Adaptive stocking strategies of Hybrid Striped Bass in a Nebraska reservoir impacted by White Perch

Figures & data

Figure 1. Catch per net night of age-1 and PSD Q-P Hybrid Striped Bass collected in fall gill nets (top) and White Perch collected in fall fyke nets (bottom) in Branched Oak Reservoir from 1988 to 2019 with associated standard error bars. Dotted lines separate stocking eras of spring age-0 (1988-1997), fall age-0 (1998-2015), and spring age-1 (2016-2019) Hybrid Striped Bass (top) and establishment (1989-1996), peak (1997-2013), and recent (2014-2019) periods of White Perch invasion (bottom).

Table 1. Stocking era, year, number of fish stocked, mean TL of stocked fish, and stocking density (fish/ha) of Hybrid Striped Bass in Branched Oak Reservoir, Nebraska, 1988-2019. Asterisks denote years with multiple stocking events.

Era	Year	Number stocked	Mean TL (mm)	Stocking density (fish/ha)
Spring age-0	1988	1,660,000	Fry	922.2
	1989	1,000	32	0.6
	1990	1,765,000	Fry	980.6
	1991	25,000	25	13.9
	1992	1,906,000	Fry	1,058.9
	1993	17,860	76	9.9
	1994	18,030	89	10
	1995	22,850	76	2.7 − 10*
	1996	17,688	76	1.9 − 4.9*
	1997	17,250	79	9.6
Fall age-0	1998	18,000	140	10
	1999	32,625	122	18.1
	2000	87,050	135	48.4
	2001	92,835	135	51.6
	2002	13,992	168	7.8
	2003	2,573	178	1.4
	2004	1,890	127	1.1
	2005	3,000	109	1.7
	2006	3,106	178	1.7
	2007	1,468	203	0.8
	2008	3,900	147	2.2
	2009
	2010	7,365	137	4.1
	2011	8,500	127	4.7
	2012
	2013	6,895	137	3.8
	2014
	2015
Spring age-1	2016	3,988	197	2.2
	2017	980	203	0.5
	2018	5,200	160	2.9
	2019	2,693	152	1.5

Figure 2. Catch per net night of PSD Q-P (top) and age-1 (bottom) Hybrid Striped Bass collected with fall gill nets during fall age-0, spring age-0, and spring age-1 stocking eras at Branched Oak Reservoir. Letters above plots denote significant differences among eras.

Figure 3. Linear regressions of age-1 Hybrid Striped Bass catch per net night from fall gill nets plotted against White Perch CPUE, spring inflow (cfs), spring elevation (m), fall elevation (m), spring water temperature (°C), and summer water temperature (°C). Associated r² and P-values included for relationship description.