Alosa aestivalis
(Mitchill, 1814)
Common Name:
Blueback Herring
Synonyms and Other Names:
blueback shad, river herring
Identification:
This fish is silvery in color, has a series of scutes (modified scales that are spiny and keeled) along its belly, and is characterized by deep bluish green backs. The most distinguishing characteristic of this species is the black to dusky in color of its peritoneum (the lining of the abdominal cavity). Blueback Herring and Alewife are difficult to distinguish from one another and are often regarded collectively as river herring. Alewife has larger eyes, greater body depth, and pearly to white peritoneal linings. Jenkins and Burkhead (1994); Owens et al. (1998); Page and Burr (1991); Smith (1985); Whitehead (1985). Comparisons between morphological and genetic identification methods found that identification between Blueback Herring and Alewife may be incorrect up to 16% of the time when using morphological methods alone (Kan et al., 2017).
Size:
40 cm
Native Range:
Atlantic Coast from Cape Breton, Nova Scotia, to the St. Johns River, Florida. Ascends coastal rivers during spawning season (Page and Burr 1991).
Great Lakes Nonindigenous Occurrences:
Blueback Herring was first recorded in the Mohawk River upstream of Cohoes Falls in 1934 (Greeley 1935). Juveniles were apparently present in Oneida Lake by 1981 or 1982. Blueback Herring was first collected in Lake Ontario in 1995 (Owens et al., 1998). They are established in Oneida Lake, the Oswego River in Minetto, Lake Champlain, and the upper Mohawk River upstream of Cohoes Falls, New York (Greeley 1935; Limburg et al. 2001; D. MacNeill and R. Owens, personal communication).
Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Alosa aestivalis are found here.
Full list of USGS occurrences
Table last updated 6/6/2026
† Populations may not be currently present.
* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).
Ecology:
Anadromous; living in marine systems and spawning in deep, swift freshwater with a hard substrate. Migrate to spawning grounds in the spring. In Connecticut, Blueback Herring spawn in 14–27oC temperatures. Usually spawns later in the spring than Alewife, when water temperatures are slightly warmer. During spawning, many eggs are deposited over the stream bottom where they stick to gravel, stones, logs, or other objects. Juveniles spend 3–7 months in freshwater, then migrate to the ocean (Yako et al. 2002). Blueback Herring are a planktivorous forage species (Winkelman and Van Der Avyle 2002). The landlocked Lake Theo, Texas population attained a smaller maximum size and had a shorter life span than anadromous native populations (Schramm et al. 1991).
Great Lakes Means of Introduction:
In most areas other than New York, these fish were intentionally stocked for forage. In New York these fish expanded their range using ship locks and canals.
Great Lakes Status:
Overwintering and reproducing in the Oswego River and eastern Lake Ontario.
Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...
Alosa aestivalis has a high potential environmental impact in the Great Lakes.
Alosa aestivalis may have impact similar to alewife (Alosa pseudoharengus) if it were to reach similar population densities, but currently this species is limited to Lake Ontario and at low densities relative to alewife. A. aestivalis could impede recovery of depressed populations of native fishes such as cisco (Coregonus artedi) and Lake trout (Salvelinus namaycush) (Owens et al. 1998). It could also displace Rainbow smelt (Osmerus mordax) and/or native forage fishes (Marsden and Hauser 2009). There is little or no evidence to support that Alosa aestivalis has significant socio-economic impacts in the Great Lakes.
There is little or no evidence to support that Alosa aestivalis has significant beneficial effects in the Great Lakes.
In the eastern US, River herring (A. aestivalis and A. pseudoharengus) is used for fish meal and fish oil to be added to fertilizer, pet food and domestic animal feed (Mellage 2016). One study in headwater lakes of Massachusetts indicates that this is a beneficial prey item for largemouth bass (Micropterus salmoides) introduced near the blueback’s native range (Yako and Mather 2000).
