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92-699: The European anchovy ( Engraulis encrasicolus ) 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. This species can be fished from the shore with simpler gear, such as beach seines , and it has been widely-eaten for millennia. The species has been fished since ancient times. Both

184-430: A few centimeters. Herrings are pelagic feeders. Their prey consists of a wide spectrum of phytoplankton and zooplankton , amongst which copepods are the dominant prey. Young herring usually capture small copepods by hunting them individually— they approach them from below. The (half speed) video loop at the left shows a juvenile herring feeding on copepods . In the middle of the image a copepod escapes successfully to

276-402: A few milliseconds ( filter feeding ). In the photo on the right, herring ram feed on a school of copepods . The fish all open their mouths and opercula wide at the same time (the red gills are visible—click to enlarge). The fish swim in a grid where the distance between them is the same as the jump length of their prey, as indicated in the animation below. In the animation, juvenile herring hunt

368-475: A group of small crustaceans found in ocean and freshwater habitats . They are the biggest source of protein in the sea, and are important prey for forage fish. Krill constitute the next biggest source of protein. Krill are particularly large predator zooplankton which feed on smaller zooplankton. This means they really belong to the third trophic level, secondary consumers, along with the forage fish. Together, phytoplankton and zooplankton make up most of

460-598: A memorable storm in Friesland and Holland , and came from the North Sea, breaking and destroying several dams and dunes and transforming it into a bay which was then called the Zuiderzee, meaning Southern Sea . The name "Zuiderzee" came into general usage around this period. The size of this inland sea remained largely stable from the 15th century onwards due to improvements in dikes , but when storms pushed North Sea water into

552-536: A predator. The herrings keep a certain distance from a moving scuba diver or cruising predator like a killer whale, forming a vacuole which can look like a doughnut from a spotter plane. The intricacies of schooling is far from fully understood, especially the swimming and feeding energetics. Many hypotheses to explain the function of schooling have been suggested, such as better orientation, synchronized hunting, predator confusion and reduced risk of being found. Schooling also has disadvantages, such as excretion buildup in

644-450: A preeminent forage fish, often marketed as sardines or pilchards . The term "forage fish" is a term used in fisheries , and is applied also to forage species that are not true fish but play a significant role as prey for predators. Thus invertebrates such as squid and shrimp are also referred to as "forage fish". Even the tiny shrimp-like creatures called krill , small enough to be eaten by other forage fish, yet large enough to eat

736-456: A small number of corporate fishing and processing companies. Forage fish populations are very vulnerable when faced with modern fishing equipment. They swim near the surface in compacted schools, so they are relatively easy to locate at the surface with sophisticated electronic fishfinders and from above with spotter planes . Once located, they are scooped out of the water using highly efficient nets, such as purse seines , which remove most of

828-503: A teardrop shaped body. Like other crustaceans they have an armoured exoskeleton , but they are so small that this armour, and the entire body, is usually transparent. Copepods are usually the dominant zooplankton . Some scientists say they form the largest animal biomass on the planet. The other contender is the Antarctic krill . But copepods are smaller than krill, with faster growth rates, and they are more evenly distributed throughout

920-1133: A thousand of the fish were obtained in two days from the pilchard boats fishing near Plymouth; these were caught near the Eddystone. In areas around the Black Sea, the European anchovy is called gávros (Γαύρος) in Greek , hamsie in Romanian , ქაფშია ( Kapshia ) or ქაფშა ( Kapsha ) in Georgian , hamsi in Turkish , hapsi in Pontic dialect of Turkish, hapsia (plural) in Pontic Greek , Hapchia in Laz , хамсия ( hamsiya ) in Bulgarian , and хамса ( hamsa ) in Russian and Ukrainian . Its Ancient Greek name

1012-721: A town in Overijssel , and later also towns in Holland such as Amsterdam, Hoorn , and Enkhuizen . These towns traded at first with ports on the Baltic Sea , in England, and in the Hanseatic League , but later also with the rest of the world when the Netherlands established its colonial empire . When that lucrative trade diminished, most of the towns fell back on fishing and some industry until

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1104-800: A traditional item for long-distance trade. Anchovies are also used as fishing bait . Forage fish The typical ocean forage fish feed at the lower trophic level of the food chain , often by filter feeding . They include particularly fishes of the order Clupeiformes ( herrings , sardines , shad , hilsa , menhaden , anchovies , and sprats ), but also other small fish, including halfbeaks , silversides , smelt such as capelin and goldband fusiliers . Forage fish compensate for their small size by forming schools . Some swim in synchronised grids with their mouths open so they can efficiently filter plankton. These schools can become immense shoals which move along coastlines and migrate across open oceans. The shoals are concentrated energy resources for

