Hatchery Incubation Research Articles

The carryover effects of embryonic incubation temperature on subsequent growth and thermal tolerance in white sturgeon

Environmental variation experienced during early periods of development can lead to persistent phenotypic alteration, known as carryover effects. Such effects increase concern for threatened or endangered species such as the white sturgeon (Acipenser transmontanus), particularly considering expected thermal changes due to climate change. We evaluated how temperature during embryonic development affects physiological parameters such as larval and early juvenile growth and thermal tolerance. Nechako River white sturgeon embryos were incubated at different environmental temperatures (Te) of 12 °C (the natural spawning temperature of this population), 15 °C (the hatchery incubation temperature), and 18 °C (representing potential increases in river temperatures given global climate change). After hatch, fish were reared at a common 15 °C for 80 days post-hatch (dph). Individuals from each temperature treatment were tested for thermal tolerance using the critical thermal maximum method (CTmax), euthanized, and measured. Fish were examined at regular intervals from 13 to 80 dph, which bridged the time from the start of exogenous feeding through the transition into early juveniles. We found carryover effects of high embryonic Te in the short term for both thermal tolerance and growth. Fish that developed at 18 °C had the lowest thermal tolerance during the start of exogenous feeding. However, differences in thermal tolerance were small for early juveniles and were unlikely to be ecologically relevant in the longer term. Fish that developed at 18 °C were smallest over the observation period, indicating a possible cost for survival from increasing environmental temperatures during embryonic development. This research represents a window into a critical period of development during which fish are particularly vulnerable to climatic variation, and shows that cooler temperatures (12 °C) during incubation are optimal for this population. The results can inform environmental managers on the best strategies to help conserve current white sturgeon populations across their range.

Negative Effects on Neurogenesis, Ovariogenesis, and Fitness in Sea Turtle Hatchlings Associated to ex situ Incubation Management

Sea turtle egg relocation and hatchery incubation (hereafter termed ex situ incubation) is an effective strategy to protect clutches when in situ egg incubation is not viable. Nevertheless, it negatively affects the ontogenesis of male gonads and brain areas homologous to the mammalian hippocampus, as well as body size and fitness. Thus, it is imperative to analyze the effects of ex situ incubation on other developmental aspects and extend these observations to females. This work evaluated the effect of ex situ management on neurogenesis (cell proliferation in the dorsal and medial ventricular zones, neuronal integration in the dorsomedial and medial cortices), ovary cell proliferation, body size (mass and length) and self-righting ability. Additionally, this study examined if the incubation microenvironment is different between in situ and ex situ nests and whether it could contribute to explain the biological traits. An analysis of principal components showed differences in biological variables of hatchlings between in situ and ex situ clutches, driven by contrasting temperatures and silt composition. Each biological variable was also analyzed with linear mixed models using in situ vs. ex situ clutches, abiotic variables and their interaction. Turtles from ex situ clutches showed: (1) fewer proliferating cells in the dorsal and medial ventricular zones; (2) less mature neurons in the dorsomedial and medial cortices; (3) ovaries with a lesser number of proliferating cells; (4) lower body mass and length at emergence; and (5) slower self-righting time. Together, the results suggest that ex situ incubation in hatcheries is related to a slowing down of neurogenesis, ovariogenesis, body size and self-righting ability in hatchlings. Future studies should evaluate the effect of ex situ incubation on cognitive and reproductive performance to understand the long-term consequences of altered organogenesis. These studies should also disentangle the differential contribution of egg movement, reburial, nesting environment and parental origin to development. This information would likely result in better conservation strategies for sea turtles.

Cold-shock androgenesis in common carp (Cyprinus carpio)

