Examination of Mottled Sculpin Distribution, Age and Growth Rates within the Huron River Watershed, Washtenaw Co., Michigan
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Modification of the landscape through a variety of human-influenced land uses often increases the flow of sediment into streams. Increased sedimentation can, potentially, alter lotic habitat integrity and possibly fish distribution and growth rates. Distribution, age and growth were examined for mottled sculpin (Cottus bairdi) collected in the fall of 1996 from within the Huron River watershed of Washtenaw Co., Michigan. Sculpin utilized cobble and gravel substrates more frequently than heavily sedimented areas at all sampling locations. Historical distributional data for sculpin from 1938 showed a wider distribution of Sculpin in the watershed when compared with a survey completed in the summer of 1996. Sculpin were found predominantly in sites throughout Washtenaw County. 221 sculpin were collected from 14 sites to determine their ages and growth rates. Seven age groups of sculpin were determined from observation of otoliths. A conventional von Bertalanffy and a simple linear regression model of sculpin growth in the watershed were compared and found to be similar for these fish. No statistically significant difference in sculpin growth in length was identified among sampling locations, but significant differences in condition offish among sites was observed (P<0.0001). Differences in the length-weight relationship of mottled Sculpin among sites may be due to differences in land use characteristics at those locations.