YORK, Pa. — Civilization has caught up with the smallmouth bass.

The fish are among the species that call the river their home — along with American shad and eel — that have been most affected by human activity. Shad and eel — species that migrate to spawn — are hampered by the four large hydroelectric dams on the lower section of the river.

Smallmouth bass, though, are more indicative of water quality, often referred to as “the canary in the coal mine” because of its sensitivity to pollution and disease