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Presented at the NABS Annual meeting, La Crosse, Wisconsin, 2001
HABITAT PREFERENCE OF RIO PECOS FLUVIAL CYPRINIDS
C. W. Hoagstrom. U. S. Fish & Wildlife Service, New Mexico Fishery Resources Office, Albuquerque, NM 87113
Habitat utilization by fluvial cyprinids (Macrhybopsis aestivalis, Notropis jemezanus, Notropis simus) was studied at two spatial scales within the middle Rio Pecos, NM at low to moderate discharge (0.2 to 7.0 m3/s). Channel type discriminated macrohabitats (reaches, 44.0 to 122.0 river km). Year round distribution, abundance, and population structure surveys over eight years determined that fluvial cyprinids were most persistent, abundant, and demographically intact within active sandbed reaches. Mean depth/velocity of individual seine hauls (1.5 to 54.0 m2) discriminated mesohabitats. Analysis of 1839 hauls from 20 sampling trips over five years concluded that fluvial cyprinids utilized swift mesohabitat compared to other fishes but exhibited broad mesohabitat preference. Availability of preferred mesohabitat was similar between reaches and did not correspond with fluvial cyprinid reach preference. Qualitative observations deduced that microhabitat distribution and abundance varied between reaches and did correspond with fluvial cyprinid reach preference. Sediment transport regimes (bedforms) in active sandbed reaches sustained high microhabitat heterogeneity that was lacking in inactive reaches. Increased understanding of fluvial cyprinid microhabitat utilization in relation to bedforms is critical for conservation since sediment transport regimes are constrained by water and sediment supply.
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