Greg A. Kindschi

Method for Quantifying Degree of Fin Erosion

Abstract An equation was developed for comparing the degree of fin erosion among populations of the same fish species, regardless of fish size, or against a reference population with uneroded fins: fin factor (%) = (fin length x 100)/(total length). This replaces more subjective approaches used in the past for estimating the degree of fin missing.

Elevated Water Temperature, Crowding, and Food Deprivation Accelerate Fin Erosion in Juvenile Steelhead

Abstract We studied the effects of water temperature, density as measured by density index (DI), and food deprivation (alternating cycles of daily feeding and fasting) on dorsal fin erosion of steelhead Oncorhynchus mykiss through a factorial experiment lasting 22 weeks. Dorsal fin index (DFI) correlated inversely with age, length, and weight of fish and was significantly affected by crowding (i.e., DI). Increasing DI (from 0.0 to 0.5) also improved feed conversions and slightly depressed survival, but DI had no significant effects on weight gain, condition (K), or carcass composition. Water temperature (10°C or 15°C) had a strong and significant effect on DFI; colder water improved DFI while slowing body growth. Low temperature treatments improved survival slightly and altered carcass composition by increasing moisture at the expense of fat and protein. The effects of density and temperature were also strongly interactive. Food deprivation slightly improved final DFI at low DIs, but greatly reduced the a...

Noninvasive, mass marking of fish by immersion in calcein: evaluation of fish size and ultrasound exposure on mark endurance

Calcein was administered into the caudal fin rays of three different sized rainbow trout Oncorhynchus mykiss (0.2, 0.3 and 1.0 g). Two different delivery techniques were studied: immersion and immersion preceded by a 30-s ultrasound exposure. The presence of fluorescent marks in the rays of the caudal fins was monitored at different times post treatment up until 12 months, and the delivery techniques were compared by determining the average pixel luminosity of digitally captured fluorescent images of the rays. The experimental fish were also monitored throughout the study period in terms of both growth and survival. Differences were not found in growth rates between control fish and the different treatments within any of the size groups. The same was true for survival rates. Endurance of the marks produced in the fish was found to be controlled by two distinct factors. The more dominant of the two was the size of the fish at the time of treatment, where a positive correlation was found between mark endurance and fish size. Ultrasound exposures were found to increase mark endurance in the small- and medium-sized fish. Although a steady decrease in luminosity was found in the marks of the fish over time, differences were not found between the ultrasound and non-ultrasound treated fish in the large group over the period of sampling. Results of the study will contribute to the development of a non-invasive, mass marking and nonlethal mark retrieval procedure of hatchery-reared fish in both aquaculture and stock enhancement programs. The results will also benefit ongoing research for using ultrasound as a non-invasive method for mass administering compounds into fish.

Effects of Surface Water Spray, Diet, and Phase Feeding on Swim Bladder Inflation, Survival, and Cost of Production of Intensively Reared Larval Walleyes

Abstract Three experiments were conducted to determine the effects of a surface water spray and diet on survival and swim bladder inflation of intensively reared larval walleyes. Survival and swim bladder inflation were determined at 30 d posthatch. In each experiment, 275-L cylindrical tanks were stocked with 20 fry/L. In experiment 1, a spray of water was applied to the surface of three tanks, and three additional tanks received no surface spray. BioKyowa FFK-B diet was fed to fish in all tanks. Survival of fish with the spray (11.8%) and without the spray (9.1%) was not significantly different, but the incidence of swim bladder inflation was higher with (98.4%) than without the spray (51.7%). In experiment 2, larval walleyes were fed one of three commercially available larval feeds—FFK-B, San Francisco Bay Brand EPAC, and Zeigler Larval AP200—and all tanks received a surface spray. Only the fish fed FFK-B had reasonable 30-d survival (33.1%) and swim bladder inflation rates (95.6%). In experiment 3, ph...

Survey of Swim Bladder Inflation in Walleyes Reared in Hatchery Production Ponds

Abstract We examined pond-reared fingerling walleyes (Stizostedion vitreum) for inflation of the swim bladder at harvest. We evaluated 120,064 fish from 15 facilities in nine states during 1989, 1990, and 1993. Samples of walleye were collected from 188 ponds, and only 3.5% (4,229) of the fish examined lacked an inflated swim bladder during the 3-year period. Walleyes with uninflated swim bladders were observed at each facility during one or more years. Of the 188 ponds, 53.7% (101) contained walleyes that lacked inflated swim bladders, and these fish (after freezing) were shorter and lighter in weight and had less body fat than walleyes with inflated swim bladders. There appeared to be no relationship between size of fish at pond harvest and the incidence of swim bladder inflation in any pond. Incidence of uninflated swim bladders reached 55% in one pond. Although only a small percentage of walleyes overall lacked an inflated swim bladder in this survey, we feel that walleye fingerlings should be sampled...

