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Overfishing is the removal of a species of
fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...

fish
from a
body of water (Lysefjord) in Norway Norway, officially the Kingdom of Norway,Names in the official and recognised languages: Bokmål Bokmål (, ; literally "book tongue") is an official written standard for the Norwegian language, alongside Nynorsk. ...

body of water
at a rate that the species cannot replenish, resulting in those species becoming underpopulated in that area. Overfishing can occur in water bodies of any sizes, such as ponds, rivers, lakes or oceans, and can result in
resource depletion Resource depletion is the consumption of a resource faster than it can be replenished. Natural resources are commonly divided between renewable resource File:Global Vegetation.jpg, Global vegetation A renewable resource, also known as a flo ...
, reduced biological growth rates and low
biomass Biomass is plant or animal material used as fuel to produce electricity or heat. Examples are wood, energy crops and waste from forests, yards, or farms. Since biomass technically can be used as a fuel directly (e.g. wood logs), some people use t ...
levels. Sustained overfishing can lead to
critical depensation In population dynamics, depensation is the effect on a population In biology, a population is a number of all the organisms of the same group or species In biology, a species is the basic unit of biological classification, classificati ...
, where the fish population is no longer able to sustain itself. Some forms of overfishing, such as the overfishing of sharks, has led to the upset of entire
marine ecosystem Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in Saline water, waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% ...
s. Types of overfishing include: Growth overfishing, recruitment overfishing, ecosystem overfishing. The ability of a fishery to recover from overfishing depends on whether the
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

ecosystem
's conditions are suitable for the recovery. Dramatic changes in species composition can result in an ecosystem shift, where other equilibrium energy flows involve species compositions different from those that had been present before the depletion of the original fish stock. For example, once trout have been overfished, carp might take over in a way that makes it impossible for the trout to re-establish a breeding population. Since the growth of global fishing enterprises after the 1950s, intensive fishing has spread from a few concentrated areas to encompass nearly all fisheries. The scraping of the ocean floor in bottom dragging is devastating to
coral Corals are marine invertebrates Marine invertebrates are the invertebrates that live in marine habitats. Invertebrate is a blanket term that includes all animals apart from the vertebrate members of the chordate phylum. Invertebrates lack a vert ...

coral
,
sponges Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the Diploblasts. They are Multicellular organism, multicellular organisms that have bodies full of pores and channels allowing water ...

sponges
and other long-lived species that do not recover quickly, and that provide a habitat for commercial fisheries species. This destruction alters the functioning of the ecosystem and can permanently alter species' composition and
biodiversity Biodiversity is the biological variety and of . Biodiversity is a measure of variation at the , , and level. Terrestrial biodiversity is usually greater near the , which is the result of the warm and high . Biodiversity is not distributed ev ...

biodiversity
.
Bycatch Bycatch (or by-catch), in the fishing industry The fishing industry includes any industry or activity concerned with taking, culturing, processing, preserving, storing, transporting, marketing or selling fish or fish products. It is defined by t ...
, the capture of unintended species in the course of fishing, is typically returned to the ocean only to die from injuries or exposure. Bycatch represents about a quarter of all marine catch. In the case of
shrimp Shrimp are decapod crustacean Crustaceans (Crustacea ) form a large, diverse arthropod taxon which includes such animals as crabs, lobsters, crayfish, Caridea, shrimp, krill, Dendrobranchiata, prawns, woodlice, barnacles, copepods, amphipo ...

shrimp
capture, the bycatch is five times larger than the shrimp caught. A report by
FAO The Food and Agriculture Organization of the United Nations (FAO)french: Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is a specialized agency ...
in 2020 stated that "in 2017, 34 percent of the fish stocks of the world’s marine fisheries were classified as overfished". Mitigation options include: Government regulation, removal of
subsidies A subsidy or government incentive is a form of financial aid or support extended to an economic sector (business, or individual) generally with the aim of promoting economic and social policy. Although commonly extended from the government, the term ...
, minimizing fishing impact,
aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the farming of fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in ...
and consumer awareness.


Scale

Overfishing has stripped many fisheries around the world of their
stocks Stocks are restraining devices that were used as a form of corporal punishment and public humiliation. Form and application The stocks, pillory, and pranger each consist of large wooden boards with hinges; however, the stocks are distinguished ...
. The
United Nations The United Nations (UN) is an intergovernmental organization that aims to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and be a centre for har ...

United Nations
Food and Agriculture Organization The Food and Agriculture Organization of the United Nations (FAO)french: Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is a list of specialized ...
estimated in a 2018 report that 33.1% of world fish stocks are subject to overfishing. Significant overfishing has been observed in pre-industrial times. In particular, the overfishing of the western
Atlantic Ocean
Atlantic Ocean
from the earliest days of
European colonisation of the Americas Although the Norse had explored and colonized northeastern North America c. 1000 CE, a later and more well known wave of European colonization of the Americas took place in the Americas between about 1500 CE and 1800 CE, during the Age of Expl ...
has been well documented. The fraction of fish stocks that are within biologically sustainable levels has exhibited a decreasing trend, from 90% in 1974 to 66.9% in 2015. In contrast, the percentage of stocks fished at biologically unsustainable levels increased from 10% in 1974 to 33.1% in 2015, with the largest increases in the late-1970s and 1980s. In 2015, maximally sustainably fished stocks (formerly termed fully fished stocks) accounted for 59.9% and underfished stocks for 7% of the total assessed stocks. While the proportion of underfished stocks decreased continuously from 1974 to 2015, the maximally sustainably fished stocks decreased from 1974 to 1989, and then increased to 59.9% in 2015. In 2015, among the 16 major statistical areas, the
Mediterranean The Mediterranean Sea is a sea The sea, connected as the world ocean or simply the ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.
Mediterranean
and
Black Sea , with the skyline of Batumi Batumi (; ka, ბათუმი ) is the second largest city of Georgia Georgia usually refers to: * Georgia (country) Georgia ( ka, საქართველო; ''Sakartvelo''; ) is a country locat ...

