identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
E642879AFFAEFFE1342D156751E4FE2A.text	E642879AFFAEFFE1342D156751E4FE2A.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Alosa pseudoharengus (Wilson 1811)	<div><p>2 | ALEWIFE</p><p>2.1 | Life history</p><p>2.1.1 | Diet</p><p>Alewife begin their lives in freshwater, feeding on small, planktonic crustacean nauplii before they grow and move toward the sea (Bozeman Jr &amp; Van Den Ayvle, 1989). Although the pelagic diet of invasive alewife in the Laurentian Great Lakes is well understood (e. g., Pothoven &amp; Vanderploeg, 2004; Stewart et al., 2009; Strus &amp; Hurley, 1992), thorough descriptions of the diet of anadromous alewife in the Atlantic are still limited. Some insights into their diet in the marine environment were, however, gathered from stomach content analyses from alewife caught along the continental shelf from New England to Cape Hatteras, North Carolina (Bowman et al., 2000). In that study, non-decapod crustaceans represented the majority of the alewife's prey by weight, and adults were found to primarily filter-feed on copepods and krill. However, the stomach contents of larger individuals (&gt; 20 cm) included mollusks, cnidarians, and juvenile fish, suggesting an ontogenic shift in alewife from primarily filter feeding to a mixed strategy that includes predation on a higher diversity of taxa (Table 1; Bowman et al., 2000).</p><p>2.1.2 | Growth</p><p>In the Chesapeake Bay estuary, juveniles were found to grow to about 114 – 127 mm long in their first year (Table 1; Hildebrand &amp; Schroeder, 1927); however, once alewife enter the sea, there is a distinct lack of information regarding their rate of growth from the time they enter the ocean to when they return inshore. Several studies have shown that alewife are sexually dimorphic where females spend a longer time at sea and reach a larger average adult length of 284.3 mm (standard deviation = 15.77), whereas males reach an average length of 271.6 mm (standard deviation = 13.09; Table 1; Fay et al., 1983; Marjadi et al., 2019). The observed sexual dimorphism is also exhibited in the model parameters from the von Bertalanffy growth function (VBGF; Bertalannfy, von L., 1938) where L ∞ is the mean asymptotic length of fish, K is the Brody growth coefficient and represents how quickly fish approach L ∞, and t 0 is the hypothetical age at which fish length is equal to zero (x -intercept; Gilligan-Lunda et al., 2021). For alewife, L ∞ ranged from 291.67- (males) to 310.48 mm (females), K ranged from 0.4 (females) to 0.441 (males), and t 0 ranged from 0.103 (females) to 0.142 (males; Messieh, 1977). Alewife take 3 – 6 years to mature at sea before returning to rivers to spawn (Table 1; Loesch, 1987). Individuals at lower latitudes are typically shorter lived and quick to mature, which is consistent with the latitudinal relationship across ectotherms (Table 1; Munch &amp; Salinas, 2009).</p><p>2.1.3 | Spawning</p><p>Alewife preferentially return to their natal stream or pond, relying on olfactory mechanisms to detect the odor of the water from which they hatched (Table 1; Thunberg, 1971). The frequency of iteroparity in alewife populations is latitudinally influenced, with northern latitudes having a higher percentage of repeat spawners annually (Table 1; Fay et al., 1983). Iteroparity also varies at smaller spatial scales between sites, suggesting that river-specific drivers, like anthropogenic impacts (habitat degradation, overfishing, dams, and loss of river connectivity), are primary determinants of the survival and fidelity of anadromous alewife populations (Hare et al., 2021; Spares et al., 2023). In the Gaspereau River in Nova Scotia, the alewife stock is heavily impacted by overfishing; of the previously spawned adults, only 11.1% of males and 7.4% of females returned the following years, compared to an estimated 50% return rate in rivers with minimal anthropogenic stressors (Gibson, 2000). Unlike salmonids, for which males expend more energy spawning and females have higher rates of repeat spawning (Jonsson et al., 1991), interannual returns are higher among male alewife than females (Table 1). However, this may be attributed to artificial selection, with the longer mean length of females at spawning age increasing their likelihood of being caught in gillnets, decreasing their survival during spawning season (Spares et al., 2023).