Engraulis
Engraulis is a genus of small, schooling marine fish in the family Engraulidae, commonly referred to as anchovies, comprising nine extant species distributed worldwide in tropical and temperate coastal waters from 60°N to 43°S.[1][2][3] These fish typically reach lengths of 9.5 to 24.8 cm, featuring elongated, slightly oval bodies with a prominent pointed snout, a short maxilla, and fine teeth on the lower jaw, adapted for filter-feeding on plankton.[2][1] Taxonomically, Engraulis belongs to the order Clupeiformes, subfamily Engraulinae, and is distinguished from other anchovy genera by the absence of pre- or post-pelvic scutes, a dorsal fin positioned at the midpoint of the body, and 27 to 45 slender gill rakers.[2] The recognized species include E. anchoita (Argentine anchovy), E. australis (Australian anchovy), E. capensis (Southern African anchovy), E. encrasicolus (European anchovy), E. eurystole (silver anchovy), E. japonicus (Japanese anchovy), E. maeoticus, E. mordax (northern anchovy), and E. ringens (Peruvian anchoveta).[1] Recent systematic studies have highlighted potential distinctions within European populations, proposing species status for coastal forms like E. maeoticus based on genetic and morphological evidence.[4] Engraulis species inhabit neritic and epipelagic zones, often favoring areas of coastal upwelling where nutrient-rich waters support abundant plankton, their primary food source.[2][5] They exhibit high fecundity and rapid growth, contributing to their ecological role as key prey for larger predatory fish, seabirds, and marine mammals, while forming the base of complex food webs in productive marine ecosystems.[6] Economically, the genus is of immense importance, supporting major global fisheries; for instance, E. ringens sustains the world's largest single-species fishery, with Peruvian anchoveta catches historically exceeding 13 million tons annually and remaining significant in recent assessments.[2][7] Other species, such as E. encrasicolus in the Mediterranean and E. mordax off North America, underpin commercial, live-bait, and aquaculture-related industries, though populations face pressures from overfishing, climate variability, and environmental changes.[8][6]Taxonomy
Etymology and History
The genus name Engraulis derives from the Ancient Greek term ἔγγραυλις (éngraulis), which directly translates to "anchovy," a name historically applied to small, schooling clupeoid fishes resembling those in this genus.[9] This etymological root may stem from γρυλίζω (grulízō), meaning "to grumble," potentially alluding to the fish's subtle jaw movements or the sound produced by schools in water, though the precise connection remains interpretive.[10] The genus Engraulis was formally established by Georges Cuvier in 1816 within his work Le Règne Animal, where he designated Clupea encrasicolus Linnaeus, 1758, as the type species, elevating it from earlier classifications under broader clupeid groupings.[2] Linnaeus had initially described this species, the European anchovy, in his 1758 Systema Naturae, marking one of the earliest binomial nomenclatures for an anchovy, though the genus-level distinction awaited Cuvier's systematic revision amid 19th-century ichthyological advancements.[11] Fossil records indicate that the Engraulidae family, to which Engraulis belongs, originated in the Eocene epoch, with the earliest known specimen, Eoengraulis fasoloi, discovered at the Monte Bolca Lagerstätte in Italy and dated to approximately 50 million years ago.[12] This fossil, representing a stem-engrauline, provides evidence of the family's early diversification in shallow marine environments during the Paleogene, predating modern Engraulis species by tens of millions of years. Throughout the 19th and 20th centuries, Engraulis was classified within the order Clupeiformes, reflecting its shared traits with herrings and sardines, as outlined in major works like those of Gill (1893) and Grande & Nelson (1985), which refined subfamily boundaries.[13] Contemporary molecular phylogenies, utilizing mitochondrial and nuclear markers, have confirmed the monophyly of Engraulis within Engraulidae, positioning it as a distinct lineage sister to other clupeoids and resolving prior ambiguities in species delimitation through analyses of genetic divergence.[14]Classification and Phylogeny