Black Sea
had the highest percentage (62.2%) of unsustainable stocks, closely followed by the Southeast
Pacific The Pacific Ocean is the largest and deepest of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. T ...

Pacific
61.5% and Southwest 58.8%. In contrast, the Eastern Central Pacific, Northeast Pacific (Area 67), Northwest Pacific (Area 61), Western Central Pacific and Southwest Pacific had the lowest proportion (13 to 17%) of fish stocks at biologically unsustainable levels.
Daniel Pauly Daniel Pauly is a French-born marine biologist Marine biology is the scientific study of the biology of marine life, organisms in the sea. Given that in biology Biology is the natural science that studies life and living organisms, i ...
, a
fisheries scientist Fishery is the enterprise of raising or harvesting fish and other aquatic life. Commercial fisheries include wild fisheries and Fish farming, fish farms, both in fresh water (about 10% of all catch) and the oceans (about 90%). About 500 million pe ...
known for pioneering work on the human impacts on global fisheries, has commented: According to the Secretary General of the 2002
World Summit on Sustainable Development The World Summit on Sustainable Development 2002, took place in South Africa, from 26 August to 4 September 2002. It was convened to discuss ustainable developmentorganizations, 10 years after the first Earth Summit in Rio de Janeiro. (It was the ...
, "Overfishing cannot continue, the depletion of fisheries poses a major threat to the food supply of millions of people." The fishing down the food web is something that occurs when overfishing arises. Once all larger fish are caught, the fisherman will start to fish the smaller individuals, which would lead to more fish needing to be caught to keep up with demand. This decreases fish populations, as well as genetic diversity of the species, making them more susceptible to disease, and less likely to adapt to their stressors and the environment. Additionally, catching smaller fish leads to breeding of smaller offspring, which can be problematic for fish. In many species, the smaller the female, the less
fecund Fecundity is defined in two ways; in demography, human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capabi ...
it is, impacting the fish population.


Examples and evidence for overfishing

Examples of overfishing exist in areas such as the
North Sea The North Sea is a sea The sea, connected as the world ocean or simply the ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.Grand Banks of Newfoundland The Grand Banks of Newfoundland are a series of underwater plateaus south-east of the island of Newfoundland (island), Newfoundland on the North American continental shelf. The Grand Banks are one of the world's richest fishing grounds, supporting ...
and the
East China Sea The East China Sea is an arm of the Western Pacific Ocean, located directly offshore from East China (hence the name), covering an area of roughly . Its northern extension between mainland China and the Korean Peninsula Korea is a regi ...

East China Sea
. In these locations, overfishing has not only proved disastrous to fish stocks, but also to the fishing communities relying on the harvest. Like other extractive industries such as forestry and hunting, fisheries are susceptible to economic interaction between ownership or stewardship and
sustainability Sustainability is the capacity to endure in a relatively ongoing way across various domains of life. In the 21st century, it refers generally to the capacity for Earth's biosphere and human civilization to co-exist. For many, sustainability is d ...

sustainability
, otherwise known as the
tragedy of the commons In economic science, the tragedy of the commons is a situation in which individual users, who have open access to a resource unhampered by shared social structures or formal rules that govern access and use, act independently according to their o ...
. * Tuna has been caught by the locals in the upper Adriatic for centuries. Increasing fishing prevented the large schools of
little tunny The little tunny (''Euthynnus alletteratus'') is the most common tuna A tuna (also called tunny) is a saltwater fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatom ...
from migrating into the
Gulf of Trieste The Gulf of Trieste ( it, Golfo di Trieste, sl, Tržaški zaliv, hr, Tršćanski zaljev, german: Golf von Triest) is a very shallow bay of the Adriatic Sea The Adriatic Sea () is a body of water separating the from the . The Adriatic is t ...

Gulf of Trieste
. The last major tuna catch was made in 1954 by the fishermen of Santa Croce, Contovello and
Barcola Barcola is a maritime neighbourhood of Trieste, Italy. It is a popular tourist place with beaches and long promenade walkways, near to the Habsburg-established Miramare, Miramare Castle. Barcola is highly valued for the high quality of life and li ...
. * The Peruvian coastal
anchovy An anchovy is a small, common forage fish 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 ocea ...
fisheries crashed in the 1970s after overfishing and an
El Niño es, El Niño, translation=The Boy (; ) is the warm phase of the El Niño–Southern Oscillation El Niño–Southern Oscillation (ENSO) is an irregular periodic variation in winds and sea surface temperatures over the Tropics, tropical easte ...
season largely depleted anchovies from its waters. Anchovies were a major natural resource in
Peru , , image_flag = Flag_of_Peru.svg , image_coat = Escudo_nacional_del_Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto ...

