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Aquatic Food Production

Aquatic Food Production

"I started a new business farming microscopic fish...

I call it a small-scale operation."


We even have a name for some microscopic fish... zooplankton! We can farm (culture) them, although not for large or commercial-scale purposes yet.

Global demands for food from aquatic environments are expected to increase in future decades because these foods will help to meet the needs and preferences of a growing human population. Many sources suggest global population growth of 2.4 billion, giving us a population of over 9.7 billion, by 2050. Food demand is set to rise even faster than population growth.

With the different types of aquatic food production that exist nowadays, from large-scale commercial operations to small-scale subsistence farms, it is vital that we give ourselves the time to learn more about their characteristics and what can make them more sustainable.

Aquatic Food Production (Definition)

Ordering seafood at a restaurant has never been easier - just navigate to the "seafood" menu and find lobsters, mussels... but wait, aren't these from the sea only? what if you wanted freshwater mussels?

Aquatic foods include anything that originated from a body of water and can be consumed.

Aquatic food production is the process of raising aquatic organisms for food. Aquaculture operations typically involve the raising and harvesting of fish, algae, aquatic plants, crustaceans, etc. in controlled environments such as ponds, tanks, or cages. These activities are carried out in salty, brackish and fresh water, meaning that they can be sourced from in-land wetlands, coastal areas like estuaries, or seas, oceans, etc.

Different organisms thrive in different environmental conditions. Farmed Atlantic cod prefer cold waters, whereas tilapia thrives in warm waters.

Have you ever had a green smoothie from a health shop? Some of them get their intense green colour from the spirulina. This cynobacteria, along with microalgae, such as chlorella, can be harvested from cultivation ponds in countries that benefit from high solar input, such as Spain or California.

Fishing communities, as well as massive industries, depend on this form of farming, and the activities of both can be sustainable and unsustainable, depending on a few factors which we will... dive into below!

Aquatic Food Production System

The aquatic food production system comprises different sectors. These are:

  • The commercial (industrial) sector, which intends to sell aquatic food resources, also called the seafood industry, for example, Atlantic Salmon farms in Scottish Lochs (lakes).

  • The traditional sector, which is comprised of societies and communities that practice subsistence aquaculture. They have practice aquaculture for a minimum determined amount of time or in specific ways that are deemed cultural heritage (e.g. Danube Delta communities within the Biosphere Reserve).

  • The recreational sector, where some fish farms are tourist attractions, offers services such as fish feeding and fishing, e.g. Kilnsey Park in Yorkshire Dales.

Moreover, the aquatic food production system is usually separated into freshwater and saltwater systems.

Saltwater food production systems are also called food mariculture, a word coming from the Latin mare, maris (“sea”) + culture. Mariculture occurs in open spaces that are enclosed, as opposed to tanks.

Freshwater includes mostly fish, crustaceans, molluscs and algae, and the primary environments are freshwater ponds, lakes, reservoirs and tanks.

The demand for aquatic food products increases with population growth. Seafood quality, however, remains highly dependent on two factors:

  • food
  • environmental quality

Both allow it to naturally reach desirable characteristics such as size, nutritional content and fat.

In 2018, fish harvested from aquaculture around the globe amounted to 114.5 million metric tons, with an estimated first-sale value of US$160.2 billion.1

Japan has specific aquaculture and storage laws in place to allow consumers to buy raw fish (sashimi) to be consumed as is, without heating or further processing. The lack of processing or burning fuels in preparing sashimi dishes makes the industry seem more sustainable from this point of view.

The highest aquaculture productivity rates correlate with the highest stress on biodiversity. This is because marine aquaculture is carried out in the upwelling and nutrient enrichment zones.

This coastal productivity is also related to the living preferences of humans and is one reason why the majority of the human population can be found living near the coast.

In 2003, it was reported that approximately 3 billion people — about half of the world's population — live within 200 kilometres of a coastline. By 2025, that figure is likely to double.2

Strategies to Improve Aquatic Food production

Some strategies are more impactful in improving aquatic food production and others are less impactful.

