Article

Vertebral deformities in triploid Atlantic salmon (Salmo salar L.) underyearling smolts

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Abstract

This study investigated the prevalence of vertebral deformities in triploid and diploid Atlantic salmon smolts. Four full-sibling families were either subjected to hydrostatic pressure (655 bar, 6.25 min, 8 °C) (triploid) 37 min post-fertilization, or were maintained as untreated controls (diploid), and then reared to the smolt stage. Some 800 fish (100 per ploidy/family group) were palpated for vertebral deformities, and 480 (60 per ploidy/family group) of these were selected at random for radiography and evaluation for vertebral deformities. There was a significantly higher prevalence of triploid individuals classified as spinally deformed during palpation (triploids; 1–3%, diploids; 0–1%), and of individuals with one or more deformed vertebrae on radiographs (triploids; 30–35%, diploids; 8–13%). The trunk region (V9-30) of the vertebral column was the predominant location for deformities in triploids, with vertebra number 24 being the most often affected. Of the triploids, 7.6% had a malformation in this particular vertebra, which is located beneath the dorsal fin.

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... Wilkins et al. 1995). Although the frequency of lower jaw, gill and skeletal deformities is higher in triploid populations of Atlantic salmon than in diploid populations (Sutterlin et al. 1987;Sadler et al. 2001;Pepper et al. 2004;Powell et al. 2009;Fjelldal & Hansen 2010;Leclercq et al. 2011;Fraser et al. 2013Fraser et al. , 2014aTaylor et al. 2013Taylor et al. , 2014Tibbetts et al. 2013), most triploid individuals do not exhibit such abnormalities. However, when present, they can affect swimming performance, metabolic scope for activity and the ability to recover from exhaustive exercise Powell et al. 2009). ...
... Although several earlier studies have suggested that triploids may have different dietary requirements than diploids (e.g. Fjelldal & Hansen 2010), this is the first study to clearly demonstrate this. ...
... A number of studies have reported on key culture characteristics of triploid Atlantic salmon, focusing on freshwater production, smolt characteristics and postsmolt performance in sea water (Fjelldal & Hansen 2010;Leclercq et al. 2011;Taylor et al. 2011Taylor et al. , 2012Taylor et al. , 2013Taylor et al. , 2014Taylor et al. , 2015Fraser et al. 2013Fraser et al. , 2014a. Although triploids are generally smaller than diploids at hatch, they have superior growth rates through the freshwater phase, with no difference in survival after the eyed-egg stage. ...
Article
Atlantic salmon (Salmo salar) dominates aquaculture production in its native North Atlantic range, raising concerns about the impacts of escaped farmed fish on wild populations. While physical confinement and operational management practices have improved steadily with the development of this industry, some escapes are inevitable. In the absence of effective measures for the rapid recapture of escaped fish, the only practical method currently available to minimize their impacts on wild populations is to ensure that they are female triploids and therefore reproductively sterile. The technology for producing all-female triploid populations of Atlantic salmon is simple and easily applied on a commercial scale, and routinely results in populations that are entirely female and >98% triploid. Aside from sterility, there are no population-wide phenotypic effects of triploidy, although triploids do tend to perform less well than diploids with respect to commercial culture characteristics and are also less likely than escaped diploids to outcompete or displace native salmon. Some uncertainties exist with respect to their disease resistance and their potential to become reservoirs for the spread of pathogens to wild populations. If the spawning potential of escaped farmed Atlantic salmon is deemed to pose an unacceptable risk to native populations, then all-female triploid populations could be used as an alternative to reduce risk. Research should continue to focus on improving triploid performance through breeding programmes and optimization of husbandry conditions (including nutrition, environmental conditions and fish health), with the goal of making triploids an attractive option for fish farmers.
... However, triploidy results in numerous physiological differences when compared to diploids and this can lead to inconsistent farm performance, reduced welfare, and reduced harvest quality. For example, triploidy is a risk factor for vertebral deformities (Fjelldal and Hansen, 2010) and ocular cataracts (Wall and Richards, 1992), both of which can limit growth and reduce welfare. In addition, triploidy leads to other morphological differences, such as a reduced mass of pyloric caeca within the gut (Peruzzi et al., 2015), lower fillet colouration (Smedley et al., 2016), and an increased occurrence of gill deformities (Sadler et al., 2001) in Atlantic salmon. ...
... Hybridisation did not significantly reduce the incidence of triploids with deformed vertebra. Triploidy is a well-known risk factor for skeletal deformities in Atlantic salmon (Fjelldal and Hansen, 2010), rainbow trout (Oncorhynchus mykiss) (Weber et al., 2014), brown trout (Preston et al., 2017), and Arctic char (Salvelinus alpinus) . Bone health in triploid Atlantic salmon is improved by increasing the dietary phosphorus level (Fjelldal et al., 2016), particularly during the very early life stages when dietary phosphorus requirements are generally at their highest (Sambraus et al., 2020). ...
... As such, our value in triploid hybrids is not particularly high compared to other studies, although our triploid salmon were towards the higher end of commonly reported values. Our triploid Atlantic salmon had a deformity peak around vertebra 27 to 29, which is commonly reported in both juveniles (Fjelldal and Hansen, 2010) and harvest size fish (Fraser et al., 2013). The triploid hybrids had a similar peak as juveniles (6-8% of vertebrae no. ...
Article
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Interspecific hybridisation may improve the farm performance of sterile triploid salmonids via heterosis (i.e. hybrid vigour). We assessed growth over the final 293 days in seawater, and harvest quality, in diploid and triploid Atlantic salmon (Salmo salar) × brown trout (Salmo trutta) hybrids compared to diploid and triploid Atlantic salmon. We measured vertebral deformities, cataracts, flesh colour, gut mass, and body shape at harvest. In triploids, hybridisation had no effect on harvest size, vertebral deformities, cataracts, or body shape in triploids, but did improve fillet colouration (Mean digital SalmoFan™ score [95% CI]: 24.6 [24.4–24.9] and 26.0 [25.7–26.2] for triploid salmon and triploid hybrids, respectively) and lower relative gut size (34% lower). Compared to diploid salmon, triploid salmon were significantly heavier at harvest, triploid hybrids tended to be heavier (Post-hoc, least square means, p = 0.08), whereas diploid hybrids were 83% lighter (Mean mass [g] at harvest [95% CI]: 2676 [2470–2898], 3395 [3134–3679], 462 [401–534], and 3086 [2832–3363] for diploid salmon, triploid salmon, diploid hybrids, and triploid hybrids, respectively). However, both triploid groups had a significantly higher incidence of fish with one or more deformed vertebra (Mean % [95% CI]: 23 [14–35], 60 [47–71], 38 [20–60], and 44 [31–57] % in diploid salmon, triploid salmon, diploid hybrids, and triploid hybrids, respectively), more severe cataracts (Mean cataract score [95% CI]: 3.0 [2.7–3.3], 3.5 [3.2–3.8], 2.2 [1.7–2.6], 3.6 [3.3–4.0] for diploid salmon, triploid salmon, diploid hybrids, and triploid hybrids, respectively), and a smaller relative gut size (21% smaller) compared to diploid counterparts. In conclusion, triploid hybrids have no growth advantage over triploid salmon and suffer from similar welfare issues while only benefiting from increased fillet colour.
