Sperm Cryopreservation in fish
Prof. Dr. Shamim Akhter
University of Arid Agriculture, Rawalpindi
Email:shamim@uaar.edu.pk
Sperm cryopreservation enables long term preservation of male germplasm for future use in assisted
reproduction across the species. The ultimate aim of sperm cryopreservation is genetic improvement,
controlled/desired breeding of valuable breeds and conservation of endangered species. In the context of fisheries,
the hatcheries start production using a small number of brood stock, repeatedly selecting breeders from the
successive generations. Therefore, the hatcheries are facing stock retrogression due to lesser size of effective
population, insensible selection, poor management of brood stock, inbreeding stress, genetic drift and domestic
stock erosion. Such undesirable changes in genome due to genetic drift and inbreeding may lead to developmental
uncertainty, lower viability and slow growth in fishes. To address these issues, sperm cryopreservation has been
approved as a substantial plan for the protection of fish genetic stock as it enables the gamete preservation for
several years. Milt cryopreservation assists aqua-culturists to overcome the consequences of inbreeding as it allows
easy transportation of milt to be used in selective breeding programs for genetic improvement of brood stocks,
reducing inbreeding. In addition, cryopreserved spermatozoa can be used for in-vitro fertilization in case of
asynchronous maturation of males and females. Also, the number of male brooders maintained at hatchery can be
reduced. Moreover, in case of disease outbreaks, overexploitation and natural disaster, cryopreservation can help in stock protection from being totally eliminated. It is therefore of relevance to introduce sperm cryopreservation as a
tool to produce quality seed and genetically improved varieties. However, the success of cryopreservation depends
upon development of species specific extenders, cryoprotectants and procedures for freezing and thawing. All such
avenues / opportunities and challenges for the Zoologists in the field of fish sperm cryopreservation will be
discussed in the invited lecture.