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River-Specific Salmon Fecundity Is Studied
FRANKLIN — With Atlantic salmon populations in Maine in steep decline for the last decade, experiments are underway to study the fecundity of river-specific Atlantic salmon.
The study — a joint effort of the National Marine Fisheries Service, Maine Atlantic Salmon Commission, and U.S. Fish and Wildlife Service, and occupying two quonset-style buildings at the University of Maine Center for Cooperative Aquaculture Research (CCAR) in Franklin — comes in response to the addition of Gulf of Maine Atlantic salmon to the Endangered Species List and experimentation with introducing pen-raised adult salmon into their native rivers in hopes that these fish would spawn naturally and seed the rivers. Reproduction rates of stocked salmon reared in pens — representing 140 families of salmon from five rivers and streams around Maine — have been relatively low in recent years, and the project has taken a selection of salmon to study possible reasons. Although fertilization and egg-survival rates were very high, reproductive performance remained low. The study, “Estimation of gamete viability and fecundtiy of river-specific marine net pen reared Atlantic salmon in Maine,” is seen to be a means to supplement populations in several Down East salmon rivers, according to CCAR information. The three agencies stocked river-specific Atlantic salmon adults in 2000 and 2001 that were reared in marine net pens by the aquaculture industry. Attempts to evaluate the reproductive success of these adults suggest the fish achieved relatively low reproductive success. However, new tests are in place to test the hypothesis that poor gamete quality may be limiting reproduction. Twenty-six pen-reared adults were moved to CCAR in October 2001, where they spawned and the eggs were incubated. The resulting high rate of fertilization and survival suggested gametes are not the limiting factor in reproduction. However, a low rate of sexual maturation was considered a possible explanation of poor reproductive performance. Elsewhere on the farm, a crop of baby Atlantic halibut has been successfully reared for the first time ever in the U.S. The event occurs three years after a halibut in captivity spawned for the first time at CCAR. The project represents the groundwork to be done toward facilitating the start of a halibut farming industry. This first crop and subsequent crops will be sold to Maine Halibut Farms, Inc., for grow-out using land-based farming techniques. In a related project, CCAR is home to a study to develop diets for the broodstock. The goal is to produce formulated feeds that will replace the raw marine components currently used to feed the broodstock. Specifically, the food must be high-quality and pathogen-free. Feed trials are underway now. CCAR is in the third year of a NOAA Saltonstall-Kennedy-funded grant to determine the feasibility of on-growing juvenile Atlantic cod in net pens. CCAR is assisting with work to develop the farming of nori (Porphyra), the most valuable sea vegetable in the world, using a net-seeding technique. Over the past two years, marine worms have been the focus of Seabait Maine, which has worked to improve harvesting and feeding techniques, moving the operation from the status of research pilot project to manufacturing plant. |
