I was thinking of making a size limit for mixed BC and WC crappie in my pond to protect the breeders and increase trophy potential.
last year I'd estimate the overall average weight is 1#, since stocking in 2018.
My thought is to start releasing all over 13" and harvesting slot of 9-13"
I feel the 1-acre pond is well balanced including the BG and LMB
any advice or thoughts on this approach?
thanks
To work ... on the recruitment side ... you must not get excessive recruits <9". It would depend on that.
Most ponds, (though there are exceptions ... like Pat's), have too many recruits less than 9". In most water, some exploitation of sizes smaller than 9" would be required to get them into the 10+ territory. Let recruitment be your guide on that and if you get numerous fish in the smaller bracket adjust for that. There should be a limit to how much biomass you remove in the adult sizes (> 10"). Ideally, your exploitation would not exceed 25 to 35% of the adult biomass in any given year. If overexploited that real estate could be taken over by BG.
I will mention that the idea of protecting brooders and taking 9" to 13" crappie does seem a bit contradictory. These sizes are brood sized fish and contribute meaningfully to recruitment. Another thing to consider is that >10" crappie depend in large part on small fish prey. In that sense, they are like little bass and because of that their biomass cannot be all that high. A practical limit for fish of that size is probably between 60 and 100 lbs/acre and such a population would be limited to between 40 and 60 adult (adult being >10") crappie/acre. It depends on natural mortality, but looking at this in the past with natural mortality of 15% and exploitation at 25% .... annual recruitment of 20 BCP to the 10" class allowed for annual exploitation of 13 adult BCP per acre-year where the 13" milestone is reached at 5 years of age at a population density of ~1 BCP/acre. There could be several years of successive recruitment, however, so the total population density of >13" fish could be as high as 4 or 5 to the acre (here assuming you are not harvesting > 13" BCP)
The biggest obstacle is the recruitment piece which can be unreliable from two perspectives. One is under-recruitment where insufficient BCP are recruited into the 10" class annually. The other is over-recruitment where too many BCP are recruited and they grow too slowly to reach 10". What makes BCP so challenging is that a pond will not support a large number of adults but they have the capacity to greatly over recruit what is needed to sustain a modest adult population. Because of irregular recruitment, you may not be able to recruit at 20 per acre year. But rather you may get 4 years of no recruitment and then a boom year. If you can recruit consistently that would be most ideal. For example, purchasing 20 10" BCP per year and stocking them. I like the idea of marking by fin clips the BCP you want to protect. Fin clipped, you know to throw them back if you have already met quota for the year. When a fish is not fin clipped, you know to remove it indiscriminately.