Performance and Oxygen Consumption of Snake River Cutthroat Trout Reared at Four Densities with Supplemental Oxygen

Abstract Snake River cutthroat trout (Oncorhynchus clarki) of the Bar BC strain were reared at four densities in triplicate for 18 weeks. Supplemental oxygen was required in the rearing units holding the three highest densities to maintain adequate dissolved oxygen (DO) levels of 6–7 ppm (61–71% of saturation) after the last feeding in the afternoon. Density indices (lb!ft3 per inch of fish length) achieved for each treatment averaged 0.48, 1.40, 2.12, and 2.30, and fish density averaged 3.43, 10.56, 15.56, and 15.42 lb/ft3, respectively, at the conclusion of the study. Survival, weight gain, feed conversion, and fish health were adversely effected by increased density; however, dorsal and pectoral fin condition, total length, length variation, and water quality were not adversely effected. Neither un-ionized ammonia (maximum, 0.0051 ppm) nor total carbon dioxide (maximum, 24.2 ppm, pH 7.5) concentrations reached detrimental levels. Over a 24-h period at the end of the study, daily DO consumption averaged...

Use of Raceway Baffles in Rainbow Trout Culture

Abstract Aluminum baffles were installed in two raceways and tested for use in a production situation. Rainbow trout (Oncorhynchus mykiss) of the Eagle Lake strain were reared for two studies (211 and 157 d) conducted in consecutive years. During the first study, we evaluated two raceways with baffles and two without. In baffled raceways, dorsal fin quality of the fish was improved and cleaning time was shortened. However, feed conversion was more efficient in control raceways without baffles. Weight gain, mortality, total length, and condition factor of fish and suspended solids in the effluent water did not differ between raceway types. During the second study, the baffled raceways were not equipped with a settling area; instead, baffles were added at the downstream end of the raceway, so solids were continually flushed. Among the variables monitored, only cleaning time was affected, because the baffled raceways were self-cleaning. Two major fish mortalities (1,101 and 4,442 fish) resulted from suffocat...

Enhanced transport of calcein into rainbow trout, Oncorhynchus mykiss, larvae using cavitation level ultrasound

Enhanced diffusion of calcein into rainbow trout, Oncorhynchus mykiss, larvae was examined using cavitation level ultrasound for the purpose of mass-marking. Three variables, consisting of two voltage amplitudes (90 and 120 mV), two calcein concentrations (600 and 900 mg/l) and two duration of treatments (5 and 15 min) were examined. Thirty-day-old yolk sac fry (n=640) were treated with calcein and/or ultrasound. Overall mean diffusion of calcein ranged from 3.8 to 36.2 ng/fish. The highest absorption level was observed with highest amplitude applied for 15 min in 900 mg/l of calcein solution. Significantly higher diffusion resulted with 120 mV when compared against 90 mV (P<0.05). A high level of background autofluorescence (7.8 ng/fish) was also measured. Results from these experiments demonstrate that a several-fold increase in the rate of diffusion of calcein into fish can be achieved when treated with cavitation level, low frequency ultrasound (40 kHz and 90 or 120 mV). The technique has potential for use in delivery of compounds for marking fish as well as for delivery of therapeutants such as vaccines and antibiotics.

Performance of Two Strains of Rainbow Trout Reared at Four Densities with Supplemental Oxygen

Abstract Wild and domesticated strains of rainbow trout (Oncorhynchus mykiss) were reared in triplicate groups at four fish densities in two separate studies. Fish weight gain, survival, length increase, length variability, feed conversion (weight fed/weight gain), dorsal fin condition, fish health, and water quality were monitored during each 4-month test. Dissolved oxygen was supplemented to maintain afternoon effluent oxygen levels at 6–7 ppm (61–71% saturation). Survival decreased with increasing density for both strains: wild strain survival was reduced because of cannibalism, and domesticated strain survival was reduced because of mechanical failures that reduced dissolved oxygen. Weight gain and total length increased with increasing densities for the wild strain, but the opposite occurred for the domesticated strain. Length coefficient of variation (SD/mean) increased directly with increasing fish density. Feed conversions of both strains were adversely affected by increased densities, but dorsal ...

Oxygen Consumption of Two Strains of Rainbow Trout Reared at Four Densities with Supplemental Oxygen

Abstract Dissolved oxygen (DO) consumption, concentrations of ammonia and carbon dioxide, and pH were monitored in two studies with wild and domesticated strains of rainbow trout (Oncorhynchus mykiss). Each strain was reared at four densities for 4–5 months during which supplemental oxygen was added to maintain between 6 and 7 mg DO/L in the effluent water. As fish became larger, their DO consumption decreased. No differences in average DO consumption of rainbow trout were caused by the different rearing densities for each 2-week period. During the study, rainbow trout of the wild Eagle Lake strain and domesticated Arlee strain consumed DO at an average rate of 213 (SD, 45) and 233 (SD, 47) mg/kg of fish per hour, respectively. There were two periods of daily maximum DO consumption – during the first daily feeding and after the last daily feeding. The daily DO consumption averaged 190 g/kg of feed (SD, 22) for fish of the Eagle Lake strain and 241 g/kg of feed (SD, 30) for the Arlee strain. Neither ammoni...