Methods of induction of uniparental inheritance have been developed for model organisms as well as for species of commercial interest to fix sex-specific traits in breeding programs or to restore breeds or lines from cryopreserved sperm in aquaculture important species. Androgenesis in common carp (Cyprinus carpio) has been successfully induced by egg nucleus inactivation with γ-, X- or UV-ray irradiation but these techniques are not widely applicable for laboratory or commercial use on practical, financial and safety grounds. In the past decade a promising low-cost, low-tech cold-shock approach for successfully inducing androgenesis has been demonstrated for loach, Japanese flounder and zebrafish. The aim of the current study was to develop a cold shock methodology for application in common carp, a freshwater species of high commercial interest and a widely used model species. Gametes were collected from wild-type females (dominant green phenotype) and Koi males (recessive blonde phenotype) to enable easy identification of successful induction of androgenetic haploid progeny. A combination of different temperature treatments (0, 2, 4, 6, 8 °C) and different cold-shock durations (15, 30, 45, 60, 75 min) applied shortly after gamete activation (3 s after fertilization) were initially trialed. Optimal condition for egg nucleus elimination was a cold-shock at 2 °C for 60 min duration where hatching rate of haploid progeny reached 35.6% and 26.26 ± 10.19% across two attempts. Double haploid induction was then attempted with three replicates (300 g egg) with following parameters 2 °C cold-shock for 60 min, then transferred into 20 °C and subsequently treated by a heat shock arresting first mitotic cleavage applied 40 min at 40 °C for 2 min. These combined treatments resulted in reduced fertilization and hatching rates for all replicates and low yield of progeny (1.09–1.28% in experimental incubation, <1% in hatchery incubation). A genome wide SNP analysis of a subset of progeny confirmed that they were double haploids. Cold-shock androgenesis was found to be effective in common carp, providing a new possibility of uniparental inheritance induction for isogenic line production.

The efficacy of pulsed ultraviolet light processing for table and hatching eggs

In the United States, every year an average of 287.1 eggs are consumed per person, and over 14.1 billion eggs are set in hatchery incubators to produce chicks destined for the egg and meat bird industries. By reducing the microbial load on eggs, food-borne–associated outbreaks can be reduced while good chick health is maintained. Pulsed ultraviolet (PUV) light system delivers an energy-intense broad spectrum (100–1,100 nm) pulse derived from a xenon flashlamp. In recent years, PUV light has been shown to reduce microbial pathogens on the surface of shell eggs by using a static PUV light system. In this study, shell eggs were surface inoculated with Escherichia coli or Enterococcus faecium and treated with PUV light using a modified egg candling conveyor that provided complete rotation of eggs under a flashlamp. Pulsed UV light treatment inactivated both microbial strains, with greater energy resulting in a greater germicidal response (P < 0.05). Treatments of 1.0, 2.4, 3.1, and 4.9 J/cm2 resulted in microbial reductions (Log10 CFU/cm2) of 3.83, 4.26, 4.28, and 4.62 for E. coli and 2.04, 3.12, 3.11, and 3.82 for E. faecium, respectively. This study also evaluated the effects of PUV light treatment of hatching eggs (commercial Leghorn hybrids) on both embryo and chick growth parameters. Using the same system, 4 replicates of 125 fertile eggs per rep were treated with 0 (control), 4.9, 24.4, or 48.8 J/cm2 of PUV light. After processing, eggs were placed in a commercial incubator under normal incubation conditions. There was no significant effect of the PUV light treatment on percent fertility, hatchability, or hatch (P > 0.05). Furthermore, there were no significant effects on posthatch observations, including livability and average bird weight at hatch or at 42 d of age (P > 0.05). In conclusion, this study supports the application of PUV light as an effective antimicrobial intervention for both table and hatching eggs.

Rapid de-adhesion of northern pike Esox lucius eggs using sodium hypochlorite.

The elimination of egg stickiness is required for effective artificial reproduction of northern pike, but until now, available methods have required at least 40min. Sodium hypochlorite was tested under laboratory conditions, and exposure to aqueous concentrations of 0.025-0.05% for 40s effectively eliminated stickiness without adverse effects. Fertilization and hatching rates in laboratory trials were similar to those observed in eggs treated with traditional methods using clay or milk for 40 or 60min, respectively, as well as those without treatment. Testing using conventional hatchery incubation techniques did not reveal differences in fertilization rates, while the number of hatched larva was significantly higher in eggs treated with sodium hypochlorite vs. clay. Eggs treated with sodium hypochlorite retained transparency, which facilitated monitoring of embryo development.

Flavobacteria colonizing the early life stages of hatchery-incubated Chinook salmon Oncorhynchus tshawytscha (Walbaum 1792) are markedly diverse.