Peru
; indeed, 1971 alone yielded 10.2 million metric tons of anchovies. However, the following five years saw the Peruvian fleet's catch amount to only about four million tons. This was a major loss to Peru's economy. * The collapse of the
cod Cod is the common name Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common Boston Common (also known as the Common) is a central public park in downtown Boston, Massachusetts. It is sometim ...

cod
fishery off
Newfoundland Newfoundland and Labrador (, ) is the easternmost provinces and territories of Canada, province of Canada, in the country's Atlantic Canada, Atlantic region. It is composed of the island of Newfoundland (island), Newfoundland and the continental ...
, and the 1992 decision by
Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean, Atlantic to the Pacific Ocean, Pacific and northward into the Arctic Oce ...

Canada
to impose an indefinite moratorium on the
Grand Banks The Grand Banks of Newfoundland are a series of underwater plateau In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Eart ...

Grand Banks
, is a dramatic example of the consequences of overfishing. * The sole fisheries in the
Irish Sea The Irish Sea or , gv, Y Keayn Yernagh, sco, Erse Sie, gd, Muir Èireann , Ulster-ScotsUlster Scots, also known as Scotch-Irish, may refer to: * Ulster Scots people The Ulster Scots (Ulster-Scots The Ulster Scots (Ulster ...
, the west
English Channel The English Channel,, "The Sleeve"; nrf, la Maunche, "The Sleeve" (Cotentinais Cotentinais is the dialect The term dialect (from Latin , , from the Ancient Greek word , , "discourse", from , , "through" and , , "I speak") is used in two ...

English Channel
, and other locations have become overfished to the point of virtual collapse, according to the UK government's official Biodiversity Action Plan. The United Kingdom has created elements in this plan to attempt to restore the fishery, but the expanding global human population and the expanding demand for fish has reached a point where demand for food threatens the stability of these fisheries, if not the species' survival. * Many
deep sea fish Deep or The Deep may refer to: Places United States * Deep Creek (Appomattox River tributary), Virginia * Deep Creek (Great Salt Lake), Idaho and Utah * Deep Creek (Mahantango Creek tributary), Pennsylvania * Deep Creek (Mojave River tributary), Ca ...
are at risk, such as
orange roughy The orange roughy (''Hoplostethus atlanticus''), also known as the red roughy, slimehead and deep sea perch, is a relatively large deep-sea fish belonging to the slimehead family In human society, family (from la, familia) is a group of ...

orange roughy
and
sablefish The sablefish (''Anoplopoma fimbria'') is one of two members of the fish family Anoplopomatidae and the monotypic, only species in the genus ''Anoplopoma''. In English language, English, common names for it include sable (US), butterfish (US), b ...
. The deep sea is almost completely dark, near freezing, and has little food. Deep sea fish grow slowly because of limited food, have slow metabolisms, low reproductive rates, and many do not reach breeding maturity for 30 to 40 years. A fillet of orange roughy at the store is probably at least 50 years old. Most deep sea fish are in international waters, where there are no legal protections. Most of these fish are caught by deep trawlers near
seamount A seamount is a large geologic landform that rises from the ocean floor The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.
s, where they congregate for food.
Flash freezing In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its Motion (physics), motion and behavior through Spa ...
allows the trawlers to work for days at a time, and modern
fishfinder 250px, Cabin display of a commercial or oceanographic fathometer sonar A fishfinder or sounder (Australia) is an instrument used to locate fish underwater by detecting reflected pulses of sound energy, as in sonar. A modern fishfinder displays mea ...

fishfinder
s target the fish with ease. * became extinct in the
Great Lakes The Great Lakes also called the Great Lakes of North America or the Laurentian Great Lakes, is a series of large interconnected freshwater lake A lake is an area filled with water, localized in a basin, surrounded by land Land ...

Great Lakes
in the 1980s. Until the middle of the 20th century, the walleye was a commercially valuable fish, with about a half million tonnes being landed in the period from about 1880 to the late-1950s, when the populations collapsed, apparently through a combination of overfishing,
anthropogenic Anthropogenic ("human" + "generating") is an adjective that may refer to: * Anthropogeny, the study of the origins of humanity Counterintuitively, anthropogenic may also refer to things that have been generated by humans, as follows: * Human imp ...
eutrophication Eutrophication (from Greek ''eutrophos'', "well-nourished") is the process by which an entire body of water (Lysefjord) in Norway Norway, officially the Kingdom of Norway,Names in the official and recognised languages: Bokmål Bokmå ...

eutrophication
, and
competition Competition is a rivalry A rivalry is the state of two people or groups engaging in a lasting competitive relationship. Rivalry is the "against each other" spirit between two competing sides. The relationship itself may also be called "a riv ...
with introduced
rainbow smelt The rainbow smelt (''Osmerus mordax'') is a North American species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is oft ...

rainbow smelt
. * The
World Wide Fund for Nature The World Wide Fund for Nature (WWF) is an international non-governmental organization An international non-governmental organization (INGO) is an organization which is independent of government involvement and extends the concept of a non-go ...
and the
Zoological Society of London The Zoological Society of London (ZSL) is a charity devoted to the worldwide and their . It was founded in 1826. History On 29 November 1822, the birthday of , "the father of modern zoology", a meeting held in the in Soho Square led by R ...

