Ultrasonic sound effect in fish breeding:
A case study : Dr. S.N.Biswas* ; Sri D.Basu** ; Sri A.Roy** and Sri S. Ghosh***

Abstracts :

The success of induced breeding using pituitary gland/ synthetic hormone and captive breeding of fishes has revolutionized aquaculture all over the world. Multiple spawning of carp fishes is also very common now a day especially in West Bengal. But the quality of seed produced in the first spawning (Early season) significantly differs with the seeds produced in the mid or late season. This has been the practical observation of the farmers in the state of West Bengal. Seed produced in the first spawning always do better performance in survivality, growth rate and disease resistance. Beside this, quantity of eggs spawned and percentage of fertilized eggs observed to be less in the early and late spawning.

In this study, effect of ultrasonic sound on the complex process of egg maturation, their release and rate of fertilization were studied. It has been observed that brooders subjected to continuous emission of ultrasonic and sonic sound (at a certain frequency) induces to a significant level in the spawning behaviours which resulted complete spawning in case of natural breeding and easy and smooth spawning without causing little stress to the brooders during stripping. In both the cases, brooders responded perfectly even at very lower dose, resulting enhanced quantity of eggs and spawn.
This justifies that ultrasonic sound might have a positive effect on successful spawning and breeding of fishes.

Key words: Induced breeding, ultrasonic sound effect, fish spawning

Introduction :

Aquaculture in the state of West Bengal as well as in India in parity with the international scenario in this aspect has become an important economic activity and also a potential sector for diversification and value addition in farming. With the blend of traditional know-how to new sciences, efficiencies have been enhanced and the blue revolution is becoming a reality.

All this have been possible because of success of captive breeding of fishes especially carps in the hatchery using induced breeding technology. There are still some limitations in the response of brooders in spawning behaviours. This in many occasion causes death to brooders especially females in stripping methods and in normal cases always total spawning is not achieved; even in many cases female does not respond at all or very less quantity of eggs and spawn are produced and thereby hatchery/ seed production centre suffers.

Efforts have been made in this study to overcome this problem in the hatchery management.

Materials and Methods :

Two different hatcheries were selected for this purpose.

• Carp hatchery at Freshwater Fisheries Research Station, Kulia, Kalyani, Nadia, West Bengal.
• Magur (Clarias batrachus), air-breathing fish seed hatchery at Harinavi, Sonarpur, West Bengal.
  
  In the present study 10 kg female Carp fishes (Catla, Rohu, Mrigal, Bata and Kalbasu) and equal quantity of similar male fishes were selected for the four sets of experiments. The fishes were injected with pituitary gland @ 6-8 mg/kg in case of female and 3-5 mg/kg in case of male for the first set of experiment. In case of second and third set of experiment, the fishes were injected @ half and one third of the dose respectively as was applied in first set.
  
  Similar application was also made for magur fish (Clarias batrachus). Here, instead of pituitary gland fishes were injected with Ovaprim@ 2ml/kg in case of female and 0.5 ml/kg in case of male for the first set of experiment. In the third series, males were not injected with any inducing agent. For each experimental design one control was made.
  
  All the fishes of experimental sets (Except control) were subjected to continuous exposure to ultrasonic sound since they were selected from the pond and kept in the cistern, and subsequently placed in the hatchery for breeding till the spawning is over. One pair of TELENET Fish Chaser an electronic device, cylindrical in look with one end conical—16/17 inches (L), 1.7/2 inches (D); device embedded inside the cylinder and operated by 2 x 1.5 volts D-cell batteries was placed in all cases in such a manner that the fishes were always subjected to constant emission of ultrasonic sound.

Results :

In case of natural breeding response to spawning was found to be total for all the brooders and rate of fertilized eggs were also much higher than the control.

In case of stripping readiness for spawning for both male and female were found to be so high that even in slight touch at vent position causes release of eggs and milt. Without causing stress to the brooders, complete spawning was achieved.

In both the cases quantity of egg released and percentage of fertilized eggs are much higher. Each cases brooder positively responded to breeding irrespective of the dose of inducing agent used. (Table-1)

In one experiment in the extreme climatic condition when the temperature was 42C and the male showing no sign of maturity (milt; when caught from pond) observed to show high maturity (release of milt with slight touch at vent position) after those are subjected to ultrasonic sound effect for four hours (in the cistern) without injected with pituitary extract.

In case of magur, natural breeding is not happened normally in the hatchery. Females are stripped to get eggs and males are sacrificed to get milt by squeezing the whole testes as the milt quantity is very less and because of heavy stress during stripping, sometimes blood comes out and female get died, which is a great loss to the hatchery.