</p><p>2.1.4 | Mortality</p><p>Southerly alewife live only 3 – 4 years, compared to their northern counterparts, which can live up to 9 – 10 years (Table 1; Fay et al., 1983). Predation is a primary cause of natural mortality, and alewife contribute to the diet of piscivorous fishes, birds, and mammals (Hare et al., 2021). Freshwater predation is a major bottleneck, and some predators may feed exclusively on alewife during their spawning migration (Hare et al., 2021), whereas predation at sea is more diffuse. Anadromous alewife store substantial energy from the ocean in their fatty tissues, contributing to the nutrient input of freshwater systems following their annual spawning events. Similar subsidies to the marine environment must be relevant, although they are less commonly considered than the subsidies provided to freshwater systems for anadromous species (Table 1; Dias et al., 2019). Although there is ample research on marine isotopes carried by anadromous fishes into fresh water (Durbin et al., 1979), there is little comparable work to find freshwater isotopic signatures in the marine environment that might suggest how alewife provide a reciprocal subsidy to the ocean via their anadromy. Nevertheless, alewife have shown to be significant to the diets of demersal groundfish, indicating a high degree of predation mortality at sea (Link &amp; Garrison, 2002). Young of year (YOY) alewife immigrating from estuaries to the northeastern coastal shelf have even been suggested to influence the movement behavior of predator species (i.e., co-migration; Hare et al., 2021). Historically, the pursuit of alewife by Atlantic cod ( Gadus morhua and other gadids) may have been a key driver of gadid movement into estuaries and river mouths where alewife aggregate to spawn (Ames &amp; Lichter, 2013). In estuaries where alewife were extirpated, inshore gadid populations also disappeared and did not return, suggesting a high predator – prey linkage between gadids and alewife in the northeastern Atlantic and a role of freshwater – marine nutrient subsidies (Table 1; Ames &amp; Lichter, 2013). Further, modeling suggests that if alewife populations increase, their migrations to and from the marine environment could positively impact species of economic importance and conservation concern by acting as a stable food source during unpredictable changes in climate for key marine species (Dias et al., 2019).</p><p>2.2 | Behavior</p><p>2.2.1 | Migration and foraging</p><p>Anadromous alewife range from North Carolina to Newfoundland (Table 1; Collette &amp; Klein-Macphee, 2002; ASMFC, 2009). YOY alewife typically migrate to marine environments in June and July (Schmidt et al., 1988). Once at sea, juveniles join large intraspecific feeding schools of similar-sized individuals, with smaller alewives preferring shallower regions compared to larger adults (Table 1; Stone and Jessop, 1981). These feeding schools are mixed-stock, meaning that several different alewife populations are moving and feeding together (DFO, 1986; Rulifson &amp; Dadswell, 2020). Alewife are also known to form mixed-species schools with other herrings like menhaden ( Brevoortia spp.) or blueback herring ( A. aestivalis; Bigelow &amp; Schroeder, 1953; Rulifson &amp; Dadswell, 2020).</p><p>Abbreviation: VBGF, von Bertalanffy growth function.