... However, comprehensive studies revealed that triplodization exhibited inconsistent growth performance on different marine and freshwater species Tiwary et al., 2004). On the other hand, increased malformation rates in different fish species have been observed as a result of triploidy induction (Fjelldal and Hansen, 2010;Liu et al., 2018;Smedley et al., 2018). ...
... The caudal region of the vertebra, the haemal arch, and the neural arch were the sections with the highest prevalence of malformations, resulting in significant differences in the prevalence of malformations within each section of the neural arch. On the contrary, a higher prevalence of vertebral malformation was reported in triploid Atlantic salmon fry compared to diploid counterparts (Fjelldal and Hansen, 2010;Peruzzi et al., 2018). Hernandez-Urcera et al. (2012) reported low and similar skeletal malformations in triploid turbot at 6-and 12-months of age compared to their diploid full-siblings. ...
... Similar deformity frequencies have been reported in both diploids and triploids (Kacem et al., 2004;Sutterlin et al., 1987). Comparatively higher malformations in triploids were rarely reported during the early life stage of fish Fjelldal and Hansen, 2010;Lijalad and Powell, 2009). ...
Article
Understanding the early life stage of fish can improve performance during the grow-out phase of the fish. In the present study, skeletal development and malformations were investigated in diploid and cold shock-induced triploid turbot during the early life stages. Diploid and triploid fish were reared in triplicate tanks starting from the hatching date. Thirty fish from each ploidy group (390 triploid and 390 diploid turbot) were randomly sampled at 5-day intervals. Fish skeletons were co-stained with Alician blue and Alizarin red. Growth metric (length), skeletal development, meristic characters, and malformations were examined from hatching to 60 days post-hatch (dph). There was no difference between ploidy groups in skeletal development. The vertebral elements (vertebral centra, neural arch, and haemal arch) mostly remained cartilaginous until 15 dph. Ossification of vertebral elements started on the arch and spine bases at 15 dph and were completely ossified at 20 dph. Ossification of the fins started at 15 dph at the tips of the pterygiophores and completed at 50 dph. The vertebral column ranged between 29 and 31 vertebrae, including 2–7 cephalic vertebrae, 5–9 pre-haemal vertebrae, 14–16 haemal vertebrae, and 3–5 caudal vertebrae. Between ploidy groups, there was a significant difference in the number of vertebrae. Moreover, a significant difference was also detected among ploidy groups in the number of fin rays except for pectoral fin rays. Among all of the factors, dorsal fin rays, anal fin rays, and their pterygiophores caused the main difference between ploidy groups. A total of twelve different types of malformations were detected. At least one type of malformation was observed on 260 diploid and 260 triploid fish. The most frequently encountered malformation was of the neural arch or spine. The frequency of malformed vertebra, haemal arch, and neural arch of diploid turbot was significantly higher than that of triploid counterparts on the caudal region. Malformations were most frequently observed on the caudal region of the vertebra, haemal arches, and neural arches where statistically significant differences were determined. According to the results of this study, cold shock-induced triploid turbot had no disadvantage in terms of development and remain a feasible alternative for the turbot aquaculture industry.
... As a result of their chromosomal state, triploids are sterile, hence offering potential advantages for farming such as reproductive containment of escapees and potential for faster growth with subsequent reduction of production cycle length (Benfey, 2016). However, specific dietary requirement trials in triploids are limited to date, although it was previously suggested that differences between ploidy might exist (Fjelldal and Hansen, 2010). Apparent digestibility coefficients for dry matter, protein, or lipid do not appear to differ between ploidy (Burke et al., 2010;Tibbetts et al., 2013), whereas energy and nitrogen retention efficiencies may be higher in triploids than diploids (Burke et al., 2010). ...
... However, growth rates (SGRwt) were comparable between ploidy and relative weight gain did not differ between ploidy, with the exception of diet L2. Recent studies have shown triploids to have greater growth potential than diploids in freshwater phases of development (Fjelldal and Hansen, 2010;Taylor et al., 2012;Fraser et al., 2013;Taylor et al., 2013;Fjelldal et al., 2016), so the apparent lack of better growth was unexpected. This may in part be due to higher water temperatures (15-16°C) experienced for 7 weeks prior to, and the initial first two weeks of feeding at start of the trial, under which conditions triploids have been reported to show sub-optimal growth (Sambraus et al., 2017). ...
... This may in part be due to higher water temperatures (15-16°C) experienced for 7 weeks prior to, and the initial first two weeks of feeding at start of the trial, under which conditions triploids have been reported to show sub-optimal growth (Sambraus et al., 2017). However, specific dietary requirement trials in triploids are also limited to date, although it has been suggested that differences between ploidy might exist (Fjelldal and Hansen, 2010) particularly with regards to energy and nitrogen retention efficiencies (Burke et al., 2010), dietary phosphorous (Fjelldal et al., 2016;Smedley et al., 2018) and histidine requirements (Taylor et al., 2015;Sambraus et al., 2017). To date, no study has examined the interaction of ploidy and micronutrients when fed low marine ingredient diets. ...
Article
Previously we showed that, for optimum growth, micronutrient levels should be supplemented above current National Research Council (2011) recommendations for Atlantic salmon when they are fed diets formulated with low levels of marine ingredients. In the present study, the impact of graded levels (100, 200, 400%) of a micronutrient package (NP) on vertebral deformities and bone gene expression were determined in diploid and triploid salmon parr fed low marine diets. The prevalence of radiologically detectable spinal deformities decreased with increasing micronutrient supplementation in both ploidy. On average, triploids had a higher incidence of spinal deformity than diploids within a given diet. Micronutrient supplementation particularly reduced prevalence of fusion deformities in diploids and compression and reduced spacing deformities in triploids. Prevalence of affected vertebrae within each spinal region (cranial, caudal, tail and tail fin) varied significantly between diet and ploidy, and there was interaction. Prevalence of deformities was greatest in the caudal region of triploids and the impact of graded micronutrient supplementation in reducing deformities also greatest in triploids. Diet affected vertebral morphology with length:height (L:H) ratio generally increasing with level of micronutrient supplementation in both ploidy with no difference between ploidy. Increased dietary micronutrients level in diploid salmon increased the vertebral expression of several bone biomarker genes including bone morphogenetic protein 2 (bmp2), osteocalcin (ostcn), alkaline phosphatase (alp), matrix metallopeptidase 13 (mmp13), osteopontin (opn) and insulin-like growth factor 1 receptor (igf1r). In contrast, although some genes showed similar trends in triploids, vertebral gene expression was not significantly affected by dietary micronutrients level. The study confirmed earlier indications that dietary micronutrient levels should be increased in salmon fed diets with low marine ingredients and that there are differences in nutritional requirements between ploidies.
