Induced Fish Breeding

A Practical Guide for Hatcheries

Nihar Ranjan Chattopadhyay

• Publisher: Academic Press
• Year: 2016
• ISBN:
  9780128018477
• Topic: Technologie et ingénierie
• Subtopic: Pêche et aquaculture

Induced Fish Breeding: A Practical Guide for Hatcheries takes a successive approach to explaining the use of breeding technology with proven scientific methods. It provides real-life examples for the purpose of maximizing fish and seed production to support overall sustainability in aquaculture. It is a concise reference to understanding the latest developments in the field, useful for anyone who is involved in fisheries or hatchery management as well as researchers and students who need to understand the technology.

A practice originally developed to produce quality seed in captivity, induced breeding has made great strides in fish populations for India. The book offers a practical and succinct overview—from existing methods and operations to recent trends and their impacts on aquaculture for the future.

• Provides detailed information about empirical breeding practices like mixed spawning and indiscriminate hybridization
• Presents the environmental and hormonal influence on maturation and spawning of fish with real-life fish breeding examples from around the world
• Includes step-by-step scientific measures to help solve problems arising from common fish-farming mistakes
• Provides real-life examples for the purpose of maximizing fish and seed production to support overall sustainability in aquaculture

Part I

Induced Breeding—A Scientific Approach Towards Modern Fish Breeding Procedure

Outline

Part I. Induced Breeding—A Scientific Approach Towards Modern Fish Breeding Procedure

1 Eco-Hatchery for Fish Breeding of Carps in Captivity

2 Reproductive Cycle, Maturation, and Spawning

3 Hybridization

4 Selective Breeding

5 Negative Aspects of Breeding Practice

6 Influence of Ecological Factors on Maturation, Spawning, and Hatching of Carps

Part I. Induced Breeding—A Scientific Approach Towards Modern Fish Breeding Procedure

The implementation of scientific breeding procedure by fishermen goes way back since they first introduced bundh breeding. However, problems were encountered by the fishermen as the bundh breeding of fishes were erratic and in 1960s, the spawn production industry of the districts faced a serious problem. It was reported by the local fish farmers of Bankura that a large number of bundhs turned sterile where the fishes did not response to breed even when possible congenial conditions were created. Hence further scientific approach in bundh breeding was taken up in the year 1968 when a group of scientists from the Fisheries Research Station, Kulia, Kalyani, introduced the system of induced breeding by application of hormone injections to 10–15% of fishes of the bundhs. This introduction of injection system to fishes gave a new dimension to the spawn production industry of the districts and also opened a new avenues for breeding fishes by sympathetic induction, that is, when injecting a part of the brood stock the rest of the stock is induced being influenced by the induced stock. In spite of immense economic potentialities, few attempts have been made to improve upon existing methods of artificial induction of spawning in fishes. Our study indicate, the fish breeders of India practicing the same technique developed nearly 60 years ago by the pioneers Prof. B.A. Houssay, University of Buenos Aires, and Dr. Von Ihering, Department of Fisheries, Brazil. Even in the most developed countries, there exists a compartmentalization between theory and practice. In reality, it is observed that the investigator is either a fish physiologist or endocrinologist, not conversant with the practical aspects of fish breeding and behavior. Similarly the fish breeders at field are not aware of the scientific information of breeding, spawning, and hatching. Now, to make the seed production industry more profitable, an integrated approach is needed.

1

Eco-Hatchery for Fish Breeding of Carps in Captivity

Abstract

Induced breeding, i.e., technology for development of fish seed in captivity, which was developed through the injection of pituitary extract and subsequent rearing of fertilized eggs, spawn, and fry in Chinese hatcheries is a significant landmark in aquaculture production. The success of the induced program is dependent primarily upon the preparation of the right brood stock and its steady supply and replenishment at certain intervals. Though the technology, at present, has been modified by incorporating several innovations by the fish breeders and scientists, still it is getting set back through several profit-making propositions and unscientific approaches. The new concept for the genetically improved strains, conservation hatchery, and gene banking will certainly restore the concept of quality seed production through captive breeding.

Keywords

Induced breeding; hatching and spawning pool; duck-beak; inlet; genetically improved strain; gene banking

Chapter Outline

1.1 Overhead Tank 3

1.2 Spawning Pool 4

1.3 Incubation or Hatching Pools 6

1.4 Breeding Technique 8

1.5 Spawn Collection Tank 8

1.6 Breeding Protocols 9

1.7 Brood Stock Collection and Development 9

1.7.1 Gene Banking 12

References 13

Cement circular hatchery, also known as eco-hatchery and Chinese hatchery system, comprises of an overhead tank, spawning pool, incubation and hatching tank, and spawn collection tank.

1.1 Overhead Tank

The overhead (double chambered) tank is made of R.C.C. and has a capacity of about 30,000–50,000 L. It is used to supply sufficient water for spawning to the incubation and spawn collection tanks. (Fig. 1.1). Water is poured into the tank by two separate G.I. pipes of 7.5 cm. diameter, for two separate tanks (one for natural surface water and another for ground water) inside one tank. The pond water before storing is properly filtered, but in the case of ground water it is oxygenated by a mechanical air-diffusion method. After mixing the water, in the ratio of 1:1, it becomes more suitable for spawning.