</p><p>Despite sustaining a critical fishery, there are limited investigations of the marine migratory movement of alewife (Gibson et al., 2017; Huveneers et al., 2016; Neves, 1981; Stone &amp; Jessop, 1992; Tsitrin et al., 2020; Tsitrin et al., 2022; Ogburn et al., 2024). However, a recent acoustic telemetry study demonstrated that alewife from Choptank River, Maryland, migrated northward into Georges Bank and the Gulf of Maine in the summer and moved southward in the fall and winter (Ogburn et al., 2024). These findings validate the yearly migratory patterns inferred from catch and by-catch data, which suggest that alewife move northward and inshore in the spring, as many prepare to return to fresh water for spawning, and finally offshore and southward in the fall (Table 1; Neves, 1981; Stone &amp; Jessop, 1992). This migration pattern was observed in populations from the Mid-Atlantic Bight, where summer and fall catches were concentrated in Nantucket Shoals, Georges Bank, and coastal Gulf of Maine regions, suggesting they moved northward from their natal stream (Neves, 1981). Furthermore, winter catches indicated they return to the Mid-Atlantic coastline in the winter and spring (Table 1; Neves, 1981; Tsitrin et al., 2022). These migratory patterns were further validated by alewife catch data along the coast of Nova Scotia that indicated alewife distribution shifted inshore and northward in spring along the Scotian Shelf and offshore and southward in fall toward the Gulf of Maine and Bay of Fundy (Stone &amp; Jessop, 1992). The extent of offshore overwintering for alewife is still unknown; however, the theorized seasonal distribution of alewife closely resembles American shad migratory movements, which suggests that alewife may use a mixture of inshore and offshore foraging areas annually (Table 1; Neves, 1981).</p><p>Alewife movement at sea is presently thought to be regulated by biological factors as they follow zooplankton productivity (DFO, 1986; Neves, 1981; Tsitrin et al., 2022). When alewife feed on plankton, they undertake diel vertical migrations following the vertical movement of zooplankton throughout the water column (Table 1; Neves, 1981; Stone &amp; Daborn, 1987). Stomach content analyses suggest alewife particulate feed on macrozooplankton when water visibility is high during the day and filter feed on microzooplankton during low visibility at night (Table 1; Gilmurray, 1980; Stone &amp; Jessop, 1992).</p><p>Recent studies have demonstrated that alewife marine movement is also influenced by water temperature, tidal currents, salinity, and depth (Tsitrin et al., 2022; Turner et al., 2016), suggesting their distributions are constrained by suitable oceanographic conditions. For instance, seasonal spawning migrations are thought to be triggered by water temperatures around 5 – 10 C (Jessop &amp; Parker, 1988; Tsitrin et al., 2022). Therefore, mature alewife begin spawning migrations toward rivers in late March in the south and progressively later into July further north (Table 1; Cole et al., 1980; Mullen et al., 1986). A recent tagging study also suggests that alewife strongly avoid marine temperatures above 14 C (Tsitrin et al., 2022). In this study, postspawned alewife emigrating from Gaspereau River, Nova Scotia, remained in the Minas basin and foraged in nearshore habitat for 20 days before water temperatures warmed, cueing offshore migration (Table 1; Tsitrin et al., 2022). Similar behavior was observed in American shad, which use cold tidal currents as migration corridors throughout at-sea movement (Neves &amp; Depres, 1979; Tsitrin et al., 2022).</p></div>	https://treatment.plazi.org/id/E642879AFFAEFFE1342D156751E4FE2A	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Brown, Caliyena R.;Sergio, Ava J. A.;Bate, Caitlin S.;Koopman, Natalie;Roland, Joshua B.;Notman-Grobler, Oscar D. P.;Mastrodimitropoulos, Paris M. B.;Piczak, Morgan L.;Lennox, Robert J.	Brown, Caliyena R., Sergio, Ava J. A., Bate, Caitlin S., Koopman, Natalie, Roland, Joshua B., Notman-Grobler, Oscar D. P., Mastrodimitropoulos, Paris M. B., Piczak, Morgan L., Lennox, Robert J. (2025): A review of migratory Alosidae marine ecology in the northwest Atlantic. Journal of Fish Biology 106 (3): 677-695, DOI: 10.1111/jfb.15977, URL: https://doi.org/10.1111/jfb.15977