Zoological Society of London
jointly issued their "Living Blue Planet Report" on 16 September 2015 which states that there was a dramatic fall of 74% in worldwide stocks of the important scombridae fish such as
mackerel Mackerel is a common name applied to a number of different species of pelagic fish, mostly from the family Scombridae. They are found in both temperate and tropical seas, mostly living along the coast or offshore in the oceanic environment. Ma ...

mackerel
,
tuna A tuna is a saltwater fish Fish are , , -bearing animals that lack with . Included in this definition are the living , s, and and as well as various extinct related groups. Around 99% of living fish species are ray-finned fish, be ...

tuna
and
bonito Bonitos are a tribe (biology), tribe of medium-sized, ray-finned predatory fish in the family Scombridae – a family it shares with the mackerel, tuna, and Spanish mackerel tribes, and also the butterfly kingfish. Also called the tribe Sardini, ...

bonito
s between 1970 and 2010, and the global overall "population sizes of mammals, birds, reptiles, amphibians and fish fell by half on average in just 40 years." * Overfishing of the critically endangered
Pacific bluefin tuna The Pacific bluefin tuna (''Thunnus orientalis'') is a predatory Predation is a biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships b ...

Pacific bluefin tuna
has resulted in the few still caught selling for astronomical prices. In January 2019, a 278 kilogram (612 pound) tuna sold for 333.6 million yen, or over US$3 million, US$4,900 per pound. Fishers, driven by the fish's high value, use extraordinary techniques to catch them, leaving the population on the verge of collapse. *
Shark Sharks are a group of elasmobranch fish characterized by a Chondrichthyes#Skeleton, cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified withi ...

Shark
s and rays: The global abundance of oceanic sharks and rays has declined by 71% since 1970, owing to an 18-fold increase in relative fishing pressure. As a consequence, three-quarters of the species comprising this group are now threatened with extinction. *A study in 2003 found that, as compared with 1950 levels, only a remnant (in some instances, as little as 10%) of all large ocean-fish stocks are left in the seas. These large ocean fish are the species at the top of the food chains (e.g.,
tuna A tuna is a saltwater fish Fish are , , -bearing animals that lack with . Included in this definition are the living , s, and and as well as various extinct related groups. Around 99% of living fish species are ray-finned fish, be ...

tuna
,
cod Cod is the common name Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common Boston Common (also known as the Common) is a central public park in downtown Boston, Massachusetts. It is sometim ...

cod
, among others). This article was subsequently criticized as being fundamentally flawed, although much debate still exists and the majority of fisheries scientists now consider the results irrelevant with respect to large
pelagic The pelagic zone consists of the water column A water column is a concept Concepts are defined as abstract ideas A mental representation (or cognitive representation), in philosophy of mind Philosophy of mind is a branch of philosophy ...
s (the open seas).


In management

Several countries are now effectively managing their fisheries. Examples include
Iceland Iceland ( is, Ísland; ) is a Nordic Nordic most commonly refers to: * Nordic countries, written in plural as Nordics, the northwestern European countries, including Scandinavia, Fennoscandia and the List of islands in the Atlantic Ocean#N ...

Iceland
and
New Zealand New Zealand ( mi, Aotearoa ''Aotearoa'' (; commonly pronounced by English English usually refers to: * English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon Engl ...

New Zealand
. The
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

United States
has turned many of its fisheries around from being in a highly depleted state.


Consequences

According to a 2008 UN report, the world's fishing fleets are losing US$50 billion each year due to depleted stocks and poor
fisheries management The goal of Fisheries management is to produce sustainable biological, social, and economic benefits from renewable aquatic resources. Fisheries are classified as renewable because the organisms of interest (e.g., fish, shellfish, reptiles, amphi ...
. The report, produced jointly by the
World Bank The World Bank is an international financial institution An international financial institution (IFI) is a financial institution that has been established (or chartered) by more than one country, and hence is subject to international law. Its o ...
and the UN
Food and Agriculture Organization The Food and Agriculture Organization of the United Nations (FAO)french: Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is a list of specialized ...
(FAO), asserts that half the world's
fishing fleet A fishing fleet is an aggregate of commercial fishing Ship, vessels. The term may be used of all vessels operating out of a particular port, all vessels engaged in a particular type of fishing (as in the "tuna fishing fleet"), or all fishing vessel ...
could be scrapped with no change in catch. In addition, the
biomass Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...
of global
fish stockFish stock or stock fish may also refer to: *Fish stocks Fish are aquatic, craniate, gill A gill () is a respiration organ, respiratory organ found in many aquatic ecosystem, aquatic organisms that extracts dissolved oxygen from water and ...
s have been allowed to run down to the point where it is no longer possible to catch the amount of fish that could be caught. Increased incidence of
schistosomiasis Schistosomiasis, also known as snail fever, bilharzia, and Katayama fever, is a helminthiasis, disease caused by parasitism, parasitic flatworms called schistosomes. The urinary tract or the intestines may be infected. Symptoms include abdomina ...
in Africa has been linked to declines of fish species that eat the snails carrying the disease-causing parasites. Massive growth of
jellyfish Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum In zoological nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted Con ...

jellyfish
populations threaten fish stocks, as they compete with fish for food, eat fish eggs, and poison or swarm fish, and can survive in oxygen depleted environments where fish cannot; they wreak massive havoc on commercial fisheries. Overfishing eliminates a major jellyfish competitor and predator, exacerbating the jellyfish population explosion. Both climate change and a restructuring of the ecosystem have been found to be major roles in an increase in jellyfish population in the Irish Sea in the 1990s. According to the 2019 ''
Global Assessment Report on Biodiversity and Ecosystem Services The ''Global Assessment Report on Biodiversity and Ecosystem Services'' is a report by the United Nations The United Nations (UN) is an intergovernmental organization that aims to maintain international peace and international security, se ...
'' published by the
Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) is an intergovernmental organization established to improve the interface between science and policy on issues of biodiversity Biodiversity is the biol ...
, overfishing is a primary driver of mass
extinction Extinction is the termination of a kind of organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by ...

extinction
in the world's oceans. A 2021 study published in the journal ''
Nature Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including planets, stars, galaxy, galaxies, and all other forms of matter an ...
'' asserted that the "primary cause" of ocean
defaunation Defaunation is the global, local or functional extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the endling, las ...
is overfishing. Other studies have shown that overfishing has reduced fish and marine mammal
biomass Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...
by 60% since the 1800s, and is currently driving over one-third of
sharks Sharks are a group of characterized by a , five to seven s on the sides of the , and s that are not fused to the head. Modern sharks are classified within the Selachimorpha (or Selachii) and are the to the . However, the term "shark" has a ...

sharks
and rays to extinction.