Flavobacterial diseases are significant impediments to hatchery-based fishery conservation and aquaculture productivity worldwide. Recent studies revealed a multitude of novel flavobacteria within the reproductive fluids and unfertilized eggs of feral Chinook salmon Oncorhynchus tshawytscha broodstock, some of which were associated with systemic disease. Herein, embryonated eggs/fry from these broodstock were assayed for flavobacteria while in incubator stacks in three hatcheries over 2years, as was the water entering hatchery incubators. Overall, >65% of sampled eggs and 38% of fry were colonized by flavobacteria. One hundred and ninety-one egg and fry-associated flavobacterial isolates were characterized phenotypically and via 16S rRNA gene sequencing and phylogenetic analyses, revealing that the majority fell into 22 clades (i.e., 15 Flavobacterium spp. groups and seven Chryseobacterium spp. groups) that varied in presence by facility. Although some matched previously described fish-pathogenic species, the majority were distinct from all described flavobacteria and likely represent novel species. Of concern, iodophor disinfection at the commonly utilized dose/duration for egg-surface disinfection did not eliminate flavobacteria. Results also implicated maternal routes of infection and source water for some flavobacteria. In total, study findings underscore the complexity of flavobacterial ecology within hatchery environments and highlight the need for improved hatchery biosecurity practices.

Enclosing the Air Gap from Formalin Delivery Tubing to Vertical-Flow Fish Egg Incubators Does Not Decrease Aerosolized Formaldehyde Levels

Formalin treatments are frequently used to control water molds during hatchery incubation of salmonid eggs, creating potential occupational safety and health issues. This investigation evaluated the use of a novel technique to enclose the air gap from formalin treatment tubes to 16-tray vertical-flow incubation stacks. Standard formalin treatments of 1667 mg/L for 15-minutes were administered to one, three, or five stacks, both with, and without air gap enclosures. Enclosing the air gap did not significantly reduce aerosolized formaldehyde levels. Even during the treatment of five incubation stacks when formalin amounts were the greatest, mean (SE) peak airborne formaldehyde levels were 1.6 (0.2) mg/L and 1.5 (0.2) mg/L, either with or without air gap enclosure, respectively. The failure of air gap enclosure indicates other techniques are required to decrease aerosolized formaldehyde during formalin treatments of fish eggs in vertical-flow incubators.

Airborne Formaldehyde Levels During Simulated Formalin Egg Treatments in Vertical-Flow Tray Incubators at a Production Fish Hatchery.

Formalin, an aqueous solution of formaldehyde and methanol, is widely used in aquaculture facilities to treat water molds during egg incubation. Given the carcinogenic properties of formaldehyde, an understanding of the occupational exposure of aquaculture workers is essential. This study evaluated formaldehyde levels in a production fish hatchery incubation room under six different formalin treatment scenarios: one, three, or five vertical flow incubation stacks received 1,667 mg L-1 formalin treatments for 15 min with the incubation room door either open or closed. The results indicate that the level of formaldehyde being aerosolized increased as the number of stacks treated increased, with maximum levels ranging from approximately 0.5 ppm when only one stack was treated to over 2.0 ppm when five stacks were treated and the door was closed. Having the door open during formalin treatment resulted in significantly lower aerosolized formalin levels when three or five stacks were treated and a reduction in the time required for a return to basal levels when five stacks were treated. Based on these results, it is imperative that hatchery workers are able to leave confined incubation locations or use appropriate safety equipment during formalin treatments.

Efficacy of combination chemicals as sanitizers of Salmonella-inoculated broiler hatching eggshells

SUMMARY Sanitization of broiler hatching eggs provides an opportunity to reduce the eggshell bacterial load entering hatchery incubators, which can be subsequently carried with the chicks to the grow-out farm and ultimately into the processing plant. Two experiments evaluated combination chemicals containing ammonium chlorides (NH4Cl), biguanide (C2H7N5R; BG), bronopol (C3H6BrNO4; BP), quaternary ammonium (NR4), or hydrogen peroxide (H2O2) for efficacy in eliminating inoculated Salmonella from the shell of broiler hatching eggs. These chemicals were compared with no treatment, water sprayed (to account for spray rinsing of eggshells independent of sanitization), and to 1.4% H2O2, a demonstrated effective hatching egg sanitizer for Salmonella. All 4 combination chemicals tested (2NH4Cl+H2O2, 2NR4+BP+BG, 4NR4, and 4NR4+BG) significantly reduced the recovery of Salmonella (80% to 100%) in comparison to the water-sprayed controls (a 9% to 20% reduction following water spray). In the second experiment, the chemical 4NR4+BG (containing 4 quaternary ammoniums and a biguanide) at 200 mg/L was as effective as H2O2 at 1.4% in sanitizing hatching eggs for both Salmonella strains when the inoculum levels were 1 × 10 4 (0% positive) or 1 × 10 6 cfu/eggshell (3% positive). Following hatchability and chick quality trials for 4NR4+BG, this chemical should be considered for evaluation in commercial hatchery operations for the reduction of Salmonella on the shells of hatching eggs.

