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The effects of oxygenation and aeration on water quality and the production of rainbow trout Oncorhynchus mykiss were compared in eight raceways from 2002 to March 2003. Mean dissolved oxygen (DO) concentrations were significantly higher in the oxygenated (9.5 mg/L) than aerated raceways (7.4 mg/L). Total sedimented solids loads per day were significantly greater in aerated (10.3 g/L) than oxygenated (8.8 g/L) raceways. Dissolved nitrogen, total gas pressure, and other water quality variables (CO2, NO2 −, total ammonia nitrogen, alkalinity, and pH) did not differ significantly between the treatments. Trout carrying capacity was significantly higher (1,138 kg/raceway) in the oxygenated raceways. However, trout production, growth rates, feed conversion rate, hematocrit, and fish survival were not significantly different between treatments. Oxygen injection was an effective method of increasing carrying capacity and improving water quality by reducing effluent solids loads, but it did not enhance tr...

Immediate and delayed (96 h) mortality, descaling, and injury rates of striped bass Morone sax-atilis and rainbow trout Oncorhynchus mykiss that were inserted into the entrance (suction side) of a Hidrostal pump were compared to those of control fish that were inserted at the exit (pressure side). Comparisons were made in 158-paired trials of striped bass and 86 trials with rainbow trout. The Hidrostal pump had no significant effect on immediate or delayed (96 h) mortality. Immediate mortality for striped bass and rainbow trout averaged 0.1 and 0%, respectively, and delayed mortality averaged 2.9 and 0.1%, respectively. Mean scale loss after passage for striped bass and rainbow trout was low (0.2 and 1.0%, respectively). Frequency of injury to the head, eyes, skin, and tins of pumped striped bass averaged 1.9, 2.8, 1.9, and 18.7%, respectively, and those of rainbow trout averaged 2.3, 0, 2.4, and 3.1%. No significant relationships were detected between fish mortality and pump speed, injected fish density, and debris load. Results suggest that large Hidrostal pumps have the capacity to transport live striped bass and rainbow trout at high density (1-6 fish/L) with little mortality and body injury.

We examined the cortisol stress response of juvenile chinook salmon Oncorhynchus tshawytscha to passage through Archimedes lifts and a Hidrostal pump operating at speeds used for commercial water delivery. In 1998, plasma cortisol was measured for Archimedes-passed salmon at 0, 1, 3, 6, 12, and 24 h after passage. Concentrations among treatment groups did not differ significantly from those among control groups, which were treated similarly but not passed through pumps. In 1999, cortisol was measured at 0, 1, 1.5, 3, 6, and 12 h after passage for both pump types. Concentrations did not differ significantly between treatment and control groups for the Archimedes lifts. A relatively small pump effect, less than 50 ng/mL of cortisol, was measured for the Hidrostal pump 3 h after passage. A handling control comparison demonstrated that much of the measured stress response was due to capture, confinement, and transport of fish before insertion into pumps. In general, these results indicated that pump-...

The passage survival, descaling, and injury rates of marked splittail Pogonichthys macrolepidotus and juvenile chinook salmon Oncorhynchus tshawytscha that were inserted into the entrance (suction side) of a Hidrostal pump were compared with those of control fish inserted at the exit (pressure side) in 130 paired trials conducted from December 1998 to July 1999. The Hidrostal pump had no significant effect (P < 0.001) on immediate or latent (96-h) mortality, descaling, or body injury rates for all flow rates and sizes and densities of fish tested, except for the 96-h mortality of splittail in June. The immediate survival rates for splittail and chinook salmon averaged 99%, and the cumulative (96-h) survival for these species averaged 93% and 96%, respectively. Average scale loss on splittail and chinook salmon usually was low (1.9% and 2.4%, respectively), and the frequency of injury to head, eyes, skin, and fins typically was low and not significantly different among quality control, control, an...

The effect of infrared (>880 nm) and visible (400–700nm) illumination was compared to determine delay rates (percent of population) and delay times (min) of migratory chinook salmon Onchorhynchus tshawytscha, coho salmon O. kisutch, and steelhead (anadromous rainbow trout O. mykiss) in the fish ladder viewing chamber at Prosser Dam during the fall 1996 spawning season. Overall, a significantly (P < 0.05) greater proportion of migratory fish were delayed under visible (41%) than infrared illumination (28%). Species-specific comparisons indicated that significantly (P < 0.05) greater numbers of chinook and coho salmon were delayed under visible (57% and 33%, respectively) than infrared (25% and 12%, respectively) lighting. No significant difference was detected in the proportion of steelhead delayed under visible (35%) and infrared (25%). Passage rates for chinook salmon under infrared light were significantly (P < 0.001, chi square = 10.12) greater at night (70%) than day (30%), whereas under visi...

Continuing education priorities of 696 fisheries biologists and 185 natural resource agency administrators in 48 state agencies were requested by mail questionnaire and assessed in November 1993. The survey indicated that fisheries biologists were remarkably homogeneous in their continuing education needs regardless of job title, years of professional experience, level of education, or geographic location. Fisheries biologists identified high demands for continuing education in computer science, data collection and analysis, experimental design, and database management. The great demand for these particular skills indicates the popularity of computer technology and the growing recognition of the importance of and costs associated with collecting and managing fisheries data. Other areas of high educational demand were population biology (limiting factors, demographics) and habitat management (restoration, enhancement, protection). Agency administrators placed a higher priority on nontechnical skil...