Types

There are three recognized types of biological overfishing: growth overfishing, recruit overfishing, and ecosystem overfishing.


Growth overfishing

Growth overfishing occurs when fish are harvested at an average size that is smaller than the size that would produce the maximum yield per recruit. A is an individual that makes it to maturity, or into the limits specified by a fishery, which are usually size or age. This makes the total yield less than it would be if the fish were allowed to grow to an appropriate size. It can be countered by reducing fishing mortality to lower levels and increasing the average size of harvested fish to a size that will allow maximum yield per recruit.


Recruitment overfishing

Recruitment overfishing happens when the mature adult population (spawning
biomass Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...
) is depleted to a level where it no longer has the reproductive capacity to replenish itselfthere are not enough adults to produce offspring. Increasing the spawning stock biomass to a target level is the approach taken by managers to restore an overfished population to sustainable levels. This is generally accomplished by placing moratoriums,
quotas Quota may refer to: Economics * Import quota An import quota is a type of trade restriction A trade restriction is an artificial restriction on the trade Trade involves the transfer of goods or services from one person or entity to an ...
, and minimum size limits on a fish population.


Ecosystem overfishing

Ecosystem overfishing occurs when the balance of the
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

ecosystem
is altered by overfishing. With declines in the abundance of large predatory species, the abundance of small increases causing a shift in the balance of the ecosystem towards smaller fish species.


Acceptable levels

The notion of overfishing hinges on what is meant by an "acceptable level" of fishing. More precise
biological Biology is the natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes knowl ...

biological
and bioeconomic terms define acceptable level as follows: * Biological overfishing occurs when fishing
mortality Mortality is the state of being mortal, or susceptible to death (1906) Death is the permanent, Irreversible process, irreversible cessation of all biological process, biological functions that sustain a living organism. Brain death is some ...
has reached a level where the stock
biomass Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...
has negative marginal growth (reduced rate of biomass growth), as indicated by the red area in the figure. (Fish are being taken out of the water so quickly that the replenishment of stock by breeding slows down. If the replenishment continues to diminish for long enough, replenishment will go into reverse and the population will decrease.) * Economic or bioeconomic overfishing additionally considers the cost of fishing when determining acceptable catches. Under this framework, a fishery is considered to be overfished when catches exceed
maximum economic yield In mathematical analysis, the maxima and minima (the respective plurals of maximum and minimum) of a function (mathematics), function, known collectively as extrema (the plural of extremum), are the largest and smallest value of the function, ei ...
where resource rent is at its maximum. Fish are being removed from the fishery so quickly that the profitability of the fishery is sub-optimal. A more dynamic definition of economic overfishing also considers the present value of the fishery using a relevant discount window, discount rate to maximise the flow of resource rent over all future catches.


Harvest control rule

A model proposed in 2010 for predicting acceptable levels of fishing is the Harvest Control Rule (HCR), which is a set of tools and protocols with which management has some direct control of harvest rates and strategies in relation to predicting stock status, and long-term maximum sustainable yields. Constant catch and constant fishing mortality are two types of simple harvest control rules.


Input and output orientations

Fishing capacity can also be defined using an input or output orientation. * An input-oriented fishing capacity is defined as the maximum available capital stock in a fishery that is fully utilized at the maximum technical efficiency in a given time period, given resource and market conditions. * An output-oriented fishing capacity is defined as the maximum catch a vessel (fleet) can produce if inputs are fully utilized given the biomass, the fixed inputs, the age structure of the fish stock, and the present stage of technology. Technical efficiency of each vessel of the fleet is assumed necessary to attain this maximum catch. The degree of capacity utilization results from the comparison of the actual level of output (input) and the capacity output (input) of a vessel or a fleet.