  • beneficial strategies: improving the population health of certain ocean microorganisms
  • harmful strategies: may harm the biota long-term, such as the removal of predators so that we can be the sole apex predator harvesting the food.

Improving primary producer population health

One of the most useful strategies to improve aquaculture is to promote the population health of phytoplankton (which uses photosynthesis) and of other natural food chains or processes (e.g. zooplankton). Phytoplankton supports most aquatic food chains and produces most of the Omega-3 fatty acids (healthy molecules) present there.

The dry food fish receive can range from vegetal pellets to dog food! Food is a vital part of aquacultural success, as it influences the taste, quality and nutritional benefits of fish that are consumed by both humans and other animals, or which end up as fertilizer.

Fish in the wild, known for their Omega-3s content, such as Atlantic salmon, present much fewer quantities of O-3s in captivity due to what they are fed. Salmon can't naturally synthesize O-3 and must obtain it from other sources.

Krill is a (sometimes microscopic) crustacean that feeds on phytoplankton with Omega-3 and represents the main food source of whales such as Blue Whales, polar seals, Adélie penguins, fish such as sardines and salmons, cephalopods such as squids, etc. Unfortunately, krill cannot be farmed at present, but only harvested from the wild. Nonetheless, it is possible for krill farming to be one of the sustainable farming methods of the future.

Using mechanical means

Mechanical food production techniques include cleaning the organisms by hand, or introducing cleaning species in penned fisheries. Specifically, cleaning species feed on external parasites which are extremely prevalent in fisheries.

Lumpfish Cyclopterus lumpus introduced among penned salmons ameliorates or decreases the chances of fish lice infestations. Infestations are detrimental to the fish's life quality and lifespan.

Using photochemical means

Photochemical food production enhancement techniques include:

  • the use of antibiotics to treat external and internal parasites, which can adversely affect human and animal health

  • the control of light and temperature levels to ensure maximum yield and comfort.

All fish species can be controlled to become either male or female, through artificial hormone injections and water treatments. Many aquaculture farms employ this technique to ensure maximum yield.

Consumer behaviour

Consumer behaviour can improve aquatic food production by mitigating harmful practices such as bottom trawling, and promoting sustainable aquaculture practices (e.g. farming and consuming seaweeds).

Bottom trawlers are heavy nets dragged across the seafloor which tend to destroy the habitats and shelters there present.

In the UK, ecologically sustainable farmed food options are Arctic chars and saltwater crabs, as opposed to wild Atlantic halibut for instance which is endangered.

Laws and Guidelines

Lastly, laws and regulations play an important role in managing aquatic food production. These are known as Food Industry Water Guidelines3, and they can differ from one country to another.

The Sustainability of Aquatic Food Production

Fish farming is considered more sustainable than hunting wild stocks!

Fish farming is considered more sustainable than hunting wild stocks!

The food conversion ratio (FCR) has the potential to show aquaculture gains and losses. It doesn't measure nutrient density but calculates the rate at which animal food gets converted into meat, milk, etc. It simply uses mass for mass values (usually calculated in kilograms).

Aquaculture salmon, carp and catfish have some of the best FCR ratios of farmed animals, at around 1.0. From this specific point of view, it is more sustainable than commercial breeds of beef (e.g. Angus), which hits a value of 7.0, sheep or poultry (such as broilers).

One of the most common problematic interactions with captive salmon is that migrating fish such as wild salmon come in contact with the captive ones, who tend to be infested with lice - thus also catching these external parasites. Captive fish infestations occur due to fish density inside pens and lack of abrasive surfaces or lack of interaction options with other marine organisms.

Bottom trawlers and other fishing techniques that destroy habitats are seen as unsustainable ways to obtain food for aquaculture fish.

Fish and seafood waste processing facilities in coastal communities are excellent options to avoid waste and turn it into fertilizer, pet food, fish lure, fuel, etc. However, the placement of aquaculture farms can be problematic, especially if it's an upwelling zone and/or blocks wildlife migration.