1196-557: A year later, in the unlikely event that they survive, they will be 9–10 cm (3.5–3.9 in) long. The females are larger than the males. When they reach a length of 12–13 cm (4.7–5.1 in), they spawn for the first time. A survey in southwestern Africa found no specimens older than three years. European anchovies are abundant in the Mediterranean and formerly also the Black and Azov seas (see below). They are regularly caught on

1288-464: Is a spectacular migration by millions of silvery sardines along the southern coastline of Africa. In terms of biomass, the sardine run could rival East Africa's great wildebeest migration . Sardines have a short life-cycle, living only two or three years. Adult sardines, about two years old, mass on the Agulhas Bank where they spawn during spring and summer, releasing tens of thousands of eggs into

1380-515: Is affected by ocean currents . Around Iceland maturing capelin make large northward feeding migrations in spring and summer. The return migration takes place in September to November. The spawning migration starts north of Iceland in December or January. The diagram on the right shows the main spawning grounds and larval drift routes. Capelin on the way to feeding grounds is coloured green, capelin on

1472-581: Is an invasive species which eats European anchovy eggs. Some past fluctuations are likely due to climate change . European anchovies are caught with purse seines , lamparas , trawls and beach seines . Bycatch is thought, on the basis of insufficient data, to be minor. European anchovies are widely eaten. Anchovies are considered an oily fish ; they have a salty, strong taste. Some people eat them raw. European anchovies are sold fresh, dried, smoked, salted, in oil, frozen, canned, and processed into fishmeal and fish oil. Their ease of preservation has made them

1564-554: Is mentioned among others in a life of saints written by Anglo-Saxon Bishop Saint Boniface in 753, and a deed of gift from the town of Urk . Its etymology may be eels , in Dutch aal or ael , so: ael mere = "eel lake" Presumably, the water of Lake Almere at that time was fresh water or slightly brackish . The name of the new town of Almere in Flevoland was given in 1984 in memory of this body of water. A number of occurrences during

1656-405: Is performed by algae . This is a contrast to land, where most primary production is performed by vascular plants . Algae ranges from single floating cells to attached seaweeds , while vascular plants are represented in the ocean by groups such as the seagrasses . Larger producers, such as seagrasses and seaweeds, are mostly confined to the littoral zone and shallow waters, where they attach to

1748-484: Is the staple food of the local Black Sea cuisine, widely used in pan dishes, baked goods, even as dessert. In Bulgaria hamsiya is traditionally fried and served in cheap fast-food restaurants along the shore, typically with beer . Since the 1990s the dominant position of fried hamsiya is fading but still popular. In Spain, they are called “anchoa” or “boquerón”, when they are eaten pickled. They are so typical in Malaga that

1840-524: Is usually based primarily on zooplankton, although, since they are omnivorous, they also take in some phytoplankton. Young forage fish, such as herring, mostly feed on phytoplankton and as they mature they start to consume larger organisms. Older herrings feed on zooplankton , tiny animals that are found in oceanic surface waters , and fish larvae and fry (recently hatched fish). Copepods and other tiny crustaceans are common zooplankton eaten by forage fish. During daylight , many forage fish stay in

1932-551: The Coriolis effect . Wind-driven surface currents interact with these gyres and the underwater topography, such as seamounts and the edge of continental shelves , to produce downwellings and upwellings . These can transport nutrients which plankton thrive on. The result can be rich feeding grounds attractive to the plankton feeding forage fish. In turn, the forage fish themselves become a feeding ground for larger predator fish. Most upwellings are coastal, and many of them support some of

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2024-442: The copepods in synchronization: The copepods sense with their antennae the pressure-wave of an approaching herring and react with a fast escape jump. The length of the jump is fairly constant. The fish align themselves in a grid with this characteristic jump length. A copepod can dart about 80 times before it tires out. After a jump, it takes it 60 milliseconds to spread its antennae again, and this time delay becomes its undoing, as

2116-472: The plankton in the sea. Plankton is the term applied to any small drifting organisms that float in the sea ( Greek planktos = wanderer or drifter). By definition, organisms classified as plankton are unable to swim against ocean currents; they cannot resist the ambient current and control their position. In ocean environments, the first two trophic levels are occupied mainly by plankton . Plankton are divided into producers and consumers. The producers are