E642879AFFAAFFE3342D120A5058FAAF.text	E642879AFFAAFFE3342D120A5058FAAF.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Alosa aestivalis (Mitchill 1814)	<div><p>3 | BLUEBACK HERRING</p><p>3.1 | Life history</p><p>3.1.1 | Diet</p><p>Blueback herring consume a variety of prey, including pelagic and benthic species; however, their diet is more selective compared to alewife and primarily feed on zooplankton (Mullen et al., 1986; Stone &amp; Daborn, 1987). As juveniles grow and move from their natal rivers into estuaries, larger zooplankton, such as adult copepods (e. g., Eurytemora affinis and Cyclops vernalis), become the primary diet (Table 1; Mullen et al., 1986). Adults in the marine environment are predominantly planktivorous and continue to consume zooplankton, although they also consume small fishes, eggs of other fish, and crustaceans such as pelagic shrimp (Table 1; Bigelow &amp; Schroeder, 1953; Munroe, 2002).</p><p>3.1.2 | Growth</p><p>Adult blueback herring can reach lengths of 197 – 322 mm in fork length and weigh 93 – 468 g for ages 3 – 12 (Jessop, 1993). Like alewife, adults are sexually dimorphic, where females are slightly larger and have an average total length of 289 mm, whereas males average 277 mm in length (Table 1; Bowlby &amp; Gibson, 2016; Loesch &amp; Lund, 1977). However, it is unclear whether there are further size similarities between alewife and blueback herring. Contradictory reports on size differences in Nova Scotia stated that blueback herring were substantially smaller than alewife on average (Bowlby &amp; Gibson, 2016), whereas a different study found blueback herring to be only marginally smaller (Jessop, 1993). Parameters from the VBGF for blueback herring demonstrate the observed sexual dimorphism and the argument that blueback herring are smaller in size than alewife, with L ∞ ranging from 231.33- (males) to 259.85 mm (females), K ranging from 0.469 (females) to 0.590 (males), and t 0 ranging from 0.283 (females) to 0.338 (males; Messieh, 1977).</p><p>Most of the growth in blueback herring occurs during the first couple of years at sea and plateaus after they reach sexual maturity. Adults exhibit very little growth between spawning events, such that individuals ranging from 3 to 5 years old only grow an average of 13 mm between annual spawning (Table 1; Mullen et al., 1986; Bowlby &amp; Gibson, 2016). Therefore, blueback herring that have spawned multiple times are smaller for their given age, particularly in weight, suggesting an energetic trade-off between frequent spawning and at-sea growth (Table 1; Bowlby &amp; Gibson, 2016). Sex-specific variation exists within age at first reproduction, where maturation takes 4 – 5 years for females and 3 – 4 years for males. For instance, the highest proportion of first-time male spawners is at ages 3 and 4, accounting for 46.9% and 49.8% of the individuals in each age class, respectively (Marcy, 1969), whereas most first-time female spawners are older, ages 4 and 5, and account for 74.6% and 16.4% of individuals observed at each age class during spawning events (Marcy, 1969). The causes for this variation remain unclear (Bowlby &amp; Gibson, 2016).</p><p>3.1.3 | Spawning</p><p>Blueback herring are iteroparous and will spawn up to four times before death (Table 1; McBride et al., 2014; Bowlby &amp; Gibson, 2016). They exhibit a degree of spawning site fidelity and will typically return to the same river to spawn (Table 1; Bozeman Jr &amp; Van Den Ayvle, 1989); however, the frequency of return and the proportion that stray to novel spawning sites are unclear. It is speculated that blueback herring rely on olfactory mechanisms, similar to alewife; however, their migratory cues back to natal rivers are not well understood. Additionally, it is unknown whether ovary weight and fork length are related, but research suggests fecundity positively correlates with age and decreases with increasing latitude when measured gravimetrically (Table 1; Jessop, 1993). The length of the spawning season prolongs with increasing latitude and may be a function of cooler northern temperatures (Loesch &amp; Lund, 1977; Lynch et al., 2015), likely compensating for the decreased fecundity at these latitudes.