In case of male exposed to ultrasonic sound, the testes on opening the belly was found to be fully ripe and bigger in shape in comparison to control and the quantity of milt squeezed out was also found to be significantly higher than the control. In case of female it responded easily with slight pressure over the belly (towards vent) and eggs come out without causing any injury to the ovary. No blood observed to be come out even at the end. The spawning, fertilization and spawn production efficiency in comparison to control are shown in Table-2.

Discussion :

Wildhaber et.al.2005 and Whiteman et.al. 2005 studied spawning aggregations and gender identification applying ultrasonic imaging. The present author in another experiment (Biswas et. al. 2004) have studied positive effect on the growth of fish spawn (towards fingerlings) using ultrasonic sound and observed 35% higher growth rate in the spawn to fingerlings. Prince, E. D. & Maughan, O. E. 1978 and Yeager, D.M.1982 studied the typical movement of fishes due to ultrasonic effect. However, very scanty work on the effect of ultrasonic sound on the fish breeding have been done.

The present study revealed that the breeding efficiency of carp fishes increased to a significant level using ultrasonic sound. The spawn production level raised from 60% (in case of control) to 76.67% as studied in Experiment 1. In all experiments the quantity of egg released and percentage of fertilized eggs are much higher in comparison to control irrespective of doses of pituitary gland applied. In case of Experiment-3, 74% hatching success achieved using very low dose of pituitary extract. Therefore, it is established that the ultrasonic sound induces physiological process in a much better manner as is caused by artificial injection of pituitary gland/ synthetic hormone and it has a synergistic effect with inducing agent on fish breeding and maturation.

In case of magur, here also the quantity of eggs spawned and percentage of fertilization is much higher than the control. Present experiment confirms that 78% hatching success can be achieved using ultrasonic effect. The male fish showing high degree of maturation while exposed to ultrasonic treatment. The testes of the male fish of experiment –3 were observed to be highly developed, matured with large in structure and full of milt. The milt was thick when injected with inducing agent but watery (normal) when not injected with any inducing agent but were subjected to ultrasonic exposure. This shows that ultrasonic exposure induces male magur fishes quite significantly for normal spawning.

With the wild introduction of Clarias garipineus and its wide spread effects on the bio diversity total ban of breeding and culture of this fish species is urgently necessity. Government of India as well as State Government has been putting all endevours to stop this breeding and culture practices and success of this experimentation hopefully shows a way (path) towards this in encouraging Clarias garipineus (African canal cat fish) hatchery owners in adopting breeding and seed production of Clarias batrachus.

On the other side, using ultrasonic sound effect in carp hatchery- hatchery owners may get better performance in egg quantity and quality as well as costly brooders suffers less in case of stripping.

However, effect of such ultrasound on the other economic fish species need further study.

Table: 1 Performance of ultrasonic sound on carps

Table: 2 Performance of ultrasonic sound on Magur (Clarias batrachus)

Comment:

The result shows that the Fish Chaser definitely have a positive impact on the breeding behavior of both carp and air breathing fishes; it enhances breeding efficiency to a significant level and proper application of the may solve the problem of getting desired quantity of spawn without much hazard and less injury/pain to the costly brooder. And likely this may revolutionize fish seed hatchery once again and may also create a boom in the ornamental fish sector. This study shows the way to work further on this line.

References:

• Wildhaber M. L. et.al.2005; Gender identification of shovelnose sturgeon using ultrasonic and endoscopic imagery and the application of the method to the pallid sturgeon Journal of Fish Biology; vol-67; issue-1; p-114.
• Whiteman, E.A., Jennings, C.A., Nemeth, R.S.2005; Sex structure and potential female fecundity in a Epinephelus guttatus spawning aggregation: applying ultrasonic imaging Journal of Fish Biology; vol-66; issue-4; p-983
• Prince, E. D. & Maughan, O. E. 1978. Ultrasonic telemetry technique for monitoring bluegill movement. Progressive Fish-Culturist 40: 90-93.
• Yeager, D.M.1982. Ultrasonic telemetry of striped bass x white bass hybrids in the Escambia River, Florida. Proceedings of the Annual Conference of the S.E. Association of Game & Fish Wildlife Agencies, 36: 62-73.
• Biswas, S.N., Basu, D., Roy, A., 2004. Study on the effect of emission of ultrasonic sound in fish pond on the growth of fish (unpublished)

Fig-1: Diagram of Telenet Fish Chaser.

Photo-1:Typical Low Cost Air breathing Hatchery Set Up

Photo-2: Collection of brooder for breeding.

Photo-3: Gravid Female Magur.

Photo-4: Gravid Male Magur.

Photo-5: Hormone injection.

Photo-6: Brooders after injection released in the cistern with Tele net installed.

Photo-7: Inside of a Tele Net

Photo-8: Testes being dissected out.

Photo-9:Collected eggs after fertilization.

Photo-10:Thousands of larvae hatched out from the brooders subjected to Tele net exposure.

Photo-11: Hatchlings under rearing.