Mitigation

In order to meet the problems of overfishing, a precautionary approach and Harvest Control Rule (HCR) management principles have been introduced in the main fisheries around the world. The Traffic Light color convention introduces sets of rules based on predefined critical values, which can be adjusted as more information is gained. The United Nations Convention on the Law of the Sea treaty deals with aspects of overfishing in articles 61, 62, and 65. *Article 61 requires all coastal states to ensure that the maintenance of living resources in their exclusive economic zones is not endangered by over-exploitation. The same article addresses the maintenance or restoration of populations of species above levels at which their reproduction may become seriously threatened. *Article 62 provides that coastal states: "shall promote the objective of optimum utilization of the living resources in the exclusive economic zone without prejudice to Article 61" *Article 65 provides generally for the rights of, inter alia, coastal states to prohibit, limit, or regulate the exploitation of marine mammals. According to some observers, overfishing can be viewed as an example of the
tragedy of the commons In economic science, the tragedy of the commons is a situation in which individual users, who have open access to a resource unhampered by shared social structures or formal rules that govern access and use, act independently according to their o ...
; appropriate solutions would therefore promote property rights through, for instance, privatization and fish farming. Daniel K. Benjamin, in ''Fisheries are Classic Example of the 'Tragedy of the Commons, cites research by Grafton, Squires and Fox to support the idea that privatization can solve the overfishing problem: According to recent research on the British Columbia halibut fishery, where the commons has been at least partly privatized, substantial ecological and economic benefits have resulted. There is less damage to fish stocks, the fishing is safer, and fewer resources are needed to achieve a given harvest." Another possible solution, at least for some areas, is fishing quota, quotas, restricting fishers to a specific quantity of fish. A more radical possibility is declaring certain areas of the sea "Exclusion zone, no-go zones" and make fishing there strictly illegal, so the fish have time to recover and repopulate. In order to maximise resources some countries, e.g., Family planning in Bangladesh, Bangladesh and Thailand, have improved the availability of family planning services. The resulting smaller populations have a decreased environmental footprint and reduced food needs. Controlling consumer behavior and demand is critical in mitigating action. Worldwide, a number of initiatives emerged to provide consumers with information regarding the conservation status of the seafood available to them. The "Guide to Good Fish Guides" lists a number of these.


Government regulation

Many regulatory measures are available for controlling overfishing. These measures include fishing quotas, bag limits, licensing, closed seasons, size limits and the creation of marine reserves and other marine protected areas. A model of the interaction between fish and fishers showed that when an area is closed to fishers, but there are no catch regulations such as individual transferable quotas, fish catches are temporarily increased but overall fish
biomass Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...
is reduced, resulting in the opposite outcome from the one desired for fisheries. Thus, a displacement of the fleet from one locality to another will generally have little effect if the same quota is taken. As a result, Fisheries management, management measures such as temporary closures or establishing a marine protected area of fishing areas are ineffective when not combined with individual fishing quotas. An inherent problem with quotas is that fish populations vary from year to year. A study has found that fish populations rise dramatically after stormy years due to more nutrients reaching the surface and therefore greater primary production. To fish sustainably, quotas need to be changed each year to account for fish population. Individual fishing quota, Individual transferable quotas (ITQs) are fishery rationalization instruments defined under the Magnuson-Stevens Fishery Conservation and Management Act as limited access permits to harvest quantities of fish. Fisheries science, Fisheries scientists decide the optimal amount of fish (Total Allowable Catch, total allowable catch) to be harvested in a certain fishery. The decision considers carrying capacity, regeneration rates and future values. Under ITQs, members of a fishery are granted rights to a percentage of the total allowable catch that can be harvested each year. These quotas can be fished, bought, sold, or leased allowing for the least-cost vessels to be used. ITQs are used in
New Zealand New Zealand ( mi, Aotearoa ''Aotearoa'' (; commonly pronounced by English English usually refers to: * English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon Engl ...

New Zealand
, Australia,
Iceland Iceland ( is, Ísland; ) is a Nordic Nordic most commonly refers to: * Nordic countries, written in plural as Nordics, the northwestern European countries, including Scandinavia, Fennoscandia and the List of islands in the Atlantic Ocean#N ...

Iceland
,
Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean, Atlantic to the Pacific Ocean, Pacific and northward into the Arctic Oce ...

Canada
, and the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

United States
. In 2008, a large-scale study of fisheries that used ITQs compared to ones that didn't provided strong evidence that ITQs can help to prevent collapses and restore fisheries that appear to be in decline. China bans fishing in the South China Sea for a period each year. The United Nations has included sustainable fishing and ending subsidies that contribute to overfishing as key targets for 2030 as part of their Sustainable Development Goal 14, Sustainable Development Goal 14: Life Below Water.


Removal of subsidies

Because government provided financial subsidies can make it economically viable to fish beyond biologically sustainable levels, several scientists have called for an end to Fisheries subsidy, fishery subsidies paid to deep-sea fisheries. In international waters beyond the 200 nautical mile exclusive economic zones of coastal countries, many fisheries are unregulated, and
fishing fleet A fishing fleet is an aggregate of commercial fishing Ship, vessels. The term may be used of all vessels operating out of a particular port, all vessels engaged in a particular type of fishing (as in the "tuna fishing fleet"), or all fishing vessel ...
s plunder the depths with state-of-the-art technology. In a few hours, massive nets weighing up to 15 tons, dragged along the bottom by Bottom trawling, deep-water trawlers, can destroy deep-sea corals and sponge beds that have taken centuries or millennia to grow. The trawlers can target
orange roughy The orange roughy (''Hoplostethus atlanticus''), also known as the red roughy, slimehead and deep sea perch, is a relatively large deep-sea fish belonging to the slimehead family In human society, family (from la, familia) is a group of ...

orange roughy
, Rattail, grenadiers, or sharks. These fish are usually long-lived and late maturing, and their populations take decades, even centuries to recover. Fisheries scientist
Daniel Pauly Daniel Pauly is a French-born marine biologist Marine biology is the scientific study of the biology of marine life, organisms in the sea. Given that in biology Biology is the natural science that studies life and living organisms, i ...
and economist Ussif Rashid Sumaila have examined subsidies paid to bottom trawl fleets around the world. They found that US$152 million per year are paid to deep-sea fisheries. Without these subsidies, global deep-sea fisheries would operate at a loss of US$50 million a year. A great deal of the subsidies paid to deep-sea trawlers is to subsidize the large amount of fuel required to travel beyond the 200 mile limit and drag weighted nets.
"There is surely a better way for governments to spend money than by paying subsidies to a fleet that burns 1.1 billion litres of fuel annually to maintain paltry catches of old growth fish from highly vulnerable stocks, while destroying their habitat in the process" – ''Pauly''. "Eliminating global subsidies would render these fleets economically unviable and would relieve tremendous pressure on over-fishing and vulnerable deep-sea ecosystems" – ''Sumaila''.
Over 30 billion euros in public Subsidy, subsidies are directed to Fishery, fisheries annually.


