Californian anchovy | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Clupeiformes |
Family: | Engraulidae |
Genus: | Engraulis |
Species: | E. mordax |
Binomial name | |
Engraulis mordax Girard, 1854 | |
Distribution map of three Californian (northern) anchovy subpopulations. | |
Synonyms | |
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The Californian anchovy or northern anchovy (Engraulis mordax) [2] is a species of anchovy found in the Eastern Pacific Ocean, ranging from Mexico to British Columbia. [3] It is a small, Clupeoid fish with a large mouth and a long, laterally compressed body, which strongly resembles the European Anchovy (Engraulis encrasicolus) with only slight differences in girth and fin position [4] [5] [6] . They have a euryhaline lifestyle defined by regular migrations between bays and open ocean for both spawning and foraging. [5] Like Pacific sardines (Sardinops sagax), they compose a large fraction of the marine biomass in waters off the west coast of North America, where they are a vital keystone species in coastal pelagic waters. [5] [7] However, they are subject to seasonal boom & bust cycles that are chiefly caused by changes in water temperature and food availability; regularly switching places as the forage fish of prominence with the sardine during years defined by colder water temperatures, which makes them vulnerable to climate change. [8] [9] [10] They have a small commercial fishery; mainly used as bait for fishermen or fish meal, with a dedicated small following as a food fish in San Francisco. [7] [11]
Californian anchovies exhibit the basic anchovy body form like a large sub-terminal mouth that extends past the eye, a centrally located single dorsal fin on a compressed & elongated body, a forked caudal fin, the absence of a visible lateral line, and weak, shiny scales colored by crystalline guanine that complete its countershaded camouflage. The only way to confidently tell them apart from the European anchovy besides their range is to measure where the posterior side of their dorsal fins terminate on their body, which vertically matches exactly where the anal fin begins for Californian anchovies. [12] [5] [4]
Trawling surveys in San Francisco Bay starting from the 1920s by famous ichthyologist Carl Leavitt Hubbs up to the present by scientists from UC Davis seem to support the existence of a separate "bay" form of the Californian anchovy that has fewer vertebrae than the oceanic "green-back" form, a proportionally larger head, a tan to transparent dorsum due to the near absence of guanine crystals in their chromatophores, and a residential lifestyle with no migration to coastal waters. Hubbs was confident enough about its existence that he described it as a subspecies named Engraulis mordax nanus Girard. However, all anchovies undergo regular shifts in dorsum color due to salinity changes during their migrations and transitions between their life stages, and that anchovies that closely resemble the "bay" form have been collected off the coast of Northern California. More research, preferably genetic analyses, on the "bay" form present in San Francisco Bay is needed to support its existence as a separate subspecies. [13] [14] [15]
The native range of the Californian anchovy is demarcated roughly between the nearshore waters off Haida Gwaii to the north and the Gulf of California to the south. Their range is divided into 3 phenotypically distinct sub-populations: a northern subpopulation between British Columbia and Monterey Bay, a central subpopulation between San Francisco Bay and coastal waters near El Rosario in central Baja California, and a southern subpopulation from Cedros Island southwards into the mouth of the Gulf of California. Although these subpopulations somewhat differ in certain characteristics like operculum width, body size, transferrin pattern types, and spawning times, they are not genetically distinct enough to warrant reclassification into separate subspecies. [15] [16] [17]
Most California anchovies begin their lives hatching in coastal waters or in estuaries in late spring, though spawning is known to happen year-round. The larvae live in the photic zone of the waters near their birth as ichthyoplankton, where they float around at the mercy of tidal and oceanic currents and are thus regularly consumed by planktivores like pacific herring and other anchovies until the
survivors mature into schooling sub-adults and begin moving into more saline waters, which physiologically corresponds with the increased guanine crystals (and therefore bluer & greener dorsum coloration) in their chromatophores; eventually making it into the open ocean where they become adults. Adult schools of anchovies regularly move between deeper and shallow waters to feed on plankton during their diel vertical migration until temperature and prey abundance cues certain cohorts of the population to either begin spawning in shallow inshore waters or inside large estuaries like the Salish Sea or San Francisco Bay. They typically have a lifespan between 4 to 7 years, with reproduction occurring yearly after maturing throughout their lives. [14] [18] [5]
As sardine populations declined in the Pacific during the 1940s and 50's, fish packers in America started canning the more abundant local anchovies. Total hauls increased over this time from 960 tons in 1946 to 9,464 tons in 1947 and peaking at almost 43,000 tons in 1953. From 1949 to 1955, they were restricted for all uses but bait fish in California. [1] In 2010, reported American hauls totaled 2,100 metric tons. Most Californian anchovies today are fished for use in animal feed and as bait fish, with a small but dedicated community of gastronomic fans wherever they are sold fresh. [11] [7]
They are taken by anglers for use as bait or for personal consumption. [19]
California anchovies in the Monterey Bay have been observed with heightened levels of microplastics, mistaking them for floating particulates of food. [20] However, their low trophic level means that their rate of bioaccumulation is relatively low compared to higher trophic level fish like lingcod or striped bass, which makes them a safer bet for eating in large portions similar to salmon.