There are human ethical and legal issues around the "biorights" of indigenous communities and conservation laws preventing them from continuing traditions and/or fishing subsistence living.

Aquaculture Pros and Cons

Aquaculture farms can both contribute to pollution and be under threat from pollution, from sources such as:

  • Oil spills

  • Sludge overflows

  • Pharmaceutical or hormonal chemicals.

The water table can be impacted by water used for aquaculture. Specifically, freshwater overuse may lead to drought and will lower the water table of a region. Both sea and freshwater can further be polluted with waste, nutrients, and medicine administered to fish. Antifouling agents, such as preservatives and dyes that prevent food from decaying, can also leak into the water.

Aquaculture can prevent diseases. Ciguatera food poisoning occurs especially in the sub-tropical and tropical waters of the world, and is caught by people fish that consume certain algae.

Bivalve mollusks feed by filtering large amounts of seawater, which can collect harmful pathogens that cause gastrointestinal problems in sensitive people.

Certain aquatic species can carry neurotoxic compounds originating from industrial processes, like PCBs (polychlorinated biphenyls), which are believed to affect brain development in children.

Recent advancements in farming techniques have led to us being able to cater to the nutritional needs of fish, mass-produce equipment and pellets and transport aquafoods from farms to consumers while keeping them refrigerated. This has meant that access to fresh produce became more widespread.

There are numerous health benefits associated with fish consumption, both wild and from aquaculture. Generally, they are a good source of Zinc, Iron, Magnesium, Copper, B vitamins, and others. In aquaculture however, the total nutritional content of fish depends on what they are fed with4.

Habitat occupation and destruction remain a risk, especially with the aquacultural practices and applications of shrimp farming in South-East Asian and South-American mangrove forests.

Mangroves are tropical tree species forming ecosystems, especially through their intricate system of roots. They are incredibly valuable as carbon sinks and host high levels of biodiversity.

Non-native escaped species can cause ecological problems. For example, the Eurasian and Asian carp are included in the world's topmost invasive species due to their resilience, being able to live in highly degraded and oxygen-deprived aquatic environments. As a result, they are considered invasive in countries like the United States and Australia. Although they are used as food, they reproduce faster than they are being caught, by wild predators and humans alike. Some invasive species can also interbreed with their wild "relatives", thus altering the gene pool.

The problem of escaped individuals becomes more acute when genetically modified organisms escape and breed in the wild, with unknown ripple effects throughout the ecosystem.

If a fish that is genetically modified to grow fast escapes into the wild, it may outcompete native fish during food abundance seasons in body size and aggressiveness, which may lead to increased mating rates among genetically modified individuals. However, when food stocks eventually get low, genetically modified fish and their offspring that are unable to essentially pause their growth start to exhibit strong cannibalistic tendencies to survive. This can lead to a population collapse.

Examples of Aquatic Food Production Systems

Food production systems can focus on one single species (monoculture) or on multiple species being bred in the same place or ponds (polyculture). They can also be employed for vegetables, where the soil is replaced with water enriched with essential nutrients (aquaponics).

Trout fisheries

Trout is a popular fish, which has both edible meat and roes (female fish eggs). Clear Springs in Idaho has the largest rainbow trout fishery in the world, with a constant number of around 10 million fish.

Sturgeon fish farming

The Sturgeon fish roes, known as caviar, are highly appreciated for their taste and nutritional content, but habitat destruction due to water body diversions and hydropower dams have plummeted their numbers in the wild. The only (relatively more) sustainable method of harvesting sturgeon fish, such as beluga, is farming, although the roe extraction methods are sometimes questioned.

Oyster farming

Molluscs that filter water for phytoplankton are eaten both cooked and raw, and produced by extensive farms.

Algaculture

A branch of aquaculture that focuses on growing seaweed or microalgae. Certain cultures are more interested in harvesting and consuming seaweed than others, for example, Japan and South Korea.

Aquatic vs Terrestrial Food Production Systems

Agricultural production systems can be broadly classified as aquatic or terrestrial, with distinct pros and cons. Aquatic production systems are defined as those that use water bodies to grow crops, which we described in this lesson. In contrast, terrestrial production systems are based on land (wheat, fruit trees, berries, mushrooms, guinea fowl, etc.).