Figure 1.1 Overhead tank of 30,000–50,000 L capacity.

1.2 Spawning Pool

The spawning pool was evolved in China in 1970 and thereafter introduced to different countries of the world. It is a circular cement tank of 8–9 m diameter and 1–1.5 m depth with 50 cubic meters of water holding capacity. A spawning pool is composed of two parts: (1) a circular breeding pool (6–8 m dia. and 1.2–1.5 m height) and (2) a rectangular spawn collection chamber (3 m × 2.5 m × 1.6 m) located at the base of a circular pool adjacent to it and connected to the pool by a 10 cm diameter G.I. pipe. The bottom of the pool has a slope gradient of 1:30 toward the central aperture, called the orifice, through which the fertilized eggs are transferred automatically to the spawn collection tank or directly to the incubation pool. During transfer the orifice is guarded by a 25 mm meshed wire screen to provide easy passage of fertilized eggs but at the same time prevent the escape of breeders. The wall of the tank is provided with diagonally fitted duck-beak inlet for circular water flow to create riverine fluviatile conditions, as a result the carps are stimulated, engage in sex play, and ultimately spawn. About 70 kg of brooders (2 males:1 females) can be used at a time, which will yield about 8–10 million fertilized eggs in one operation. The outlet pipe (Fig. 1.2), from initiation of breeding till spawning, remains fixed to the central orifice in an erect posture so that excess water will be removed from the pool. As soon as spawning is completed the brooders are removed and at the same time the outlet pipe is dislodged (Fig. 1.2). The central orifice is covered by a 25 mm meshed wire screen which allows the fertilized eggs to incubation pool but not the brooders. In order to increase the dissolved oxygen content in the tank a perforated galvanized iron pipe is fitted above the breeding tank in such a manner that a fine shower falls inside the breeding pool (Fig. 1.3). The water holding capacity of the circular pool is 35–70 m³ at its maximum level, but only 20–30 m³ water is normally maintained for breeding 25–40 sets of brooders at a time. The water inlet to the pool is a 10 cm diameter G.I. pipe emerging out from the overhead tank, which branches into three 5 cm diameter pipes that enter into pool through three separate entry points, and is guarded by a screw valve to maintain clockwise movement of water inside the pool. These pipes are placed 15 cm above the bottom to maintain a steady flow of water at the entire column of water and a flow rate of 30–50 L/min is maintained by adjusting the screw valve.

Figure 1.2 Central orifice for automatic transfer of fertilized eggs to hatching pool.

Figure 1.3 Breeding pool in operation with showering in the pool.

Nowadays, fish breeders have rejected the concept of conducting breeding operations in a breeding pool to avoid the involvement of huge amounts of water, although some are of the opinion that the central sloping prevents a thorough mixing of all eggs with milt and this reduces the fertilization rate.

1.3 Incubation or Hatching Pools

The incubation or hatching pools are circular in shape and constructed of brick and cement. Generally, 2–3 incubation tanks are connected to one spawning pool (Fig. 1.6). Each has an inside diameter of 3–4 m and a depth of about 1 m with a water holding capacity of 9–12 m³. It usually holds about 0.7–1.0 million eggs per cubic meter of pool. The incubation pool is directly connected to the overhead tank by a 7.5 or 10.0 cm diameter G.I. pipe, which after being branched into two 5.0 cm diameter pipes joins two 5.0 cm diameter circular pipes fitted below the cemented bottom of the outer chamber. Finally, the base line remains attached to both the inner and outer circular pipe from which 21–24 duck-beak inlets of 2.0 cm diameter, are projected above the bottom at a 90 degree angle at regular intervals and in a clockwise fashion. All this arrangement of pipe is to create a centrifugal force of water toward the inner chamber through the monofilament markin cloth and out through the outlet pipe.

Water circulation is very important for the proper hatching of fertilized eggs and the said arrangement of duck-beak inlets creates a three directional flow (Fig. 1.4) at the bottom which ultimately creates a centrifugal force. This three directional water flow does not allow any settlement of eggs at the bottom. The water inlets at the bottom and the sides of the incubating pools are technically arranged so as to create a circular movement of water (Fig. 1.5). This keeps the developing eggs in a constant circular movement. The inner chambers of the incubation tanks are separated by a fine monofilament markin cloth (Fig. 1.6). This nylon screen is stretched and fitted on an iron frame. A rubber belt is fastened very tightly to seal the compartment. In the center is the overflow pipe at a particular level below the level of inner chamber through which excess water is led out; as a result a constant water level is maintained in the inner chamber. The water speed is controlled by means of a gate valve. The desired flow rate of 45–60 L/min is an important criteria for the steady dev...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• Preface
• Introduction: Preexisting (Traditional) and Modern Fish Breeding Methods in Practice Among Fish Farmers
• Part I: Induced Breeding—A Scientific Approach Towards Modern Fish Breeding Procedure
• Part II: Case Studies
• Part III: Innovations
• Index