Blueback herring (Alosa aestivalis) is also known as summer herring and is known collectively with alewives and other clupeids as river herring. You may find bluebacks in bait stores sold as river herring, sawbellies, or even bunker.
Bluebacks are known as alose d'ete in France (literally, shads of the summer), blueback glut herring or shad herring in United Kingdom vernacular, and sinisilli in Finnish vernacular.
Perception Channels: tactile ; chemical
The blueback herring is has been the subject of fisheries. It is more commonly known with come other clupeids as river herring, which includes the alewife. Very general "river herring" labels may include other bait fish such as the American shad and menhaden (Brevoortia tyrannus), or bunker.
Blueback herring are planktivores and eat anything the size of larval fish to zooplankters. Blueback herring also consume small fishes and shrimps. (Froese and Pauly, 2001)
The blueback herring (Alosa aestivalis) ranges from Prince Edward Island in the northwest Atlantic south to the mouth of the St. John's River in Florida.
There are landlocked populations, but the furthest inland the bluback herring exists is Lake Champlain and the Mohawk river, New York.
Biogeographic Regions: atlantic ocean (Native )
The blueback is anadromous and develops in freshwater, then migrates to marine, and then migrates back to freshwater to spawn.
Average lifespan
Status: captivity: 8 years.
The blueback herring is slender like the alewife (Alosa pseudoharengus) and several papers that exist only for identification purposes between these two species (MacLellan et.al. 1981). The blueback herring has a smaller eye, its otolith has more hooked shape than the alewife's L-shaped otolith, and the lining of the viscera is black instead of silver (this is the most distinguishing characteristic). However, if you do not want to sacrifice the fish just to identify it: the dorsal surface of blueback herrings have a blue color, and they have 41 to 51 gill rakers. Also characteristic of bluebacks are one dark spot on the shoulder. The American shad (Alosa sapidissima) often has 4-5 spots in the same location.
Blueback herrings grow to a maximum of 15 inches, but are more commonly around one foot long. Smith (1985) notes that most adults are 10 to 12 inches long in the Hudson River, NY.
In general Clupeids, or the herring, shad, and menhaden (among others) family, are silvery with a sharp ventral keel. This keel has given them the common name of "sawbellies," which is an adaption for optimal schooling movement and organization. They have forked caudal fins and the anal fin is usually longer than the dorsal fin. Their body shape is teardrop, but more elongate than faster moving fishes such as the tunas. The maximum depth of the fishes' body is just anterior to the dorsal fin.
Range mass: 400 (high) g.
Other Physical Features: bilateral symmetry
Blueback herring, like many other clupeids are anadromous fish, meaning they spawn and spend larval development in freshwater, and then they migrate out to spend most of their lives in marine waters. Landlocked populations will make spawning runs up rivers and streams, but spend most of their life in the pelagic zone of lakes. Many fish can make extensive spawning runs. In New York, the species can reach the Mohawk river, more than 150 kilometers from the Atlantic Ocean. Ian Blackburn and Karin Limburg, researchers at the SUNY college of environmental science and forestry, are trying to determine whether some of these individuals found here are migratory or residents of the Mohawk River.
Spawing runs can get large and begin in mid to late April (as soon as the water is 4-9 degrees Celcius) and last until mid-August. The blueback herring is also known as the summer herring since most of the large spawning runs occur from mid-may to mid-july. (This is another environmentally friendly way to separate alewives and bluebacks: the spawning runs are spatially and temporally separated from each other). Spawning occurs in separate runs in groups through the season, but the fish can be inhibited by high temperatures (27 deg C). Bluebacks prefer spawning habitat with swift water and a hard bottom, and fish from ages 3-7 normally spawn.
During courtship, the female is often pursued by several males--all of which will swim as a group in circles. Males nudge the vent region of the female with their snouts, most likely to stimulate the female to release her gametes. All together, they make a dive towards the bottom, stop short, face the current and release their gametes. The eggs need 50 hours of incubation at 72 deg F to develop.
Average age at sexual or reproductive maturity (male)
Sex: male: 1277 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 1460 days.
