Blueback Herring

Predators:

In the water, blueback herring has large predators, such as striped bass and bluefish, and is also preyed upon by gulls, terns and other coastal birds.

In addition, human influence threatens its existence, for example through habitat impediments like dams, habitat degradation and loss, and commercial and recreational fishing.

Habitat and Migration Pattern:

The blueback herring is native to the Atlantic Ocean and ranges from Prince Edward Island in the northwest Atlantic south to the mouth of the St. John’s River in Florida. Landlocked populations exist, for example in Lake Champlain and the Mohawk River, New York.

Blueback herring are anadromous, meaning that they spawn and spend larval development in freshwater, and then migrate out to spend most of their lives in marine water.

Spawning:

In mid to late April, when the water temperature is 39°C-48°C, blueback herring migrate from saltwater to brackish or freshwater to spawn. These spawning runs last until mid-August and occur in separate runs in groups through the season while most of the large spawning runs are made from mid-May to mid-July. Landlocked populations will make spawning runs up rivers and streams when the water reaches about 70°F. Blueback herrings prefer spawning habitats with swift water and a hard bottom, so after being deposited their eggs can stick to gravel, rocks, plants and wood. Many adults die after the spawn, but in freshwater they are more likely to survive it. Adult fish then migrate quickly downstream and little is known about their life history while in the marine environment. The larval herring live for a few months in spawning areas, until they leave freshwater as juvenile fish when they are about two inches long and migrate out to the sea. Female herring are fully mature at five years old and produce 60,000 to 100,000 eggs. Males are smaller and mature at three to five years of age.

Conservation status:

The Blueback Herring is a NOAA Fisheries Species of Concern. It was determined that listing blueback herring rangewide or as any of the identified Distinct Population Segments as threatened or endangered under the ESA is not warranted as of June 2019. However, blueback herring populations are declining because of loss of habitat due to decreased access to spawning areas from the construction of dams and other impediments to migration, habitat degradation, fishing, and increased predation due to recovering striped bass populations.

Dams like the Montgomery Dam have blocked the blueback herrings from migrating to the Megunticook river for spawning. In order to return to the Megunticook dams would need to be removed.

Literature:

• NOAA Fisheries. April 6, 2020. “Not Warranted Listing Determination for Alewife and Blueback Herring”. NOAA Fisheries. https://www.fisheries.noaa.gov/action/not-warranted-listing-determination-alewife-and-blueback-herring

• “Blueback Herring”. Fish and Aquatic Conservation. U.S. Fish & Wildlife Service. https://www.fws.gov/fisheries/freshwater-fish-of-america/blueback_herring.html

• “Blueback Herring”. Chesapeake Bay Program. https://www.chesapeakebay.net/S=0/fieldguide/critter/blueback_herring

• Dennis, C. 2002. “Alosa aestivalis”. Animal Diversity Web. https://animaldiversity.org/accounts/Alosa_aestivalis/

• Garrison, R. April 15, 2018. “Species Profile: Blueback Herring”. Liveabout Dotcom. https://www.liveabout.com/facts-about-blueback-herring-1311591

Image credit:

https://ncfishes.com/marine-fishes-of-north-carolina/alosa-aestivalis/