2208-437: The unaided eye . They can appear as a green discoloration of the water when they are present in high enough numbers. Since they increase their biomass mostly through photosynthesis they live in the sun-lit surface layer ( euphotic zone ) of the sea. The most important groups of phytoplankton include the diatoms and dinoflagellates . Diatoms are especially important in oceans, where they are estimated to contribute up to 45% of

2300-434: The 20th century when tourism became the major source of income. Contained within the Zuiderzee were five small islands, the remains of what were once larger islands, peninsulas connected to the mainland , or in the case of Pampus , an artificial island. These were Wieringen , Urk , Schokland , Pampus and Marken . The inhabitants of these islands also subsisted mainly on fishing and related industries and still do in

2392-625: The East (Oostelijk) Flevoland Polder, built in 1957; and the South (Zuidelijk) Flevoland Polder, completed in 1968. A fifth, Markewaard, began construction in 1963, and became partially complete, but was abandoned in the mid-1980s. Collectively, this system of dams, dikes, and polders is called the Zuiderzee Works . Around the Zuiderzee many fishing villages grew up and several developed into walled towns with extensive trade connections, in particular Kampen ,

2484-567: The Gambia , and Senegal , it is not an important commercial species. South of the Angola / Namibia border, Engraulis encrasicolus (the European anchovy) mixes with Engraulis capensis , the South African anchovy. The Namibian fishery is significantly involved in fishmeal and fish oil production. European anchovies are also found in upwelling areas off the east coast of Africa. The IUCN considers

2576-806: The Mediterranean, it goes to depths of 200 m in winter), and it may go as deep as 400 m. As it is euryhaline , it can live in water with a salinity of 5–41 PSU (sea water salinity is usually 35 PSU). It can therefore live in brackish water in lagoons , estuaries , and lakes . European anchovies eat plankton , mostly copepods and the eggs and larvae of fish, molluscs , and cirripedes . They are migratory, often travelling northwards in summer and south in winter. They form large schools , and may form bait balls when threatened (see image, below). European anchovies are eaten by many species of fish, birds and marine mammals. The species spawn multiply in warm periods from about April to November, depending on when

2668-559: The Middle Ages led to the transformation of the lake to an inland sea that would be called the Zuiderzee, which are: Especially during the 12th century, particularly in 1219 and 1282, high tides and storms eroded the western banks of the Vlie and submerged large areas of land. The land between Stavoren, Texel, and Medemblik was washed away around 1170. The waterway between Stavoren and Enkhuizen, however, did not appear until around 1400. The erosion

2760-646: The Zuiderzee became the IJsselmeer , and the outer portion of the Zuiderzee became the Wadden Sea . Large areas of land, mainly for agricultural use, were subsequently reclaimed from the water through the construction of polders with dams, pumping, and other hydrological technology. Four had been built by the early 1980s. They were the Wieringermeer Polder built in 1930; the Northeast (Noordoost) Polder, built in 1942;

2852-506: The Zuiderzee, and these must derive from the previous summer's spawning. There is no evidence to decide the question whether all the young anchovies as well as the adults leave the Zuiderzee in autumn, but, considering the winter temperature there, it is probable that they do. Eggs have also been found in the Bay of Naples , near Marseilles , off the coast of the Netherlands , and once at least off

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2944-555: The Zuiderzee. The construction between 1927 and 1932 of a 19-mile long dam (the Afsluitdijk ), under plans originating from Cornelius Lely , enclosed the Zuiderzee. The creation of this dam was hastened by the Flood of January 1916 . Plans for closing the Zuiderzee had been made over thirty years earlier but had not yet passed in parliament . With the completion of the Afsluitdijk in 1932,

3036-726: The Zuiderzee. It was separated from the sea by a belt of marsh and fen ; at the time, the original coastline ran along the line of the Frisian Islands . A number of streams, including the Vecht , Eem , and Ysel , fed into the lake. The lake itself fed out into the North Sea through the Vlie (Latin Flevus ). It existed in Roman times and the early Middle Ages . From the Indo-European root *plew- "flow",

3128-806: The almost endless stream of herrings allows a herring to eventually snap the copepod. A single juvenile herring could never catch a large copepod. Forage fish often make great migrations between their spawning, feeding and nursery grounds. Schools of a particular stock usually travel in a triangle between these grounds. For example, one stock of herrings have their spawning ground in southern Norway , their feeding ground in Iceland , and their nursery ground in northern Norway. Wide triangular journeys such as these may be important because forage fish, when feeding, cannot distinguish their own offspring. Fertile feeding grounds for forage fish are provided by ocean upwellings. Oceanic gyres are large-scale ocean currents caused by

