The assessment of fish sperm motility in fish and mollusc hatcheries is usually based only upon subjective estimation of the percentage of motile cells and duration of motility.  However, these techniques are much less sensitive than objective evaluation of sperm motility using computer-aided sperm analysis (CASA).  It has been proven that CASA parameters analysed with this simple and rapid method are well correlated with fertilisation.

Apart from laboratory conditions, where CASA gives the opportunity to study the mechanisms of initiation, activation, inhibition and chemotaxis (a simple response, either positive or negative, to chemical stimuli) of sperm motility, there are many applications of CASA analysis in aquaculture.  The sub lethal effects of pollutants that are manifested by decreased sperm quality could be, for example, easily detected using CASA. Testing different media used to extend sperm longevity in short-time or cryopreservation, and the examination of the efficiency of different spermiation stimulants demonstrate how usefulness this method is for aquaculture applications.

The advantages of CASA in aquaculture are obviously not restricted to fish sperm.  The recent studies have given records of usefulness of this method in monitoring quality of sea urchin and mollusc sperm. For example, heavy metals, phenols and very low (comparable to environmental), UV-B irradiances manifest themselves by decreasing motility of sea urchin sperm.

Another positive feature of CASA is that videotaping of sperm movement can be done in the field, with more detailed analysis of videotapes being done later in the laboratory. This therefore, requires no need to transport expensive equipment to the farm. It simply depends on the farmer’s decision to analyse sperm quality using CASA parameters himself, or if he prefers to invite specialists to do it for him. In the first case, he should have the necessary equipment: a microscope with negative phase-contrast or dark field and x10, or x20 negative phase objective, black and white CCD camera (for example Sony, SPT-M108CE), videorecorder, TV monitor, tapes and multi-test slides (for example 12-well slides from ICN (Cat No. 6041205)) with cover slips and pipettes.

Ongoing experiments in this laboratory are generally concerned with freshwater fish and mollusc sperm.  The majority of the applications mentioned above are used for monitoring of negative effects of heavy metal pollutants on salmonid and sturgeon sperm. All experiments are carried out in close co-operation with aquaculturists. For more information we invite you to see TL2001-014.

The project is supported by Polish Academy of Scientific Research, Project PBZ-KBN-084/P06/2002/5.8.