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29 Cards in this Set
- Front
- Back
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Define aquaculture and salmonoid
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Aquaculture - farming of aquatic organisms e.g. fish and crustaceans Salmonoid - include salmon and trout Production of fish from aquaculture exceeded production of fish from fish catcher |
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Background to fish and crustacean
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Part of a well balanced diet Consumption is 20kg globally and rising World capture fisheries peaked yielding 75 million tonnes Aquaculture produced 90 million tonnes per year, grown at 8.2% per year. 4th source of meat |
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3 different types of fish
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Fresh water Sea water - pelagic swim near surface e.g. herring or demersal swim close to sea bed e.g. cod Shell fish and mollusc - cockles and muscles or crustacean e.g. prawn |
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World fishery production
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Less of capture fishery going to human consumption - used for fish meal and oil for feed Capture for human consumption will be less than aquaculture - overtaking in the future Asia biggest producer of farmed fish and crustacean e.g. China. Carnivorous fish e.g. salmon most sought after Europe - produce salmonids (global production around 3.5 million tonnes) |
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Production in Europe
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1243,000 tonnes Salmonoids, 211,000 tonnes carp and 21,000 tonnes of cod and haddock People prefer carnivorous fish species e.g. salmonids, sea bass and cod Norway - farming of flat fish and cod but production is low |
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Aquaculture in UK
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160,000 tonnes of salmon (Scotland) and 7000 tonnes of trout in UK 27,000 tonnes Shellfish farmed in South West and North Wales UK 20th for fish and shellfish produced globally |
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The life cycle of salmon
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Wild: Migratory - spawning, hatching, first feed in freshwater, then to sea water after 1 year. Anadromous - return to river as spawn Farming - eggs hatched to produce Fry and grown to 4-5cm. 1 year transferred to seawater, stimulate migration of fish to wild. Reared to 3-4kg for supermarkets and 5-6kg for restaurants. Vaccination, no antibiotics. |
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Sea fish pens in Scotland
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Sea lice - parasite affects appearance so may not be suitable for marketing 40-50 tonnes of fish for harvest for pens. Feed come in bulk, taken into account temperature and size of fish, it is very expensive. |
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Feeding carnivorous fish and crustacean
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Cold blooded so energy efficient - need to consume more food in higher temperatures. Optimum temp is 8-12 degrees. 40% of feed is fat (main source of energy), and 50% energy intake protein. Carbohydrate kept to minimum as not utilised well. 1 tonne of feed produces 1 tonne salmon. Fin-fish and shrimp - fishmeal and fish oil feed |
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Substitution of fishmeal in feed
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Outside EU poultry meal used as substitute for fish meal or fed trash fish in Asia. In Norway 20% fish products and 80% vegetable products used in fish feed. High feed conversion efficiency of 1:1 - around 1:8:1 in chicken Composition of body fat in fin fish reflects what they are fed. |
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Nutrients in typical Scottish salmon feed
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35% protein, 20-22mj/kg energy, 32-35% fat Contain protein (maize-gluten), oils and fats (soya, rapeseed, palm), carbohydrates, vitamins and minerals Fish oil expensive, palm fat used to coat pellets to keep nutrients in. 15% oil in feed mixture and rest sprayed on pellet Twice energy in fat compared to carbohydrates, nutrient dense. |
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The effiency of fish
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Very efficient - suspended in water so don't need to expend energy to stand up or keep warm. not as active in farming 27% energy from feed to food in salmon - 12% chicken and 16% pork 30% protein from feed to food in salmon - 18% in chicken and 13% pork |
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The substitution of fishmeal
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Fishmeal costs $2000 per tonnes (3-5 times cost of vegetable protein) Soya, wheat and maize glutens, legume concentrate and sunflower meal can substitute 75% of fish meal without reducing growth. Worsens feed conversion due to introduction of fibre which has to be broken down No poultry meal in UK due to BSE problems |
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The substitution of fish oil
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75% can be replaced with rapeseed oil (high omega 3) or soya/sunflower oil (less omega 3, mostly 6). Substitution in mid growth period, bring fish oil back in late stages to restore Omega 3 fatty acid content. Reduces cost and improves eco-efficiency |
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Consequences of substitution of feed
