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Basin-wide/Regional |
Topic |
Fish: Presence/Absence of Coho Salmon in Mendocino County |
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Caption: The chart above shows the findings of field surveys to determine the presence or absence of juvenile coho salmon in Mendocino coastal streams in the early 1990's as presented in Brown et al. (1994). Coho were missing from 50% of the small tributaries that drain directly to the Pacific Ocean (Coastal), 27% of Ten Mile River tributaries surveyed, 8% of Noyo River tributaries and 21% of Navarro River tribs. Tributaries known to harbor coho in the past but not surveyed are shown as NO DATA above. The loss of coho salmon from tributary basins and portions of large rivers shows fragmentation of the distribution of coho which is a warning sign for declines toward extinction, according to the authors. Noyo River presence data may be influenced by hatchery operation. Absence data are provisional pending more extensive study because coho may exist in some streams but only occur in some years because of complete losses of year classes. See InfoLinks for more information.
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brownpresabs.dbf (size 695 bytes) .