3220-567: The autumn, returning there the following spring. They were believed to be an isolated population, for none come from the south in summer to occupy the English Channel , though the species does exist off the coast of Portugal . The explanation appears to be that in summer, the shallow and landlocked waters of the Zuiderzee and the sea off the Dutch coast get warmer than the coastal waters off Britain, so anchovies can spawn and maintain their numbers in warmer Dutch waters better. Dutch naturalists on

3312-415: The best facilities aquaria can offer they become sluggish compared to their quivering energy in wild schools. Copepods are a group of small crustaceans found in ocean and freshwater habitats . Many species are planktonic (drifting in the ocean water), while others are benthic (living on the sea floor). Copepods are typically one millimetre (0.04 in) to two millimetres (0.08 in) long, with

3404-537: The biomass of pollock has declined in recent years, perhaps spelling trouble for both the Bering Sea ecosystem and the commercial fishery it supports. Acoustic surveys by NOAA indicate that the 2008 pollock population is almost 50 percent lower than last year's survey levels. Some scientists think this decline in Alaska pollock could repeat the collapse experienced by Atlantic cod , which could have negative consequences for

3496-466: The body is round and slender. The record weight for a single fish is 49 g (1.7 oz). The maximum recorded length is 21 cm ( 8 + 1 ⁄ 8  in). 13.5 cm (5.3 in) is a more typical length. It has a silver underbelly and blue, green or grey back and sides. A silver stripe along the side fades away with age. The European anchovy is a coastal pelagic species; in summer, it usually lives in water less than 50 m deep (although, in

3588-621: The breathing media and oxygen and food depletion. The way the fish array in the school probably gives energy saving advantages, though this is controversial. On calm days, schools of herring can be detected at the surface a mile away by little waves they form, or from several meters at night when they trigger bioluminescence in surrounding plankton . Underwater recordings show herring constantly cruising at high speeds up to 108 cm per second, with much higher escape speeds. They are fragile fish, and because of their adaptation to schooling behaviour they are rarely displayed in aquaria . Even with

3680-625: The coast of Lancashire . The occurrence of anchovies in the English Channel has been carefully studied at the Marine Biological Association Laboratory in Plymouth . They were most abundant in 1889 and 1890. In the former year considerable numbers were taken off Dover in drift nets of small mesh used for the capture of sprats. In the following December large numbers were taken together with sprats at Torquay. In November 1890

3772-609: The coast of the Netherlands in summer when they entered the Wadden Sea and Zuiderzee . After the closing of the Zuiderzee they were still found in the Wadden Sea until the 1960s. They were also caught in the estuary of the Scheldt . There is reason to believe that anchovies at the western end of the English Channel in November and December migrate from the Zuiderzee and the Scheldt in

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3864-716: The coast towns still promote the traditional practice of fishing by lateen sail boats for tourism and festivals. Pilchard fishing and processing thrived in Cornwall between 1750 and 1880, after which stocks went into an almost terminal decline. Recently (2007) stocks have been improving. The industry has featured in many works of art, including Stanhope Forbes and other Newlyn School artists. Traditional commercial fisheries were directed towards high value ocean predators such as cod , rockfish and tuna , rather than forage fish. As technologies developed, fisheries became so effective at locating and catching predator fish that many of

3956-410: The coastline. When threatened, sardines instinctively group together and create massive bait balls . Bait balls can be up to 20 meters (66 feet) in diameter. They are short lived, seldom lasting longer than 20 minutes. As many as 18,000 dolphins, behaving like sheepdogs, round the sardines into these bait balls, or herd them to shallow water (corralling) where they are easier to catch. Once rounded up,

4048-492: The coasts of Bulgaria , Croatia , France , Georgia , Greece , Italy , Albania , Romania , Russia , Spain , Turkey and Ukraine . The range of the species also extends along the Atlantic coast of Europe to the south of Norway . In winter it is common off Devon and Cornwall ( United Kingdom ), but has not hitherto been caught in such numbers as to be of commercial importance. Formerly they were caught in large numbers off

4140-403: The connection to the sea and the lake were significantly enlarged. A period of lower sea levels followed. The Marsdiep was once a river ( fluvium Maresdeop ) which may have been a distributary of the Vlie . During the early Middle Ages this began to change as rising sea levels and storms started to eat away at the coastal areas which consisted mainly of peatlands. In this period the inlet

