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The treatment performance of a 6 m wide by 67 m long by 0.8 m deep, baffled sedimentation basin receiving rainbow trout ( Oncorhynchus mykiss ) raceway effluent was evaluated with and without the installation of artificial substrates (Aquamats ® ). Treatment efficiency was also determined using normal rearing condition effluent loading versus cleaning and harvesting events. Total suspended solids (TSS) removal for the total basin averaged 79% and 71% during normal rearing conditions, as compared to 92% and 79% during cleaning and harvesting operations, when the Aquamats ® were installed versus removed, respectively. Total phosphorus (TP) removal by the total basin, with and without Aquamats ® , was 20% and 23% during normal rearing conditions as compared to 55% and 65% under cleaning and harvesting conditions, respectively. Higher TP removal during cleaning operations was attributed to sedimentation of particulate fractions. Dissolved nutrient removal ( ortho -phosphate (OP), total ammonia nitrogen (TAN), nitrate, nitrite, and total organic carbon (TOC)) was not consistent throughout the basin and did not improve when the Aquamats ® were installed. A short contact time and periphyton grazing by isopods may have limited the capacity of the Aquamats ® . Calculated retention times with and without Aquamats ® for the first half and total basin were 37% and 32% and 27% and 17% less than theoretical values, respectively based on a rhodamine WT dye study. Average surface overflow rates were adjusted accordingly and measured 19.1 m 3 /m 2 day when the Aquamats ® were installed, versus 14.8 m 3 /m 2 day when the Aquamats ® were removed for the overall basin. These rates are lower than previous recommendations for treating aquaculture effluents, but resulted in high solids removal and consistently low TSS effluent (average 2 mg/L by 50%. For the first half of the sedimentation basin, the overflow rate averaged 44.1 m 3 /m 2 day with Aquamats ® versus 35.8 m 3 /m 2 day without Aquamats ® . The majority of effluent treatment occurred within the first half of the basin, which was responsible for 84% and 94% of overall TSS removal, 42% and 100% of overall NH 3 -N removal and 61% and 80% of overall TP removal during normal and cleaning/harvesting conditions, respectively.

The leaching of nutrients from settled rainbow trout ( Oncorhynchus mykiss ) sludge into overlying water was evaluated over a 7-day period. Nutrient leaching was assessed in a stagnant reaction tank and one agitated by aeration to simulate turbulent conditions in stocked production raceways. Leaching of total phosphorus (TP), ortho -phosphate (OP), total Kjeldahl nitrogen (TKN), total ammonia nitrogen (TAN), and total organic carbon (TOC) occurred rapidly during the first 24 h in both stagnant and agitated conditions. The highest 24 h leaching occurred in the agitated tank, and power regression equations accurately described the varying rates of increasing TP, OP, TAN and TKN. In the stagnant tank, linear increases of TP, OP, TKN and TAN concentrations occurred during the first 24 h. These linear increases continued from days 2 to 7, but at slower rates than occurred during the first 24 h. Average nutrient leaching rates (mg leached/g sludge-h); (dry weight basis) were calculated based on linear concentration increases. In the agitated tank, nutrient concentrations decreased after 60 h, as aerobic bacterial uptake and/or chemical precipitation was suspected. Therefore, average leaching rates could not be determined. These findings reveal that daily cleanout of settling areas could eliminate the release of TP, OP, TAN, TKN, and TOC from settled solids by 66%, 65%, 39%, 76%, and 51%, respectively, as compared to weekly cleanout schedules. Sustained leaching rates indicate nutrient release will likely continue beyond 7 days. This information suggests aggressive and continuous sludge management is most beneficial for maintaining high water quality and regulatory discharge compliance in fish production.

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...

Five Virginia trout farms were selected for examination of effluent impacts on downstream water quality, periphyton production, and composition of macroinvertebrate and fish communities during fall 1994 and summer 1995. Annual trout production and feeding rates varied from 18.5 to 59.5 thousand kilograms and 15.6 to 87.6 thousand kilograms, respectively, and were correlated with discharge. Substrate embeddedness increased significantly (P < 0.07) downstream at two farms, but settleable solid concentrations in effluent were always less than 0.1 mL/L. Total ammonia nitrogen, un-ionized ammonia nitrogen, and nitrite nitrogen levels increased significantly (P < 0.001) downstream but were well below recommended thresholds for lethal exposure for aquatic organisms. Dissolved oxygen levels were significantly reduced (P < 0.001) downstream at postfeeding and predawn hours but were typically greater than 7.0 mg/L. Effluent water temperatures, pH, nitrate nitrogen, and total phosphorus concentrations did n...