Larval and juvenile blueback herring (Alosa aestivalis) are obligate planktivores that prey upon any copepods or cladocerans, or any other zooplankton small enough to fit in their mouths (Burbidge, 1974; Janssen, 1982). Adult blueback herring are opportunistic predators that feed on an array of prey items including plants, zooplankton, insects, crustaceans, small fish, and fish eggs (Fay et al., 1983; Simonin et al., 2007). Research on competitors of A. aestivalis is limited, however, many specialists agree that spatially overlapping populations of A. aestivalis and alewife (A. pseudoharengus) may result in competition for food and resources, such as protection from predators in submerged aquatic vegetation (Atlantic States Marine Fisheries Commission, 1997; Fay et al., 1983).
Blueback herring are preyed upon by fish species such as striped bass (Morone saxatilis), blue catfish (Ictalurus furcatus), flathead catfish (Pylodictis olivaris), bluefish (Pomatomus saltatrix), Atlantic halibut (Hippoglossus hippoglossus), and spiny dogfish (Squalus acanthias) (Juanes et al., 1993; Manooch, 1973; Mellage, 2016; Moran et al., 2015). Additionally, aerial predators, including seagulls (family Laridae) and terns (family Sternidae), prey upon A. aestivalis (Fay et al., 1983).
A. aestivalis may act as a host for parasites, including acanthocephalan and nematodes (Bigelow et al., 1963). In a study conducted by Lovy and Hutcheson (2016), a parasite of the myxozoan subphylum was identified as inhabiting between approximately 2% and 20% of the young-of-year (YOY) blueback herring in 3 New Jersey Rivers: the Maurice River (20%), the Great Egg Harbor River (5%), and the Delaware River (2%). This study demonstrated the first observation of this parasite, Myxobolus mauriensis n. sp., in blueback herring and the similar species alewife. Lovy and Hutcheson (2016) suggest that the YOY river herring were more susceptible to this parasite as it is able to attach to the still developing rib cage.
In a study conducted by Mcbride et al. (2014), 4.4% of blueback herring and alewife (112 individuals) sampled from 34 rivers ranging from Massachusetts, U.S. to New Brunswick, Canada were genetically identified as blueback-alewife hybrids.
The Smithsonian Environmental Research Center (SERC) has developed a citizen science program, known as the Chesapeake Bay River Herring Project, to assess the health of blueback herring (Alosa aestivalis) as well as the similar species alewife (Alosa psuedoharengus), collectively termed river herring, in the tributaries of the Chesapeake Bay – the middle section of its entire range. Following training provided by SERC, citizens help collect field data, such as water temperature and flow. Additionally, volunteers can evaluate data in the lab by processing water samples in search of herring larvae and eggs, counting fish recorded by the Dual-Frequency Identification Sonar (DIDSON), and determining individual river herring size estimates based on the DIDSON footage. This work contributes to understanding the abundance and range of river herring (Sharova, 2016).
Towards the northern extent of the river herring range, in Medford, Massachusetts, the Herring Monitoring Program, developed by the Mystic River Watershed Association, coordinates volunteers to conduct visual counts of blueback herring, as well as alewife, as they utilize a single fish ladder in the Department of Conservation Resources Mystic Lakes Dam (Mystic River Watershed Association, 2015). The monitoring framework for this program is structured on the Massachusetts Department of Marine Fisheries (MA-DMF) protocol where monitoring lasts for the duration of the spawning season – April 1st to mid-June, or until two consecutive weeks pass without herring sightings (Massachusetts Division of Marine Fisheries, 2013). Volunteer counters record fish sightings three times at ten-minute intervals, within each counting period (morning, mid-day, and afternoon) on a data sheet that will later contribute to spawning run estimates in the Mystic River. This citizen science program aims to assess river herring health in the Mystic River, as well as utilize results to predict overall herring population trends throughout Massachusetts (Mystic Monitoring Network, 2012).
Here follows a list of other citizen science programs focused on monitoring river herring populations and/or working to assist in river herring recovery: Rivers Alliance of Connecticut (CT); Farmington River Watershed Association (CT); Lloyd Davis Anadromous Fish Trust (ME); Kennecbec Estuary Land Trust (ME); Ipswich River Watershed Association (MA); Jones River Watershed Association (MA); North and South Rivers Watershed Association (MA); Parker River Clean Water Association (MA); Association to Preserve Cape Cod (MA); Harwich Conservation Trust (MA); Weymouth Herring Run Committee (MA); Ten Mile River Watershed Council (RI); River Herring Watch (NJ); Neuse Riverkeeper Foundation (NC) (Herring Alliance, 2013).
