The following list describes the key criteria which should be specified for each species and summarized for the project notebook:
- Species description
Identify the species or stock to be cultured. Provide information on life history, experience under aquaculture conditions and marketability, if applicable. Broodstock sources should be identified; if non-native stock is selected, the reason for its use, assurance of availability and any potential restrictions governing importation should be noted. Use of native stocks will also require an assessment of availability and possible harvesting restrictions.
- Behavioural characteristics
Animal behaviour during all stages of its production should be described to the extent relevant to facility design and operation. Characteristics to be considered may include jumping, burrowing, cannibalism, competitive or symbiotic relationships with other species, behaviour which might facilitate harvesting, photo-sensitivity, etc. If controlled breeding is part of the production programme, unique behavioural characteristics of brood animals as well as larval and juvenile stages must also be addressed.
- Culture techniques
An appraisal should be made of state-of-the-art techniques in reproducing and growing the selected species. Consideration should be given to common practices as well as experimental programmes in order to select the most appropriate technology as well as indicate changes in techniques likely to occur over the life of the facility. The selection of production methodology should not only be based upon technical limitations, but also site conditions, financial constraints, project objectives and the experience of the operator. It is important to assess carefully and realistically the likelihood of modifications in techniques over time and determine the necessity of providing flexibility for the future. Such changes could necessitate increasing the initial capital investment in order to facilitate modifications at a later date. An overview of the history of culturing the selected species, similar culture projects and research programmes, both past and present, is often of value. Indicate if any particular project or technology is to be used as a model for this project. Describe unique techniques or facilities to be used and provide a basis for recommending their use in the proposed programme.
- Environmental requirements
This section should contain quantifiable information to be used as the basis for assisting in site selection and designing infrastructure. The basis for determining all requirements should be well-documented. To the extent laboratory data are used, consideration must be given to possible changes in requirements and behaviour under a production environment.
Density: provide criteria on the number of animals or animal weight allowable in a given surface area or volume of water. If these requirements change based upon animal size during the rearing cycle, it should be noted. The basis for the criteria should be specified, as the use of static versus running water systems, grading and population thinning during the production cycle, and the supply of supplemental diets may all have a bearing on the criteria adopted.Water exchange: the volume and rates of water exchange required will be based upon the quality of the supply as related to the animals' tolerance of a variety of chemical properties, the population density as it affects oxygen and nitrogen concentrations, temperature as it affects respiratory rates and oxygen saturation levels, and the reliance on natural as opposed to supplementary feed. In addition to these basic biological requirements are physical limitations based upon water availability, the cost of delivering and removing it from the production units, and evaporation rates.
When possible, criteria for the tolerance of water quality should be used as the basis for determining water exchange rates. They must always be used for determining requirements under intensive culture conditions. For semi-intensive and intensive systems, rates based upon percentage (%) exchange may be used.
Water quality: lethal and acceptable ranges for temperature, and the most critical chemical parameters should be determined. Ideally, the synergistic effects should be considered when determining criteria. The most important to any project are temperature, pH, salinity and dissolved gases (oxygen and nitrogen). When in doubt about the suitability of any particular water supply, a bioassay is recommended. Tolerance levels may change depending upon the size of the animal and level of stress as influenced by rearing density and habitat. Water quality criteria should be used to ensure the supply is well within the animals' range of tolerance as population intensification, inherent in any aquaculture system, results in both degradation of water conditions and a reduction in tolerance levels.
- Nutritional requirements
The dietary requirements and the form in which they will be supplied must be determined for every project. The selection will be based upon the acceptability, availability, and cost of commercially available diets compared with the cost and effectiveness of producing food within production units. The type of culture methodology used is directly related to feeding methods.
The criteria should indicate if there is a change in nutritional requirements and diet availability during the rearing cycle. Also they should address the amount of food to be fed, feeding frequency, method of supplying feed, and special infrastructure requirements for the production and storage of supplemental rations.
- Growth rates
Anticipated growth rates will be influenced by the species selected, ambient temperatures, population densities, and nutritional inputs. Normally rates are expressed on a straight-line basis as weight and/or length gain per unit of time. More sophisticated criteria may be expressed as a logarithmic growth equation. In either case, to apply the criteria it is necessary to know ambient water temperatures and expected seasonal variations as well as fish length/weight ratios for the target species.
- Mortality rate
Expected rate of mortality during the rearing cycle should be determined and conveniently expressed as a percentage of the population per time increment. This rate will assist in determining stocking rates and projecting harvest levels.
- Diseases
The most common types of diseases affecting the animals to be produced should be reported. The frequency of occurrence and virulence will affect the financial risk associated with the project as well as influence the need for environmental control features in the design, such as quarantine areas, water treatment, and water re-use. The availability and effectiveness of prophylactics and vaccines should also be addressed.
