- •Р.А. Юсупова
- •От автора
- •Unit 1 aquaculture Active vocabulary
- •1 Aquaculture
- •1.1 Read the following international words and translate them. (Mind the part of speech).
- •1.2 Give Russian equivalents of the following words and word combinations.
- •1.3 Read and translate the text with the help of a dictionary.
- •1.4 Answer the questions
- •1.6 Translate the given Russian words into the English ones:
- •1.7 Match the words with their definitions.
- •1.8 Read the text without a dictionary. Aquaculture’s beginnings
- •2 Ancient and modern aquaculture
- •2.1 Read the following international words and translate them. (Mind the part of speech).
- •2.2 Give Russian equivalents of the following words and word combinations.
- •2.3 Read and translate the text with the help of a dictionary.
- •2.4 Give English equivalents:
- •Vocabulary
- •4.5 Give English equivalents:
- •4.6 Translate the given Russian words into the English ones:
- •4.7 Match the words with their definitions.
- •4.8 Topics for discussion
- •Feeding the world through agriculture
- •5 Control over reared species
- •5.1 Read the following international words and translate them. (Mind the part of speech).
- •5.2 Give Russian equivalents of the following words and word combinations.
- •5.3 Read and translate the text with the help of a dictionary.
- •5.4 Give English equivalents:
- •5.9 Answer the questions
- •Unit 2 fish culture Active vocabulary
- •6 The big two in fish culture
- •Choose the equivalents:
- •Aquaculture species in the united states
- •1 Rainbow, brown
- •7.4 Give English equivalents:
- •4Bullhead
- •7.13 Render the following verbs with ing-forms into infinitives and translate them:
- •8 Culture systems
- •8.1 Read the following international words and translate them.
- •8.2 Give Russian equivalents of the following words and word combinations.
- •8.3 Read and translate the text with the help of a dictionary.
- •8.4 Give English equivalents:
- •8.5 Match the words with their definitions.
- •8.6 Fill in the gaps using the words given below:
- •8.7 Answer the questions
- •8.8 Read the text without a dictionary. Types of aquaculture opeations
- •Vocabulary
- •8.9 Match the words with their definitions.
- •8.10 Answer the questions
- •Vocabulary
- •Vocabulary
- •10.5 Translate the given Russian words into the English ones:
- •Vocabulary
- •Vocabulary
- •Vocabulary
- •Vocabulary
- •12.5 Answer the questions
- •13 Potential adverse effects
- •13.1 Read and translate the text with the help of a dictionary.
- •Vocabulary
- •13.2 Answer the questions
- •14 Carp Aquaculture
- •Carp as ornamental fish
- •15 Tilapia Fish farming
- •Nutrition
- •Exotic species
- •Uses other than supplying food
- •In aquaria
- •16 Trout Anatomy
- •Habitat
- •As food
- •River fishing
- •17 Salmon Life cycle
- •Species
- •Atlantic Ocean species
- •Pacific Ocean species
- •Salmon fisheries
- •Salmon aquaculture
- •18 Shrimp Farming
- •Marketing
- •Life cycle
- •19 Grass carp
- •Ecology
- •Invasive species
- •Use as weed control
- •Fishing for grass carp
- •Triploid Grass Carp
- •20 Channel catfish
- •21 Pond
- •Technical definitions
- •Formation
- •Characteristics
- •22 Cage
- •Site Criteria
- •Pond Problems
- •Water Quality
- •Temperature
- •Turbidity
- •23 Raceway
- •Site selection
- •Water flow
- •Maximum load
- •Waste water
- •Appendix
- •Proverbs
- •Библиографический список
23 Raceway
A raceway, also known as a flow-through system, is an artificial channel used in aquaculture to culture aquatic organisms. Raceway systems are among the earliest methods used for inland aquaculture. A raceway usually consists of rectangular basins or canals constructed of concrete and equipped with an inlet and outlet. A continuous water flow-through is maintained to provide the required level of water quality, which allows animals to be cultured at higher densities within the raceway.
Freshwater species such as trout, catfish and tilapia are commonly cultured in raceways. Raceways are also used for some marine species which need a constant water flow, such as juvenile salmon brackish water seabass and seabream and marine invertebrates such as abalone.
Site selection
The most important factor to consider when selecting a site for a raceway farm is the water supply. Water sources for raceway aquaculture operations are usually streams, springs, reservoirs or deep wells. Trout do best in spring water because it keeps a constant temperature, while catfish need a strong flow, about 80 litres per second for every 0.4 hectares of raceway. A backup water supply should be positioned so, if the water supply or pump fails, it can flow by gravity into the start of the raceway.
Construction
Most raceways are made of reinforced concrete, though some earthen raceways are also built. Earthen raceways with plastic liners cost little and are easy to build, but cleaning and disinfecting them is difficult and plastic linings are fragile. Reinforced concrete is more expensive, but is durable and can be shaped in complex ways. Raceway tanks can also be built from polyester resin. These tanks have smooth walls, and are mobile and easy to service. However, their cost limits them to small sizes, under 5 cubic metres.
Size
A raceway is most often a rectangular canal with a water current flowing from a supply end to an exit end. The length to width ratio is important in raceways. To prevent the fish stock from swimming in circular movements, which would cause debris to build up in the centre, a length to width ratio of at least six to one is recommended. If the width is too large this could result in a feeble current speed which is not desirable (see below). The length of a raceway unit is usually constrained by the water quality or by how much stock a unit can hold for ease of management. The average depth of a raceway for fin fish, such as rainbow trout, is about one metre. This means each section in a raceway should be about 30 m long and 2.5–3 m wide. The landscape should sloped to one or two percent, so the flow through the system can be maintained by gravity. The raceway should not be curved, so the flow will be uniform.
A raceway farm for freshwater fin fish usually has a dozen or more parallel raceway strips build alongside each other, with each strip consisting of 15 to 20 or more serial sections. The risk of unhygienic conditions increases towards the lower level sections, and can be kept in check by ensuring there are not too many sections and the water flow is adequate. In order to isolate any diseased section and avoid transmitting the disease back to the upper raceways, each section should have its own drainage channel. Controls, such as weirs, are also needed to ensure individual raceways can’t accidentally overflow or empty.