Induced breeding using hormonal stimulation
Explanation
A major challenge in traditional fish farming is the availability of quality seed (spawn). Historically, seeds were collected from natural riverine sources, which resulted in a mixture of desirable species along with predatory and weed fishes. This mixture is referred to as "impure seed." To address this, the technique of induced breeding was developed.
Detailed Analysis:
- Importation of exotic seeds is incorrect: Importing exotic seeds does not solve the issue of generating pure seeds for local or specific culturable species. It also carries ecological risks regarding invasive species.
- Induced breeding using hormonal stimulation is correct: Induced breeding (also known as Hypophysation) involves injecting mature fish with pituitary extracts or synthetic hormones to stimulate spawning in confined waters. This method allows for the production of pure seeds of a single, desired species, completely eliminating the contamination found in wild collections.
- Selective rearing of a single species is incorrect: Selective rearing relates to the growing of a single species (monoculture) after the seeds have been obtained. It is a farming practice, not a seed production technique that solves the initial purity issue.
- Collection of seeds from natural riverine sources is incorrect: Collection from natural riverine sources is the primary source of the problem, as it inevitably leads to the collection of mixed spawn that is difficult to segregate.
Key Takeaway:
Induced breeding is the primary method in aquaculture to ensure the supply of pure, high-quality fish seed, overcoming the limitations of mixed and uncertain yields from natural riverine collection.