... Conclusive evidence could be achieved only through a longitudinal assessment of vertebral development in individuals raised at different temperatures. A higher prevalence of deformed triploids than diploids (displaying at least one deformed vertebra) is in accordance with all previous studies (Fjelldal & Hansen 2010;Fjelldal et al. 2015;Fraser et al. 2013aFraser et al. , 2014bLeclercq et al. 2011;Taylor et al. 2013). Higher prevalence of vertebral deformities in triploids, irrespective of temperature, can be explained by the higher requirement of dietary P that triploids have compared to diploids, particularly during a fast growth period (Fjelldal et al. 2015). ...
... This implies an effect of temperature and as a consequence of higher SGR, as observed in our study, on regional occurrence of vertebral deformities. Other studies found a positive correlation between fast growth and the prevalence of vertebral deformities (Fjelldal, Nordgarden & Hansen 2007b;Fraser et al. 2013aFraser et al. , 2014bGrini et al. 2011;Hansen et al. 2010;Leclercq et al. 2011;Taylor et al. 2013). Fjelldal et al. (2012) reported that using high temperature to accelerate growth in Atlantic salmon can affect normal skeletal development. ...
... Nevertheless, the time frame of our experiment did not allow detection of possible occurrence of vertebral deformities in R4 in diploids in later stages. The presence of individuals with vertebrae affected in the caudal-trunk region (R2) in freshwater, in correspondence of the dorsal fin, is in accordance with previous studies (Sullivan et al. 2007;Fjelldal & Hansen 2010;Grini et al. 2011;Fraser et al. 2013a;: Fraser et al. 2014b). Similarly to Fraser et al. (2013aFraser et al. ( , 2014b, but differently from that reported by Fjelldal et al. (2009) and Grini et al. (2011), we found fish with vertebral deformities in the caudal-fin region (R3) in freshwater. ...
Article
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Triploid Atlantic salmon tend to develop a higher prevalence of skeletal anomalies. This tendency may be exacerbated by an inadequate rearing temperature. Early juvenile all-female diploid and triploid Atlantic salmon were screened for skeletal anomalies in consecutive experiments to include two size ranges: the first tested the effect of ploidy (0.2-8 g) and the second the effect of ploidy, temperature (14 °C and 18 °C) and their interaction (8-60 g). The first experiment showed that ploidy had no effect on skeletal anomaly prevalence. A high prevalence of opercular shortening was observed (average prevalence in both ploidies 85.8%) and short lower jaws were common (highest prevalence observed 11.3%). In the second experiment, ploidy, but not temperature, affected the prevalence of short lower jaw (diploids > triploids) and lower jaw deformity (triploids > diploids, highest prevalence observed 11.1% triploids and 2.7% diploids) with a trend indicating a possible developmental link between the two jaw anomalies in triploids. A radiological assessment (n = 240 individuals) showed that at both temperatures triploids had a significantly (P < 0.05) lower number of vertebrae and higher prevalence of deformed individuals. These findings (second experiment) suggest ploidy was more influential than temperature in this study.
... The triploid Argentinian silverside (Odontesthes bonariensis Valenciennes, 1835) exhibited ocular deformities, dilation of the pericardial cavity, bulges in the head, and either curling or bending of the body (Strüssmann et al. 1993), while a short curved tail and an edematous body were described in the triploid Mozambique tilapia Oreochromis mossambicus Peters, 1852 (Varadaraj & Pandian 1990). Jaw and body deformities (scoliosis, lordosis and humpback deformities), a short opercula and non-cranial deformities were described in triploid Atlantic salmon (O'Flynn et al. 1997;Sadler et al. 2001;Fjelldal & Hansen 2010), whereas triploid brook trout (Salvelinus fontinalis Mitchill, 1814) exhibited scoliosis, lordosis, presence of spiral larvae and double-headed larvae (Galbreath & Samples 2000). Deformed individuals show problems with swimming and difficulties in food intake (Boglione et al. 2013). ...
... 1.8%) was observed in the brown trout Salmo trutta m. fario (Preston et al. 2013). In the Atlantic salmon, deformity rates ranged from 2 to 48.9% in triploids and from 0.66 to 24.4% in their diploid counterparts (O'Flynn et al. 1997;Sadler et al. 2001;Cotter et al. 2002;Fjelldal & Hansen 2010: Leclercq et al. 2011Fraser et al. 2013;Taylor et al. 2014). Studies on triploidization of the Atlantic cod showed that 72% of triploids and 42% of their diploid siblings had body abnormalities (Opstad et al., 2013). ...
... Deformities in the thoracic region led to the observation of fish with humpback, while deformities in the caudal area resulted in the phenotype with a shortened tail (Fig. 2D). Similar deformities were previously described in the triploid rainbow trout (Weber et al. 2014) and in the triploid Atlantic salmon (Cotter et al. 2002;Fjelldal & Hansen 2010). The presence of body deformities in aquaculture species is one of the most important problems in fish farming. ...
Article
Full-text available
Due to the cytogenetic incompatibility, triploid fish are usually infertile and are not affected by a decline in growth, survival and meat quality, which accompanies the process of sexual maturation in diploid specimens. Thus, artificial triploidization has been proposed for fish production in the case of species with early sexual maturation, such as rainbow trout. However, the use of this technique is limited by increased ratios of skeletal deformities observed in triploid specimens. The main objective of this research was to compare the proportion and variety of body abnormalities in diploid and triploid 14-month-old rainbow trout from commercial stocks, using external body shape examination, radiography and whole-mount skeletal staining. Individuals with externally observed body deformities (scoliosis, humpback, shortened tail and jaw deformities) accounted for 0.45% of the diploid stock and 3.83% of the triploid stock. X-rays and whole-mount skeletal staining of deformed individuals showed spine deformities, including compressions and fusions of vertebrae. Abnormalities observed in diploid and triploid rainbow trout examined during this study were non-lethal, however, they may negatively affect the condition of fish. Fish with skeletal deformities are not aesthetically pleasing, thus an increased ratio of such deformations in fish produced for commercial purposes may result in real economic losses.
... More recently, licences have been approved for commercial triploid S. salar production in Norway (Kjøglum et al., 2016) and Canada (DFO, 2016), and triploidy is used as a safeguard against environmental contamination following approval for production of genetically modified S. salar (DFO, 2019). Nonetheless, the commercial uptake of triploid use has been slow because of a higher incidence of lower-jaw deformities (Amoroso et al., 2016;Fraser et al., 2015;Sutterlin et al., 1987) and vertebral compression/fusion (Fjelldal & Hansen, 2010) compared to diploids. Of note, Whitt et al. (1972) also observed an increased occurrence of jaw deformities in interspecific sunfish hybrids compared to the parental species. ...