4232-462: The current into waters off the west coast, where the larvae develop into juvenile fish. When they are old enough, they aggregate into dense shoals and migrate southwards, returning to the Agulhas banks in order to restart the cycle. Herring has been known as a staple food source since 3000 B.C. In Roman times, anchovies were the base for the fermented fish sauce called garum . This staple of cuisine

4324-401: The currents, tides and winds instead. Zooplanktons can reproduce rapidly, their populations can increase up to thirty percent a day under favourable conditions. Many live short and productive lives and reach maturity quickly. Particularly important groups of zooplankton are the copepods and krill . These are not shown in the images above, but are discussed in more detail later. Copepods are

4416-632: The day and plants at night, while others alternate summer carnivory with winter herbivory. They are in turn eaten by billfish , mackerel , and sharks . Forage fish are the food that sustains larger predators above them in the ocean food chain. The superabundance they present in their schools make them ideal food sources for top predator fish such as tuna , striped bass , cod , salmon , barracuda and swordfish , as well as sharks , whales , dolphins , porpoises , seals , sea lions , and seabirds . Forage fish compensate for their small size by forming schools . These sometimes immense gatherings fuel

4508-486: The dolphins and other predators take turns plowing through the bait balls, gorging on the fish as they sweep through. Seabirds also attack them from above, flocks of gannets , cormorants , terns and gulls . Some of these seabirds plummet from heights of 30 metres (98 feet), plunging through the water leaving vapour-like trails behind like fighter planes. The eggs, left behind at the Agulhas Banks, drift northwest with

4600-424: The entire Bering Sea ecosystem. Salmon, halibut, endangered Steller sea lions, fur seals, and humpback whales eat pollock and depend on healthy populations to sustain themselves. Eighty percent of the forage fish caught are fed to animals, in large part due to the high content of beneficial long chain omega-3 fatty acids in their flesh. Ninety percent is processed into fishmeal and fish oil . Of this, 46 percent

4692-419: The fisheries to be abundant and fully exploited, and in need of careful monitoring. The highly international species has no concerted management plan. Local populations fluctuate, and have shown large fluctuations in the past. These fluctuations are not well understood. Some past declines have been due to environmental problems, local overfishing , and invasive species from ballast water . Mnemiopsis leidyi

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4784-401: The great marine predators. The predators are keenly focused on the shoals, acutely aware of their numbers and whereabouts, and make migrations themselves that can span thousands of miles to connect, or stay connected, with them. The ocean's primary producers , mainly contained in phytoplanktons , produce food energy and biomass photosynthetically from sunlight and are the raw fuel for

4876-399: The inhabitant of this Andalusian city is also called "boquerón". Anchovy populations in the Mediterranean were severely depleted in the 1980s by the invasive comb jelly Mnemiopsis leidyi which eats the eggs and young, they have since stabilized albeit at a much lower level. European anchovies are commercially important down the west coast of Africa, although they are most abundant at

4968-451: The inlet, the Zuiderzee became a volatile cauldron of water, frequently resulting in flooding and the loss of ships. For example, on 18 November 1421, a seawall at the Zuiderzee dike broke, which flooded 72 villages and killed about 10,000 people. This was the Second St. Elizabeth's flood . The process of creating polders had developed to a point by 1667 that the damming of the Zuiderzee

5060-402: The left. The opercula (hard bony flaps covering the gills ) are spread wide open to compensate the pressure wave which would alert the copepod to trigger a jump. If prey concentrations reach very high levels, the herrings adopt a method called "ram feeding". They swim with their mouth wide open and their opercula fully expanded. Every several feet, they close and clean their gill rakers for

5152-455: The lines of the diagram at the right, which show how biomass or productivity changes at each trophic level in an ecosystem . The first or bottom level is occupied by primary producers or autotrophs ( Greek autos = self and trophe = food). These are the names given to organisms that do not feed on other organisms, but produce biomass from inorganic compounds, mostly by a process of photosynthesis . In oceans, most primary production

5244-468: The losing side when faced with the machinery of contemporary industrial fishing. Altogether, forage fish account for 37 percent (31.5 million tonnes) of all fish taken from the world's oceans each year. However, because there are fewer species of forage fish compared to predator fish, forage species fisheries are the largest in the world. Seven of the top ten fisheries target forage fish. The total world catch of herrings, sardines and anchovies alone in 2005

5336-710: The most productive fisheries in the world. Regions of notable upwelling include coastal Peru , Chile , Arabian Sea , western South Africa , eastern New Zealand and the California coast. Capelin are a forage fish of the smelt family found in the Atlantic and Arctic oceans. In summer, they graze on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat krill and other crustaceans . The capelin move inshore in large schools to spawn and migrate in spring and summer to feed in plankton rich areas between Iceland , Greenland , and Jan Mayen . The migration