Blueback herring (Alosa aestivalis) are commonly mistaken for the nearly identical fish species, alewife (Alosa psuedoharengus), therefore the two species are collectively termed “river herring” (“Maine River Herring Fact Sheet,” 2016, U.S. Fish and Wildlife Service, n.d.). Both species are comprised of primarily silver scales with a black dot behind each eye and scutes along their stomach (Northeast Fisheries Observer Program, 2012; U.S. Fish and Wildlife Service, n.d.). Externally, the eyes of an alewife are larger proportionally to their head, than that of a blueback herring, and the stomach of an alewife protrudes lower than that of a blueback herring (Anita C. Leight Estuary Center, n.d.). Both species have sharply-rising jaw lines, opposite that of their hickory shad (Alosa mediocris) and American shad (Alosa sapidissima) relatives that exhibit gently sloping jaw-lines (Northeast Fisheries Observer Program, 2012).
However, the variations in these characteristics may be too subtle to confirm without expert identification, so internal verification must be done. Upon dissection, the gut peritoneum of the blueback herring species is black, whereas alewife exhibits a light peritoneum speckled with black (“Tips for Identifying Common Fish Species in the Bush River,” n.d.).
While blueback herring migration into estuaries for spawning typically begins in mid-May, alewife migration occurs approximately 2-4 weeks earlier in the season (Turner & Limburg, 2016; U.S. Fish and Wildlife Service, n.d.). Due to this temporal separation, juvenile alewife tend to be larger than juvenile blueback herring when caught in one collection event (“Tips for Identifying Common Fish Species in the Bush River,” n.d.). This difference may aid in species differentiation paired with other known physical differentiation techniques.
Both species utilize freshwater and estuary systems as nursery habitat (Turner & Limburg, 2016). Unlike blueback herring that prefer to lay their eggs in fast-moving water bodies during the day, alewife prefer slower moving streams at night to spawn (U.S. Fish and Wildlife Service, n.d.).
Blueback herring (Alosa aestivalis) are anadromous, meaning they spend the majority of their life in the open ocean of the Atlantic and return to freshwater tributaries along the eastern coast of North America to spawn each year (Fuller et al., 2016; U.S. Fish and Wildlife Service, n.d.). When ocean temperatures reach approximately 14°C, blueback herring begin migrating from the open ocean into freshwater systems to spawn. The entire spawning season occurs from late April to mid-September, but the greatest activity is exhibited from mid-May to mid-July. The herring select spawning sites based on the amount of water flow and type of benthic substrate, preferring quick-moving water and hard, stable bottoms (Loesch & Lund, 1977).
The blueback herring fry remain in freshwater streams until they transition into the later juvenile life stage, where they then migrate downstream into estuarine systems (Pardue, n.d.). As estuary water temperatures begin to decline from mid July through early November, juvenile blueback herring begin the migration out of the estuaries into the Atlantic Ocean (“Maine River Herring Fact Sheet,” 2016). The first groups of fish begin this migration when water temperatures hit 21°C and the greatest movement is observed between 14°C and 15°C, then concludes at 10°C (O’Leary & Kynard, 1986).
Pre-adult, juvenile and young-of-year (fish within the first year of hatching), blueback herring are obligate planktivores meaning that they feed on prey such as copepods and cladocerans (water fleas) (Burbidge, 1974; Janssen, 1982). This fish is opportunistic such that if a prey species comes within or above its field of vision, the herring will approach the surface to engulf the prey (Janssen, 1982). As a result of this predation method, young-of-year only feed during daylight (Burbidge, 1974). Adult blueback herring consume a variety of prey including plants, zooplankton, insects, small fish and fish eggs (Simonin et al., 2007).
The blueback herring, blueback shad, or summer shad (Alosa aestivalis) is an anadromous species of herring from the east coast of North America, with a range from Nova Scotia to Florida. Blueback herring form schools and are believed to migrate offshore to overwinter near the bottom.
These fish are silvery in color, have a series of scutes (modified, spiny and keeled scales) along their bellies, and are characterized by deep bluish-green backs.[2] They reach a maximum size of approximately 40 centimetres (16 in) and are believed to live up to 8 years. The most distinguishing characteristic of this species is the black to dusky color of its peritoneum (the lining of the abdominal cavity).[2] It is one of the "typical" North American shads. They are often confused with alewifes because blueback shad and alewives are difficult to distinguish from one another, and together these two species are often regarded collectively as "river herring". Alewives have larger eyes, greater body depth, and pearly to white peritoneal linings.