... These values are similar to the levels found in diploid S. salar but lower than those observed in S. salar × S. alpinus. For triploid S. salar, data were available for only 2 year classes, and the number of deformed fish was almost double than that seen in diploid S. salar, but this was to be expected based on numerous publications in similar-sized fish (e.g., Fjelldal & Hansen, 2010;Peruzzi et al., 2018). ...
... Similarly, peaks were observed in deformity prevalence in the vertebra found beneath the dorsal fin, which is a common characteristic of triploids (Fjelldal & Hansen, 2010). The reason behind this increase in triploid deformities is still unclear. ...
Article
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Vertebral deformities in salmonid interspecific hybrids, some of which were triploidised, were assessed across three separate year classes during the freshwater life stage. Initially we crossed the eggs from a farmed Atlantic salmon Salmo salar with the sperm from either an S. salar, arctic char Salvelinus alpinus, or brown trout S. trutta. For S. salar × S. trutta, half the eggs were triploidised. In a second‐ and third‐year class, the eggs from a farmed S. salar were crossed with the sperm from either an S. salar or a S. trutta, and half of each group was triploidised. In the two initial year classes, all hybrids were larger than the S. salar controls and triploid S. salar × S. trutta were larger than diploid counterparts. In the third year class, the S. salar × S. trutta were smaller than the S. salar, in contrast to the initial two year classes, although the triploid hybrids were still larger than the diploids. In the third year class we also observed a high degree of spontaneous triploidy in the putative diploid groups (between 16%–39%). Vertebral deformities were consistently higher in pressure‐shocked triploids than diploids, irrespective of hybridisation, but there was no consistent effect of hybridisation among experiments. Although we are not able to explain the contrasting results for vertebral deformities between year classes, triploid S. salar × S. trutta can demonstrate impressive freshwater growth that could be of interest for future farming programs.
... The effect of ploidy on growth rate, survival, skeletal deformities, reproduction, viability of eggs and developing embryos mainly of commercially important fish species have been studied (BENFEY 1999;FELIP et al. 2001;TIWARY et al. 2004;MAXIME 2008;PIFERRER et al. 2009;FJELLDAL & HANSEN 2010;FRASER et al. 2013). The physical or chemical manipulation of ploidy level induces a higher incidence or severity of deformities and lower survival of triploid larvae (PIFERRER et al. 2009). ...
... etal.2006;MAXIME 2008;PIFERRER et al. 2009;FJELLDAL & HANSEN 2010;BOGLIONE et al. 2013;FRASER et al. 2013). ...
... Some data indicate that induced triploids are sterile and grow faster than diploids, but their larvae are characterized by a higher incidence of deformities and a lower survival rate in comparison with diploid ones (TIWARY et al. 2004;PIFERRER et al. 2009;FJELLDAL & HANSEN 2010;FRASER et al. 2013). Interestingly, the larvae of triploid Cobitis females were longer than those of C. taenia but only during the first two weeks of life (JUCHNO et al. 2013). ...
Article
Full-text available
Polyploid fishes of the genus Cobitis represent a valuable model system to study the origin and consequences of hybridization and polyploidization within vertebrates. These naturally accessible polyploids are an excellent subject to determine the advantages or disadvantages of polyploidy. We investigated the embryonic and larval development with skeletal morphology of diploid and polyploid Cobitis progeny, obtained from crosses between females and males of Cobitis taenia and between allotriploid Cobitis females and C. taenia males. Observations were made during first fourteen days post fertilization. The pattern of development of all investigated individuals was the same. However the diploids developed synchronically, achieving successive stages faster than the polyploid ones; hatching was observed at 50 and 63 hours post fertilization, respectively. Statistically significant differences in hatching success and survival rate between diploid and polyploid progeny were not observed. All newly hatched larvae were characterized by a large amount of yolk, forty myomeres, body pigmentation and four external gills. Skeletal elements of the chondrocranium in the first days post hatching consisted of the otic capsule, ethmoid plate, trabeculae cranii and Meckel's cartilage. In contrast to the diploids, the polyploid larvae were characterized by a higher number of deformities. This study gives new comparative data on the features of early development of diploid and polyploid Cobitis progeny. © Institute of Systematics and Evolution of Animals, PAS, Kraków, 2016.
... In addition, ALP activity is influenced by many factors including feed intake (Sauer and Haider 1979;Congleton and Wagner 2006), temperature (Lie et al. 1988), stress transport (Dobšíková et al. 2009), life stage (Johnston et al. 1994) and diet especially phosphorus metabolism (Shao et al. 2008;Š egvic-Bubic et al. 2013). In addition, bone health issues can be influenced by ploidy (Fjelldal and Hansen 2010) and rearing temperature (Grini et al. 2011). ...
... Interestingly, the type and location of deformity differed between ploidy, with 73 % of deformity associated with decreased intervertebral space in diploids principally located within the tail region, while triploids displayed a wider range of deformity type including decreased intervertebral space, compression and fusion, representing 88 % of total deformity observed. Deformity was principally located within the cranial trunk and caudal trunk areas in triploid trout as opposed to the tail region observed in diploids (Fjelldal and Hansen 2010). The prevalence of deformities reduces the aesthetic and commercial value of the fish, but could also affect swimming ability and subsequently the fighting qualities of a sport fish (Powell et al. 2009). ...
... The prevalence of deformities reduces the aesthetic and commercial value of the fish, but could also affect swimming ability and subsequently the fighting qualities of a sport fish (Powell et al. 2009). Indeed, most studies indicate that the causal mechanisms for deformity prevalence in triploids are physical (Fjelldal and Hansen 2010;Leclercq et al. 2011) or dietary related . Present results suggest that deformity prevalence in diploid and triploid brown trout may be less of a concern compared to other salmonids, e.g. ...
Article
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The physiological effect of temperature on feed intake and haematological parameters after exhaustive swimming in diploid and triploid brown trout (Salmo trutta) was investigated. Trout were exposed to an incremental temperature challenge (2 °C/day) from ambient (6 °C) to either 10 or 19 °C. Feed intake profiles did not differ between ploidy at 10 °C; however, triploids had a significantly higher total feed intake at 19 °C. After 24 days, each temperature–ploidy group was exposed to exhaustive swimming for 10 min. The haematological response differed between ploidy, with the magnitude of the response affected by temperature and ploidy. Post-exercise, acid–base and ionic differences were observed. Plasma lactate increased significantly from rest for both temperature and ploidy groups, but glucose increased significantly at higher temperature. Post-exercise, triploids at 19 °C had significantly higher osmolality and cholesterol than diploids, but differences were resumed within 4 h. Elevated alkaline phosphatase (ALP) and aspartate aminotransferase (AST) in fish at higher temperature suggested greater tissue damage; however, both ploidy responded similarly. Despite no significant differences in deformity prevalence, the type and location of deformities observed differed between ploidy (decreased intervertebral space with higher prevalence in tail area and fin regions for diploids, while vertebral compression, fusion in cranial and caudal trunks for triploids). These results suggest triploids have greater appetite than diploids at elevated temperature and that triploids suffer similar blood disturbances after exercise as diploids. These findings have implications for the management of freshwater ecosystems and suggest that stocking triploid brown trout may offer an alternative to diploid brown trout.