Factors that must be considered when choosing between an aquatic or terrestrial system for food production include climate, land and water availability, and the species being grown.

  • Climate: Aquatic production systems are more efficient in tropical and subtropical climates, with a plentiful supply of warm water. On the other hand, terrestrial production systems are better suited to temperate and arid climates.

  • Availability of land and water: aquatic production requires less land than terrestrial production, but it also demands a reliable source of water which disperses pollutants more easily.

  • Types of crops being grown. Some crops, such as rice, are better suited to semiaquatic production systems, while others, such as wheat, do better in terrestrial systems.

Aquatic Food Production - Key takeaways

  • The sustainable management of aquatic food production is paramount to avoiding over exploitation of necessary biotic and abiotic factors.
  • Enhancement techniques are used to boost aquaculture production, and they include hormonal treatments, cleaner fish, light and temperature control, etc.
  • Aquaculture can still negatively impact marine stocks by transmitting diseases or parasites, colonizing non-native environments, blocking migration paths, or being fed threatened organisms used as food pellets.
  • Aquaculture positively impacts fishing stocks by giving them respite from industrial hunting.
  • Aquatic food production can be done in saltwater, brackish water or freshwater, and it can benefit commercial, tourism and cultural sectors.

References

  1. Global Aquaculture, NOAA, 2021, https://www.fisheries.noaa.gov/national/aquaculture/global-aquaculture. Accessed 10.09.22
  2. Ripple Effects: Population and Coastal Regions, PRB, 2003, https://www.prb.org/resources/ripple-effects-population-and-coastal-regions/. Accessed 10.09.22
  3. Food Industry Water Guidelines, die pat, 2022, https://www.die-pat.co.uk/food-industry-water-guidelines-risks-use-regulations. Accessed 10.09.22
  4. Can we eat fish sustainably and maintain health benefits?, medical news today, 2021, https://www.medicalnewstoday.com/articles/can-we-eat-fish-sustainably-and-maintain-health-benefits. Accessed 10.09.22

Frequently Asked Questions about Aquatic Food Production

Aquatic food production is the process of raising aquatic organisms for food.

We can increase aquatic food production through genetic manipulation, abiotic elements control (light, temperature), promoting general phytoplankton and zooplankton health, consumer behaviour, or having appropriate laws and industry guidelines.

Aquatic food systems are the complex trophic processes, either domesticated or wild, that influence the social, economical, and environmental spheres of where they are found.

The more efficient production systems at the moment according to a simple FCR are aquatic food production systems.

An example of aquatic food production would be abalone farming. 

Final Aquatic Food Production Quiz

Question

What is ocean productivity?

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Answer

Ocean productivity is the primary production of single-celled phytoplankton suspended in the ocean.

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What is net productivity?

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Answer

Net productivity is the amount of organic material available to support the heterotrophs of the ocean.

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What is the Redfield Ratio (C:N:P)?

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120:16:1

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What element is used by diatoms to make their unique glass wall?

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Answer

Silicon

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What is a thermocline?

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A thermocline is a vertical temperature gradient driving density stratification across the ocean.

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What is the photic zone?

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Answer

The upper part of the ocean that is penetrated by enough light to enable photosynthesis.

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Which part of the ocean has the lowest productivity?

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Answer

Open ocean

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What are upwellings?

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Upwellings are areas where cold, nutrient-rich deep water flows upwards towards the surface

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What are phytoplankton?

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Phytoplankton are single-celled organisms that live in aquatic environments. They are autotrophs, meaning that they produce their own food via photosynthesis.

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Nekton refers to floating animals. True or false?

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Answer

False

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How can you calculate the primary productivity of the oceans?

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Primary productivity is calculated by measuring the uptake of CO2, or the output of oxygen.

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What seasons experience peaks in phytoplankton abundance?

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Spring, and a secondary peak in autumn

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Coastal zones are highly productive systems. What are the reasons for this?

