aquaculture

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 In 2020, 70% of salmon produced worldwide is farmed.

The largest marine fisheries are in the countries:

1. Norway
2. Chile
3. Scotland
4. Canada
5. Faroe Islands

The largest marine fisheries are operated by these companies:

1. Cremaq 
2. Leroy Seafood
3. Mowi
4. SalMar (Senja Sjøfarm and Norskott Havbruk)
5. Bakkafrost (Faroe Islands)

 Salmon fisheries and jellyfish 

Jellyfish and salmon fisheries can have an impact on each other, although the nature of this impact can vary depending on the specific circumstances. Some of the ways in which jellyfish and salmon fisheries can interact include:

1. Competition for food: In some areas, jellyfish and salmon compete for the same food sources, such as small fish and plankton. This can lead to reduced food availability for salmon and potentially affect their growth and survival.
2. Changes in water temperature: Some species of jellyfish are more abundant in warmer waters, and rising ocean temperatures due to climate change can result in an increase in jellyfish populations. This can affect salmon migration patterns and make it more difficult for salmon to find suitable habitats.
3. Impacts on fishing gear: Jellyfish can become tangled in fishing gear, such as nets and lines, and cause damage to the gear or reduce its efficiency. This can increase the costs of fishing for salmon and make it more difficult to catch salmon in areas with high jellyfish populations.
4. Changes in ocean chemistry: Some species of jellyfish can release large amounts of carbon dioxide and other chemicals into the ocean, which can affect the ocean chemistry and potentially harm salmon and other marine species.

Overall, the impact of jellyfish on salmon fisheries can be significant, but it is difficult to predict and varies depending on the specific circumstances. Further research is needed to better understand the relationship between jellyfish and salmon fisheries and to develop effective management strategies to mitigate any negative impacts.

 How do jellyfish kill salmon in farms 

Jellyfish can have a negative impact on salmon in aquaculture farms by:

1. Competition for food: In crowded aquaculture conditions, jellyfish and salmon can compete for the same food sources, leading to reduced food availability for salmon and impacting their growth and survival.
2. Clogging of water intake systems: Jellyfish can clog the water intake systems of aquaculture farms, reducing water flow and potentially harming the health and growth of the salmon.
3. Physical damage to fish: Jellyfish can physically damage salmon in aquaculture farms by entangling them in their tentacles or rubbing against their skin, causing injury or irritation.
4. Increase in disease: Jellyfish can also introduce new diseases or parasites into the aquaculture environment, potentially spreading to the salmon and causing harm.

It is important to note that these impacts can vary depending on the specific circumstances of each aquaculture farm and the species of jellyfish and salmon involved. Effective management strategies, such as proper water filtration systems and regular monitoring for jellyfish and disease outbreaks, can help reduce the negative impact of jellyfish on salmon in aquaculture farms.

What are the largest countries salmon was killed by jellyfish blooms

It is difficult to determine the largest countries where salmon have been killed by jellyfish blooms, as these events can be unpredictable and may not be well documented. However, some areas with significant salmon farming industries, such as Scotland, Norway, Canada, and Chile, have reported incidents of jellyfish blooms affecting their salmon farms. In these cases, the jellyfish blooms can cause physical damage to the salmon, clog water intake systems, and compete with salmon for food, leading to reduced growth and survival rates. Effective management strategies, such as proper water filtration systems and regular monitoring for jellyfish and disease outbreaks, can help reduce the impact of jellyfish blooms on salmon in these areas. 

> 70% - Salmon (Salmo salar) was the farmed species most affected by jellyfish abundances, followed by:

• Gilthead seabream (Sparus aurata),
• European seabass (Dicentrarchus labrax)
• Bivalves (Mytilus sp.) 

The most common negative impacts of jellyfish on fish farming concerned:

74% - Fish mortality

44% - Macroscopic damage on gill epithelia

24% - Skin ulcerations

The last scientific reports included different events in northern Europe and the Mediterranean Sea: Irish and Scottish aquaculture repeatedly suffered huge economic losses (up to US$1.3 million) due to mass salmon mortalities caused by recurring P. noctiluca invasions.

In 2009 fish mortalities in Tunisian farming facilities entailed dramatic economic losses, leading to near bankruptcy.

Since 2011, seabass marine farms from Spain recorded mortality events due to different jellyfish species leading to relevant economic losses.

Jellyfish and fishery sector interactions

The majority (82%) of reports of jellyfish direct impacts on fishing activities refers to (at least) 8 taxa, namely the scyphozoan representatives of:

Aurelia spp.

Chrysaoraspp.

Cyanea sp.

Pelagia noctiluca

Nemopilema nomurai

Rhopilema nomadica

Rhizostoma pulmo 

and the hydrozoan jellyfish Aequorea sp.

Species of the worldwide common jellyfish taxa Aurelia and Chrysaora, as well as the mauve stinger P. noctiluca, may form very large population outbreaks with millions of individuals that may spoil fishing nets with stinging mucus, broken pieces of umbrellas, oral arms and tentacles that enter in contact and damage the fish catch.

https://doi.org/10.1080/23308249.2020.1806201