We are trying to find out where the young-of-the-year Aspius of lake Mälaren (Sweden) stay during their first month after hatching in the tributaries. The eggs can usually be found from around the 20th of april and when sampling fry in the beginning of june it is rather difficult to determine what species we get. The other cyprinids that hatch in the area we are currently working in are Leuciscus idus, Rutilus rutilus, Scardinius erythrophthalmus, Tinca tinca, Carassius carassius, Alburnus alburnus, Abramis brama and Blicca bjoerkna. Probably only L. idus and maybe R. rutilus are large enough in june to possibly cause problems. Is it possible to sort this out by counting myomeres? I attach a picture of one of the larger specimens we caught a few days ago. The length is 15,5 mm and it has 23-24 postanal myomeres and ca 50 in total. I think the shape of the mouth speaks for Aspius.
myomeres may be equal to adult's vertebrate count (49-51 in asp & 47 in ide ).
shape and position of mouth in asp and ide are similar but the gap is larger in asp. check atachments
According to Kazanskiy (1925), hatched larval asps had 47-47 miotomes (myomeres?) in this 28-29 were in trunk part of body. In age 5-10 days (about 8.5 mm length) they have 48-50 miotomes (myomeres?), in this 28-29 in trunk part of body (after Kazanskiy 1928). Both sources are cited in my book about asp (Mamcarz et al. 2008 - Aspius aspius monography).
According to Spindler (1988) larval asps differ from other larval cyprinids by greater size of snout and characteristic doubled pigmentation on the spine (see Figure 32 in my monography of asp).
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