suggests that integrated hatchery stocks, which incorporate natural fish into the broodstock, have higher mini-jack rates than domesticated stocks," the report continued. "Research on this topic by NOAA Fisheries is continuing. The research outcome has implications for supplementation programs that are trying to rebuild natural populations through use of integrated hatchery stocks, as recommended by the Hatchery Scientific Review Group."
The ISRP said managers of the fall Chinook program need to estimate the importance of the various factors contributing to adult returns, like changes in hatchery operations, hydro operations, supplementation, and ocean conditions, to help develop future management actions. With a recovery plan still in the works, the ISRP said the Lower Snake plan needs to find a balance with it, and to develop biologically-based recovery goals.
"Currently, total adult returns to the Snake River are meeting program goals but largely because harvest rates have been cut for conservation purposes, leading to large numbers of spawning fish that contribute to density-dependent survival and low productivity (return per spawner)," said the ISRP review. In 2013, about 73 percent of fall Chinook adults on the lower Snake were hatchery fish, but 20,000 were of natural origin. In 1990, only 78 wild fish returned.
The panel called for some improvements, including visibly marking all hatchery fish to make better estimates of spawning distributions and the proportion of natural and hatchery-origin fish returning to the lower Snake.
The panel noted that many spring and fall Chinook supplementation populations have a proportion of natural spawners that is considerably lower than what is recommended by the HSRG, and no plans are in place to do something about it.
"Given the recent upsurge in Snake River fall Chinook abundance, it would be prudent to incorporate planning of this type into the fall Chinook Recovery Plan that is currently under development. Furthermore, harvest of surplus hatchery fish would help achieve the mitigation goals."
The ISRP said another challenge for the program would be to find out if density-dependent effects are limiting production in rivers where fish numbers are supplemented by hatchery-origin spawners.
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