</p><p>Although spawning typically occurs in freshwater (Bigelow &amp; Schroeder, 1953), blueback herring will also fertilize eggs in slightly brackish (Kuntz &amp; Radcliffe, 1918) and fully brackish waters (Breder, 1948). Regardless of salinity, studies suggest that spawning occurs beyond the influence of the tide (Bigelow &amp; Schroeder, 1953; Hildebrand, 1963; Hildebrand &amp; Schroeder, 1927). Despite the overwhelming similarities between alewife and blueback herring, there can be some spatial and temporal isolation between the two species during spawning events (Loesch &amp; Lund, 1977). Both species can differ spatially by spawning in different systems or within the same river system but in different areas depending on spawning habitat preferences (Loesch &amp; Lund, 1977). Temporal isolation occurred during the spawning migration to the Tusket River, Nova Scotia; alewife returned to spawn more than 4 weeks earlier than blueback herring (Table 1; Bowlby &amp; Gibson, 2016).</p><p>3.1.4 | Mortality</p><p>In situ observations during field studies in Nova Scotia suggest that the maximum age of blueback herring is variable. In the Tusket River, the oldest individual observed was 8 years old (Bowlby &amp; Gibson, 2016); however, during sampling across the Tusket, Mactaquac, Gaspereau, and Margaree rivers, the maximum age observed was 12 (Table 1; Jessop, 1993). Females tend to live longer than males, and males are more abundant in younger age classes (3 – 5 years), whereas the abundance of older female blueback herring (7+ years) tends to be far greater (Loesch &amp; Lund, 1977).</p><p>As forage fish, blueback herring provide an important connection between marine and estuarine food webs, transferring nutrients from their oceanic zooplankton food source to coastal piscivore predators (Ames &amp; Lichter, 2013). Death in the marine environment is largely due to predation by a variety of predators, including spiny dogfish ( Squalus acanthias), Atlantic cod ( Gadus morhua), silver hake ( Merluccius bilinearis), white hake ( Urophycis tenuis), Atlantic halibut ( Hippoglossus hippoglossus), bluefish ( Pomatomus saltatrix), weakfish ( Cynoscion regalis), striped bass ( Morone saxatillis), seals, gulls, and terns (Munroe, 2002).</p><p>3.2 | Behavior</p><p>3.2.1 | Migration and foraging</p><p>Blueback herring have a marine range from Florida (Hildebrand &amp; Schroeder, 1927) to Nova Scotia (Table 1; Bigelow &amp; Schroeder, 1953; Rulifson &amp; Dadswell, 2020), where prespawned individuals spend 2 – 5 years growing and feeding after leaving their natal rivers (Loesch, 1987). Despite the extensive proportion of their lives spent at sea, relatively little is known about blueback herring marine ecology in comparison to their freshwater, riverine migrations (Bethoney, Stokesbury, &amp; Cadrin, 2014; Neves, 1981; Rulifson &amp; Dadswell, 2020; Stone &amp; Jessop, 1992). However, recordings of long-distance feeding migrations show migratory routes from North Carolina to Nova Scotia, which align with the routes of American shad (Rulifson &amp; Dadswell, 2020). There is also evidence of the separation into migratory contingents, where a proportion of blueback herring are semi-resident in estuarine regions near their natal rivers and use inshore embayments for feeding instead of undertaking large offshore migrations (Table 1; Stone &amp; Jessop, 1992; Rulifson &amp; Dadswell, 2020). Due to the complex movement dynamics in each population, summer foraging aggregations consist of mixed stocks and therefore include multiple contingents from different spawning rivers (Table 1; Rulifson &amp; Dadswell, 2020).