The genus Engraulis belongs to the kingdom Animalia, phylum Chordata, class Actinopterygii, order Clupeiformes, family Engraulidae, and subfamily Engraulinae.[15][9] Phylogenetically, Engraulis occupies a position within the monophyletic subfamily Engraulinae, which comprises the Old World clade including Engraulis and the New World clade featuring genera such as Anchoa.[16] Molecular analyses using mitochondrial markers like 16S rRNA and cytochrome b genes confirm the close relationships among Engraulinae genera, with Engraulis sharing a recent common ancestry with Anchoa and others, reflecting a divergence of the subfamily approximately 45–60 million years ago during the late Eocene.[17][18] As of 2025, Engraulis includes 9 valid species, as recognized by databases such as FishBase and the World Register of Marine Species (WoRMS).[19][15] No formal subgenera are established within Engraulis, though informal groupings distinguish Atlantic and Pacific clades based on biogeographic patterns and genetic divergences observed in mitochondrial DNA sequences.[20]Description
Morphology
Species in the genus Engraulis exhibit a distinctive body structure characterized by an elongate, slender form that is rounded in cross-section and compressed laterally, facilitating agile swimming in pelagic environments. The head features a prominent, pointed snout and a large mouth that extends beyond the posterior margin of the eye, with the maxilla typically reaching or approaching the posterior border of the preoperculum. This configuration supports their planktivorous feeding strategy.[21][22][23] The fin configuration is adapted for stability and maneuverability in open water. The dorsal fin lacks spines and possesses 14-19 soft rays, positioned near the midpoint of the body; the anal fin similarly lacks spines and has 19-26 soft rays, originating under or behind the last dorsal ray. Pectoral fins are low on the body, short, and pointed, while pelvic fins are abdominal in position. No adipose fin is present, distinguishing Engraulis from some related clupeoids.[23][22][2] The gill apparatus is specialized for filter-feeding, with the lower branch of the first gill arch bearing 27-49 long, slender rakers that strain small plankton from water passing through the mouth. Gill rakers are also present on the hind face of the third epibranchial in some species, enhancing filtration efficiency.[2][24][21] Engraulis species are covered in easily shed cycloid scales, which are smooth-edged and contribute to their silvery appearance, though a distinct lateral line is absent. Instead, well-developed sensory pores and canals on the head provide mechanosensory input for detecting water movements and prey.[23][25] Internally, individuals possess a small swim bladder, typically dual-chambered in adults, which aids in buoyancy regulation but contributes modestly to acoustic scattering compared to larger gas bladders in other fishes; this feature is consistent across the genus, with no significant adipose fin or other specialized internal structures noted.[26][27]Size, Coloration, and Variations
Species in the genus Engraulis are small pelagic fishes, with maximum standard lengths typically ranging from 15 to 25 cm across the genus, though adults rarely exceed 20 cm. For example, the European anchovy (E. encrasicolus) reaches up to 20 cm SL, while the northern anchovy (E. mordax) can attain 24.8 cm SL, but most individuals mature at lengths around 10-12 cm.[28] These sizes reflect their fast-growing, short-lived life history, adapted for high reproductive output in schooling formations.[2] The coloration of Engraulis species features a silvery-blue or metallic blue-green dorsum that fades to a shiny silver or white ventral surface, providing camouflage in open water. Scales exhibit iridescence, contributing to a reflective sheen, while the dorsal fin often has a dark margin. Juveniles display greater translucency, with reduced pigmentation that intensifies to the characteristic silvering in adults.[5][29] Sexual dimorphism in Engraulis is subtle, with females generally attaining slightly larger sizes than males; for instance, in E. encrasicolus populations from the Moroccan Atlantic coast, the size at 50% maturity (L50) is 9.82 cm for males and 9.96 cm for females.[30] Intraspecific variations include regional morphs, such as paler forms in coastal or brackish-influenced waters compared to darker offshore variants, as observed in eastern Mediterranean populations where "silver" and "blue" ecotypes differ in pigmentation intensity. Age-related changes are also evident, progressing from nearly transparent larvae to fully silvered adults, enhancing their pelagic camouflage.[31]Distribution and Habitat
Geographic Range