... The effect of ploidy on growth rate, survival, skeletal deformities, reproduction, viability of eggs and developing embryos mainly of commercially important fish species have been studied (BENFEY 1999;FELIP et al. 2001;TIWARY et al. 2004;MAXIME 2008;PIFERRER et al. 2009;FJELLDAL & HANSEN 2010;FRASER et al. 2013). The physical or chemical manipulation of ploidy level induces a higher incidence or severity of deformities and lower survival of triploid larvae (PIFERRER et al. 2009). ...
... etal.2006;MAXIME 2008;PIFERRER et al. 2009;FJELLDAL & HANSEN 2010;BOGLIONE et al. 2013;FRASER et al. 2013). ...
... Some data indicate that induced triploids are sterile and grow faster than diploids, but their larvae are characterized by a higher incidence of deformities and a lower survival rate in comparison with diploid ones (TIWARY et al. 2004;PIFERRER et al. 2009;FJELLDAL & HANSEN 2010;FRASER et al. 2013). Interestingly, the larvae of triploid Cobitis females were longer than those of C. taenia but only during the first two weeks of life (JUCHNO et al. 2013). ...
... In some of these cases, the occasional triploid farmed salmon has been detected based upon its multi locus microsatellite genetic profile (i.e., displayed three alleles at multiple loci). While the Atlantic salmon aquaculture industry is currently conducting research into the potential use of triploid salmon for commercial production [26][27][28][29], during the period in which samples from this study were collected, there was either no or next to no commercial production of triploid salmon in Norway, and this only occurred on a very low number of farms. This has been confirmed by the three principal breeding companies in Norway (see acknowledgements). ...
... Thus, the reported triploids arose as a result of spontaneous event, as has been observed previously for Atlantic salmon [40,41], and a range of other fish species in culture [31][32][33]35,36], and in the wild [30]. While the Atlantic salmon farming industry has very recently started experimental production of triploid salmon in Norway [26][27][28][29], for the timescale in which the samples in this study were collected, very few triploid salmon were commercially produced. Furthermore, in all cases where triploid salmon were deliberately produced by these farming companies, triploids were sold to a very limited number of farms in specific locations. ...
Article
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Spontaneous triploidy has been reported in a number of fish species, and is often linked with in vivo or in vitro ageing of eggs post ovulation. Here, we provide the first investigation into the frequency of spontaneous triploidy in farmed Atlantic salmon by analysing more than 4000 fish from 55 farms, and approximately 1000 recaptured escapees, all sampled in the period 2007–2014. In addition, we compare microsatellite genotyping against flow cytometry and red blood cell diameter in a set of 45 putatively diploid and 45 putatively triploid Atlantic salmon. The three methods implemented for ploidy determination gave consistent results, thus validating the methods used here. Overall, 2.0% spontaneous triploids were observed in salmon sampled on farms. The frequency of spontaneous triploids varied greatly among sea cages (0-28%), but they were observed in similar frequencies among the three primary breeding companies (1.8-2.4%). Spontaneous triploids were observed in all farming regions in Norway, and in all years sampled. Spontaneous triploids were also observed among the escapees recaptured in both the marine environment and in rivers. Spontaneous triploidy in commercially produced Atlantic salmon is likely to be a result of the practices employed by the industry. For logistical reasons, there is sometimes a pause of hours, and in some cases overnight, between killing the female broodfish, removal of her eggs, and fertilization. This gives the eggs time to age post ovulation, and increases the probability of duplication of the maternal chromosome set by inhibition of the second polar body release after normal meiosis II in the oocyte.
... Although triploids demonstrate the same production deformities as seen in diploids, the most significant finding is that triploids have a higher prevalence of malformations (see review by Fraser et al., 2012). For example, higher prevalence of vertebral deformities has been reported in triploid salmonids compared to diploids (Madsen et al., 2000;Fjelldal and Hansen, 2010). ...
... Similarly, Solar et al. (1984) and Meyers and Hershberger (1991) observed higher occurrence of deformities (macrocephalia, lordosis and twisted body) in triploid rainbow trout embryos and larvae. There are also reports of higher incidence of vertebral deformities in triploids than diploids in other species studied (Sugama et al., 1992;Zanuy et al., 1994;Fjelldal and Hansen, 2010;Grimmett et al., 2011). Higher incidence of deformity observed in triploids may be related to the method employed for triploid production. ...
... Mortality during freshwater (vaccination to smolt) and seawater (smolt to harvest) generally remained below 10% in all vaccine groups, with no significant effect of ploidy. Comparable ploidy mortality concurs with previous research into triploid vaccination [42,43] as well as recent grow-out studies [33,45,[54][55][56][57]. It can be suggested that this is linked to advances in triploid nutrition [31][32][33] and environmental requirements [30,35,36,58,59]. ...
... Within R2 at smolt, and R2 and R3 at harvest, triploids had significantly higher prevalence of dV than diploids which supports previous reports [32,33]. In both ploidy at smolt, R2 had the highest deformity prevalence which concurs with previous studies indicating this as the most affected vertebral region during freshwater growth [32,54,81,82]. By harvest, the region exhibiting the highest deformity prevalence in both ploidy had shifted from R2 to R3, again supporting previous research [27,32,33,43,83]. ...
Article
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While triploid Atlantic salmon represent a practical and affordable solution to the issues associated with sexual maturation in the salmonid aquaculture industry, empirical evidence suggests triploids are more susceptible to disease and vaccine side-effects than diploids. With vaccination now part of routine husbandry, it is essential their response be studied to confirm their suitability for commercial production. This study tested the response of triploid and diploid Atlantic salmon to vaccination with commercially available vaccines. Triploid and diploid Atlantic salmon siblings were injected with one of three commercial vaccines (or sham-vaccinated) and monitored for performance throughout a commercial production cycle. Sampling at smolt and harvest was undertaken along with individual weight and length assessments through the cycle. Antibody response to Aeromonas salmonicida vaccination was similar in both ploidy, with a positive response in vaccine-injected fish. For both adhesions and melanin, analysis found that higher scores were more likely to occur as the anticipated severity of the vaccine increased. In addition, for adhesion scores at smolt and melanin scores at smolt and harvest, triploids were statistically more likely to exhibit high scores than diploids. Triploids maintained a significantly higher body weight during freshwater and until 11 months post-seawater transfer, with diploids weighing significantly more at harvest. Growth, represented by thermal growth coefficient (TGC), decreased in both ploidy as the severity of adhesions increased, and regression patterns did not differ significantly between ploidy. Vertebral deformity prevalence was consistently higher in triploids (smolt 12.3 ± 4.5%; harvest 34.9 ± 5.9%) than diploids (smolt 0.8 ± 0.5%; harvest 15.9 ± 1.9%), with no significant difference between vaccine groups in each ploidy. This study demonstrates that triploids respond as well to vaccination as diploids and provides further supporting evidence of triploid robustness for commercial aquaculture.