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Sunlight penetrates to the bottom, allowing benthic organisms to photosynthesise. Sinking organic matter supports benthic communities before being recycled back into primary nutrients.

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What are heterotrophs?

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Heterotrophs are organisms that live on compounds produced by other organisms.

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What happens to the majority of organic matter produced by phytoplankton?

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It is respired back into dissolved organic forms in the surface ocean.

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Seafood contains many nutrients and minerals, including:

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Protein

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Define commercial fishing.

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Commerical fishing is the activity of catching fish and other seafood for commercial profit.

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Which of the following is a selective fishing method?

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Pelagic trawling

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Which fishing method is considered the most destructive?

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Demersal trawling is considered the most destructive fishing method.

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Define overfishing.

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Overfishing is the rapid depletion of a fish species by excessive commercial fishing.

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How many of the world's fish stocks are being overfished?

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34%

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Removing larger fish may lead to population decline. Why?

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Larger fish are mature and able to breed. Targeting larger fish may limit reproduction, causing population decline.

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Define bycatch.

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Bycatch is unwanted marine species that are unintentionally caught during commercial fishing.

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What is ghost fishing?

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Ghost fishing refers to discarded, abandoned, or lost fishing gear in the marine environment.

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What is recruitment?

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Recruitment is the process of small young fish transitioning into larger, mature fish.

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What is the maximum sustainable yield?

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The maximum sustainable yield for a fish stock is the highest possible annual catch that can be sustained over time.

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How does trawling work?

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Large cone-shaped nets are towed by boats. Fish are trapped in the closed 'cod-end' of the net.

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What are acoustic deterrent devices used for?

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Acoustic deterrent devices are used to scare away marine mammals from commercial fishing boats.

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How can ghost fishing be reduced?

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Using biodegradable equipment

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Define carrying capacity.

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The carrying capacity of a species is the maximum population size that can be sustained by their environment.

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Which ones are NOT a product of aquaculture?

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Answer

Roes

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Which trio from the below is produced by aquaculture?

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Spirulina, chlorella, kelp

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Is wheat better suited for land or aquatic production systems?

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Land production

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What are the three main sectors driving aquaculture?

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Commercial (industrial), cultural (& subsistence) and recreational.

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Name an aquatic food production farm, what it produces, and its location. 

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e.g. Kilnsey, rainbow trout, Yorkshire Dales.

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Is the quality of aquacultured fish related to their feed?

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Yes

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What type of aquaculture is practiced in Lochs?

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Freshwater. Atlantic salmon are grown there, especially.

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What are roes and are they important to aquaculture?

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The roes are the female eggs of fish which can be consumed as food. They are important because they can sell well and provide nutritional benefits.

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What is algaculture?

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Algaculture is a branch of aquaculture that grows algae.

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How are genetically modified organisms a good element of aquaculture?

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They can grow quicker, reproduce faster and thus consume less resources. 

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How are genetically modified organisms a possible danger to the environment?

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By escaping into the wild, they can outcompete their wild counterparts based on visual selection factors, but then collapse as a population due to a lack of resilience to certain environmental stressors. 

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Give at least one example of an invasive species escaped from aquaculture or introduced intentionally.

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Answer

Eurasian and Asian carps.

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Question

How are mangrove environments and shrimp farms linked?

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Answer

Mangroves may be cut down to make space for shrimp farms.

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What types of chemicals can leak from aquaculture farms into the environment?

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Antibiotics, antifouling agents, nutrients.

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Question

What is the FCR of farmed salmon?

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1.0

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Humans have been fishing for at least ___________.

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40,000 years

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Evidence suggests that the earliest forms of fish farming activity took place around __________, in ________.

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3,000 years ago; China

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The earliest description of a farmed fish species were those of the Cyprinidae family, commonly known as _____.

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Carp

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Define aquaculture.

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Aquaculture involves the farming of aquatic organisms (animals and plants) in a captive, controlled environment.

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Question

Aquaculture can be divided into two kinds, which are?

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Inshore

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