Skewed Sex Ratio In Burrhead Shiners?

I asked on the NANFA mailing list yesterday if anyone knew anything about skewed sex ratios in North American minnows. Only Jeremy Tiemann had anything, sending me a .pdf of an article from a 1929 issue The American Naturalist about bluntnose minnows (Pimephales notatus). The article actually showed sexual size dimorphism, but it was interesting on its own. I spent some time today wrangling through Google and found some interesting references on the question. As far as most researchers say anything about it, it's that they've found essentially 1:1 M:F ratios in various species of interest. But some skew surfaced in some research, although no one seems to have thought much about it. For example, Brooks Burr and Richard Mayden found a male skew in three populations of Notropis chihuahua, only one of which was statistically significant (Copeia 1981(2) 255-265), but they ascribed no significance to their observation. Shawn Dahle found in his study of N. topeka in Minnesota that females made up 59% and 62% of the Age-1 and Age-2 populations he sampled, but again ascribed no significance to the observation (M.S. Thesis, 2001, University of Minnesota). And Glazier & Taber found more females in their study of the Ozark Minnow, Dionda nubila. But they ascribed this to an artefact of sampling, since they felt that smaller males were more likely to swim through the seines they used for collection (Copeia 1980(3) 547-550).

So there might be something to my observed sex skew in burrhead shiners, N. asperifrons. I found 29 males to 42 females, which is not quite statistically signifcant as a deviation from 1:1. This touches on a lot of evolutionary and sexual selection theory. Being a female may be advantageous for reproduction in this case; female burrheads are significantly larger than males. One data set of 71 fish is not enough to make a definitive statement in this case, but it raises interesting questions. Hmmmmm.....