It sort of depends on how big the pond is and how much new production one desires. IMO the larger the pond the more new BG one would want or need. All BG do not need to spawn all in one area. There can be several spawning areas based on need, desire and diversity. BG nests for large individuals (8"-10") are normally at a density of 1 every 3-4 sqft. For a small pond 1/3 ac a 10x10ft or 10x20ft area may suffice. Thus there would be about 25 nests in 100sqft. IF each nest results in 5000 surviving fry to 1" there would be abt 125000 estimated offspring. Don't rely heavily on that 125K number because recruitment from BG nests can be highly variable by factors of at least 10.

Using the above suggestion a one ac pond could suffice to have at least a 30'x30' (900sqft) or larger 30x60 gravalized area for BG spawning of 250-400 male nest builders. Note that many ponds can get buy with smaller BG nesting areas if habitat and refuge areas are optimum which encourages survival of fry.

IMO one of the important things to NOT do is to spread the gravel out too thin such as 3"-5". Thin layers of gravel tend to become blended into the mud sediment bottom of water soaked clay.

Better gravel depths are 6-12" thick. Large BG (9-10") will "dig" circular nests that can be twice their body length and 5-6" deep into the sediment depending on the consistancy of the bottom materials. In hard bottoms or coarse gravel (1/2"-1"), nests are often dug shallower into the bottom. Sometimes larger BG will use old LMB nests. IMO coarser gravel (1/2"-3/4") underlying a thin layer of sand (2"-3") provides higher survival and hatch rates of the eggs. A mixture of sand and gravel or segregated areas of sand and gravel are also good. Diversity is advantageous.

Last edited by Bill Cody; 01/31/10 06:01 PM.

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