... This results in triploid eggs with two sets of chromosomes from the female and one set from the male, rendering the offspring sterile. Comparative studies have shown that triploid salmon have a higher prevalence of ocular cataracts (Fraser et al. 2012;Olsvik et al. 2020;Oppedal, Taranger, and Hansen 2003;Sambraus et al. 2017a), skeletal deformities such as those of the lower-jaw (Amoroso et al. 2016;Benfey 2001;Sadler, Pankhurst, and King 2001;Sutterlin, Holder, and Benfey 1987) and vertebral compression or fusion (Fjelldal and Hansen 2010), compared to diploids. However, triploid salmon production can be optimized by fulfilling their triploid-specific requirements, including a lower thermal optimum (Fraser et al. 2015;Sambraus et al. 2017b) and higher requirements for key nutrients such as phosphorus (Fjelldal et al. 2016;Sambraus et al. 2020;Smedley et al. 2016Smedley et al. , 2018 and histidine (Taylor et al. 2015b) The performance of triploid salmon has been monitored during full production cycles in Scotland (Taylor et al. 2013) and Norway (Fraser et al. 2013). ...
... Although the sampled triploid fish were generally smaller than the sampled diploids, there were no statistically significant differences in SGR. This is in contrast to earlier studies showing that triploid growth rates in seawater are typically lower than those of diploids (Fjelldal and Hansen 2010;Fraser et al. 2014Fraser et al. , 2013Leclercq et al. 2011;Taylor et al. 2014Taylor et al. , 2015aTaylor et al. , 2013. However, it is well established that smaller fish have a higher SGR than larger fish; thus, the smaller size at the start may explain some of this difference. ...
Article
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Avoiding genetic interactions between wild and farmed Atlantic salmon is regarded as one of the major requirements for a sustainable salmon aquaculture industry. For this reason, farming functional sterile triploids has been suggested as a possible solution. However, knowledge about how triploids cope under commercial conditions is lacking. In the present study, we compared the performance of diploid and triploid Atlantic salmon among four Norwegian aquaculture companies. Diploid and triploid groups of the same genetic line were farmed in western, mid, and northern Norway under commercial conditions from seawater transfer until slaughter.Overall, triploid salmon exhibited reduced survival, higher incidence of emaciated fish, and scored, on average, a lower quality rating during primary processing. The results highlight the need for further research on how to improve the welfare and performance of triploid salmon in commercial aquaculture operations.
... In addition to compromising fish welfare, vertebral deformities also increase harvest downgrading and present problems to automated filleting, which may result in economic losses (Michie, 2001). Recently, Fjelldal and Hansen (2010) observed a significant increase in the number of deformed vertebrae (dV) in full sibling triploids, and that increasing number of dV was significantly correlated to the reduced growth performance of Atlantic salmon . In this respect, growth performance of triploids relative to their diploid siblings has shown conflicting results. ...
... Fjelldal et al., 2007bFjelldal et al., , 2008Fjelldal et al., , 2009bWitten et al., 2006). Whilst an increased prevalence was reported in triploid salmon smolts at the end of freshwater rearing (30-35% vs. 8-13%, Fjelldal and Hansen, 2010), most of the triploid individuals examined in this study had normal bone morphology, suggesting that higher occurrence of skeletal deformities is related to external factors and not only ploidy status. In the present study, the highest prevalence of deformity per vertebra was found in the tail region R4, principally v54 in both ploidy levels, whereas the highest prevalence of deformity per region was found in both R2 and R4 for both ploidy levels, whilst only triploids showed significant deformity in R3. ...
Article
This study examined performance traits between diploid and triploid siblings within 44 full-sib families (produced by 15 sires and 44 dams) under commercial rearing conditions from first feeding to harvest. Survival did not differ between ploidy levels throughout the production cycle. Triploids grew faster (+30%) in freshwater, but slower during the seawater phase (−7.5%), although overall growth was comparable between ploidy levels (SGR 1.17 vs. 1.18% day−1). Triploids showed no visual deformity in freshwater but a significantly increased prevalence in seawater, mainly evident as jaw malformations and radiological deformed vertebrae. However, severity of deformities was considerably lower than in previous studies, as was the occurrence of cataracts. Using fixed effect linear models the combined effect of deformity and cataract only explained 50% of reduced growth performance, suggesting that other factors were also contributing to reduced performance in triploids. These differences could be due to different nutritional requirements and environmental tolerances in triploids. Family differences were obtained for growth traits (weight and length). Family ranking for production traits was also consistent between diploid and triploid siblings. Harvest quality grading was high (>99% superior) and flesh quality was comparable between ploidy levels, although triploids did have significantly higher PUFA levels at harvest. The study indicates the potential for superior triploid growth, and in conjunction with development of triploid specific diets may be sufficient in order to establish viable triploid salmon aquaculture.
... As well as inhibiting further genetic interactions with wild populations, farming triploid salmon reduces the incidence of unwanted sexual maturation and its negative effect on growth rate, flesh quality and survival [10], at least in female triploids [11]. However, despite the potential benefits of using sterile triploids for salmon aquaculture, their adoption in commercial production has been delayed by several challenges, including high incidences of skeletal deformities and cataracts [12,13], increased sensitivity to sub-optimal rearing environments [14], and the inconsistent results found relating to their relative commercial performance compared to diploids, for example growth and survival [6,8]. The mechanisms underlying these challenges are partially, but not fully known. ...
... Four families were produced: one wild, one domesticated, one maternal-domesticated hybrid cross (domesticated ♀ x wild ♂) and one maternalwild hybrid cross (wild ♀ x domesticated ♂). Thirtyseven minutes and 30 s after fertilization at 8°C, half of the eggs from each of the four families were subjected to a hydrostatic pressure of 655 bar for 6 min and 15 s [12]. This resulted in eight experimental groups consisting of four diploid and four triploid families of roughly 150 individuals each. ...
Article
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Background The Atlantic salmon aquaculture industry is investigating the feasibility of using sterile triploids to mitigate genetic interactions with wild conspecifics, however, studies investigating diploid and triploid performance often show contrasting results. Studies have identified dosage and dosage-compensation effects for gene expression between triploid and diploid salmonids, but no study has investigated how ploidy and parent-origin effects interact on a polygenic trait in divergent lines of Atlantic salmon (i.e. slow growing wild versus fast growing domesticated phenotype). This study utilised two experiments relating to the freshwater growth of diploid and triploid groups of pure wild (0% domesticated genome), pure domesticated (100% domesticated genome), and F1 reciprocal hybrid (33%, 50% or 66% domesticated genome) salmon where triploidy was either artificially induced (experiment 1) or naturally developed/spontaneous (experiment 2). Results In both experiments, reciprocal hybrid growth was influenced by the dosage effect of the second maternal chromosome, with growth increasing as ploidy level increased in individuals with a domesticated dam (from 50% to 66% domesticated genome), and the inverse in individuals with a wild dam (from 50% to 33% domesticated genome). Conclusions We demonstrate that the combined effect of ploidy and parent-origin on growth, a polygenic trait, is regulated in an additive pattern. Therefore, in order to maximise growth potential, the aquaculture industry should consider placing more emphasis on the breeding value of the dam than the sire when producing triploid families for commercial production. Electronic supplementary material The online version of this article (doi:10.1186/s12863-017-0502-x) contains supplementary material, which is available to authorized users.
