Todd Benoit’s column, “Set dinner place for wooly mammoth” (BDN, June 26-27) stated that rising ocean temperatures and global warming were “driving Atlantic salmon north to cooler waters,” and that the return of the salmon may have to wait for the return of the mammoth. He also reiterated the theories of graduate student Catherine Carlson and University of Maine professors who contend that Maine Atlantic salmon only thrived during the last little ice age which occurred from the 14th to mid-19th centuries.

Ever since North American Atlantic salmon populations began their decline in the mid 1980s, many other “experts” have also speculated that restoring salmon to Maine rivers may have to wait until the next ice age.

Atlantic salmon, master of adaptation: Because the Atlantic salmon is known as a “cold water” species most people infer that the species has a very narrow temperature tolerance; however, the native range of Atlantic salmon in North America and Europe reveals that is not the case. In Maine, and elsewhere, Atlantic salmon thrives in rivers that habitually exceed 80 degrees during summer days. In fact, as a species, Atlantic salmon is the most heat-tolerant of all salmonids in Maine, more so than native brook trout and non-native brown trout.

Similarly, European salmon are abundant in the mild climates of the British Isles and northern Europe, where rivers do not freeze and palm trees may be found growing in some areas. Considering its variable life history strategies and the broad geographical range of the species on both sides of the Atlantic, the salmon is extremely adaptable to its environment.

Those elusive salmon bones: Carlson and others concluded that since there had been very few instances where the remains of Atlantic salmon where found at archaeological sites, the salmon never existed in significant numbers.

She went on to imply that New England rivers were unsuitable for salmon because they were too warm and that the early colonists mistook American shad for salmon.

The lack of salmon remains in the archeological digs, could have a number of explanations, including: industrial development along rivers destroyed fish remains; the rapid decomposition of salmon bones in acidic soil; inappropriate study sites were considered; Native Americans didn’t have the means or didn’t attempt to catch salmon in many areas; archeological excavations conducted at important river sites were not able to make use of modern day methods for detecting fish bones; and, archaeologists have reported that Native Americans pulverized salmon bones and consumed them with the flesh.

With regard to the misidentification of salmon, the colonists clearly knew how to identify these fish, since nearly every anadromous species in New England was also found or could be compared to a similar species in England.

Finally, it is interesting to note that archeological digs along the Miramichi River in New Brunswick also failed to produce significant amounts of salmon remains. If archeologist cannot find salmon remains on one of the most productive salmon rivers in North America, the effectiveness of the sampling methods used elsewhere must be suspect.

Salmon abundance myths: Over time, numerous popular articles have exaggerated the abundance of New England salmon runs (walking across the river on their backs, using them for fertilizer, prohibiting serving the fish too often in lumber camps, etc.) Fishery scientists discounted those stories long ago, yet they persist in the media because they make good “copy.” Such stories are commonly told about fish and fishing worldwide.

Accounts of exceedingly abundant fish numbers in colonial times probably referred to all anadromous fish species combined, or of Atlantic salmon compared to the runs back in England which were declining due to dams, pollution, and over-fishing.

Maine Atlantic salmon, a recent species: University of Maine professors have suggested that the small numbers of salmon that were present in Maine arrived relatively recently. Repeating the mistaken assertion that salmon require cold climates to survive, it has been speculated that the last little ice age (600 years ago) would have been the time that stray salmon from Europe colonized New England rivers. However, modern-day research into the genetic origins of North American and European Atlantic salmon supports an opposite explanation.

Atlantic salmon from Europe are very different from salmon from North America; a number of significant differences exist in genetic attributes such as unique alleles, distinctive haplotypes, and numbers of chromosomes. Many geneticists now theorize that North American Atlantic salmon broke away from their European counterparts prior to the last period of glaciation (18,000 years ago) and evolved into unique stocks during the long period of complete separation.

Restoring Maine Atlantic salmon: Todd Benoit correctly noted that restoring a species is expensive. What he failed to mention is that restoring ecosystems, which have been ravaged by humans for over 300 years, is a monumental task.

No one knows for sure what the future holds for Maine Atlantic salmon; however, the flippant suggestion to use the $33 million price tag for the federal salmon recovery plan to lower ocean temperatures wasn’t particularly helpful. While it’s true that the marine survival of Maine salmon has declined in recent years, ocean temperatures cannot be used to explain why only 12 percent of the salmon parr in the Narraguagus River survive to the smolt stage, or why hatchery smolt survival in the Penobscot River – which is an abysmal one-tenth of 1 percent – is 10 times higher than that of smolts stocked in the Dennys River. I suggest that a better use for the $33 million would be to identify why salmon survival within our Maine rivers and estuaries is so dreadfully low.

The decimation of Maine Atlantic salmon, including its extinction from rivers south of the Kennebec, has deprived many Maine people of a valuable ecological and natural resource. While it is impossible to restore the species to the same level of its historical abundance, by restoring runs to a viable level many Americans will be able to connect or reconnect to a resource of national significance, a resource that is often characterized as a “National Treasure.”

Ed Baum is a fishery scientist with Atlantic Salmon Unlimited and a retired coordinator of statewide Atlantic salmon restoration programs with the Maine Atlantic Salmon Commission.