Golden Shiner fry calculation methods #114866 - Ask Extension


Golden Shiner fry calculation methods #114866

Asked February 17, 2013, 1:06 PM EST

What is the most accurate and easiest method for calculating the number of Golden Shiner fry from the hatchery tank that are to be transported to the pond? Is there a mathematical formula to use to figure this number? For example: number of head per ounce? Do you know how many Golden Shiner fry head count there are per ounce?

Prairie County Arkansas

Expert Response

I am not an expert on shiners (best to contact University of Arkansas at Pine Bluff), however, as is the case with estimating numbers with most fish, one can use the water displacement method.  The weight of fry will depend on multiple factors (age, how much they have consumed, genetics, etc.)  If you have a graduated container marked off by ounces (or any measurable level), fill part way with the same water in which the shiners are being held. Count shiner fry into the container until the water level raises one ounce.  That will give you an approximation of how many fry there are per ounce.  (it can be done several times to get a more accurate count by averaging.)  After that you can put a larger bucket with water on a scale and add shiner fry (allow for excess water to drip away) until you reach a measureable level.  The number of fry can be calculated from the differences in weight and the number of fry per ounce. 

FRY TRANSFER AND STOCKING (from UAPB)  Stocking is best done in early morning when water is cool and pH is not too high. Exposing young fry to high pH may result in lower survival. The pH of the pond to be stocked should be checked the afternoon before and should be below 9. At the time of stocking, pH should be below 8.5. If pH is above recommended values, stocking should be postponed for few days until pH reading are in the recommended range. If stocking has to be delayed by more than ten days due to high pH, the application of Baytex may be recommended in consultation with your aquaculture Extension specialist. When stocking is recommended, fry should be transferred to the ponds in plastic bags filled with oxygen. The number of fry per bag should be estimated by the volumetric method. The stocking rate should be within the range of 500,000-1,000,000 fry/ac. Inadequate acclimation (tempering) for temperature differences between bag water and pond water may stress or kill fry. The bags should be floated in the pond until the water in the bag is within a few degrees of the pond temperature. Ideally, bags should be tempered in vats filled with pond water before leaving the hatchery.

Brian Nerrie Replied February 20, 2013, 10:04 AM EST

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