Alewife (Alosa pseudoharengus)
Alewife are an anadromous species, meaning that they are born in fresh water, spend most of their life in the ocean, and then return to fresh water to spawn (9). Adults generally develop at sea for 2-4 years before returning to their natal rivers to spawn (8). Alewife are repeat spawners; although some adults die after spawning, most adults return to the ocean until the following year's spawning migration, and can live up to eight years (4,7).
Their spawning migration occurs in the spring when river and stream water temperatures reach 5-10°C, which generally occurs in Maine from late April to mid-May (6). Alewives ascend rivers and streams, ending their journey in lakes and ponds, where they spawn. Spawning begins when lake water temperatures reach 16-19°C, usually late April to mid-June in Maine (2).
After the eggs hatch, the juvenile alewives stay in freshwater lakes and ponds until they grow to be a few inches long. From mid-July through October, the juveniles migrate downstream to the ocean where they grow to adulthood (7).
Their spawning migration occurs in the spring when river and stream water temperatures reach 5-10°C, which generally occurs in Maine from late April to mid-May (6). Alewives ascend rivers and streams, ending their journey in lakes and ponds, where they spawn. Spawning begins when lake water temperatures reach 16-19°C, usually late April to mid-June in Maine (2).
After the eggs hatch, the juvenile alewives stay in freshwater lakes and ponds until they grow to be a few inches long. From mid-July through October, the juveniles migrate downstream to the ocean where they grow to adulthood (7).
Alewife are deep bodied fish that grow to be 14-15 inches long (7). They are grayish green along the dorsal surface and silvery on the ventral surface and sides (3).
Alewife feed primarily on zooplankton in both the ocean and in fresh water. In the ocean, they also eat small fishes, including Atlantic herring, eel, sand lance, cunner, and other alewife, as well as the eggs and larvae of other fish. Alewife are a pelagic, schooling species that make ocean migrations seasonally in response to changing ocean water temperatures. They are also known to migrate deeper during the day; diel migrations may be associated with the distribution of zooplankton in the water column (3).
The distribution of alewife along the Atlantic coast stretches from North Carolina all the way to Newfoundland. They were previously found as far south as South Carolina but have not been documented there in recent years (1). The figure below depicts the current range of alewife.
Alewife feed primarily on zooplankton in both the ocean and in fresh water. In the ocean, they also eat small fishes, including Atlantic herring, eel, sand lance, cunner, and other alewife, as well as the eggs and larvae of other fish. Alewife are a pelagic, schooling species that make ocean migrations seasonally in response to changing ocean water temperatures. They are also known to migrate deeper during the day; diel migrations may be associated with the distribution of zooplankton in the water column (3).
The distribution of alewife along the Atlantic coast stretches from North Carolina all the way to Newfoundland. They were previously found as far south as South Carolina but have not been documented there in recent years (1). The figure below depicts the current range of alewife.
Blueback Herring (Alosa aestivalis)
Blueback herring are similar in appearance and behavior to alewife, but have a different spawning strategy. They also live in the ocean as schooling adults and are known to migrate offshore to overwinter in deeper water. Males mature for 3-4 years before spawning, while females generally require 5 years to develop before spawning. Blueback herring can live for up to 8 years and grow to 16 inches in length (10).
Ocean dwelling adults migrate into shallower waters and then into fresh water streams and rivers in late spring to spawn. Blueback herring spawn in the mainstem of freshwater streams and rivers, generally in shallow, fast moving water. Their spawning migration begins about a month after the alewife migration, generally from mid-March to mid-May (10).
Ocean dwelling adults migrate into shallower waters and then into fresh water streams and rivers in late spring to spawn. Blueback herring spawn in the mainstem of freshwater streams and rivers, generally in shallow, fast moving water. Their spawning migration begins about a month after the alewife migration, generally from mid-March to mid-May (10).
Blueback herring look very similar to alewife. The dorsal surface is grayish green and the sides and ventral surface are shiny silver. Blueback herring and alewife can be distinguished from one another by body depth and eye diameter (3).
Like alewife, blueback herring feed primarily on plankton. They consume ctenophores, copepods, amphipods, mysid shrimp, and other small fish. Adult blueback herring are pelagic, schooling fish that undertake seasonal migrations and diel vertical migrations (3).
The distribution of blueback herring extends further south than that of alewife. Blueback herring have been documented as far north as Nova Scotia and as far south as the St. John's River in Florida (10). The figure below shows the current range of blueback herring.
Like alewife, blueback herring feed primarily on plankton. They consume ctenophores, copepods, amphipods, mysid shrimp, and other small fish. Adult blueback herring are pelagic, schooling fish that undertake seasonal migrations and diel vertical migrations (3).