Minimizing fishing impact

Fishing techniques may be altered to minimize bycatch and reduce impacts on marine habitats. These techniques include using varied gear types depending on target species and habitat type. For example, a net with larger holes will allow undersized fish to avoid capture. A turtle excluder device (TED) allows sea turtles and other megafauna to escape from shrimp trawls. Avoiding fishing in spawning grounds may allow fish stocks to rebuild by giving adults a chance to reproduce.


Aquaculture

Aquaculture involves the farming of fish in captivity. This approach effectively privatizes fish stocks and creates incentives for farmers to conserve their stocks. It also reduces environmental impact. However, farming carnivorous fish, such as salmon, does not always reduce pressure on wild fisheries, since carnivorous farmed fish are usually fed fishmeal and fish oil extracted from wild forage fish. The various species of Pacific salmon and Atlantic salmon are relatively easy to raise in captivity and such aquacultural operations have existed for more than 150 years. Largescale releases of salmon raised in captivity to supplement wild salmon runs will usually increase fishing pressure on the much less abundant wild salmon runs. Aquaculture played a minor role in the harvesting of marine organisms until the 1970s. Growth in aquaculture increased rapidly in the 1990s when the rate of wild capture plateaued. Aquaculture now provides approximately half of all harvested aquatic organisms. Aquaculture production rates continue to grow while wild harvest remains steady. Fish farming can enclose the entire breeding cycle of the fish, with fish being bred in captivity. Some fish prove difficult to breed in captivity and can be caught in the wild as juveniles and brought into captivity to increase their weight. With scientific progress, more species are being made to breed in captivity. This was the case with southern bluefin tuna, which were first bred in captivity in 2009.


Consumer awareness

As global citizens become more aware of overfishing and the ecological destruction of the oceans, movements have sprung up to encourage abstinence—not eating any seafood—or eating only "sustainable seafood". Sustainable seafood is a movement that has gained momentum as more people become aware of overfishing and Environmental impact of fishing, environmentally destructive fishing methods. Sustainable seafood is seafood from either fished or farmed sources that can maintain or increase production in the future without jeopardizing the
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

ecosystem
s from which it was acquired. In general, slow-growing fish that reproduce late in life, such as orange roughy, are vulnerable to overfishing. Seafood species that grow quickly and breed young, such as anchovies and sardines, are much more resistant to overfishing. Several organizations, including the Marine Stewardship Council (MSC), and Friend of the Sea, certify seafood fisheries as sustainable. The Marine Stewardship Council has developed an environmental standard for sustainable and well-managed fisheries. Environmentally responsible fisheries management and practices are rewarded with the use of its blue product ecolabel. Consumers concerned about overfishing and its consequences are increasingly able to choose seafood products that have been independently assessed against the MSC's environmental standard. This enables consumers to play a part in reversing the decline of fish stocks. As of February 2012, over 100 fisheries around the world have been independently assessed and certified as meeting the MSC standard. Thei
where-to-buy
page lists the currently available certified seafood. As of February 2012, over 13,000 MSC-labelled products are available in 74 countries around the world
Fish & Kids
is an MSC project to teach schoolchildren about marine environmental issues, including overfishing. The Monterey Bay Aquarium's Seafood Watch Program, although not an official certifying body like the MSC, also provides guidance on the sustainability of certain fish species. Some seafood restaurants have begun to offer more sustainable seafood options. The Seafood Choices Alliance is an organization whose members include chefs that serve sustainable seafood at their establishments. In the US, the Sustainable fishery, Sustainable Fisheries Act defines sustainable practices through national standards. Although there is no official certifying body like the MSC, the National Oceanic and Atmospheric Administration has create
FishWatch
to help guide concerned consumers to sustainable seafood choices. In September 2016, a partnership of Google and Oceana (non-profit group), Oceana and Skytruth introduced Global Fishing Watch, a website designed to assist citizens of the globe in monitoring fishing activities.


Barriers to effective management

The fishing industry has a strong financial incentive to oppose some measures aimed at improving the sustainability of fish stocks. Recreational fisherman also has an interest in maintaining access to fish stocks. This leads to extensive lobbying that can block or weaken government policies intended to prevent overfishing. Outside of countries' exclusive economic zones, fishing is difficult to control. Large oceangoing fishing boats are free to exploit fish stocks at will. In waters that are the subject of territorial disputes, countries may actively encourage overfishing. A notable example is the cod wars where Britain used its navy to protect its trawlers fishing in
Iceland Iceland ( is, Ísland; ) is a Nordic Nordic most commonly refers to: * Nordic countries, written in plural as Nordics, the northwestern European countries, including Scandinavia, Fennoscandia and the List of islands in the Atlantic Ocean#N ...