5428-446: The most spectacular schooling fish. They aggregate together in huge numbers. Schools have been measured at over four cubic kilometres in size, containing about four billion fish. These schools move along coastlines and traverse the open oceans. Herring schools in general have very precise arrangements which allow the school to maintain relatively constant cruising speeds. Herrings have excellent hearing, and their schools react very fast to

5520-474: The name of the body of water which lay there long ago. Over time these lakes gradually eroded their soft peat shores and spread (a process known as waterwolf ). Some part of this area of water was later called the Vlie ; it probably flowed into the sea through what is now the Vliestroom channel between the islands of Vlieland and Terschelling . During a period of rising sea level between 250 and 600 CE,

5612-470: The name was transmitted by the Roman geographer Pomponius Mela in describing this region. In his treatise on geography of 44 AD, Pomponius speaks of a Flevo Lacus . He writes: "The northern branch of the Rhine widens as Lake Flevo, and encloses an island of the same name, and then as a normal river flows to the sea". Other sources rather speak of Flevum , which could be related to today's Vlie (Vliestroom), i.e.

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5704-576: The north end of this range. The species is most commercially important in Morocco . In Mauritania , artisanal fishers do not target the species, and commercial fisheries have size limitations. In West Africa , these anchovies are widely fished and eaten. In Nigeria , Ghana , and Benin , it is an abundant and important commercial species. After the end of the upwelling season ends the Sardinella fishery, fishers change net size to catch anchovies. In Guinea ,

5796-466: The north of the Zuiderzee (cf. North Sea). In the 20th century the majority of the Zuiderzee was closed off from the North Sea by the construction of the Afsluitdijk , leaving the mouth of the inlet to become part of the Wadden Sea . The salt water inlet changed into a fresh water lake now called the IJsselmeer ( IJssel Lake) after the river that drains into it, and by means of drainage and polders , an area of some 1,500 km (580 sq mi)

5888-498: The ocean food webs . Forage fish transfer this energy by eating the plankton and becoming food themselves for the top predators. In this way, forage fish occupy the lower-central positions in ocean and lake food webs. The fishing industry sometimes catch forage fish for commercial purposes (i.e. as seafood ), but primarily for use as feeder fish to raise more valuable piscivorous animals (e.g. salmon farms ). Some fisheries scientists are expressing concern that this will affect

5980-615: The ocean food web. Most forage fish are pelagic fish , which means they form their schools in open water, and not on the bottom ( benthic fish ) or near the bottom ( benthopelagic fish ). They are short-lived, and go mostly unnoticed by humans, apart from an occasional support role in a documentary about a great ocean predator. While we may not pay them much attention, the great marine predators are keenly focused on them, acutely aware of their numbers and whereabouts, and make migrations that can span thousands of miles to connect with them. After all, forage fish are their food. Herring are among

6072-503: The ocean than there are forage fish. Forage fish occupy central positions in the ocean food webs . The position that a fish occupies in a food web is called its trophic level ( Greek trophē = food). The organisms it eats are at a lower trophic level, and the organisms that eat it are at a higher trophic level. Forage fish occupy middle levels in the food web, serving as a dominant prey to higher level fish, seabirds and mammals. Ecological pyramids are graphical representations, along

6164-423: The oceans. This means copepods almost certainly contribute more secondary production to the world's oceans than krill, and perhaps more than all other groups of marine organisms together. They are a major item on the forage fish menu. Copepods are very alert and evasive. They have large antennae . When they spread their antennae they can sense the pressure wave from an approaching fish and jump with great speed over

6256-607: The phytoplankton (Greek phyton = plant) and the consumers, who eat the phytoplankton, are the zooplankton (Greek zoon = animal). Forage fish feed on plankton . When they are eaten by larger predators, they transfer this energy from the bottom of the food chain to the top and in this way are the central link between trophic levels . Forage fish are usually filter feeders , meaning that they feed by straining suspended matter and food particles from water. They usually travel in large, slow moving, tightly packed schools with their mouths open. They are typically omnivorous . Their diet

6348-417: The phytoplankton in oceanic surface waters , and include tiny crustaceans , and fish larvae and fry (recently hatched fish). Most zooplankton are filter feeders , and they use appendages to strain the phytoplankton in the water. Some larger zooplankton also feed on smaller zooplankton. Some zooplankton can jump about a bit to avoid predators, but they cannot really swim. Like phytoplankton, they float with

