FORAGE FISH, also called PREY FISH or BAIT FISH , are small pelagic
fish which are preyed on by larger predators for food. Predators
include other larger fish, seabirds and marine mammals . Typical ocean
forage fish feed near the base of the food chain on plankton , often
by filter feeding . They include particularly fishes of the family
The ocean primary producers , mainly contained in plankton, produce
food energy from the sun and are the raw fuel for the ocean food webs.
The fishing industry catches forage fish primarily for feeding to farmed animals. Some fisheries scientists are expressing concern that this will affect the populations of predator fish that depend on them.
* 1 In the oceans
* 2 Forage fisheries
* 2.1 History * 2.2 Contemporary * 2.3 Use as animal feed * 2.4 Environmental issues
* 3 In lakes and rivers * 4 Bait and feeder fish * 5 Timeline * 6 Recent reports * 7 See also * 8 Notes * 9 References * 10 External links
IN THE OCEANS
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 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 the same zooplankton as forage fish, are often classified as "forage fish".
OCEAN FORAGE FISH
ANCHOVIES CARIBBEAN REEF SQUID MENHADEN
SARDINES SHRIMP NORTHERN KRILL
Though forage fish are abundant, there are relatively few species. There are more species of primary producers and apex predators in the ocean than there are forage fish.
OCEAN FOOD WEBS
Ecological pyramids are graphical representations, along 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 is performed by algae . This is a
contrast to land, where most primary production is performed by
vascular plants .
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 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.
PHYTOPLANKTON FORM THE BASE OF THE OCEAN FOODCHAIN
PHYTOPLANKTON DINOFLAGELLATE DIATOMS
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 the total ocean's primary production. Diatoms are usually microscopic , although some species can reach up to 2 millimetres 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 FORM THE SECOND LEVEL IN THE OCEAN FOOD CHAIN
SEGMENTED WORM TINY SHRIMP-LIKE CRUSTACEANS JUVENILE PLANKTONIC SQUID
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 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.
Together, phytoplankton and zooplankton make up most of the plankton
in the sea.
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 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 PREDATORS OF FORAGE FISH
TUNA SHARK STRIPED BASS
LEOPARD SEAL DOLPHIN GANNET
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 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 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
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 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 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 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 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 the almost endless stream of herrings allows a herring to eventually snap the copepod. A single juvenile herring could never catch a large copepod.
Coastal upwellings can provide plankton rich feeding grounds for forage fish. Migration of Icelandic capelin See also: Fish migration
Fertile feeding grounds for forage fish are provided by ocean
upwellings. Oceanic gyres are large-scale ocean currents caused by the
The diagram on the right shows the main spawning grounds and larval
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 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 .
External images Dolphins herd sardines
Gannets "divebomb" sardines
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 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 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, 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 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.
Medieval herring fishing in Scania (published 1555).
Pilchard fishing and processing thrived in
This article is one of a series on
billfish , bonito mackerel , salmon shark , tuna
anchovy , herring menhaden , sardine shad , sprat
cod , eel , flatfish pollock , ray -------------------------
carp , tilapia
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 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 a small number of corporate fishing and processing companies.
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.
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 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
USE AS ANIMAL FEED
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 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.
According to Turchini and De Silva (2008), another 2.5 million tonnes of the annual forage fish catch is consumed by the global cat food industry. In Australia, pet cats eat 13.7 kilograms of fish a year compared to the 11 kilograms eaten by the average Australian. The pet food industry is increasingly marketing premium and super-premium products, when different raw materials, such as the by-products of the fish filleting industry, could be used instead.
* The composition of landings of forage fish fisheries have changed over the past 50 years with the trophic level of fish used in fishmeal increasing over the past 20 years. * Our understanding of the role of forage fish in marine ecosystem and the impact of fishing is still limited. * Landing of forage fish peaked by the 1970s, and these high levels are highly unlikely in the future, even if fisheries are managed sustainably. * The consumption of forage fish by seabirds and marine mammals is not likely to be onerous to fisheries, except in a few localized areas. By contrast, fisheries, by reducing the biomass of small pelagics, might pose a threat to these predators, particularly to those species for which stocks have been heavily depleted by human exploitation in the past. * Some forage fish species are consumed by many people with consumption patterns changing over the last 20 years. * Aquaculture continues to increase its consumption of fishmeal and fish oil.
In 2015 sardine populations crashed along the west coast of the
United States, causing the fishery to close early and remain closed
through the 2015–2016 season. A key reason for the population
crash, alongside climate change, was overfishing due to the demand of
fish meals and fish oil used in feed for aquaculture and for human
nutritional supplements. In an effort to provide some relief from the
pressure put on forage fish populations, the World Bank along with the
University of Arizona, Monterey Bay
IN LAKES AND RIVERS
FRESHWATER FORAGE FISH
GOLDEN SHINER KILLIFISH SOUTHERN REDBELLY DACE
CHINESE MINNOW SWARM OF CARP TWAITE SHAD
Within any fresh or saltwater ecosystem, there will always be both desirable and undesirable fishes, and this varies from country to country, and often from region to region within a country. Sport fishermen divide freshwater predators of forage fish into those:
* which have a good fighting ability and are good to eat, called sport (or game) fish . * the other less desirable fish, called rough fish in North America and coarse fish in Britain
Rough or coarse fish usually refers to fish that are not commonly eaten, not sought after for sporting reasons, or have become invasive species reducing the populations of desirable fish. They compete for forage fish with the more popular sport fish. They are often regarded as a nuisance, and are not usually protected by game laws. Forage fish generally are not considered rough or coarse fish because of their usefulness as bait.
The term rough fish is used by U.S. state agencies and anglers to describe undesirable predator fish. In North America, anglers fish for salmon , trout , bass , pike , catfish , walleye and muskellunge . The smallest fish are called panfish , because they can fit in a standard cooking pan. Some examples are crappies , rock bass , perch , bluegill and sunfish .
The term coarse fish originated in the United Kingdom in the early
19th century. Prior to that time, recreational fishing was the sport
of the gentry , who angled for trout and salmon which they called
FRESHWATER PREDATORS OF FORAGE FISH
BROOK TROUT BLACK CRAPPIE MACQUARIE PERCH
RAINBOW TROUT PINK SALMON CHANNEL CATFISH
BAIT AND FEEDER FISH
* 2006: The U.S.
National Coalition for Marine Conservation asks
U.S. fishery managers to put "Forage First!". Their campaign was
launched with the publication of their report, Taking the Bait: Are
* Pikitch E and 12 others (2012) Little Fish, Big Impact: Managing a
Crucial Link in
* ^ A B C Kils, U (1992) The ecoSCOPE and dynIMAGE: Microscale
tools for in situ studies of predator–prey interactions. Arch
Hydrobiol Beih 36: 83–96
* ^ A B C D E F G
National Coalition for Marine Conservation :
U.S. Geological Survey : Forage