Iceland
's exclusive economic zone. Fish are highly transitory. Many species will freely move through different jurisdictions. The conservation efforts of one country can then be exploited by another. While governments can create regulations to control people's behaviors this can be undermined by Illegal, unreported and unregulated fishing, illegal fishing activity. Estimates of the size of the illegal catch range from 11 to 26 million tonnes, which represents 14-33% of the world's reported catch. Illegal fishing can take many forms. In some developing countries, large numbers of poor people are dependent on fishing. It can prove difficult to regulate this kind of overfishing, especially for weak governments. Even in regulated environments, illegal fishing may occur. While industrial fishing is often effectively controlled, smaller scale and recreational fishermen can often break regulations such as bag limits and seasonal closures. Fisherman can also easily fish illegally by doing things such as underreporting the amount of fish they caught or reporting that they caught one type of fish while actually catching another. There is also a large problem with the surveillance of illegal fishing activity. In 2001, the UN
Food and Agriculture Organization The Food and Agriculture Organization of the United Nations (FAO)french: Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is a list of specialized ...
(FAO), passed the International Plan of Action to Prevent, Deter and Eliminate Illegal, Unreported and Unregulated Fishing (IPOA-IUU). This is an agreement with the intention to stop port states from allowing boats to dock that participated in illegal, unreported or unregulated fishing. It also gives details for port states on effective measures of inspecting and reporting illegal fishing. Some illegal fishing takes place on an industrial scale with financed commercial operations. The fishing capacity problem is not only related to the conservation of
fish stockFish stock or stock fish may also refer to: *Fish stocks Fish are aquatic, craniate, gill A gill () is a respiration organ, respiratory organ found in many aquatic ecosystem, aquatic organisms that extracts dissolved oxygen from water and ...
s but also to the sustainability of fishing activity. Causes of the fishing problem can be found in the property rights regime of fishing resources. Overexploitation and rent dissipation of fishermen arise in open-access fishery, fisheries as was shown in Gordon. In open-access resources like fish stocks, in the absence of a system like individual transferable quotas, the impossibility of excluding others provokes the fishermen who want to increase catch to do so effectively by taking someone else' share, intensifying competition. This
tragedy of the commons In economic science, the tragedy of the commons is a situation in which individual users, who have open access to a resource unhampered by shared social structures or formal rules that govern access and use, act independently according to their o ...
provokes a capitalization process that leads them to increase their costs until they are equal to their revenue, dissipating their rent completely.


Resistance from fishermen

There is always disagreement between fishermen and government scientists... Imagine an overfished area of the sea in the shape of a hockey field with nets at either end. The few fish left therein would gather around the goals because fish Pelagic fish#Floating objects, like structured habitats. Scientists would survey the entire field, make lots of unsuccessful hauls, and conclude that it contains few fish. The fishermen would make a beeline to the goals, catch the fish around them, and say the scientists do not know what they are talking about. The subjective impression the fishermen get is always that there's lots of fish - because they only go to places that still have them... fisheries scientists survey and compare entire areas, not only the productive fishing spots. – ''Fisheries scientist
Daniel Pauly Daniel Pauly is a French-born marine biologist Marine biology is the scientific study of the biology of marine life, organisms in the sea. Given that in biology Biology is the natural science that studies life and living organisms, i ...
''


See also

* Biodiversity *
Bycatch Bycatch (or by-catch), in the fishing industry The fishing industry includes any industry or activity concerned with taking, culturing, processing, preserving, storing, transporting, marketing or selling fish or fish products. It is defined by t ...
* Catch and release * Environmental impact of fishing * Factory ship **
Pacific bluefin tuna The Pacific bluefin tuna (''Thunnus orientalis'') is a predatory Predation is a biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships b ...

Pacific bluefin tuna
**Shark finning * Holocene extinction * Human overpopulation * Jellyfish#Blooms, Jellyfish blooms * Life history theory * List of harvested aquatic animals by weight * Natural environment * Maximum sustainable yield * Oceanic carbon cycle * Perverse subsidies * Population dynamics of fisheries * Sustainable fishing * The United Nations Ocean Conference * Tragedy of the commons * World Oceans Day


References


Citations


Sources

* MN DNR. (2018). Improving fishing: Adjust regulations - Division of Fisheries - Minnesota DNR - MN Department of Natural Resources. Retrieved from https://www.dnr.state.mn.us/fisheries/management/regs.html


Bibliography

* * Allan, J David; Abell, Robin; Hogan, Zeb; Revenga, Carmen; Taylor, Brad W; Welcomme, Robin L; Winemiller, Kirk (2005
''Overfishing of inland waters.''
BioScience, 5 December. * Clover, Charles (2004) ''End of the Line: How overfishing is changing the world and what we eat''. Ebury Press, London. * * * * * * Ransom A. Myers, Myers, Ransom A. and Boris Worm (2003)
Rapid Worldwide Depletion of Predatory Fish Communities
" Nature'', 423, 280–283. * Ransom A. Myers, Myers, Ransom A. and Boris Worm (2005)
Decline of Pacific tuna populations exaggerated
" ''Nature'' 434:E1-E2. * * Roberts, Callum (2007
''The Unnatural History of the Sea''
Island Press. *


External links


The World Is Running Out of Fish Faster Than We Thought
(15 December 2016), ''Vice (magazine), Vice'' * *
Microdocs

Bye bye bluefin: Managed to death
The Economist. 30 October 2008. Retrieved 6 February 2009.
We’ve removed 90% of all large fish from the oceans. Just 10% to go.
Australian Broadcasting Corporation. 13 February 2021. {{Doomsday Environmental impact of fishing Environmental controversies Fisheries law Environmental crime Illegal occupations Illegal, unreported and unregulated fishing