Michael E. Barnes

A Review of Flavobacterium Psychrophilum Biology, Clinical Signs, and Bacterial Cold Water Disease Prevention and Treatment

Bacterial coldwater disease and other infections caused by Flavobacterium psychrophilum are a worldwide concern, particularly for freshwater salmonid hatcheries. F. psychrophilum infections can be difficult to control; antibiotic resistance is common and no effective vaccines are currently available. This review summarizes the biology and charac- teristics of this important pathogen, as well as the techniques required for isolation and identification. In addition, the epi- demiology, clinical signs, treatment, and possible preventative measures of bacterial coldwater disease are discussed.

Initial Observations on the Inclusion of High Protein Distillers Dried Grain into Rainbow Trout Diets

An initial investigation into the inclusion of high protein distillers dried grain with solubles (HPDDG) in juvenile rainbow trout Oncorhynchus mykiss diets was conducted during a 36-day feeding trial. Four experimental diets containing either 10% or 20% HPDDG with supplemental amino acids, and either with or without phytase, were compared to a fish-meal-based, non-HPDDG, diet. There was no significant difference among any of the diets in total weight gain, percent weight gain, feed conversion ratio, or percent mortality. There was also no significant difference in length, weight, condition factor, hepatosomatic index, viscerosomatic index, or any fish health parameter in fishes fed any of the diets. Fillet composition, as determined by crude protein, crude lipid, water, and ash were also not significantly different from fish reared on any of the diets. Estimated protein digestibility coefficients were significantly less in the fish receiving the diet void of HPDDG compared to any of the other diets. The addition of phytase had no effect on any rearing parameters. The results suggest that HPDDG, if supplemented with essential amino acids, may be included at concentrations of at least 20% (dry weight) in rainbow trout diets and that more detailed investigation into the use of HPDDG is warranted.

Rainbow Trout Rearing Performance, Intestinal Morphology, and Immune Response after Long-term Feeding of High Levels of Fermented Soybean Meal

AbstractThe incorporation of PepSoyGen (PSG), a commercially produced fermented soybean meal product, was evaluated in a 205-d feeding trial. Three isonitrogenous and isocaloric experimental diets containing 0, 35, or 50% PSG and 40, 15, and 0% fish meal, respectively, were fed to Rainbow Trout Oncorhynchus mykiss. The diets containing either 0% or 35% PSG produced similar total tank weight gains, percent gains, and feed conversion ratios and were significantly different from the diets containing 50% PSG at the end of the trial. Mean individual fish lengths and weights were significantly greater in the fish receiving 35% PSG than either of the other two diets. Specific growth rate (SGR) was significantly lower in the 50% PSG treatment, but there was no significant difference in SGR between the other two diets. Viscerosomatic index was significantly lower in the fish fed 35% PSG. Hepatosomatic index was not significantly different among the diets, but fish receiving 50% PSG had a significantly poorer liver...

Decreased Hatchery Rearing Density Improves Poststocking Harvest and Return to Spawning of Landlocked Fall Chinook Salmon

Abstract Juvenile landlocked fall Chinook Salmon Oncorhynchus tshawytscha were coded-wire-tagged and reared in 1.8-m-diameter circular tanks at a low or high density for up to 52 d prior to stocking in Lake Oahe, South Dakota, during late May of 1999, 2003, and 2004. Final hatchery rearing densities ranged from 7.29 to 11.72xa0kg/m3 for the low-density tanks and from 15.02 to 25.22xa0kg/m3 for the high-density tanks, with the higher densities being at least double the lower densities in each year. Flows were adjusted to maintain similar loadings (kg·L−1·min−1) between the treatments each year. The fish used in this study came from spawns collected during the October prior to stocking; TL at the end of hatchery rearing ranged from 103xa0mm in 1999 to 124xa0mm in 2004. In each year-class, the percentage of fish that were harvested by anglers or that returned to spawn was significantly greater for the lower-density treatment than for the higher-density treatment. Angler harvest primarily consisted of age-3 fish, wit...

Preliminary Evaluation of Rainbow Trout Diets Containing PepSoyGen, a Fermented Soybean Meal Product, and Additional Amino Acids

Juvenile rainbow trout Oncorhynchus mykiss diets containing PepSoyGen, a commercially-available fermented soybean meal product, were supplemented with methionine and other amino acids. A fish meal-based control and four ex- perimental diets were used in a 36-day feeding trial; two diets contained 40% PepSoyGen and 10% fish meal, and two di- ets contained 50% PepSoyGen and no fish meal. Each of these diets was supplemented with either methionine, or me- thionine and additional amino acids. One mortality was observed during the trial. Overall weight gain, percent gain, and feed conversion ratio were significantly greater for the fish meal control than for any of the PepSoyGen diets, although feed conversion ratios from all of the diets were still below 1. Apparent protein digestibility was significantly less in the fish receiving the control diet compared to any of the experimental diets, and significantly increased with increasing Pep- SoyGen concentrations. There was no significant difference in length, weight, condition factor, hepatosomatic index, vis- cerosomatic index, or any fish health responses among dietary treatments. Fillet composition, as determined by crude pro- tein, crude lipid, water, and ash, was also not significantly different among fish reared on any of the diets. The supplemen- tation of other amino acids in addition to methionine had no noticeable effect. The results from this study indicate that PepSoyGen with amino acid supplementation can completely replace fish meal in juvenile rainbow trout grower diets over a relatively short time-frame, albeit with some decrease in rearing performance.

