The use of stocking programs to rehabilitate depressed populations of lake sturgeon Acipenser fulvescens requires the optimization of early life stage growth in hatchery settings. We evaluated the performance of juvenile lake sturgeon fed different proportions of two natural food types—adult brine shrimp Artemia spp. and larval bloodworms Chironomus spp.—over a 10‐week laboratory experiment. The following five diet treatments were provided: (1) 100% bloodworms; (2) 75% bloodworms : 25% brine shrimp; (3) 50% bloodworms : 50% brine shrimp; (4) 25% bloodworms : 75% brine shrimp; and (5) 100% brine shrimp. Lake sturgeon growth was positively related to bloodworm content in the diet and was significantly different among treatments. Although the initial sizes of fish were similar, mean fork length and wet weight were greatest for the 100% bloodworm treatment (183.1 mm and 37.5 g, respectively) and lowest for the 100% brine shrimp diet (118.4 mm and 9.5 g) by the end of the study. Mean specific and absolute growth rates in length (0.93% and 1.28 mm/d, respectively) and weight (2.61% and 0.45 g/d) were greatest for the 100% bloodworm diet, followed by the other treatments in order of decreasing amount of bloodworms in the diet. Percent weight gain (525%) and food conversion efficiency (67%) were also greatest for the 100% bloodworm diet, followed by the other treatments in order of decreasing dietary bloodworm content. Whole‐body protein (13.9%), lipid (2.5%), and gross‐energy (3.77 kJ/g) content were greatest for fish fed 100% bloodworms, with these proximate‐composition measures also ranked in order of decreasing dietary bloodworm content for the other treatments. We recommend that juvenile lake sturgeon reared in hatchery environments be fed high proportions of bloodworms to maximize growth, body size, and lipid content for rehabilitation stocking programs.

We evaluated the effects of four absorbable suture strand diameters (numbers 3/0, 0, 1, and 2 [from smallest to largest diameter]) on the short‐term retention of externally attached dummy radio transmitters by juvenile lake sturgeon Acipenser fulvescens (fork‐length range, 257–293 mm; wet‐weight range, 100–132 g). Four lake sturgeon were contained in each of 10 aquaria, and one fish in each tank was assigned to each of the four suture treatment groups. Transmitter retention was positively related to suture strand diameter, the mean retention duration for number 2 sutures being nearly twice as long (21 d) as that of number 3/0 sutures (11.8 d). The smallest suture (number 3/0) also exhibited the fewest number of days to transmitter loss (25% loss, 9 d; 50% loss, 11 d; and 75% loss, 14 d). In contrast, the largest suture (number 2) had the greatest number of days to transmitter loss (25% loss, 16 d; 50% loss, 21 d; and 75% loss, 26 d). Based on the diameter of sutures examined in this study, we recommend number 2 absorbable sutures for externally affixing radio transmitters to ensure adequate retention of short‐term tags using this novel attachment approach for telemetry studies involving juvenile lake sturgeon.

A floating vertical raceway is a system designed to provide a constant, unidirectional flow of water to fish confined in a flexible raceway that is suspended vertically in the water column. This study evaluated the potential of floating vertical raceways for the culture of phase‐II sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis) reared at two densities (125 and 188 fish/m3). Fish with a mean starting weight of 0.7 g were fed a diet containing 40% crude protein to satiation for 121 d. Fish in the low‐density treatment reached a significantly higher final mean weight (160.0 g) than those in the high‐density treatment (136.9 g). Survival was also significantly higher in the low‐density treatment (81.1%) than in the high‐density treatment (73.8%). No significant differences in water quality were detected for dissolved oxygen, total ammonia, un‐ionized ammonia, or temperature between high‐density and low‐density treatments. Unlike the surrounding reservoir, water temperature inside the raceways remained destratified throughout the growing period. Based on the performance of fish, the high water quality maintained inside the enclosures, and ease of use, the floating vertical raceway system offers considerable promise as an alternative rearing system for deepwater impoundments.

The hatchery performance attributes of three strains (Lake Nipigon [Nipigon], Siskiwit Bay [Siskiwit], and Tobin Harbor [Tobin]) of fingerling coaster brook trout Salvelinus fontinalis were compared during a 12‐week laboratory experiment. Despite similar initial sizes, the final mean length and weight of Nipigon fish (94.1 mm and 9.9 g) were significantly greater than those of the Siskiwit (86.7 mm and 7.7 g) and Tobin (90.4 mm and 7.2 g) strains. There were no differences in mean specific growth rates in length and weight or mean daily growth rate in length among the strains. However, there was a difference in the mean daily absolute growth rate in weight, the Nipigon and Siskiwit strains (0.10%/d and 0.08%/d, respectively) displaying a greater rate of growth than Tobin Harbor (0.07%/d) fish. Mean survival rates (range = 97–98%) and relative weights (range = 100.1–101.1 g) did not differ significantly among the three strains. Based on our results, we recommend that these strains of fingerling coaster brook trout be reared similarly in hatchery environments and that strain selection for rehabilitation stocking purposes consider hatchery residence time and the natural genetic variation of the source population of broodstock fish.