The Californian anchovy is currently not a listed species even though its biomass has seen a decline during the 21st century. This is due to the natural oscillations in population size between anchovies and pacific sardines that are determined by water temperature, prey availability and rate of upwelling. The processes that drive these oscillations, or boom & bust cycles, are still largely unknown. Population stressors like overfishing or unusual oceanic conditions can have an outsized effect on a bust, which nearly drove pacific sardines to local extirpation. As climate change accelerates, the coastal upwelling that pelagic species in East Pacific waters rely on may weaken due to increasingly invariable winds, which can be detrimental to the spawning and rearing of forage fish. [21] [22] Californian anchovies are going to be heavily affected as their population biomass usually booms during cooler water years with high coastal productivity. Their boom & bust cycles will be stronger and occur more frequently than previously observed, which has already resulted in a measurable population bottleneck effect on their genetic diversity. If left unchecked, anchovy fisheries may experience a similar collapse to the sardines during the mid 20th century, which will put the countless species that rely on their continued abundance at serious risk. [23]
Bryde's whale, or the Bryde's whale complex, putatively comprises three species of rorqual and maybe four. The "complex" means the number and classification remains unclear because of a lack of definitive information and research. The common Bryde's whale is a larger form that occurs worldwide in warm temperate and tropical waters, and the Sittang or Eden's whale is a smaller form that may be restricted to the Indo-Pacific. Also, a smaller, coastal form of B. brydei is found off southern Africa, and perhaps another form in the Indo-Pacific differs in skull morphology, tentatively referred to as the Indo-Pacific Bryde's whale. The recently described Omura's whale, was formerly thought to be a pygmy form of Bryde's, but is now recognized as a distinct species. Rice's whale, which makes its home solely in the Gulf of Mexico, was once considered a distinct population of Bryde's whale, but in 2021 it was described as a separate species.
Sardine and pilchard are common names for various species of small, oily forage fish in the herring suborder Clupeoidei. The term 'sardine' was first used in English during the early 15th century; a somewhat dubious etymology says it comes from the Italian island of Sardinia, around which sardines were once supposedly abundant.
The Benguela Current is the broad, northward flowing ocean current that forms the eastern portion of the South Atlantic Ocean gyre. The current extends from roughly Cape Point in the south, to the position of the Angola-Benguela Front in the north, at around 16°S. The current is driven by the prevailing south easterly trade winds. Inshore of the Benguela Current proper, the south easterly winds drive coastal upwelling, forming the Benguela Upwelling System. The cold, nutrient rich waters that upwell from around 200–300 m (656–984 ft) depth in turn fuel high rates of phytoplankton growth, and sustain the productive Benguela ecosystem.
The Humboldt Current, also called the Peru Current, is a cold, low-salinity ocean current that flows north along the western coast of South America. It is an eastern boundary current flowing in the direction of the equator, and extends 500–1,000 km (310–620 mi) offshore. The Humboldt Current is named after the German naturalist Alexander von Humboldt even though it was discovered by José de Acosta 250 years before Humboldt. In 1846, von Humboldt reported measurements of the cold-water current in his book Cosmos.
The Peruvian anchoveta is a species of fish of the anchovy family, Engraulidae, from the Southeast Pacific Ocean. It is one of the most commercially important fish species in the world, with annual harvests varying between 3.14 and 8.32 million tonnes from 2010 to 2021.
Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that live on or near the bottom, and reef fish that are associated with coral reefs.
Thyrsites atun, known as the snoek in South Africa and as the barracouta in Australasia, is a long, thin species of snake mackerel found in the seas of the Southern Hemisphere, and a popular food fish in South Africa, particularly along the west and southwest coast. Despite its Australasian name, it is not closely related to the barracuda.
The queenfish is a species of fish in the family Sciaenidae, the drums and croakers. It is native to the eastern Pacific Ocean, where it occurs along the North American coastline from Oregon to Baja California; it has been recorded as far north as British Columbia. Its centre of distribution is the Southern California Bight. It is also known commonly as the queen croaker. This is the only species in the monotypic genus Seriphus.
