In Newfoundland and Labrador (hereafter, Newfoundland), all farmed Atlantic Salmon Salmo salar originate from the Saint John River, New Brunswick, strain, raising the question of potential impacts of escapees on wild, genetically distinct stocks. Unfertilized eggs of farmed and wild salmon were assessed for diameter, mass, adenosine triphosphate (ATP) content, and fertilization success, this is the first study to assess ATP content in Atlantic Salmon eggs. Results demonstrated that farmed salmon egg mass (0.1046 g), diameter (6.2 mm), and ATP content (0.0281 nmol/egg) were significantly lower than the same characteristics in wild salmon. Among and within females, variability in egg size was similar in both wild and farmed groups. This study lends some evidence to the fact that in the Newfoundland context, eggs of escaped farmed salmon may be less likely to produce viable, large larvae compared with their wild counterparts.

A better understanding of the parameters a¡ecting egg quality and larval survival is of importance for continued development of cod broodstock and e⁄cient husbandry practices. Decision tree analysis (DTA) was applied to analyse 3 years of egg quality data in an e¡ort to extract the most important variables (i.e. predictors) in explaining di¡erences in egg quality. The e¡ect of three predictors (spawning time, maternal and paternal di¡erences) has been studied on early cleavage pattern parameters, egg diameters, fertilization and hatching rates and has shown that females are the dominant variable and that time has a limited and inconsistent impact on the data.When using maternal, paternal di¡erences and batch number (instead of spawning time) as predictors, the results con¢rm that no particular relationship is found between batch order (i.e. order in time) and egg quality. Moreover, batches with a higher egg quality show a consistency in the parameters assessed (i.e. batches with higher rates of normality in any parameter tend to be normal for other parameters). This is con¢rmed by the signi¢cant correlations found between cleavage parameters. Our results highlight that spawning time is of less importance than female parent contribution in ensuring high rates of fertilization and larval hatch, and maximizing general egg quality.Maximum and minimum values are provided between brackets. Length and mass were recorded at paired mating. N, total number of spawners considered, n, total number of ¢sh weighed and measured.Data were transformed using arcsin square root transformation. Numbers underlined indicate a signi¢cant correlation (probability levels for statistical signi¢cance are Bonferroni-adjusted for multiple comparisons). Egg £oat, % £oating eggs (% live eggs), Fert.

The in vitro effect of produced water released by oil and gas platforms was assessed by exposing cod sperm cells to realistic concentrations of this mixture (100, 200, 500 ppm). We investigated produced water impact on enzymes of the aerobic (citrate synthase) and glycolytic metabolism (lactate dehydrogenase), lipid catabolism (lipase), as well as an anti-oxidant enzyme (catalase). Fertilization rates, viability, respiration, ATP, and total motility duration were also evaluated. To explore correlations between these parameters, we have also tested the effect of conserving sperm for 24 h at 4 degrees C. After conservation, fertilization success was decreased but other parameters were not affected. Produced water did not result in a significant change in fertilization; a significant increase in sperm protein amounts and citrate synthase activity can be observed. No correlations are found between parameters showing that sperm viability and unchanged energy levels do not translate into equivalent fertilization capacity. To conclude, exposure of sperm to produced water resulted only in subtle effects on cells. These findings bring information on the effect of produced water on sperm itself rather than on spermatogenesis or testis development of an exposed fish.

Aspects of sperm motility and metabolism are important for understanding gamete quality. The objectives of this study were to investigate changes in adenosine 5¢-triphosphate (ATP), and lactate dehydrogenase (LDH) of Atlantic cod sperm over time following activation, and to determine if initial semen parameters (ATP, LDH, Na + , K + , Ca 2+ , total protein, osmolality, pH, and spermatocrit) are indicative of sperm quality. Analyses of ATP and LDH were also performed on sperm cells at 0.5, 2, and 90 min post-activation, while sperm activity was recorded at 0.5 and 2 min. Initial semen parameters did not appear to be strong indicators of sperm quality but some correlations were observed between pH, LDH, K + , and protein and motility parameters in the first two min post-activation. The lack of significant correlation may be attributed to the low variability of almost all parameters observed between males in this study. There was a significant effect of post-activation time on sperm ATP and LDH with both ATP and LDH decreasing with time after activation. The decrease in ATP levels during the course of sperm motility suggests that the metabolic activity is too low to substitute the energy consumed. Continued research on sperm motility and metabolism will lead to a better understanding of fertilization and gamete quality in this species.

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Differences in sperm metabolism and morphology between wild and non-local farmed Atlantic salmon Salmo salar were assessed by measuring metabolic enzyme activities and length of sperm flagella. No differences were observed between wild and farmed S. salar sperm with regards to cell counts or any of the biochemical variables assessed. Flagella of sperm cells were significantly longer in wild than farmed S. salar; however, this did not result in higher energy levels or different fertilization rates.

The direct exposure of fish eggs to ozonated water has generated interest as a means of ensuring pathogen-free eggs without the use of harsh chemicals. However, there are numerous knowledge gaps, including safe contact times, exposure levels, and potential long-term effects on aquaculture species in both freshwater and seawater. The effect of different ozone (O3) doses (0.5-1.0, 1.5-2.0, and 2.5-3.0 mg of O3/L for 90 s) on recently fertilized eggs of Atlantic Cod Gadus morhua and eyed eggs of Atlantic Salmon Salmo salar and Rainbow Trout Oncorhynchus mykiss was evaluated in comparison with the effects of two commercial disinfectants: Perosan (0.004 mg/L) and Ovadine (100 mg/L). The impact of ozone application was evaluated based on hatching success, larval nucleic acid concentration, larval growth, and survival. Overall, results indicated that ozonation of Atlantic Cod eggs at a dose less than 3.0 mg/L for 90 s produced no negative effect on the larvae up to 30 d posthatch. Furthermore, ozonation of Atlantic Salmon and Rainbow Trout eggs generated no negative effect on the larvae, based on monitoring until 85% yolk sac re-absorption (16 d posthatch).

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