Species Regional Summary
Micropterus salmoides
San Francisco Bay ( P090 )

The Largemouth Bass, together with the Smallmouth Bass (M. dolomieu), and Channel Catfish (Ictalurus punctatus), has a possible role in extinction of Thicktail Chub (Gila crassicauda) and the decline of Sacramento Perch (Archoplites interruptus) (Cohen and Carlton 1995) in the San Francisco estuary watershed. Experimental removal of predators, dominated by Largemouth Bass, increased the survival of tagged Chinook Salmon (Oncorhynchus tshawytscha) migrating through the North Fork Mokelumne River, at the edge of the Delta (Cavallo et al. 2013). Largemouth Bass are now the most abundant piscivorous fish in the San Francisco Estuary Delta. Major prey items include Red Swamp Crayfish (Procambus clarkii) and non-native centrarchids, but predation on native fishes is also a concern (Weinersmith et al. 2019). Caging experiments in the Delta indicated that predation on Chinook Salmon was greatest in enclosures with submerged aquatic vegetation (Zeug et al. 2020).

In a survey of 1780 anglers in the San Francisco Delta complex, 30% of anglers reported fishing for 'Black Bass', dominated by Largemouths. Total value of sportfishing in the Delta for 6 major fishes (including 'Black Bass) was estimated at $470,280,821 (The Program for Applied Research and Evaluation, California State University 2013). We do not have the data to subdivide this figure, but indcates a substantial value for the Largemouth Bass sport fishery.