6440-529: The populations of predator fish that depend on them. The practice of harvesting forage fish can also be a sign of overfishing as fish stocks of larger species in the fisheries are depleted thus forcing the industry to start fishing down the food web . Typical ocean forage fish are small, silvery schooling oily fish such as herring , anchovies and menhaden , and other small, schooling baitfish like capelin , smelts , sand lance , halfbeaks , pollock , butterfish and juvenile rockfish . Herrings are

6532-419: The safety of deep water, feeding at the surface only at night when there is less chance of predation. They swim with their mouths open, filtering plankton from the water as it passes through their gills. Ocean halfbeaks are omnivores which feed on algae , plankton, marine plants like seagrass , invertebrates like pteropods and crustaceans and smaller fishes. Some tropical species feed on animals during

6624-584: The same zooplankton as forage fish, are often classified as "forage fish". Forage fish utilise the biomass of copepods , mysids and krill in the pelagic zone to become the dominant converters of the enormous ocean production of zooplankton. They are, in turn, central prey items for higher trophic levels . Forage fish may have achieved their dominance because of the way they live in huge, and often extremely fast cruising schools. Though forage fish are abundant, there are relatively few species. There are more species of primary producers and apex predators in

6716-693: The school. Spawning patterns in forage fish are highly predictable. Some fisheries use knowledge of these patterns to harvest the forage species as they come together to spawn, removing the fish before they have actually spawned. Fishing during spawning periods or at other times when forage fish amass in large numbers can also be a blow to predators. Many predators, such as whales, tuna and sharks, have evolved to migrate long distances to specific sites for feeding and breeding. Their survival hinges on their finding these forage schools at their feeding grounds. The great ocean predators find that, no matter how they are adapted for speed, size, endurance or stealth, they are on

6808-523: The seaway between the Dutch islands of Vlieland and Terschelling. This last name is grammatically more probable for a geographical indication, which is why it is assumed that Pomponius confused the declension of the word giving the name Flevo. In fact the Vlie formed outfall from the lake into the North Sea . In the second half of the twentieth century the Flevopolders and a new province, Flevoland , took

6900-583: The shores of the Zuiderzee first described their reproduction and development. Spawning takes place in June and July. The eggs are buoyant and transparent like most fish eggs, but are unusual in being sausage-shaped, instead of globular. They resemble sprat and pilchard eggs in having a segmented yolk and no oil globule. Larvæ hatch two or three days after fertilization, and are minute and transparent. In August young specimens, c. 38 to 89 mm ( 1 + 1 ⁄ 2 to 3 + 1 ⁄ 2  in) in length, are found in

6992-414: The species name, " Engraulis " ( ἐγγραυλίς ), and the specific name " encrasicolus " ( ἐγκρασίχολος ) are names from Ancient Greek , meaning "anchovy" and "small fish" respectively. It is easily distinguished by its deeply cleft mouth, the angle of the gape being behind the eyes. The pointed snout extends beyond the lower jaw. The fish resembles a sprat in having a forked tail and a single dorsal fin, but

7084-427: The stocks collapsed. The industry compensated by turning to species lower in the food chain. In former times, forage fish were more difficult to fish profitably, and were a small part of the global marine fisheries. But modern industrial fishing technologies have enabled the removal of increasing quantities. Industrial-scale forage fish fisheries need large scale landings of fish to return profits. They are dominated by

7176-500: The summer, hamsi migrates north to warm shallow waters of the Azov Sea to feed and breed, returning to the deep for the winter by migrating through the Strait of Kerch . During migration the fish moves in huge schools , and are actively hunted by gulls and dolphins . Hamsi makes up a considerable part of fishing and fish processing industries, either canned or frozen. In Turkey, it

7268-402: The temperatures are warm enough. At least some local subpopulations have separate spawning grounds, and are thus genetically distinct, although spawning grounds shift. Some spawn in fresh water. The shape of the eggs is ellipsoidal to oval. The eggs float as plankton in the upper 50 m of the water column for about 24–65 hours before hatching. The hatched larvae are transparent and grow rapidly;

7360-435: The total ocean's primary production. Diatoms are usually microscopic , although some species can reach up to 2 millimetres (0.079 in) in length. The second trophic level ( primary consumers ) is occupied by zooplankton which feed off the phytoplankton . Together with the phytoplankton, they form the base of the food pyramid that supports most of the world's great fishing grounds. Zooplankton are tiny animals found with