</p><p>When foraging in the marine environment, blueback herring benefit from schooling behavior (i.e., optimizing feeding and avoiding predators, etc.) and group into single-species aggregations at sea or school with alewife (Table 1; Bethoney et al., 2013; Rulifson &amp; Dadswell, 2020). During summer feeding migrations, blueback herring follow zooplankton throughout the marine environment. There is evidence that blueback herring undertake diel vertical migrations (Jessop, 1990), which mimic the diel movements of zooplankton (Table 1; Neves, 1981). However, the availability of suitable water temperatures may limit their vertical feeding migrations (Stone &amp; Jessop, 1992). Similar to their vertical movements, the horizontal migrations of blueback herring are likely tied to zooplankton concentrations at different latitudes throughout the year, outside of the spawning migration (Neves, 1981; Stone &amp; Jessop, 1992). Researchers in the Minas basin in Nova Scotia have found evidence of filter-feeding among anadromous blueback herring, although they may also undertake active foraging in the marine environment (Table 1; Stone &amp; Daborn, 1987).</p><p>After foraging at sea during summer, blueback herring move southward in the fall and aggregate in offshore overwintering sites in the Middle Atlantic Bight (Neves, 1981) and along the Scotian Shelf from the Gulf of Maine to the Bay of Fundy (Stone &amp; Jessop, 1992). Neves (1981) speculated that temperature and availability of zooplankton drive the selection of specific overwintering sites. Although blueback herring are typically associated with inshore habitats and remain in shallower waters than alewife (Bethoney, Stokesbury, Schondelmeier, et al., 2014; Neves, 1981), during winter, they are found comparatively deeper, likely seeking warmer bottom water, preferring water&gt;5 C offshore (Stone &amp; Jessop, 1992). This temperature preference suggests that blueblack migration strongly follows temperature contours in the northern limit of their range (Canada; Table 1; Stone &amp; Jessop, 1992).</p><p>In early spring, blueback herring start to occupy mid-depth, nearshore waters along the Atlantic coast as they move northward to reach spawning rivers in late spring (Neves, 1981; Stone &amp; Jessop, 1992). The timing of arrival for the spring spawning migration is, again, thought to be temperature-driven, timing their movements to coincide with an optimal water temperature range of 14 – 22 C for spawning (Table 1; Bi et al., 2021, Loesch &amp; Lund, 1977, Ogburn et al., 2024). Blueback herring prefer warmer spawning temperatures than alewife, and so, they generally arrive later than alewife in their shared rivers (Bigelow &amp; Schroeder, 1953). For blueback herring, this leads to a late-April arrival in spawning rivers (although this varies), and they can remain at these sites for several months into the summer before they return to sea (Jones et al., 1978).</p></div>	https://treatment.plazi.org/id/E642879AFFAAFFE3342D120A5058FAAF	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Brown, Caliyena R.;Sergio, Ava J. A.;Bate, Caitlin S.;Koopman, Natalie;Roland, Joshua B.;Notman-Grobler, Oscar D. P.;Mastrodimitropoulos, Paris M. B.;Piczak, Morgan L.;Lennox, Robert J.	Brown, Caliyena R., Sergio, Ava J. A., Bate, Caitlin S., Koopman, Natalie, Roland, Joshua B., Notman-Grobler, Oscar D. P., Mastrodimitropoulos, Paris M. B., Piczak, Morgan L., Lennox, Robert J. (2025): A review of migratory Alosidae marine ecology in the northwest Atlantic. Journal of Fish Biology 106 (3): 677-695, DOI: 10.1111/jfb.15977, URL: https://doi.org/10.1111/jfb.15977
E642879AFFA8FFEC3765158F57C4FC12.text	E642879AFFA8FFEC3765158F57C4FC12.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Alosa sapidissima (Wilson 1811)	<div><p>4 | AMERICAN SHAD</p><p>4.1 | Life history</p><p>4.1.1 | Diet</p><p>On their migration back to sea, adult American shad prey on smaller freshwater fish, including shield darters ( Percina peltata) and, at times, cannibalize juvenile American shad (Table 1; Chittenden Jr., 1976b). Beyond these nearshore data, there are only a few studies to rely on for characterizing American shad diet in the marine environment; however, adults are known to return to their planktonic diet at sea and primarily feed on copepods and mysids (Walburg &amp; Nichols, 1967). Stomach content analyses have also shown that adults prey on small fish (Table 1; Facey &amp; Van Den Avyle, 1986; Walburg &amp; Nichols, 1967). More information is needed to better understand American shad diet at sea during juvenile and adult life stages.