There have been concerns regarding tournament-related impacts on black bass Micropterus spp. for 40 years, but few studies have quantified those impacts. About 52% of anglers at Sam Rayburn Reservoir (46,356 ha) participate in tournaments, and the annual number of events probably exceeds 300. In 2003, we tagged and released 6,021 largemouth bass M. salmoides to estimate the annual proportion of the population caught and retained by tournament anglers. Tag returns were obtained via creel sampling to avoid nonreporting uncertainty, adjusted for recruitment and tag loss, and expanded to estimate the total annual tagged fish catch and harvest. We conducted simulations to evaluate the impacts of tournament mortality using rates of 10, 30, and 50% and compared those estimates with nontournament harvest and catch-andrelease mortality (simulated at 5, 10, and 15%) to assess the specific contributions to annual angling and total mortality. From 3,447 angler interviews, creel clerks identified 40 largemouth bass caught by anglers during the interview day (27 of which were immediately released, 6 harvested by nontournament anglers, and 7 retained by tournament anglers). Expansion of tag returns resulted in 1,620 fish immediately released (27% of tagged population), 372 harvested by nontournament anglers (6% of tagged population), and 274 retained by tournament anglers (5% of tagged population; 242 were released). Tournament and catch-and-release mortality each comprised a total of 1-6% of the population losses across all simulations. Tournament mortality comprised 6-28% of total angling mortality, whereas catch-and-release mortality was 10-31%. Tournament mortality contributed 1-16% of total annual mortality, compared with 2-17% for catch-andrelease mortality and 16-38% for nontournament harvest. We conclude that the tournament-related impacts on the largemouth bass population at Sam Rayburn Reservoir were low.

Since the introduction of striped bass Morone saxatilis and hybrids of striped bass and white bass Morone chrysops into reservoirs, much concern has been directed at the possibility of these predators competing with other sport fishes for limited prey. If density of striped bass is reduced or eliminated through modifications of the stocking program, the prey not consumed by striped bass may be shifted to other sport fishes. The resulting increase in biomass of other sport fishes would be a function of the amount of added prey, the percent of this additional prey eaten by other sport fishes, and the efficiency with which the prey is converted into biomass. We used bioenergetics models to estimate annual striped bass prey consumption in Norris Reservoir, Tennessee. Total annual consumption was estimated at 52 kg/ha (estimated range ϭ 17-100 kg/ha), clupeids accounting for the majority (94%), followed by lepomids (4%) and other food items (2%). Existing biomass of black basses Micropterus spp., crappies Pomoxis spp., and percids Stizostedion spp. was about 65 kg/ha (estimated range ϭ 35 Ϫ 106 kg/ha). Given the complete removal of striped bass, modeling indicated that the most probable increase in the biomass of these sport fishes would be about 3% with a 75% probability that it would be less than 12%. Thus, not even the complete removal of striped bass would measurably increase the biomass of other sport fishes.

Diet overlap and consumption patterns suggest seasonal flux in the likelihood for exploitative competition among piscivorous fishes Un resumen en españ ol se incluye detrás del texto principal de este artículo.

We estimated annual prey supply and predator demand distributions for the fish assemblage of Norris Reservoir, Tennessee, to assess potential prey deficiencies. Prey supply was defined as the surplus biomass that could be removed without affecting future prey generations and was limited to cohorts consumed by predators. Demand was represented by the annual consumption by the predator community (piscivorous fishes) and was estimated with bioenergetics models. Our demand estimates were conservative because predators may have greater demand for prey than what they actually consume. Together, clupeids (gizzard shad Dorosoma cepedianum, threadfin shad D. petenense, and alewife Alosa pseudoharengus) and Lepomis spp. accounted for 80% of overall prey fishes consumed. Median annual demand for clupeids and Lepomis spp. combined was 271 kg/ha (90% confidence interval = 183–552 kg/ha) from August 1996 to July 1997 and 182 kg/ha (92–509 kg/ha) from August 1997 to July 1998. Median supply during these times was 848 kg/ha (103–18,989 kg/ha) and 413 kg/ha (317–540 kg/ha). Dividing supply values by demand values yielded supply–demand ratio distributions with medians of 2.9:1 (0.3:1–67.5:1) and 2.3:1 (0.8:1–4.8:1) for the two periods. Using a historical area–density data set (coves sampled with rotenone; N = 22 years), we found the median annual supply to be 167 kg/ha (49–982 kg/ha), demand to be 109 kg/ha (51–239 kg/ha), and the supply–demand ratio to be 1.5:1 (0.4:1–10.4:1). Historical values of the supply–demand ratio were less than 1:1 (i.e., supply was insufficient to meet demand) 32% of the time. The latter estimate is minimal because the threshold supply–demand ratio (the ratio below which predators are forage limited) was probably greater than 1:1, as predators cannot capture all prey with 100% efficiency and our definition of demand was conservative. We suggest adjusting demand to equal the median historical supply.