Parental Male Effects on Landlocked Fall Chinook Salmon Progeny Survival

AbstractThe 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 fry length and weight, which varied significantly among progeny from individual females. These results suggest that the relatively poor survival exhibited by Lake Oahe landlocked fall Chinook salmon eggs during hatchery incubation is largely a function of initial egg quality from spawning females.

Revisiting Trends in the Evolution of Egg Size in Hatchery‐Enhanced Populations of Chinook Salmon from British Columbia

AbstractHatchery enhancement has been reported to result in an increase in egg size in coho salmon Oncorhynchus kisutch and a decline in egg size in Chinook salmon O. tshawytscha. Egg size may be directly influenced by selection, a larger egg size evolving as a consequence of hatchery incubation. Alternatively, a smaller egg size could evolve as a correlated response to fecundity selection, and a unidirectional change in egg size over time may reflect selection and an underlying genetic change in the population. To address this question, temporal trends in egg size were investigated for two hatchery‐enhanced populations of Chinook salmon from Vancouver Island, British Columbia. After the effect of female length variation was removed by standardizing egg sizes to a female of common length (the overall mean for each population), there was no temporal trend in egg size from the 1970s to 2008 for any of the hatchery‐enhanced populations evaluated. These results do not support a previous report of genetically based declines in egg size in hatchery‐enhanced Chinook salmon populations from this region.

Effect of Low-Temperature Incubation of Channel Catfish Ictalurus punctatus Eggs on Development, Survival, and Growth

To determine whether the embryonic period of channel catfish lctalurus punctatus could be extended at low temperatures, fertilized channel catfish eggs were incubated at five constant water temperatures: 4, 11. 16. 21, and 26 C. Low-temperature incubation of catfish eggs extended the embryonic period at 16 (244%) and 21 C (56%) when compared to the control hatchery incubation temperature of 26 C. All eggs incubated at 4 and 11 C died within 24–48 h. Developmental stage had a significant (P > 0.05) effect on percent hatch at 16, 21, and 26 C. Eggs held at 16 C prior to embryonic axis formation died within 48 h. Larvae from eggs hatched at 16 C were incompletely developed and died upon acclimation to 26 C for growth tests. Growth of fry reared at 26 C, following egg incubation at 21 C. paralleled that of fry from eggs incubated at 26 C. The underdevelopment of fry at 16 C combined with the significant effect of egg stage on survival at this temperature suggests that 16 C is below the lower thermal tolerance limit for normal development in this species. The period prior to the formation of the embryonic axis may be considered a vulnerable stage in channel catfish development. Increasing the embryonic period through low temperature incubation would increase the duration of juvenile availability for researchers and commercial operations.

Effect of Low‐Temperature Incubation of Channel Catfish Ictalurus punctatus Eggs on Development, Survival, and Growth

AbstractTo determine whether the embryonic period of channel catfish lctalurus punctatus could be extended at low temperatures, fertilized channel catfish eggs were incubated at five constant water temperatures: 4, 11. 16. 21, and 26 C. Low‐temperature incubation of catfish eggs extended the embryonic period at 16 (244%) and 21 C (56%) when compared to the control hatchery incubation temperature of 26 C. All eggs incubated at 4 and 11 C died within 24–48 h. Developmental stage had a significant (P &gt; 0.05) effect on percent hatch at 16, 21, and 26 C. Eggs held at 16 C prior to embryonic axis formation died within 48 h. Larvae from eggs hatched at 16 C were incompletely developed and died upon acclimation to 26 C for growth tests. Growth of fry reared at 26 C, following egg incubation at 21 C. paralleled that of fry from eggs incubated at 26 C. The underdevelopment of fry at 16 C combined with the significant effect of egg stage on survival at this temperature suggests that 16 C is below the lower thermal tolerance limit for normal development in this species. The period prior to the formation of the embryonic axis may be considered a vulnerable stage in channel catfish development. Increasing the embryonic period through low temperature incubation would increase the duration of juvenile availability for researchers and commercial operations.

