Question

2 How are spawns of fishes produced artificially?​

Answer 1

Answer:

Fish can be manually stripped of eggs and sperm by stroking the anaesthetised fish under the pectoral fins towards the anus causing gametes to freely flow out. Environmental manipulation: Thermal shock, where cool water is alternated with warmer water in flow-through tanks can induce spawning.

Explanation:

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Answer 2

How are spawns of fishes produced artificially?​

The artificial intervention in this procedure consists of ;

 (1) collection of eggs, larvae , or fry.

(2) their protection from natural enemies and unfavorable environmental    factors .

(3) raising the larvae up to the fingerling stage.

(4) distributing them for stocking in different water bodies.

-This technology of river fish seed collection can be easily adopted in other parts of the world where useful river spawning fishes are available in adequate number.

-However, this technology has several disadvantages.

-The collection is generally not pure, but a mixture of several species some of which may be predators or of undesirable type.

-It is not easy to separate the various species, particularly in the early stages.

-However, some techniques have been developed both in India and in China to segregate desirable from undesirable seed.

-These are successful only to a limited extent, and one has to wait until the larvae develop into fry with distinguishable characteristics for proper identification.

-The collection technology is labour-intensive and requires special skill in handling and transport.

-Another disadvantage is that the brood stock is unknown and there is hardly any possibility of improving the stock.