... For fish sampled during the experiment genomic DNA was extracted (Qiagen, DNeasy) from adipose fins collected from all triploid fish. Triploid status was verified using multi-loci microsatellite genetic profiling; the presence of three alleles at multiple loci [25], and any fish not triploid at all loci investigated were excluded from further analysis. ...
Article
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Triploid Atlantic salmon (Salmo salar L.) may play an important role in the sustainable expansion of the Norwegian aquaculture industry. Therefore, the susceptibility of triploid salmon to common infections such as salmonid alphavirus (SAV), the causative agent of pancreas disease (PD), requires investigation. In this study, shortly after seawater transfer, diploid and triploid post-smolts were exposed to SAV type 3 (SAV3) using a bath challenge model where the infectious dose was 48 TCID50 ml⁻¹ of tank water. Copy number analysis of SAV3 RNA in heart tissue showed that there was no difference in viral loads between the diploids and triploids. Prevalence reached 100% by the end of the 35-day experimental period in both infected groups. However, prevalence accumulated more slowly in the triploid group reaching 19% and 56% at 14 and 21 days post exposure (dpe) respectively. Whereas prevalence in the diploid group was 82% and 100% at the same time points indicating some differences between diploid and triploid fish. Both heart and pancreas from infected groups at 14 dpe showed typical histopathological changes associated with pancreas disease. Observation of this slower accumulation of prevalence following a natural infection route was possible due to the early sampling points and the exposure to a relatively low dose of virus. The triploid salmon in this study were not more susceptible to SAV3 than diploid salmon indicating that they could be used commercially to reduce the environmental impact of escaped farmed fish interbreeding with wild salmon. This is important information regarding the future use of triploid fish in large scale aquaculture where SAV3 is a financial threat to increased production.
... If one applies the new system of the recognition of six vertebral column regions to the salmonid vertebral column, in which anomalies frequently occur, most deformities are present in the posterior abdominal (Fjelldal et al. 2007;Sullivan et al. 2007;Fjelldal & Hansen, 2010) and caudal regions (Wargelius et al. 2005;Grini et al. 2011). Although the total number of vertebral centra of specimens in each temperature group is not related to temperature, the number of centra varies in each region. ...
Article
Teleost vertebral centra are often similar in size and shape, but vertebral-associated elements, i.e. neural arches, haemal arches and ribs, show regional differences. Here we examine how the presence, absence and specific anatomical and histological characters of vertebral centra-associated elements can be used to define vertebral column regions in juvenile Chinook salmon (Oncorhynchus tshawytscha). To investigate if the presence of regions within the vertebral column is independent of temperature, animals raised at 8 and 12 °C were studied at 1400 and 1530 degreedays, in the freshwater phase of the life cycle. Anatomy and composition of the skeletal tissues of the vertebral column were analysed using Alizarin red S whole-mount staining and histological sections. Six regions, termed I–VI, are recognised in the vertebral column of specimens of both temperature groups. Postcranial vertebrae (region I) carry neural arches and parapophyses but lack ribs. Abdominal vertebrae (region II) carry neural arches and ribs that articulate with parapophyses. Elastic- and fibrohyaline cartilage and Sharpey's fibres connect the bone of the parapophyses to the bone of the ribs. In the transitional region (III) vertebrae carry neural arches and parapophyses change stepwise into haemal arches. Ribs decrease in size, anterior to posterior. Vestigial ribs remain attached to the haemal arches with Sharpey's fibres. Caudal vertebrae (region IV) carry neural and haemal arches and spines. Basidorsals and basiventrals are small and surrounded by cancellous bone. Preural vertebrae (region V) carry neural and haemal arches with modified neural and haemal spines to support the caudal fin. Ural vertebrae (region VI) carry hypurals and epurals that represent modified haemal and neural arches and spines, respectively. The postcranial and transitional vertebrae and their respective characters are usually recognised, but should be considered as regions within the vertebral column of teleosts because of their distinctive morphological characters. While the number of vertebrae within each region can vary, each of the six regions is recognised in specimens of both temperature groups. This refined identification of regionalisation in the vertebral column of Chinook salmon can help to address evolutionary developmental and functional questions, and to support applied research into this farmed species.
... The fact that diploids had higher SGRs and mm day À1 at 16°C compared to 10°C in the present study, while triploids only differed in mm day À1 between the temperatures may point to that the optimum temperature for growth in freshwater is different between diploids and triploids. Growth in freshwater has often been reported superior in triploids compared to diploids (Fjelldal & Hansen 2010;Leclercq et al. 2011;Taylor et al. 2012;Taylor et al. 2013), and in the present study, triploids were significantly heavier compared to diploids at experimental start. This is likely due to generally lower temperature in freshwater rearing that is mainly within the preferred range of triploids. ...
Article
The aim of the present study was to investigate cataract development in diploid (2N) and triploid (3N) Atlantic salmon smolts and post-smolts at two water temperatures (10 and 16 °C) given diets with different histidine supplementation (LH, 10.4 and HH, 13.1 g kg(-1) ) before and after seawater transfer. In freshwater, a severe cataract outbreak was recorded in both ploidies reared at 16 °C. The cataract score was significantly higher in triploids compared to diploids, and the severity was lower in both ploidies fed the HH diet. The cataract development at 10 °C was minor. Low gill Na(+) , K(+) -ATPase activity in fish reared at 16 °C before seawater transfer was followed by osmoregulatory stress with elevated plasma electrolyte concentrations and high mortality in sea water. Both diploids and triploids reared at 10 °C developed cataracts during the seawater period, with higher severities in triploids than diploids and a reduced severity in the fish fed the HH diet. The findings of this study demonstrate the importance of environmental conditions in the husbandry of Atlantic salmon, and particularly triploids, with regard to smoltification and adjusted diets to mitigate cataract development in fresh and sea water.
... In this context, there is increasing interest in the use of triploid salmon in aquaculture, as triploid fish, with three sets of chromosomes (3N), are functionally sterile (reviewed by Benfey, 1999Benfey, , 2015Maxime, 2008;Pifferer et al., 2009). However, the aquaculture industry has been reluctant to adopt the use of triploid Atlantic salmon as reports suggest they are inferior to diploid fish due to poorer growth, higher mortalities (Carter et al., 1994;Cotter et al., 2002;Friars et al., 2001;Johnstone et al., 1991;Galbreath et al., 1994;Jungalwalla et al., 1991;O'Flynn et al., 1997;Taylor et al., 2013), and the increased prevalence of skeletal deformities (Fjelldal and Hansen, 2010) and ocular cataracts (Wall and Richards, 1992). Recent research has shown that lowering water temperature during egg incubation, and increasing dietary phosphorus and histidine can reduce the occurrence of skeletal deformities Fraser et al., 2015a) and ocular cataracts (Taylor et al., 2015) in triploid Atlantic salmon. ...