The genus Engraulis inhabits temperate to subtropical marine waters globally, with a primary distribution in coastal regions of the Atlantic, Pacific, and Indian Oceans, and is notably absent from polar areas.[2] This range reflects the genus's affinity for productive, mid-latitude upwelling zones that support their pelagic lifestyle.[9] Key populations are concentrated in several major oceanic basins: the western Atlantic hosts Engraulis eurystole (silver anchovy) from Maine southward to Brazil, including the Gulf of Mexico, and Engraulis anchoita from southern Brazil to Patagonia; the eastern Atlantic hosts Engraulis encrasicolus from the Bay of Biscay southward to South Africa, extending into the Mediterranean and Black Seas; the northeast Pacific features Engraulis mordax from Baja California northward to Alaska; the southeast Pacific includes Engraulis ringens off Peru and Chile; the southeast Atlantic and western Indian Ocean have Engraulis capensis along the Namibian and South African coasts and adjacent areas; the northwest Pacific contains Engraulis japonicus from Japan to the Yellow Sea; and southern Australia and New Zealand are home to Engraulis australis.[2] These distributions underscore the genus's coastal orientation, with species rarely venturing far offshore.[9] The latitudinal extent of Engraulis spans approximately from 60°N to 50°S, aligning with temperate and subtropical climates that favor their ecological niche.[32] Some species, such as E. mordax, exhibit seasonal migrations that extend their effective range northward during warmer periods.[5] Historically, northern populations underwent post-glacial recolonization around 10,000 years ago following the Last Glacial Maximum, enabling rapid expansion into previously glaciated areas without significant loss of genetic diversity.[33]Habitat Preferences
Species of the genus Engraulis primarily inhabit neritic and epipelagic zones of the water column, with adults typically occupying surface-oriented depths of 0-50 m, though they can range up to 400 m in some cases.[34][35][36] These fish form large schools in coastal waters over continental shelves, avoiding the deep ocean and preferring productive nearshore environments within approximately 80 km of the coast.[35][37] Some species of Engraulis, such as E. encrasicolus, exhibit euryhaline tolerances, with salinity ranges from 5 to 41 ppt, enabling seasonal entries into estuaries, lagoons, and even low-salinity areas during spawning periods.[34] They favor temperatures between 10 and 25°C, with optimal ranges varying by species—such as 7.1-18°C for E. encrasicolus and 13-23°C for E. ringens—and thrive in nutrient-rich upwelling zones like the Peruvian, California, and Benguela Currents, where cooler, plankton-abundant waters support their populations.[34][35][36] Key abiotic factors include dissolved oxygen levels exceeding 4 mg/L, below which larvae and juveniles actively avoid hypoxic regions to prevent physiological stress.[38] Ocean currents play a critical role in larval dispersal, transporting early life stages from spawning grounds in upwelling-favorable areas to suitable nursery habitats along continental margins.[39] This pelagic lifestyle aligns with their filter-feeding adaptations to exploit plankton blooms in these dynamic, oxygen-replete environments.[40]Ecology and Behavior
Feeding Habits
Engraulis species are primarily zooplanktivorous, with their diet dominated by zooplankton such as copepods, cladocerans, and crustacean larvae, though phytoplankton contributes numerically but less to biomass and energy intake.[41][42] Prey items typically range from 0.1 to 2 mm in size, including small copepods like Oncaea media and Microsetella rosea, with larger individuals occasionally consuming mysids, decapod larvae, or fish eggs up to 5 mm.[41][43] While copepods form the core of the diet across seasons and sizes, intake peaks during upwelling periods when zooplankton abundance increases, reflecting opportunistic adjustments to local prey availability.[44] Foraging occurs mainly through filter-feeding, where anchovies use their numerous gill rakers—averaging 41 on the first lower arch—to strain prey from water pumped through the open mouth while swimming in schools.[43] Smaller individuals (<12 cm) rely on continuous filter-feeding for fine particles below 1.5 mm, while larger ones (>13 cm) shift to selective particulate feeding, targeting larger, visually detected prey during daytime migrations below the thermocline.[42] This dual-mode strategy enhances efficiency in patchy plankton distributions, with diel patterns showing highest activity from dawn to dusk, though sporadic nocturnal surface feeding occurs in some populations.[45] Daily ration typically equals 3-4% of wet body weight, supporting rapid growth but varying with temperature and prey density up to higher levels in productive seasons.[42][46] As keystone forage fish, Engraulis occupy a low trophic position (around 2.0-3.0), serving as primary converters of planktonic production into energy for higher predators including tunas, seabirds, and marine mammals.[47] Their high biomass and schooling behavior amplify this role, channeling up to 10-15% of regional zooplankton production into pelagic food webs during peak abundance.[48] This positions them as critical links in marine ecosystems, influencing predator populations and fishery dynamics.[49]Reproduction and Life Cycle
