Age and growth analysis of the central mudminnow, Umbra limi (Kirtland, 1840)


Author’s address: Jason M. Robinson, Department of Natural Resources, Cornell University, Fernow Hall, Ithaca, NY 14850, USA.


A rudimentary understanding of age, growth, and life-span is lacking for many non-game fishes. Growth characteristics of the central mudminnow (Umbra limi) have not yet been accurately described using reliable hard part analysis. The utility of scales and otoliths as ageing structures and quantified growth was examined in one lake and one stream population of central mudminnow. Scales were found to be of no utility in determining age due to inconsistent formation of yearly annuli and a high incidence of regenerated scales, while otoliths were easily extracted and considered to be an accurate ageing structure. Ages determined from scales were low compared to those from otoliths, and the difference in age interpreted from the two structures increased with fish age. A power function was fitted to describe the length-weight relationship for this species (a = 0.0069, b = 3.175). Von Bertalanffy growth parameters were estimated and compared for each population (Lake: L = 114.20 mm, K = 0.30, t0 = −0.93; Stream: L = 77.59 mm, K = 0.63, t0 = −0.76). The lake population showed greater size at age compared to the stream population, especially at older ages, and achieved a larger maximum size. Growth rate was also greater in the lake population (Lake: 1.74; Stream: 1.09 g year−1). Females were larger at age than males in both populations, however all individuals greater than age 3 were males. This work represents the first successful account of central mudminnow growth using hard part analysis.