Photoperiod and temperature manipulation were used to induce out-of-season spawning in striped bass Morone saxatilis Maturational status of 40 age V striped bass, held in five environmental chambers exposed to compressed 6 mo and 9 mo cycles and a 12 mo reference cycle, was monitored by monthly egg and gonadal (ultrasound) diameter measurements. The primary effect of shortened photothermal and reproductive cycles was a reduction in egg and ovary diameters, and the number of ovulating females. Egg diameters were directly related to cycle length, averaging 845 μm, 946 μm, and 1,073 μm for females held on the 6, 9, and 12 mo cycles, respectively. Ovary diameters of females held on the 6 mo cycle were smaller (19.6 mm) than those held on the 9 mo (27.4 mm) and 12 mo (24.5 mm) cycles. Ovary diameter was highly correlated with egg diameter (r= 0.91). The number of ovulating females decreased with cycle length, totalling 38%, 88%, and 100% in the 6, 9, and 12 mo cycles, respectively. However, no differences in fecundity (58,452 eggslkg) or fertility (39%) were detected between photothermal treatments or tank-spawned and strigspawned females. When held for a second 6 mo cycle, none of the females spawned repetitively. Males held on the 6 mo cycle had smaller testicular diameters (16.2 mm) than those held on 9 mo (23.6 mm) and 12 mo (19.2 mm) cycles. Testicular diameter of spermiating males (15.7 nun) was significantly larger than that of non-spermiating males (6.9 mm) in all cycles. The low number of spawning females and small egg, ovarian, and testicular diameter offish held on the 6 mo cycle suggest that subjecting striped bass brood stock to an abbreviated cycle length (

Pond management information available to the public was assessed by content analysis of the 56 educational bulletins provided by 79 state and federal agencies in 43 states. This review indicated that an abundance and a high diversity of pond management information is available to the public in most states, except for those (primarily western states) with limited surface water resources. Certain pond management practices (stocking, population balance, weed control, fertilization, and construction) dominated the literature; fish health, habitat management, and socioeconomic aspects were treated less comprehensively. Suggested improvements to subsequent bulletins include: (1) updating the content to reflect changes in management knowledge; (2) clarifying the economic and ecological consequences of herbicide, piscicide, and fertilization applications; (3) expanding coverage to include socioeconomic benefits and liabilities of ownership; (4) developing regional or multistate sponsored bulletins to fac...

A population of rainbow trout (Salmo gairdneri) in two sections of the South Fork Holston River, Virginia was sampled quarterly from November 1979 to October 1980 to determine abundance, biomass, and annual production. Densities of trout varied from 592 to 1,734 per hectare, and mean biomass from 3.13 to 4.30 g/m 2. Age composition during the year consisted of 17% Age 0, 60% Age 1, 21% Age 2, and 3% Age 3. Mean annual production (3.6 g/m 2) was similar to other reported estimates for rainbow trout, and generally exceeded those obtained for endemic brook trout (Salvelinns fontinalis) in the southern Appalachians.

Public education programs, audiences, communication strategies, and characteristics of 16 Cooperative Extension Service fisheries specialists in 12 states were examined from responses to a mail/telephone survey. Fisheries specialists expended an average of 50% of their time on education related to fish production and about 25% each on education concerning aquatic pest control and general aquatic resources. Audiences served, in order of priority, were extension agents, landowners, fish farmers, general public, youth groups, university faculty and students, natural resource agency personnel, and citizen conservation organizations. Specialists relied heavily on telephone calls, letters, and extension publications, and used group meetings (conferences and workshops) to a lesser extent. Least used methods were the electronic media, magazine articles, and technical publications. Similarities in public education programs, audiences, and communication techniques used by specialists nationwide provided a ...

Mortality of larval bluegills Lepomis macrochirus from predation was measured in 56 nests guarded by males and 21 nests from which the male guard was removed. Mortality was significantly greater in unguarded nests (median = 68%) than in guarded nests (median = 14%). Fish traps placed in unguarded nests captured significantly more predators than traps placed in guarded nests. Bluegills (3–12 cm total length) were the most abundant nest predators. Pumpkinseeds Lepomis gibbosus (7–11 cm), largemouth bass Micropterus salmoides (4–5 cm), and whitefin shiners Notropis niveus (5–6 cm) also were nest predators. Nest preparation by male bluegills exposed coarse gravel (8–32 mm diameter) and pebbles (32–64 mm) in nest substrate and removed particles smaller than 2 mm. Particles larger than 8 mm provided suitable interstitial space to accommodate bluegill larvae. Survival of larvae was directly correlated with the proportion of coarse substrate in the nest.

On-site interviews and a mail questionnaire survey of 377 anglers on two Virginia rivers were used to evaluate the concept of recreational specialization for differentiating angler subgroups. Specialization was defined for four dimensions of angler behavior: (1) fishery resource use, (2) experience, (3) investment, and (4) centrality of angling to lifestyle. Six types of anglers, representing low to high levels of specialization, were identified by cluster analysis. The experience dimension was the most important contributor to the framework, accounting for 24% of the variance in the data. A combination of the resource, investment, and centrality dimensions explained 48% of the variance. Highly specialized anglers were likely to cite resource-related motives (e.g., trophy fish), to rely on skill to catch fish, to prefer to catch and release larger fish, and to favor restrictive harvest regulations. Less specialized anglers cited escape and family-oriented recreation as motivations for fishing, pl...