Annually-spawning sunshine bass (Morone chrysops×M. saxatilis) were exposed to 6-, 9- or 12-month photothermal regimes. Abbreviated (phase-shifted) cycles were produced by excising photothermal conditions corresponding to May 17 to August 17 (9-month cycle), or May 17 to November 17 (6-month cycle), from a simulated annual cycle. Phase-shifted cycles reduced the interval between spawning and ovarian recrudescence, advancing gonadal maturation 2 to 3 months, and permitting off-season (December and January) spawning. Rapid gonadal growth began in June (6-month), July (9-month) and August (12-month cycle), coincident with decreasing artificial photoperiods and water temperatures. The offset in initiation of maturation persisted through final maturation, as females in the 6-, 9- or 12-month cycles matured after different periods of photothermal exposure (206, 240 and 268 days, respectively). Maximum oocyte diameters (855, 893 and 844 μm) were similar among females on all cycles. All females underwent final oocyte maturation (FOM) and ovulated after human chorionic gonadotropin (hCG) injection. Testicular growth among males on the three cycles began simultaneously (June). Maximum testicular diameters (11.2, 11.9 and 11.5 mm, respectively) were achieved after 153, 174 and 199 days in the 6, 9 and 12-month cycles, respectively. Milt was produced by >90% of the males in each treatment, and the duration of production was proportional to the cycle length, lasting 38, 42 and 91 days in the 6, 9 and 12-month cycles, respectively. Sperm concentration, duration of motility, and seminal fluid pH differed among males on the three cycles, but these differences produced no changes in fertilities, which averaged 69, 59, and 68% for fish on the 6-, 9- or 12-month cycles, respectively. All sunshine bass held on a second, sequential 6-month cycle developed mature gonads and were induced to spawn. However, peak oocyte and ovarian diameters were reduced and fertility was low (29%), suggesting additional time was needed for gonadal maturation. The good reproductive performance of fish exposed to 6- and 9-month phase-shifted periods indicates that shortened cycles are effective for inducing off-season maturation of sunshine bass, and suggests merit in evaluating the efficacy of phase-shifted cycles to advance maturation of higher-value striped bass broodstock.

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...

Ultrasound images of the gonads of adult striped bass (Morone saxatilis) were recorded monthly to determine their efficacy in sexing and evaluating maturation status of broodstock throughout the year. The sex of adult (age V) broodfish was readily distinguished (95% accuracy) throughout the annual reproductive cycle. Adult (age II) female hybrid striped bass (M. saxatilis×M. chrysops) also were accurately (100%) sexed, whereas juvenile (age 1+) and adult (age II) male hybrids could not be accurately (42 and 45%, respectively) sexed with ultrasound. The maturational status of adult (age V) fish was readily differentiated throughout the annual cycle from cross-sectional measurements of gonad diameters on ultrasound scans. Maximum monthly ovary diameter ranged from a 11.4 mm in September to 26.3 mm at ovulation in March. Maximum monthly testes diameter ranged from 4.6 mm in July to 25.5 mm in March. Spermiating males exhibited larger mean (maximum) testicular diameters (23.5 mm) than non-spermiating males (13.1 mm). Maximum ovarian diameter was highly correlated (r=0.92) with oocyte diameter. Maximum gonad size, determined from scans of the entire gonad, proved to be a more consistent index of maturity than average gonad size. Ripe female and spermiating male striped bass can be characterized as having maximum ovarian and testicular diameters of > 30 and 20 mm, respectively, although fish with smaller gonads may be capable of spawning. Ultrasound is a simple, effective, and non-invasive method to sex and assess maturational status of adult striped bass and perhaps other commercially and ecologically valuable (endangered) species.

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...