</p><p>4.1.2 | Growth</p><p>In addition to freshwater environments, YOY American shad also use estuarine areas as nursery grounds (Crecco et al., 1983; McCormick et al., 1996), typically in low-velocity waters where food availability is higher (Limburg, 1996). Juveniles grow to 38 – 114 mm long before they emigrate into the marine environment in autumn (Bigelow &amp; Schroeder, 1953; Mitchell, 1925), suggesting that growth and factors associated with size influence the timing of seaward emigration (Chittenden Jr., 1969; Miller et al., 1973). Most growth occurs at sea, where prespawned fish spend 2 – 6 years until they reach sexual maturity (Table 1; Bigelow &amp; Schroeder, 1953; Walburg &amp; Nichols, 1967). Males reach maturity younger than females, at around 2 years or when they reach 290 mm (on average), whereas females mature in their third or fourth year when they are closer to 400 mm (Walburg &amp; Nichols, 1967). As such, American shad are sexually dimorphic; females are typically larger than males within their age class (Du et al., 2023). Compared to alewife and blueback herring, American shad are the largest among these Alosidae, and adults can grow up to 760 mm and weigh up to 5500 g (Bigelow &amp; Schroeder, 1953). Their maximum size depends on latitude, and northern populations reach larger sizes than their southern contingents (Table 1; Gilligan-Lunda et al., 2021; Poulet et al., 2023; Robins et al., 1986). The VBGF parameters for American shad reinforce their size difference when compared to the parameters for alewife and blueback herring, with an average of 481 mm for L ∞, 0.44 for K, and 0.32 for t 0 (Gilligan-Lunda et al., 2021).</p><p>4.1.3 | Spawning</p><p>American shad exhibit spawning site fidelity to their natal rivers (Table 1; Carscadden &amp; Leggett, 1975; Hill, 1959; Nichols, 1966; Talbot, 1954), with low levels of straying (3%; Melvin et al., 1986) in some populations (Mansueti &amp; Kolb, 1953; Williams &amp; Daborn, 1984). Spawning strategies also differ latitudinally where northern populations are iteroparous and can spawn five (Grote et al., 2014; McBride et al., 2016) to seven times (Provost, 1987), whereas southern populations are semelparous (reproduce once then die; Table 1; Leggett &amp; Carscadden, 1978; Poulet et al., 2023). Semelparous populations include those that spawn in the St. Johns River, Florida (Limburg et al., 2003) and the Ogeechee River, Georgia (Sykes, 1956). This semelparity observed in southern populations appears to be an adaptation to the consistent weather in the south, resulting in a higher probability of successful recruitment and consequently higher fecundity, when defined as the rate of successful recruitment (Carscadden &amp; Leggett, 1975; Roff, 1992).</p><p>4.1.4 | Mortality</p><p>American shad have been reported to live up to 13 years, and there is no recorded evidence of sexual dimorphism regarding maximum age, like in blueback herring populations (Altman &amp; Dittmer, 1962). However, the natural mortality rate does differ based on latitude, where northern populations reach an older maximum age due to alternate reproductive styles, much like alewife (Gilligan-Lunda et al., 2021; Poulet et al., 2023). Other barriers that limit survival include predation, target fisheries, and by-catch (Table 1; Bailey et al., 2004; Bethoney et al., 2013). At sea, American shad are preyed on by sharks, bluefin tuna ( Thunnus thynnus), kingfish ( Scomberomorus cavalla), and porpoises in the southern United States (Walburg &amp; Nichols, 1967). Passive tagging studies on American shad have also revealed that dogfish ( S. acanthias) and Atlantic cod ( G. morhua) also prey on American shad (Dadswell, 1990). Additionally, there are records of seals preying on American shad as they begin their spawning runs into river mouths (Dadswell, 1990). Although northern American shad are iteroparous, like gaspereau, it is not uncommon for adults to die on their spawning migration. For instance, in northern New Jersey, dead, egg-bound females were found during their migration upstream to spawning grounds, likely attributable to starvation (Chittenden Jr., 1976a). Therefore, attrition of American shad when they enter freshwater forms a key part of the species' marine demography.