Mathematical model for predicting the dissolved oxygen requirements of steelhead ( Salmo gairdneri) embryos and alevins in hatchery incubators

Routine metabolic rates ( V ̇ O 2 ), incipient limiting dissolved oxygen levels ( P c) and ambient oxygen levels resulting in one-half the routine metabolic rate ( P 50) were determined for steelhead embryos and alevins incubated at constant temperatures of 6, 9, 12 and 15°C. Mathematical relationships were developed to predict V ̇ O 2 , P c and P 50 values for steelhead embryos and alevins incubated under both constant and variable temperature regimes. These relationships were incorporated into models that predict both available and required dissolved oxygen levels in various types of hatchery incubators. Practical applications of the incubation model are illustrated.

Elimination of adhesiveness in eggs from the white sturgeon, Acipenser transmontanus: Chemical treatment of fertilized eggs

Chemical elimination of the adhesive jelly coat in live Acipenser transmontanus eggs was investigated. Following fertilization, urea/sodium chloride (NaCl) or sodium sulphite (Na 2SO 3) treatment followed by a tannic acid wash, successfully removed the adhesive layer. In hatchery incubators, urea/NaCl-tannic acid treatment resulted in an increase in the number of hatched larvae over Na 2SO 3-tannic acid treatment. This treatment resulted in a hatch at least as great as silt-treated control eggs. The decrease in manual labor and time required for de-adhesion of sturgeon eggs as well as the high percentage of hatched larvae indicate that the urea/NaCl treatment is superior to the manual silting method.

Effects of Complete Redd Dewatering on Salmonid Egg-Hatching Success and Development of Juveniles

Abstract The effects of prolonged stream desiccation on development of salmonid eggs were simulated for steelhead Salmo gairdneri and spring chinook salmon Oncorhynchus tshawytscha. Recently fertilized eggs were placed in artificial redds and subjected to controlled water flows in outdoor laboratory channels. Control redds were continuously submerged. “Dewatered” redds were exposed to air; water flowed through the substrate 10 cm below the eggs. Eggs were dewatered 1–4 weeks (steelhead) or 1–5 weeks (chinook salmon) before they were returned to water in hatchery incubators, where hatching success and subsequent fry development were monitored. Several combinations of cobble, coarse sediment, and fine sediment used to cover eggs did not influence egg development, provided the mixtures retained at least 4% moisture by weight. Dewatered eggs hatched sooner than control eggs; faster hatch was associated with higher substrate temperature in exposed redds. Hatching success of dewatered eggs averaged 94% for stee...

Effects of DDT and PCB's on Survival of Lake Trout Eggs and Fry in a Hatchery and in Lake Michigan, 1973–1976

Abstract To assess the role of DDT and PCB's in reproductive failure of lake trout (Salvelinus namaycush) planted in Lake Michigan, I compared mortality of eggs (1.41–5.24 μg/g DDT, 3.16–9.90 μg/g PCB's) and fry from planted Lake Michigan lake trout with that of eggs (0.05–0.20 μg/g DDT, 0.20–0.28 μg/g PCB's) and fry from hatchery lake trout. In normal hatchery incubation from fertilization to 6 weeks after swim-up, mortality of Lake Michigan trout (mean ± 95% confidence limits) was 80 ± 16% as compared to 46 ± 14% for hatchery lake trout in 1973–1974 and 50 ± 9% versus 47 ± 9%, respectively, in 1974–1975. The significantly higher mortality of Lake Michigan than of hatchery lake trout in 1973–1974 was thought due to causes other than DDT or PCB's. Mortality of Lake Michigan lake trout during different stages of development usually was not linearly correlated with DDT and PCB content. During development in enclosures in Lake Michigan from fertilization or the eyed stage, mortality of Lake Michigan lake tro...

Yolk-Sac Malformation in Pacific Salmon in Relation to Substrate, Temperature, and Water Velocity

Chum (Oncorhynchus keta), pink (O. gorbuscha), sockeye (O. nerka), and hybrid (pink × chinook) salmon alevins were susceptible to yolk-sac malformation when provided a smooth substrate as in standard hatchery incubators, at 12 C and a water velocity of 100 cm/hr. Chinook (O. tshawytscha) and coho (O. kisutch) alevins were not susceptible. In sockeye, malformations increased with increase in temperature from 8 to 12 and 14 C and, at 14 but not at 12 C, with increase in water velocity from 25 to 400 cm/hr. Replacement of the smooth substrate with a rough (gravel) substrate usually prevented the condition.