The distribution of blueback herring extends further south than that of alewife. Blueback herring have been documented as far north as Nova Scotia and as far south as the St. John's River in Florida (10). The figure below shows the current range of blueback herring.
References:
1. ASMFC. 2009. Amendment 2 to the Interstate Fishery Management Plan for Shad and River Herring. Fishery Management Report No. 35 Washington, D.C.
2. Bigelow, H.B., and W.C. Schroeder. 1953. Fishes of the Gulf of Maine. Fishery Bulletin 74 of the Fishery bulletin of the Fish and Wildlife Service, volume 53. United States Government Printing Office, Washington, D.C.
3. Collette, B.B., and G. Klein-MacPhee. 2002. Atlantic halibut, Hippoglossus hippoglossus (Linnaeus 1758). In: B.B. Collette and G. Klein-MacPhee (eds). Bigelow and Schroeder’s fishes of the Gulf of Maine: Smithsonian Institution Press, Washington, DC.
4. Jessop, B.M. 1994. Homing of alewives (Alosa pseudoharengus) and blueback herring (A. aestivalis) to and within the Saint John River, New Brunswick, as indicated by tagging data. Canadian Tech. Rep, Fish, Aquat. Sci. No. 2015:22.
5. Kocik, J. Northeast Fisheries Science Center (NEFSC). 2000. Status of Fisheries Resources off Northeastern United States – Alewife. January 2000. http://www.nefsc.noaa.gov/sos/spsyn/af/herring/.
6. Loesch, J.G. 1987. Overview of life history aspects of anadromous alewife and blueback herring in freshwater habitats. Pages 89-103 in M.J. Dadswell, R.J. Klauda, C.M. Moffitt, and R.L. Saunders, editors. Common strategies of anadromous and catadromous fishes. American Fisheries Society Symposium 1 Bethesda, Maryland.
7. Maine Department of Marine Resources (DMR). 2004. Alewife fact sheet. http://www.fws.gov/GOMCP/pdfs/alewife%20fact%20sheet.pdf
8. Neves, R.J. 1981. Offshore distribution of alewife, Alosa pseudoharengus, and blueback herring, Alosa aestivalis, along the Atlantic coast. Fishery Bulletin 79: 473-485.
9. NOAA National Marine Fisheries Service (NMFS). 2009. Species of Concern. Detailed Alewife page. http://www.nmfs.noaa.gov/pr/pdfs/species/riverherring_detailed.pdf.
10. Virginia Institute of Marine Sciences. 2003. Blueback herring page. http://www.fisheries.vims.edu/femap/fish%20pages/Blueback%20Herring.htm.
2. Bigelow, H.B., and W.C. Schroeder. 1953. Fishes of the Gulf of Maine. Fishery Bulletin 74 of the Fishery bulletin of the Fish and Wildlife Service, volume 53. United States Government Printing Office, Washington, D.C.
3. Collette, B.B., and G. Klein-MacPhee. 2002. Atlantic halibut, Hippoglossus hippoglossus (Linnaeus 1758). In: B.B. Collette and G. Klein-MacPhee (eds). Bigelow and Schroeder’s fishes of the Gulf of Maine: Smithsonian Institution Press, Washington, DC.
4. Jessop, B.M. 1994. Homing of alewives (Alosa pseudoharengus) and blueback herring (A. aestivalis) to and within the Saint John River, New Brunswick, as indicated by tagging data. Canadian Tech. Rep, Fish, Aquat. Sci. No. 2015:22.
5. Kocik, J. Northeast Fisheries Science Center (NEFSC). 2000. Status of Fisheries Resources off Northeastern United States – Alewife. January 2000. http://www.nefsc.noaa.gov/sos/spsyn/af/herring/.
6. Loesch, J.G. 1987. Overview of life history aspects of anadromous alewife and blueback herring in freshwater habitats. Pages 89-103 in M.J. Dadswell, R.J. Klauda, C.M. Moffitt, and R.L. Saunders, editors. Common strategies of anadromous and catadromous fishes. American Fisheries Society Symposium 1 Bethesda, Maryland.
7. Maine Department of Marine Resources (DMR). 2004. Alewife fact sheet. http://www.fws.gov/GOMCP/pdfs/alewife%20fact%20sheet.pdf
8. Neves, R.J. 1981. Offshore distribution of alewife, Alosa pseudoharengus, and blueback herring, Alosa aestivalis, along the Atlantic coast. Fishery Bulletin 79: 473-485.
9. NOAA National Marine Fisheries Service (NMFS). 2009. Species of Concern. Detailed Alewife page. http://www.nmfs.noaa.gov/pr/pdfs/species/riverherring_detailed.pdf.
10. Virginia Institute of Marine Sciences. 2003. Blueback herring page. http://www.fisheries.vims.edu/femap/fish%20pages/Blueback%20Herring.htm.