</p><p>4.2 | Behavior</p><p>4.2.1 | Migration and foraging</p><p>American shad exhibit a complex marine migration pattern influenced by both environmental cues and intrinsic factors. They undertake extensive seasonal migrations in surface waters (Neves &amp; Depres, 1979) along the northwest Atlantic, spanning from Newfoundland and Labrador (Dempson et al., 1983; Limburg et al., 2003) to Florida (Table 1; Williams &amp; Bruger, 1972). YOY juveniles either spend the first year in the lower estuary of their natal river (Hoffman et al., 2008; Leggett &amp; Whitney, 1972) or exhibit short residency, staying within fresh water for the summer, then migrating to sea in the fall (Greene et al., 2009; Neves &amp; Depres, 1979). Upon entering the marine environment, juveniles join large intraspecific schools of immature and postspawning adults for feeding and growth (Bigelow &amp; Schroeder, 1953; Dadswell et al., 1987). As water temperatures cool later into the fall, schools migrate in surface waters (Bigelow &amp; Schroeder, 1953) southward to overwintering sites, which include deeper waters, 40 – 175 km offshore Florida, the Mid-Atlantic Bight, and along the Scotian Shelf (Collette &amp; Klein-Macphee, 2002; Dadswell et al., 1987). The aggregations in these overwintering sites are heterogeneous mixtures of American shad populations from many rivers (Dadswell et al., 1987).</p><p>Spawning can occur when water temperatures cool to 8 – 26 C (Walburg &amp; Nichols, 1967); however, peak spawning begins when water temperatures fall between 12 and 21 C (Jessop, 1975; Jones et al., 1978). Therefore, spawning migrations are temporally influenced, and southern populations begin migrating toward natal rivers in January, with some reaching the southern limit of their range in the St. Johns River, Florida (Table 1; Limburg et al., 2003). Northern populations begin migrations to spawning rivers progressively later into the spring as latitude increases (Limburg et al., 2003). During the summer, spawning continues upstream from the Delaware River to the St. Lawrence River, and northern American shad populations concentrate in the surface waters of foraging grounds (Leim, 1924; Themelis, 1986) in the inner Bay of Fundy, the inner Gulf of St. Lawrence, and off of Newfoundland and Labrador (Table 1; Dadswell et al., 1987).</p><p>Foraging behavior varies based on life stage and habitat. Walter III and Olney (2003) demonstrated that adult stomach fullness index was highest in the marine environment (Table 1), followed by estuarine habitats, then freshwater, indicating the majority of feeding takes place at sea. There is little information about juvenile stomach fullness; however, juveniles are known to form feeding schools along the coast (Greene et al., 2009; Neves &amp; Depres, 1979) and demonstrate diel feeding patterns primarily foraging in the evening (Johnson &amp; Dropkin, 1996; Massmann, 1963). Additionally, planktivorous adults feed both passively by filtering prey as they swim and by actively ambushing (Harris &amp; McBride, 2009), suggesting that American shad mainly consume what they encounter and feed if suitable prey is available (Atkinson, 1951; Leim, 1924; Walter III &amp; Olney, 2003).</p></div>	https://treatment.plazi.org/id/E642879AFFA8FFEC3765158F57C4FC12	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Brown, Caliyena R.;Sergio, Ava J. A.;Bate, Caitlin S.;Koopman, Natalie;Roland, Joshua B.;Notman-Grobler, Oscar D. P.;Mastrodimitropoulos, Paris M. B.;Piczak, Morgan L.;Lennox, Robert J.	Brown, Caliyena R., Sergio, Ava J. A., Bate, Caitlin S., Koopman, Natalie, Roland, Joshua B., Notman-Grobler, Oscar D. P., Mastrodimitropoulos, Paris M. B., Piczak, Morgan L., Lennox, Robert J. (2025): A review of migratory Alosidae marine ecology in the northwest Atlantic. Journal of Fish Biology 106 (3): 677-695, DOI: 10.1111/jfb.15977, URL: https://doi.org/10.1111/jfb.15977
