Cryopreservation and Spermatology in Fishes

By

C. Judith Betsy and J. Stephen Sampath Kumar

Preface 

World fisheries witnessed a phenomenal change when technologies were introduced both in capture and culture fisheries. In the natural water, various fishing methods were introduced in the past and the exploitation has crossed the sustainable limit and now nearing the maximum possible point. Therefore, culture fisheries have started assuming greater importance in the production throughout the world. In Asian countries, native fishes have contributed mostly in all the countries. Nevertheless, there have been some exotic species too contributing in many countries in Asia.

Introduction of new species at many times have raised concern over the safety of indigenous and ethnic species. However, bio security measures are in place in many countries to safeguard their biodiversity at the same time producing fish and shrimp for their food and export. In all these efforts, genetic improvement has a greater role to decide the preference for the culture organisms for aquaculture.

Animal production in India has taken a quantum leap after the introduction of genetic improvement programmes. The major contribution was through the artificial insemination programmes through which the milk and meat supply have been ensured for the entire country. Cryopreservation of gametes is the base line technology that turned the artificial insemination programme in the country a major success. Even today, the cryopreservation of gametes is helping in solving many issues in the reproduction of large animals including the wild animals.

Cryopreservation of gametes has been a recent research area in fisheries. No commercial cryopreservation unit for fish gametes is presently available in any country. However, there have been shipments of cryopreserved spermatozoa of catfishes from Europe to African countries for the breeding and genetic improvement of African catfish. Although detailed reports are not available on this, it was understood from a commercial hatchery operator in Nigeria that he got the frozen spermatozoa from Europe for the breeding work in his hatchery once. Consistent use however, not very much evident in this line.

The simple use of cryopreserved spermatozoa for the breeding of fishes if established as that of animal production, would pave way for innumerable biological economical benefits in aquaculture. For instance, the successful use of cryopreserved spermatozoa can help in the easy hybridization and production of hybrids; can help in the genetic engineering work in the male, gametes; use of good quality male gametes to minimize the loss; can serve for more number of eggs than it is done in the natural breeding; can minimize or prevent the genetic deformities; fully prevent inbreeding depression and above all economically benefit the hatchery operators to keep only female brooders.

In order to harvest the large benefits, it is necessary to know the practical aspects of cryopreservation and its application for artificial fertilization.

Worldwide a variety of fish species have been cultivated. However, more diversity could not be seen in the breeding of fishes due to a general practice of external inducement, spawning in water or stripping, incubation in hatchery system, collection of hatchlings and rearing of young ones. In the above given scenario, the application of cryopreservation technology is much simpler because of its uniform procedure with alterations in the use of extenders and cryopreservation protocol.

Considering the importance, it is felt necessary to provide a comprehensive book on cryopreservation and artificial fertilization in fishes. The book is attempted to give a better understanding and enlarged vision on the cryopreservation technology for fish breeding.

Contents

1 – Introduction.

2 – Diluents and Dilution Ratios in Cryopreservation.

3 – Cryopreservation Process – An overview.

4 – Spermatology of Fishes.

5 – Energetic of Fish Spermatoza.

6 – Factors Affecting Gamete Quality.

7 – Artificial Fertilization in Fishes with Cryopreserved Spermatoza.

***for more please visit the library***

 Prep. / Ayman Ashry

Manage. / Mona Mahmoud