A 'temporary tool' for saving salmon: scientist
Conservation organization hosts 'recovery workshop' near St. Andrews
CHAMCOOK - Young salmon raised to restock depleted rivers should take a walk on the wild side, Memorial University of Newfoundland scientist Ian Flemming said Wednesday.
Atlantic salmon bred in captivity have better luck reproducing if hatchery managers expose them to conditions similar to a wild river before releasing them, he said in his keynote speech on the first day of the Atlantic Salmon Federation's "recovery workshop" at its headquarters outside St. Andrews.
"So what it suggests to us is that captive breeding environments can be altered to grow phenotypic traits that may be more favourable in nature," he said, outlining research at the Mactaquac Fish Culture Station and elsewhere.
Translation: Hatchery life affects how salmon perform when they are turned loose. Hatchery raised fish can become domesticated, not equipped for what faces them.
Jonathan Carr, the ASF's director of research and environment, chaired the day-long session. Salmon people came to hear fellow scientists explain what works and what does not in projects to restore this fish to east coast Canadian and American rivers.
Experiment shows that female salmon seek out males similar to themselves, Flemming said. Females and males raised entirely in captivity tend to breed with each other, as do salmon exposed to wild conditions in their youth.
This continues into the next generation, with the progeny of "wild exposed" hatchery stock producing more young salmon than the others, he said.
However, the number of individual fish do not tell the whole story, he said.
Restocking can increase the gross number of fish in a river at the expense of genetic diversity, with the salmon more closely related than scientists consider healthy, he said.
"We also need to recognize that captive breeding is a temporary tool," he said. Restoration projects should use this tool "to get populations self sustaining, and it should not inhibit other restoration or recovery measures, and will not be sufficient in itself to restore resiliency of these populations." Others outlined experiences in the Maritimes, Newfoundland and Labrador, Quebec and New England.
Financial pressure pushed the Miramichi Salmon Association to restock with "fry," salmon about an inch long, instead of the larger "parr" and "smolt," the group's president Mark Hambrook said in his presentation.
In 1997 the association took over the hatchery that the federal government managed on the Northwest Miramichi River since 1873.
As it works out, restocking tiny salmon in the rivers from which their parents came likely causes the least genetic impact, Hambrook said. The association restocks to fill "holes" in brooks with less than the optimum number of fry.
The association also "notches" beaver dams in the fall to let adult salmon returning from the sea get to upriver spawning beds.
The association aims to produce as many "smolts," small salmon headed out to sea, as it can. A river association cannot do much more about the large number of salmon not returning from the sea to spawn.
In recent years enough salmon are returning to the Main Southwest Miramichi, but not the Northwest Miramichi, to meet spawning requirements, he said.
Conservation groups on some other rivers react with envy when Hambrook talks about the Miramichi.
Of 45 New England rivers, 30 have lost their salmon runs, another seven are threatened, and six are maintained by restocking programs, Joan Trial, retired from the Main Department of Marine Resources, said. The status of the other two rivers is "unknown." Carr was on the afternoon program to talk about the efforts to restore salmon to the Magaguadavic River which spills into Passamaquoddy Bay at St. George. Not many years ago, 800 salmon returned to spawn each year in this river. Today, they are counted on fingers and toes in a good year despite restocking program.
Lee Sochasky from St. Andrews was on the afternoon program to talk about failed efforts to restore salmon to the St. Croix River.