Maine Sea Grant Project Seeks to Provide Scientific Answers Using DNA Studies
ORONO, ME. -- Irv Kornfield, a Sea Grant research scientist and professor of zoology at the University of Maine, knows he is on the hot-seat. NOAA's National Marine Fisheries Service and the U.S. Fish and Wildlife Service are proposing a plan to place eight river runs of North Atlantic salmon in Maine on the Endangered Species List. The listing would supplant an existing voluntary state of Maine conservation plan with federal regulations.
Whether that happens may depend, in part, on what Kornfield and his scientific team find in a newly funded $100,000 NOAA Maine-New Hampshire Sea Grant research project that will seek to answer the fundamental question, "Are there truly any 'wild' salmon in Maine rivers?"
Kornfield will undertake a two-year study to help define the genetic distinctiveness of salmon in the rivers of federal concern: the Narragauagus, Pleasant, Machias, East Machias and Dennys in Washington County; the Sheepscot and Ducktrap rivers in mid-coast region; and the Cover Brook, a tributary of the Penobscot River, below Bangor.
What Kornfield will find is uncertain. "We don't have any idea of how it will turn out - it could be either way. We certainly recognize that a great deal will be resting on this study. The answer, in part, lies on how one views the longtime program of using hatchery raised salmon to stock Maine's rivers," says Kornfield.
According to Lewis Flagg, Deputy Commissioner of the Maine Department of Natural Resources, stock enhancement has a long history in Maine. Flagg says that, between 1871 and 1995, 96 million North Atlantic salmon of hatchery origin have been placed in Maine rivers. He welcomes Kornfield's study saying, "I think the project is an excellent one in that it will shed light on a good deal of misinformation, and help eliminate some of the uncertainties about the North Atlantic salmon that are part of this discussion."
Kornfield is a nationally-recognized expert in using DNA genetic markers to determine how much genetic variation passes from one generation to the next and the population sizes needed to maintain that diversity. Among his work are studies to determine genetic differences between wild and farm-raised salmon and where genetically pure salmon reside in Maine.
The problem, Kornfield explains, is that "the fish that formed the base of hatchery brood stock for the rivers in question came from Maine's Penobscot River. The genetic stock from those fish now has been distributed, through the stocking program, throughout the regions' population of salmon. All rivers now contain genetic material in their salmon that initially came from one river, the Penobscot."
Maine officials recognized that problem in the early 1990s, and since 1992 have established a "river specific" stocking program, using only descendants of fish taken from each river. Kornfield says that is a step in the right direction, but points out that a local stock may not be truly "native" due to earlier non-river specific stocking. His goal will be to create a family tree of those salmon.
"Given that the original Penobscot River fish have not been genetically studied in detail as a source population, it is difficult to evaluate genetic information from around the state in an objective manner without going back in time to trace the genetic lines," says Kornfield.
To do that Kornfield must first do a detailed genetic DNA analysis of the Penobscot River salmon, something that has not been done. That genetic characterization, of the Penobscot River salmon, will be then bench marked in its genetic strands against a population of North Atlantic salmon in Newfoundland which has not been subject to hatchery stocking and should be a true "wild" stock.
One of the ways Kornfield establishes genetic benchmarks is through the use of dried fish scales that may be archived by various agencies or available from trophy mounted fish. To Kornfield, the scales are like dusty unread books in an old library waiting for new readers to discover their contents. Using DNA technology Kornfield can "read" the DNA sequences from the old scales and compare them to sequences taken from recent generations. The result indicates how much genetic variation passes from one generation to the next.
Once those benchmarks have been established, Kornfield, using computer modeling of stock reproduction, should be able to do a series of simulations, based on random fishery samples, to see if he can produce the patterns of genetic divergence that are now observed in each of the eight rivers' salmon.
"If we find that the same patterns emerge then we can demonstrate that the smaller river salmon are in fact derivatives of the stocked fish from the Penobscot," says Kornfield. "If the patterns do not match what we are now seeing in genetic sampling, then we will indeed have distinct strains of wild fish in these rivers."
The study will be conducted over a two-year period, but Kornfield hopes his lab will have preliminary trend results by next summer.
Materials provided by National Sea Grant College Program. Note: Content may be edited for style and length.
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