Broodfish are then stocked and spawning materials are placed around the edge of the pond. This method requires the maximum amount of water, thus is the most expensive. Alternative water use methods are now being implemented. However, these are in the experimental stages and results are varied. Surface water use includes catching rain water during the winter months and spawning in the water during spring.
Rain water has no dissolved minerals.
Liming adds minerals that stabilize against drastic pH changes which would kill fry. This method requires a system of interconnected drainages or a number of relift type pumps. Problems occur when fertility builds up. Dense plankton blooms and organic matter encourages fungal growth on the spawning mats, thus killing eggs. Enough fish are left after seining to serve as broodstock.