I hope the Int J Mol Sci. 2011; 12(11): 8086–8095 may be useful ..
However this is for molluscs and the average concentration of the total extracted genomic DNA of all samples was 271.8 ± 64.5 ng·μL−1 (mean ± SE), ranging from 200.7–370.3 ng·μL−1 (min-max).