Harbor seals eat a variety of fish, generally those that are schooling species or bottom species. The most recent food habits study for seals along the coast was at Grand Manan in 1992. Atlantic herring, Atlantic cod, squid, winter flounder, alewife, and hake were the most common food items. In the off-shore Gulf of Maine, hake were the most common food item found in 75 harbor seals. Atlantic salmon were not found in either study.
Harbor seals do enter rivers to feed if sufficient food fish are available.
While there have been no rigorous studies of incidence of take of Atlantic salmon by seals, there is anecdotal information of salmon returning with scrapes, etc. from seals. In Scotland, the predation rate on Atlantic salmon by seals was not related to the number of seals. In California, Oregon, and Washington, the 26 runs of 7 salmonid species have been listed as endangered. The National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine, reviewed this Pacific Salmon issue in 1996. The states and the Federal Government are cooperating in the management of the stocks.