This fish has, in the past, been used as a baitfish for the lobster fishing industry. It is also used for human consumption, usually smoked. It is caught (during its migration up stream) using large dip nets to scoop the fish out of shallow, constricted areas on its migratory streams and rivers.
The native range of this fish is found along the Atlantic Coast from Cape Breton, Nova Scotia, to the St. Johns River, Florida. During spawning season, it migrates into coastal rivers.
Blueback shad were first collected in Lake Ontario in 1995, and have been collected from the Tennessee River in Georgia and Tennessee; Oneida Lake, the Oswego River, and Lake Champlain in New York. In North Carolina, blueback shad were introduced into the Savannah, Broad, and Yadkin River basins, and into non-native areas of the Cape Fear and Roanoke River basins. It has been introduced to an unspecified location in the Chesapeake Bay basin in Pennsylvania. They have been collected in Lake Jocassee, Lake Keowee, Picalet River, Broad River, and Lake Murray in South Carolina. Stock obtained from the Cooper River, South Carolina, was released in Texas by the Texas Parks and Wildlife Department in Lake Theo, Briscoe County, and at an unidentified research site in North Texas in 1982 (and in the upper Red River drainage). Bluebacks have been collected from Lake Champlain, Vermont, and have been stocked in several inland reservoirs in Virginia, including Smith Mountain Lake, Occoquan Reservoir, Kerr Reservoir, and Lakes Anna, Brittle, and Chesdin. It is established as a species in Texas, New York, North Carolina, Vermont, and Virginia.
This fish is anadromous, living in marine systems and spawning in deep, swift freshwater rivers with hard substrates. It migrates to spawning grounds in the spring. In Connecticut, blueback shad spawn in 14 to 17 °C (57 to 63 °F) water, usually later in the spring than the alewife. During spawning, many eggs are deposited over the stream bottom, where they stick to gravel, stones, logs, or other objects. Juveniles spend three to seven months in fresh water, then migrate to the ocean. The blueback shad is a planktivorous forage species.
Blueback herring spawn from late March through mid-May, depending on latitude. Females usually mature by age five and produce between 60,000 and 103,000 eggs. Males generally mature earlier at between 3 and 4 years of age and at a smaller size than the females. For both species, adults migrate quickly downstream after spawning and little is known about their life history while in the marine environment; however, they are believed to be capable of migrating long distances (over 1,900 kilometres (1,200 mi)).
Blueback populations have exhibited drastic declines throughout much of their range. There are several threats that have most likely contributed to their decline. These threats include: 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.
In response to the declining trend for river herring, the states of Alabama, Massachusetts, Rhode Island, Connecticut, Virginia, Delaware and North Carolina have instituted moratoriums on taking and possession.
The blueback herring is a U.S. National Marine Fisheries Service Species of Concern. Species of Concern are those species about which the U.S. Government's National Oceanic and Atmospheric Administration, National Marine Fisheries Service, has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the U.S. Endangered Species Act (ESA).
Wikimedia Commons has media related to Alosa aestivalis. 
Alosa aestivalis The blueback herring, blueback shad, or summer shad (Alosa aestivalis) is an anadromous species of herring from the east coast of North America, with a range from Nova Scotia to Florida. Blueback herring form schools and are believed to migrate offshore to overwinter near the bottom.
These fish are silvery in color, have a series of scutes (modified, spiny and keeled scales) along their bellies, and are characterized by deep bluish-green backs. They reach a maximum size of approximately 40 centimetres (16 in) and are believed to live up to 8 years. The most distinguishing characteristic of this species is the black to dusky color of its peritoneum (the lining of the abdominal cavity). It is one of the "typical" North American shads. They are often confused with alewifes because blueback shad and alewives are difficult to distinguish from one another, and together these two species are often regarded collectively as "river herring". Alewives have larger eyes, greater body depth, and pearly to white peritoneal linings.
This fish has, in the past, been used as a baitfish for the lobster fishing industry. It is also used for human consumption, usually smoked. It is caught (during its migration up stream) using large dip nets to scoop the fish out of shallow, constricted areas on its migratory streams and rivers.