Management:
Regulations
Great Lakes Regulations pertaining to Alosa aestivalis | Jurisdiction | Regulation | Law | Description | Date Effective |
| Canada | Other | SQR/93-55 | In Canada, the use or possession of fish as live bait in any province other than from which it was taken is prohibited | 5/14/2021 |
| Illinois | Other | 515 ILCS 5/20-90 | This species is not on the Illinois Aquatic Life Approved Species List and if it is not otherwise native to Illinois it is illegal to be imported or possessed alive without a permit. | 7/9/2015 |
| NY | Other | 6 NYCRR Part 19 | New York restricts the use of anadromous river herring (including blueback) as bait in most waters | 1/15/2022 |
| NY | Other | ASMFC | New York follows the Interstate Fishery Management Plan for Shad and River herring established by the Atlantic States Marine Fisheries Commission which closes any non-sustainable commercial and recreational fisheries | 5/2009 |
| OH | Prohibited | OAC Chapter 1501:31-19 | It is illegal for any person to possess, import or sell exotic species of fish or hybrids thereof for introduction or to release into any body of water that is connected to or otherwise drains into a flowing stream or other body of water that would allow egress of the fish into public waters, or waters of the state, without first having obtained permission | 6/30/2024 |
Ontario
| Other | SQR/2007-237 | It is illegal to bring any live fish into Ontario for use as bait. | 10/25/2007 |
| Quebec | Restricted | SQR/90-214 | In Quebec, this species cannot be used as bait. | 6/1/2021 |
Note: Check federal, state/provincial, and local regulations for the most up-to-date information.
Control
Most management research relating to Alosa aestivalis appears focused on maintaining populations within the native range. Little species-specific information is available on how to control this species where it is invasive.
Biological
There are no known biological control methods for this species; top-down control by salmonids is effective for the related species Alosa pseudoharengus.
Chemical
Of the four chemical piscicides registered for use in the United States, antimycin A and rotenone are considered “general” piscicides, but no studies have been found of their effects on Alosa aestivalis (GLMRIS 2012).
Increasing CO2 concentrations, either by bubbling pressurized gas directly into water or by the addition of sodium bicarbonate (NaHCO3) has been used to sedate fish with minimal residual toxicity, and is a potential method of harvesting fish for removal, though maintaining adequate CO2 concentrations may be difficult in large/natural water bodies (Clearwater et al. 2008). CO2 is approved only for use as an anesthetic for cold, cool, and warm water fishes the US, not for use as euthanasia, and exposure to NaHCO3 concentration of 142-642 mg/L for 5 min. is sufficient to anaesthetize most fish (Clearwater et al. 2008).
It should be noted that chemical treatment will often lead to non-target kills, and so all options for management of a species should be adequately studied before a decision is made to use piscicides or other chemicals. Potential effects on non-target plants and organisms, including macroinvertebrates and other fishes, should always be deliberately evaluated and analyzed. The effects of combinations of management chemicals and other toxicants, whether intentional or unintentional, should be understood prior to chemical treatment. Other non-selective alterations of water quality, such as reducing dissolved oxygen levels or altering pH, could also have a deleterious impact on native fish, invertebrates, and other fauna or flora, and their potential harmful effects should therefore be evaluated thoroughly.
Other
Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.
Remarks:
One of the most common fish species in the Hudson River estuary (Hurst et al. 2004). Detection of a small population of Blueback Herring in Lake Ontario would be difficult because of the size of the Lake relative to the area routinely sampled and the herring's superficial similarity with Alewife, a fish sampled in large enough numbers that only a fraction of the adults are examined closely enough to distinguish between the two species (Owens et al. 1998). Owens et al. (1998) also asserted that colonizing a lake with resident population of Alewife, a fish that would be in direct competition with Blueback Herring for space and resources, and a surfeit of piscivores, both stocked and unstocked, may prove too difficult for A. aestivalis.
References
(click for full reference list)
Author:
Fuller, P., G. Jacobs, J. Larson, A. Fusaro, and M. Neilson
Contributing Agencies:
Revision Date:
3/27/2026
Peer Review Date:
6/26/2014
Citation for this information:
U.S. Geological Survey, 2026, Alosa aestivalis (Mitchill, 1814): Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/GreatLakes/FactSheet.aspx?Species_ID=488, Revision Date: 3/27/2026, Peer Review Date: 6/26/2014, Access Date: 6/6/2026
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.