Effects of Different Water Velocities on the Hatchery Rearing Performance and Recovery from Transportation of Rainbow Trout Fed Two Different Rations

AbstractWe examined the effects of exercise on hatchery rearing performance and posttransportation stress recovery, growth, and survival of Rainbow Trout Oncorhynchus mykiss reared for 9xa0weeks in one of three water velocities (0.5, 1.5, or 3.0 body lengths (BL)/s) and fed either a restricted ration or to satiation. The influence of previous exercise regimes on survival, growth, and stress recovery for 8xa0weeks after transportation of the fish fed a restricted ration was also evaluated. During hatchery rearing, reduced growth and poorer food conversion ratios at higher velocities (1.5 and 3.0 BL/s) were only observed in restricted ration-fed fish, with satiation-fed fish exhibiting no differences in hatchery rearing performance among the water velocities. Condition factor changed with exercise regime and was significantly greater in restricted ration-fed fish at 3.0 BL/s and satiation-fed fish at 1.5 and 3.0 BL/s. Hepatosomatic index was unaffected by exercise but was significantly greater in the fish fed t...

Comparative performance of two rainbow trout strains fed fermented soybean meal

The comparative response of the Shasta and McConaughy strains of rainbow trout (Oncorhynchus mykiss) to diets containing fermented soybean meal was evaluated during a 94-d feeding trial. Three isonitrogenous and isocaloric diets contained 0, 35, or 50xa0% fermented soybean meal and 40, 15, or 0xa0% fish meal, respectively. In each of the diets, rearing performance was significantly better in the Shasta strain, with an approximate 30xa0% improvement in percent gain and 20xa0% improvement in feed conversion ratio compared with the McConaughy strain. The relative response of both strains to the different diets was similar. The 50xa0% fermented soybean meal diet produced a weight gain of 172xa0% in the McConaughy strain, which was significantly less than the 219 and 250xa0% gain exhibited by the control and 35xa0% fermented soybean meal diets. Similarly, weight gain in the Shasta strain was 220xa0% in the 50xa0% fermented soybean meal diet compared to 330 and 375xa0% in the control and 35xa0% fermented soybean meal diets, respectively. Feed conversion ratio was also significantly higher in both strains in the 50xa0% fermented soybean meal diet. Distal intestine morphology was only significantly different in the Shasta strain rainbow trout fed the 50xa0% fermented soybean meal diet. The hepatosomatic index was significantly greater in the McConaughy strain, but was not influenced by diet, while the viscerosomatic index was not significantly affected by either strain or diet. Based on these results, diets containing up to 35xa0% fermented soybean meal are acceptable for either strain.

Competitor Density and Size Effects on Aggression and Feeding in Cutthroat Trout: Implications for Aquaculture

Competitor density and aggressive behavior influences the ability of fish to use food resources during aquaculture production. Using cutthroat trout Oncorhynchus clarkii (Richardson) from the same filial generation, this study investigated the effects of both body size and rearing density on aggression and feeding behavior. Four experiments were conducted using different numbers of both small and large trout obtained after grading. In each experiment, regardless of the number of each size of fish, small fish made significantly fewer attempts to forage in comparison to large fish. However, the number of aggressive interactions increased as small fish densities increased. These results suggest that grading and rearing differently-sized fish separately during rearing will likely maximize growth and rearing efficiencies in wild-strain cutthroat trout during hatchery rearing.

Full and Partial Overhead Tank Cover Improves Rainbow Trout Rearing Performance

AbstractThis study examined the effects of different overhead tank cover regimes during rearing of Rainbow Trout Onchorynchus mykiss. Three different overhead cover treatments were applied to circular tanks: near-full (98%), partial (65%), and no cover. Compared with tanks with no overhead cover, fish growth and feed conversion ratio were significantly improved in tanks with either partial cover or near-full cover. There were no significant differences in condition factor, visceral somatic index, hepatosomatic index, or hematocrit values in fish reared under either of the cover treatments. These results indicate that either partial or near-full covers may provide benefits during hatchery production of Rainbow Trout.Received May 4, 2015; accepted August 30, 2015

Parental Male Effects on Landlocked Fall Chinook Salmon Progeny Survival

Abstract The Lake Oahe, South Dakota, population of landlocked fall-run Chinook salmon Oncorhynchus tshawytscha is maintained entirely by hatchery propagation and exhibits relatively poor egg survival during hatchery incubation. This study was undertaken to determine the influence of male gametes on embryo survival. Eggs from an individual female were subdivided and subsequently fertilized with milt from four discrete males. This was repeated with three additional females using the milt from the same four males. This entire procedure was then replicated three times, using four new females and four new males each time, for a total of 16 males and 16 females. The eggs from each unique cross were then incubated discretely. There was no significant effect of spawning males on subsequent embryo survival to the eyed stage of egg development. Swim-up fry length and weight were also not significantly affected by male parentage. In contrast, there was a significant maternal effect on eyed egg survival, and swim-up...