Engraulis species exhibit iteroparous reproduction with multiple spawning seasons.[50] These fish are batch spawners, releasing eggs in multiple events spaced 1-4 days apart over extended seasons, often from spring to fall in temperate regions, though year-round spawning occurs in subtropical populations of species like E. mordax.[28][37] Eggs are pelagic and buoyant, measuring 1-1.4 mm in diameter, and are released into the upper water column where they float and hatch within 24-65 hours depending on temperature.[28][51] Batch fecundity ranges from 5,000 to 20,000 eggs per female, influenced by factors such as water temperature, food availability, and female size, with higher outputs in optimal conditions promoting recruitment success.[52][53] Engraulis species typically reach sexual maturity at approximately one year of age and a length of 8-12 cm, with variations across species such as 9.6 cm for Engraulis mordax and 10.1 cm for Engraulis encrasicolus.[37][28] This early maturation supports their rapid population turnover in dynamic marine environments. The life cycle begins with pelagic eggs hatching into larvae that inhabit the upper 0-50 m of the water column, undergoing rapid development over 2-3 weeks into post-larval stages at rates of 0.9-1.1 mm per day under typical temperatures of 15-23°C.[54][55] Juveniles quickly form schools shortly after metamorphosis, adopting schooling behavior that enhances predator avoidance and foraging efficiency.[28] Adults typically live 3-5 years, though some individuals reach up to 7-10 years in favorable conditions, with generation times estimated at 1-2 years across the genus.[37][36] Spawning occurs in open pelagic habitats, aligning with their preference for coastal and shelf waters.[28]Species
Recognized Species
The genus Engraulis comprises nine recognized species, primarily inhabiting coastal and pelagic waters of temperate to subtropical regions in the Atlantic and Pacific Oceans. These species share morphological traits such as an elongate body, a prominent snout, and numerous gill rakers adapted for filter-feeding on plankton, though each exhibits adaptations to its regional environment.[19]| Scientific Name | Common Name | Maximum Length | Primary Range | Notes |
|---|---|---|---|---|
| Engraulis anchoita Hubbs & Marini, 1935 | Argentine anchovy | 17 cm SL | Southwestern Atlantic (southern Brazil to Patagonia, Argentina) | Forms dense schools in coastal waters; supports commercial fisheries for bait and human consumption. |
| Engraulis australis Shaw, 1790 | Australian anchovy | 15 cm SL | Southwestern Pacific (Australia and New Zealand) | Occurs in estuaries and coastal bays; key prey for marine predators. |
| Engraulis capensis Gilchrist, 1913 | Southern African anchovy | 17 cm SL | Southeastern Atlantic (southern Namibia to eastern South Africa) | Abundant in upwelling zones; vital to the Benguela Current ecosystem and local fisheries. |
| Engraulis encrasicolus (Linnaeus, 1758) | European anchovy | 20 cm SL | Eastern Atlantic, Mediterranean, Black, and Azov Seas | Widespread and commercially significant; synonym Engraulis encrasicholus; enters brackish waters for spawning.[28] |
| Engraulis eurystole Swain, 1884 | Silver anchovy | 15.5 cm TL | Western Atlantic (Florida, USA to Brazil) | Inhabits coastal and shelf waters; less commercially exploited compared to congeners. |
| Engraulis japonicus Temminck & Schlegel, 1846 | Japanese anchovy | 18 cm TL | Western Pacific (Japan to Indonesia) | Forms large schools in temperate waters; important in regional fisheries for canning and drying. |
| Engraulis maeoticus Peshkov, 1926 | Azov anchovy | 9.5 cm SL | Black and Azov Seas (Mediterranean basin) | Smallest species in the genus; endemic to low-salinity inland seas; supports localized fisheries. |
| Engraulis mordax Girard, 1856 | Northern anchovy (or Californian anchovy) | 24.8 cm SL | Northeastern Pacific (British Columbia, Canada to Baja California, Mexico) | Largest species; exhibits strong population fluctuations linked to oceanographic conditions. |
| Engraulis ringens Jardine, 1842 | Anchoveta (or Peruvian anchoveta) | 20 cm SL | Southeastern Pacific (Peru to Chile) | Dominates the world's largest single-species fishery, primarily for fish meal and oil production.[35][56] |