jpsdad can you provided me the source for this bit of info ? I will check to see if I can find an answer for us , as I would like to know also.
eric, the reference can be found
here.
The study found, of the 42 ponds surveyed with total kill and collection, that where LMB and BBH co-occur the mean standing weight was 24 lbs/acre while where LMB occur without BBH, the mean standing weight was 54 lbs/acre. The study also mentions that the correlation wasn't significant at the 95% confidence limit. But lest any discount the harm that BBH can do to LMB standing weights, understand first what correlation means. We plot the standing weight of LMB versus the standing weight of BBH seeking to see if a tit in the weight of BBH responds with a negative or positive tat in the standing weight of LMB. To be sure, this is a rather coarse way to try to understand the interaction. Some ponds supported a greater total standing weight than others for example and so a tit in one pond may be a rather small in terms of relative abundance than the same standing weight in another pond. So it is pretentious to suspect that a tit for tat model would be a good predictor of the standing weight of LMB The correlation could probably be improved through normalization of the data to convert the tit and tats from standing weight to a proportion of standing weight. Even so, the interaction of BBH and LMB were not in a vacuum as there were other players in these ponds.
Looking back, I should have said this. Of 42 aged ponds, sampled with total kill, the presence of BBH was shown to be associated with lower LMB standing weights. Correlation was a poor choice of words.
I might be wrong, but my hunch is that the association of lower mean weights of LMB isn't a fluke. Generally BBH need water of greater fertility to thrive. It wouldn't make sense that ponds that carry more fish couldn't carry more LMB unless the dominate prey fish were out of balance with the LMB. One pond, which was omitted from the numbers related to with and without bullheads standing weights, turned out to be the pond with the greatest standing weight of BBH. It was omitted because no LMB were present at all in this pond. We won't ever know given the age of the study if this pond ever contained LMB prior to the survey,
but if this pond once supported LMB, given the standing weight of BBH (831 lbs of 931 lbs total standing weight), it might be a reasonable conclusion that the BBH extirpated the LMB by preventing recruitment.
