Restoring Atlantic salmon remains challenge

By Ed Baum, Special to the BDN
Posted Dec. 14, 2011, at 5:48 p.m.

The BDN’s Dec. 8 front page story, “Downeast Salmon Federation imports restocking advice from afar,” sure made it sound easy. “Peter Gray was in Washington County this week to promote the concept of restocking long-depopulated salmon habitats with young salmon raised in stream-side hatcheries to the size of “parr.” Mr. Gray is quoted as saying “with parr, you’re producing and introducing top-quality fish that are identically the same as if they were born in the river. You’re raising athletes, with the size and muscle texture and survival-of-the-fittest instincts to swim to Greenland and Iceland and then come back to reproduce in your river.”

It was reassuring to this biologist to hear that Mr. Gray had duplicated the findings of Charles Atkins, the first superintendent of Craig Brook National Fish Hatchery in Orland during the period from about 1870-1920. Improved survival of stocked salmon parr, either as fall-stocked age 0-plus, or spring-stocked age 1-year-plus fish (compared to “fry”), has also been repeatedly documented in the fisheries literature throughout the range of Atlantic salmon in both North America and Europe for decades.

In fact, the stocking of hatchery-reared Atlantic salmon parr was the primary method used to restore and maintain salmon runs right here in Maine throughout the 1940s and 1950s.

The survival of parr stocked in Maine rivers was documented by Atlantic Salmon Commission biologists Dick Cutting, Al Meister, Jim Fletcher and others in the 1950s. They marked hatchery-reared salmon parr before they were stocked in several Down East rivers, and then monitored the survival of those parr throughout their life cycle.

Let there be no doubt that Mr. Gray’s findings apparently corroborate the studies conducted by many scientists before him. Namely, larger (stocked) hatchery-reared, juvenile salmon survive better than smaller ones. Thus, salmon stocked as smolts survive better than parr and parr survive better than fry, and fry survive better than eggs planted in streams. This has been demonstrated over at least the last 125 years.

One limitation with parr stocking, however, is that the fish must be distributed extremely well throughout the area of vacant habitat. While this sounds easy, it poses significant logistical challenges, requiring the distribution of large numbers of “fingerling” size fish, over a large geographical area, during a relatively short period of time (especially in the fall and spring). This is why many salmon restoration programs utilize stocking strategies that encompass all life stages of hatchery-reared salmon.

Moving beyond the “parr stocking is the only way to go” theory espoused in the BDN article, the role of hatcheries in salmon restoration is usually grossly exaggerated, and the story about Mr. Gray’s “success” on the Tyne River in England was no exception.

The construction of the Kielder Hatchery, operated by Mr. Gray, was a result of mitigation for the 1979 construction of a dam that resulted in the loss of about 8 percent of the salmon habitat in the North Tyne. As mitigation, a stocking program was developed to rear and stock age 0-plus and 1-year-plus salmon parr annually to replace the loss of salmon production by the construction of the dam.

A peer-reviewed, scientific document published in July 2008 concluded that the Kielder Hatchery stocking program has contributed an average of 2 percent to sport catches and 7 percent of salmon returns to the Tyne. While the Kielder Hatchery certainly was successful in its mission to mitigate for the dam construction, the vast majority of the thousands of salmon now returning to the Tyne are a result of water quality improvements, improved fish passage and reduced exploitation in commercial and sport fisheries.

While the parr stocking program described by Mr. Gray can be called a “success,” it actually played a very small role in the restoration of Atlantic salmon runs to the Tyne River in England. Unfortunately, when it comes to easy Atlantic salmon restoration programs, whenever it sounds too good to be true, it always is.

In conclusion, I advise anyone interested in the Maine Atlantic salmon restoration program to keep in mind that our rivers produce smolts (6- to 8-inch juvenile salmon), while the North Atlantic Ocean produces those 8-12 pound salmon that anglers long to catch once again.

Ed Baum is a retired certified fisheries scientist and author of “Maine Atlantic Salmon, A National Treasure.” He lives in Hermon.

http://bangordailynews.com/2011/12/14/opinion/restoring-atlantic-salmon-remains-challenge/ printed on April 19, 2014