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Changing composition of fat in the feed - reduces long chain Omega 3 fatty acids and increases Omega 6 fatty acids. Undesirable nutritionally. Reduces feed costs |
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Comparing nutrition of farmed and wild salmon
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1 in 20 consumers can tell the difference - wild salmon is far more costly. Wild salmon - high long chain omega 3 fatty acid content, but only 4% fat. Farmed salmon has 14-18% fat and a lower omega 3 content so overall |
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5 issues of fish farming
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Sustainability Eco-efficiency Disease and fish escaping Pollution Contaminants |
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Sustainability
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Feed - amount of wildfish used for fishmeal and fish oil. Deforested land to produce soya Fish used for feed usually inedible - cannot make a good quality product. Caught in sustainable amounts. |
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Eco-efficiency
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Amount of wild fish needed to produce weight of farmed fish - for every 8% fish oil added to feed, one part wild fish required. Salmon needs 24% fish oil in feed (3:1 wild fish). Substitution with vegetable oil reduced dependence on wild fish to 10-12%. Cod only requires 80-10% fish oil 0.2kg wild fish to produce 1kg farm fish. 6mt global farmed fish uses 17mt feed grade fish (effiency 1:3:5) |
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Disease and fish escaping
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Vaccination - disease not a problem, antibiotics only needed in severe cases (e.g. infectious salmon anaemia in Chile). Escaping into wild - genetic pollution and disease. Wild and farm fish interbreed forming hybrids. Sea cages more robust to prevent fish escaping. |
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Pollution
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Feed wasted and excretion from fish which accumulates under cages Improve feeding techniques - detect uneaten feed and switch off feeders. Leave site for 6 months to restore fertility, remove waste and reduce disease risk |
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Contaminants
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Enter atmosphere from industry, wash onto fields and end up in rivers - enter food chain. Accumulate in larger fish (start from algae). Persistent organic toxins - concentrate in body fat and accumulate in bigger fish (banned now) Highest contaminants near river mouths. Safe level - multiplied by 10 to make sure no illness. 3.3-3pg/g for dioxins and 75ng non dioxins |
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Facts about global fisheries
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All stocks will have collapsed by 2048 if we fish like we have done in the past 3/4 of fisheries over fished 1/7th of world pop get most of protein from fish - provides 25% of all animal protein. |
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Fisheries and sustainability |
Most fisheries are unsustainable - can become sustainable using FAO action Reduced fishing pressure means industrial fisheries (not human consumption) rebuilding and stable. Huge pressure in Asia - not effective management. |
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El Nino
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Pacific warms surface water so fish migrate to coast or deeper seas to find colder waters. Could lead to starvation. High pressure on marine supplies Huge variations in weather - East Coast of USA gets large changes in weather La nina - after El Nino sea temperature may cool |
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How can sustainability be achieved
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Management controls Independent scientific assessment and monitoring Annual catch limits By-catch limits (unintended fish caught) Minimum mesh size Independent stock counts to determine whether or not fishing can go ahead - look at status of feed fish stocks |
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Organisations looking at marine sustainability
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Marine Stewardship council - effect of fishing on other biodiversity. Not flexible - cannot fish until previous stock levels reached Friend of the sea - independent assessment of stocks, will accept limited fishing if stock recovered. Cheaper and more flexible Global trust - does not consider biodiversity, less expensive and more flexible International fishmeal and fish oil association - responsibly sourced raw material from fisheries. |
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Concerns regarding farming carnivorous fish e.g. salmon
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Feed - feed wasteful use of scarce marine resources for production of fishmeal and oil. Unsustainable damage to stocks. Contaminants - fed leads to accumulation of contaminants in food chain. |
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How these issues are being resolved
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Reduction in use of marine ingredients to 20-30% from 50-60% (substitution to vegetable products). Feed grade fish well managed Forage/feed grade fish used for fishmeal are inedible and no edible product can be made from them. Contaminants - widely monitored, level falling. Build up of waste under cages - temporary and rapidly disperses. No environmental impact found in study. |