7452-413: The underlying substrate and are still within the photic zone . Most primary production in the ocean is performed by microscopic organisms , the phytoplankton. Thus, in ocean environments, the first bottom trophic level is occupied principally by phytoplankton , microscopic drifting organisms, mostly one-celled algae , that float in the sea. Most phytoplankton are too small to be seen individually with

7544-456: The water. The adult sardines then make their way in hundreds of shoals towards the sub-tropical waters of the Indian Ocean . A larger shoal might be 7 kilometers (4.3 miles) long, 1.5 kilometers (0.93 miles) wide and 30 meters (98 feet) deep. Huge numbers of sharks, dolphins, tuna, sailfish, Cape fur seals and even killer whales congregate and follow the shoals, creating a feeding frenzy along

7636-490: The way back is blue, and the breeding grounds are red. In a paper published in 2009, researchers from Iceland recount their application of an interacting particle model to the capelin stock around Iceland, successfully predicting the spawning migration route for 2008. Schooling forage fish are subject to constant attacks by predators. An example is the attacks that take place during the African sardine run . The African sardine run

7728-458: Was 22.4 million tonnes, 24 percent of the total world catch. The Peruvian anchoveta fishery is now the biggest in the world (10.7 million tonnes in 2004), while the Alaskan pollock fishery in the Bering Sea is the largest single species fishery in the world (3 million tonnes). The Alaskan pollock is said to be the largest remaining single species source of palatable fish in the world. However,

7820-422: Was a shallow bay of the North Sea in the northwest of the Netherlands . It extended about 100 km (60 miles) inland and at most 50 km (30 miles) wide, with an overall depth of about 4 to 5 metres (13–16 feet) and a coastline of about 300 km (200 miles). It covered 5,000 km (1,900 sq mi). Its name is Dutch for "southern sea", indicating that the name originates in Friesland , to

7912-616: Was fed to farmed fish , 24 percent to pigs, and 22 percent to poultry (2002). Six times the weight of forage fish is fed to pigs and poultry alone than the entire seafood consumption of the U.S. market. One of the most promising alternatives to fish oil as a source of long chain omega-3 fatty acids and certain amino acids is algal oil from microalgae , the original source of these fatty acids in forage fish. Zuiderzee The Zuiderzee or Zuider Zee ( Dutch: [ˌzœydərˈzeː] ; old spelling Zuyderzee or Zuyder Zee ), historically called Lake Almere and Lake Flevo ,

8004-528: Was produced in industrial quantities and transported over long distances. Fishing for sardela or sardina ( Sardina pilchardus ) is an ongoing activity on the Croatian Adriatic coasts of Dalmatia and Istria . It traces its roots back thousands of years. The region was then largely a Venetian dominion, part of the Roman Empire . The area has always been sustained through fishing mainly sardines. Along

8096-570: Was proposed, although a feasible method did not appear until the 20th century. The Netherlands was part of the First French Empire between 1810 and 1813. A département was formed in 1811 and named as Zuyderzée after the Zuiderzee, whose territory roughly corresponded to the present provinces of North Holland and Utrecht . In 1928, the 6-meter and 8-meter sailing events for the Amsterdam Summer Olympics were held on

8188-514: Was reclaimed as land. This land eventually became the province of Flevoland . Part of the IJsselmeer was also divided into the Markermeer . In classical times there was already a body of water in this location, called Lake Flevo (Flevo Lacus ) by Roman authors. This was the central and largest lake in a region filled with a mixture of lowland and freshwater lakes occupying the area later filled by

8280-498: Was referred to as the Almere , indicating it was still more of a lake, but the mouth and size of the inlet were much widened in the 12th century and especially after a disastrous flood in 1282 broke through the barrier dunes near Texel . The disaster marked the rise of Amsterdam on the southwestern end of the bay, since the seagoing traffic of the Baltic trade could now visit. Lake Almere

8372-425: Was stopped to the south and east by the high sandy shores of Gooi , Veluwe , Voorst , and Gasterland in the provinces of Utrecht , Gelderland , Overysel , and Friesland respectively. The even more massive St. Lucia's flood occurred 14 December 1287, when the seawalls broke during a storm, killing approximately 50,000 to 80,000 people in the fifth largest flood in recorded history. The flood occurred during

8464-552: Was ἀφύη, aphýē , later Latinized into apiuva , hence the standard Italian acciuga and the Croatian inćun through the Genoese dialectal anciúa . Modern Greek also uses αντζούγια antsúya , a variant of the Genoese form, for processed – as opposed to the fresh gávros – anchovy products. Black Sea adult anchovies can reach around 12–15 cm ( 4 + 1 ⁄ 2 –6 in). In

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