The common thresher, also known as Atlantic thresher, is the largest species of thresher shark, family Alopiidae, reaching some 6 m (20 ft) in length. About half of its length consists of the elongated upper lobe of its caudal fin. With a streamlined body, short pointed snout, and modestly sized eyes, the common thresher resembles the pelagic thresher. It can be distinguished from the latter species by the white of its belly extending in a band over the bases of its pectoral fins. The common thresher is distributed worldwide in tropical and temperate waters, though it prefers cooler temperatures. It can be found both close to shore and in the open ocean, from the surface to a depth of 550 m (1,800 ft). It is seasonally migratory and spends summers at lower latitudes.
The Argentine anchoita or Argentine anchovy is an anchovy of the genus Engraulis, found in and around waters of Argentina, Uruguay and southern Brazil.
Sardinops is a monotypic genus of sardines of the family Alosidae. The only member of the genus is Sardinops sagax. It is found in the Indo-Pacific and East Pacific oceans. Its length is up to 40 cm (16 in). It has numerous common or vernacular names, some of which more appropriately refer to subspecies, including blue pilchard, Australian pilchard, blue-bait, Californian pilchard, Peruvian Pacific sardine, South American pilchard, Chilean sardine, Japanese pilchard, Pacific sardine, and Southern African pilchard.
CalCOFI is a multi-agency partnership formed in 1949 to investigate the collapse of the sardine population off California. The organization's members are from NOAA Fisheries Service, Scripps Institution of Oceanography, and California Department of Fish and Wildlife. The scope of this research has evolved into the study of marine ecosystems off California and the management of its fisheries resources. In 2004, the CalCOFI survey area became one of 26 Long Term Ecological Research Network (LTER) research sites. This time-series of oceanographic and fisheries data allows scientists to assess the human impact and effects of climate change on the coastal ocean ecosystem. CalCOFI hydrographic and biological data, publications, and web information are distributed for use without restriction under the terms of the GNU Free Documentation License.
The European anchovy is a forage fish somewhat related to the herring. It is a type of anchovy; anchovies are placed in the family Engraulidae. It lives off the coasts of Europe and Africa, including in the Mediterranean Sea, the Black Sea, and the Sea of Azov. It is fished by humans throughout much of its range.
An anchovy is a small, common forage fish of the family Engraulidae. Most species are found in marine waters, but several will enter brackish water, and some in South America are restricted to fresh water.
The European pilchard is a species of ray-finned fish in the monotypic genus Sardina. The young of the species are among the many fish that are sometimes called sardines. This common species is found in the northeast Atlantic, the Mediterranean, and the Black Sea at depths of 10–100 m (33–328 ft). It reaches up to 27.5 cm (10.8 in) in length and mostly feeds on planktonic crustaceans. This schooling species is a batch spawner where each female lays 50,000–60,000 eggs.
The stable ocean hypothesis (SOH) is one of several hypotheses within larval fish ecology that attempt to explain recruitment variability. The SOH is the notion that favorable and somewhat stable physical and biological ocean conditions, such as the flow of currents and food availability, are important to the survival of young fish larvae and their future recruitment. In the presence of stable ocean conditions, concentrations of prey form in stratified ocean layers; more specifically, stable ocean conditions refer to “calm periods in upwelling ecosystems ” that cause the water column to become vertically stratified. The concept is that these strata concentrate both fish larvae and plankton, which results an increase of the fish larvae feeding because of the density-dependent increase in predator-prey interactions. Lasker is attributed with constructing this hypothesis in the late 1970s by building on previous larval fish research and conducting his own experiments. He based the SOH on case studies of clupeid population fluctuations and larval experimentation.
Ichthyoplankton are the eggs and larvae of fish. They are mostly found in the sunlit zone of the water column, less than 200 metres deep, which is sometimes called the epipelagic or photic zone. Ichthyoplankton are planktonic, meaning they cannot swim effectively under their own power, but must drift with the ocean currents. Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into juveniles. Fish larvae are part of the zooplankton that eat smaller plankton, while fish eggs carry their own food supply. Both eggs and larvae are themselves eaten by larger animals.
Anchoa mitchilli is a species of ray-finned fish in the family Engraulidae, the anchovies. Its common names include bay anchovy and common anchovy. It is native to the western Atlantic Ocean and the Gulf of Mexico. It is one of the most common fish species along the coastlines of the western Atlantic.
Tenacibaculum is a gram-negative and motile bacterial genus from the family of Flavobacteriaceae.
The geelbeck croaker, also known as the African weakfish or Cape salmon, is a species of marine ray-finned fish belonging to the family Sciaenidae, the drums and croakers. This species is found in the southwestern Indian Ocean off southeastern Africa.
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