Various seafood processing wastes were collected, analyzed, and evaluated for their use as primary protein sources in catfish diets. Finfish wastes (flounder racks and mixed finfish) were higher in crude protein content (60 versus 40%) than blue crab (Callinectes sapidus) wastes. Practical diets containing menhaden (Brevoortia spp.) fish meal or one of four seafood processing wastes (flounder racks, mixed finfish, blue crab, and blue crab without carapace) amounting to 10% of the diet were fed to fingerling channel catfish (Ictalurus punciatus) for 7 weeks under controlled, laboratory conditions. Weight gain and feed efficiency did not differ among treatments. Similar diets containing Atlantic herring (Clupea harengus) or blue crab meal were compared with a standard production diet containing fish meal in a 139-d field cage culture experiment. Caged channel catfish fed the control or Atlantic herring diets had greater daily gain and net production than those fed the crab diet.

Intermolt adult and juvenile Cambarus bartonii bartonii (Fabricius) from southern Appalachian Mountains streams tolerated considerable acidity when acutely exposed to greatly reduced pH levels in laboratory bioassays. Tolerance increased with increasing size or age of crayfish. Ninety-six-hour exposures yielded LC50 values of pH 2.43, 2.56, and 2.85 for adults, advanced juveniles, and early juveniles, respectively. Lowering the water temperature increased the acid tolerance and survival time of intermolt adults during severe acidification (temperatures ranged from 20.2 to 13.3 °C). Acid exposure of intermolt adults in soft water up to 96 h caused a linear decrease in hemolymph [Na]. Hemolymph [Ca] increased through 48 h and then returned to near pre-exposure levels. An initial increase in [K] was followed by a decrease to slightly below pre-exposure levels. Hemolymph [Mg] remained unchanged. No Ca was lost from carapaces. These observations indicate that occasional episodes of higher than normal acidity in southern Appalachian streams are not necessarily a threat to intermolt adult and juvenile C. b. bartonii. Nevertheless, gradually increasing acidity and loss of watershed buffering capacity could produce sublethal effects such as altered reproductive activity, or changes in early life history stages and more sensitive molt cycle stages, that could damage these populations.

Adult striped bass (Morone saxatilis) were matured under compressed 6- and 9-month photothermal cycles or under a 12-month control cycle. The length of their reproductive cycle was proportional to the length of the photothermal cycle to which they were exposed. Maturational changes in circulating levels of the yolk precursor vitellogenin (VTG) and of sex steroid hormones were similar in all groups of fish. Levels of VTG increased progressively in the blood plasma of maturing females and were highly correlated with oocyte diameter, but profiles of circulating estradiol-17 beta (E2) and testosterone (T) were biphasic. Plasma levels of E2 and T were low during most of oocyte growth, increasing sharply to peak levels just before spawning. Spent or regressed females had nondetectable or low plasma levels of the hormones and VTG. In males, plasma 11-ketotestosterone (11-KT) and T were sustained at low levels during most of the reproductive cycle, increasing only during spermiation. The main endocrine effect of compressing the photothermal and gametogenic cycles was to shorten the early period of sustained low hormone levels, during which most oocyte growth and the early stages of spermatogenesis occur. Consequently, final oocyte size and ovary or testes diameter were diminished in fish matured on short cycles. Photothermal cues appeared to initiate and terminate the reproductive cycle, but between these times, maturation rate and circulating levels of gonadal steroids were unresponsive to photothermal periodicity.

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...

During May 1979, 1,061 catchable-sized, hatchery-reared rainbow trout (Salmo gairdneri), brook trout (Salvelinus fontinalis), and brown trout (Salmo trutta) were tagged and stocked in pool and riffle habitats in Big Stony Creek, Giles County, Virginia. Of this total, the movement patterns of 275 recovered trout were determined through voluntary tag return and creek census information. Most (75%) of the trout were recovered within 1 km of their respective release sites; 16% remained within the initial stocking locations. Most of the recaptured brook trout (69%) and rainbow trout (59%) were recovered downstream, whereas brown trout (69%) moved primarily upstream. The median dispersal distances for brook trout (195 m downstream) and rainbow trout (60 m downstream) were not significantly different from one another, but were significantly different (P < 0.001) from that of brown trout (90 m upstream). Although trout stocked in pools generally exhibited less movement than those stocked in riffles, the ...