Article
The use of sterile triploids in Atlantic salmon aquaculture would mitigate the environmental risks associated with introgressive hybridization between escaped farmed and wild Atlantic salmon. However, production of farmed triploid salmon is limited due to reports of poorer growth and higher mortality when compared to diploids, in particular under sub-optimal environmental conditions. To address these concerns, we monitored triploid and diploid Atlantic salmon post-smolts at temperatures between 3 and 18 °C and 100% oxygen saturation (O2 sat), and additional periods of 60% O2 sat (hypoxia) at 6 or 18 °C, respectively. Feed intake and oxygen consumption rate were monitored throughout the experimental period. Muscle and blood samples were collected at 100 and 60% O2 sat at 6 and 18 °C for analysis of white muscle energy phosphates (creatine phosphate, adenosine triphosphate) and carbohydrate fuels (glucose, glycogen) as well as blood clinical chemistry (whole blood: hematocrit; plasma: Na⁺, K⁺, Cl⁻, glucose, lactate, pH, triacylglycerol). Mortality was similar between ploidies, but higher in triploids compared to diploids during reduced O2 sat at 18 °C. Compared to diploids, triploids had higher feed intake (% biomass) at ≤ 9 °C, but lower feed intake at ≥ 15 °C. Feed intake peaked at 12 and 15 °C for triploids and diploids, respectively. Triploids progressively reduced feed intake with increasing temperature after peak feeding, indicating reduced scope for specific dynamic action with increasing water temperature. During hypoxia, triploids had lower feed intake than diploids at 6 and 18 °C. The difference in feed intake was not associated with any ploidy effect on body weight gain or feed conversion ratio, but triploids had greater body length growth compared to diploids. At ≥ 15 °C triploids consumed less oxygen than diploids. In the white musculature, the only observed difference between ploidies was a lower level of glycogen in triploids compared to diploids at 18 °C and 100% O2 sat. In the blood plasma, the concentration of ions was lower and glucose level higher in triploids compared to diploids at 18 °C and 60% O2 sat. The results of this study indicate that triploid Atlantic salmon post-smolts can substitute diploids, but are less tolerant to high seawater temperature and low O2 sat. For sea-cage farming of triploid salmon post-smolts, this would favour production areas with maximum temperatures of 15 °C and sufficient oxygen.
... In the period in which the present study was conducted, almost no deliberate commercial production of triploid Atlantic salmon occurred. However, recent developments in production techniques have solved some of the early challenges experienced with commercial production of triploids (Fjelldal and Hansen 2010;Fraser et al. 2012;Frenzl et al. 2014;Leclercq et al. 2011;Taylor et al. 2015). In Norway, which is the worlds largest Atlantic salmon producing country, recent government licensing schemes have encouraged companies to initiate triploid production at a commercial level. ...
Article
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Each year, hundreds of thousands of farmed Atlantic salmon escape from fish farms into the wild. Some of these escapees enter freshwater, and manage to interbreed with native populations. To hinder further genetic introgression in native populations, the use of sterile triploid salmon within commercial aquaculture is being examined. However, if triploid escapees migrate into freshwater, they may still have ecological impacts on local populations. In the present study, we used microsatellite DNA genotyping to determine the ploidy of 3794 farmed escapees captured in 17 Norwegian rivers in the period 2007–2014. Although a previous study has reported an average of 2 % triploids in Norwegian fish farms during this exact period, here, we only observed 7 (0.18 %) triploids among the escapees captured in freshwater. In addition, we identified three trisomic escapees. For the triploids where the within-river capture location was determined, they were only observed in the lower reaches and not on the spawning grounds. It is concluded that propensity for triploid Atlantic salmon to migrate into freshwater following escape from a fish farm is significantly lower than for normal diploid salmon escapees. Therefore, commercial production of triploids should not only be seen as an effective way of stopping genetic introgression, it will also significantly reduce the numbers of escapees entering rivers, which in turn limits ecological interactions and potential disease transmission.
... Âî-ïåðâûõ, ïî ñêîðîñòè ðîñòà ãèáðèä âñå-òàêè îïåðåaeàåò êóìaeó (Deng et al., 1992;. Âî-âòîðûõ, ãèáðèäû ëó÷øå, ÷åì ðàäóaeíàÿ ôîðåëü, ïåðåíîñÿò ïåðåñàäêó â ìîðñêóþ âîäó è  îòëè÷èå îò ðàäóaeíîé ôîðåëè, ó àòëàíòè÷åñêîãî ëîñîñÿ óñêîðåííûé òåìï ðîñòà òðèïëîèäîâ îòìå÷àëè óaeå â ïðåñíîâîäíûé ïåðèîä aeèçíè (Boeuf et al., 1994;Wilkins et al., 2002;Burke et al., 2010;Fjelldal, Hansen, 2010), èëè, ïî êðàéíåé ìåðå, òåìï ðîñòà äèïëîèäîâ è òðèïëîèäîâ â ýòîò ïåðèîä áûë îäèíàêîâûì (ñì. ññûëêè â ðàáîòå: Piferrer et al., 2009). ...
Book
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The monograph presents the basic data on the systematics, ecology, population structure, and genetics of salmonid fish, as well as commercial significance of salmonids. The major part of the book is a detailed description of all genetic methods used in the breeding of noble salmons in a historical perspective, from hybridization and selection used since the 19th century to genetic engineering. In addition, the main methods of molecular genetic analysis are described in detail, and the results of application of these methods to studying Atlantic salmon, rainbow trout, and brown trout bred under artificial conditions are presented. The issue of population gene pool conservation under the conditions of artificial reproduction is discussed.
... Recent studies have continued to explore and elucidate the physiology and performance of triploid salmon. These results show that the commonly reported problems of deformity, poor survival and reduced growth in triploids can be addressed through refined husbandry, feeds and management, thus further supporting the application of triploids in the aquaculture industry (Burke et al. 2010;Fjelldal and Hansen, 2010;Leclercq et al. 2011;Taylor et al. 2011Taylor et al. , 2012. However, very few studies have focussed on triploid Atlantic salmon health and immunity. ...
Article
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Few studies have focussed on the health and immunity of triploid Atlantic salmon and therefore much is still unknown about their response to commercially significant pathogens. This is important if triploid stocks are to be considered for full-scale commercial production. This study aimed to investigate and compare the response of triploid and diploid Atlantic salmon to an experimental challenge with Neoparamoeba perurans , causative agent of amoebic gill disease (AGD). This disease is economically significant for the aquaculture industry. The results indicated that ploidy had no significant effect on gross gill score or gill filaments affected, while infection and time had significant effects. Ploidy, infection and time did not affect complement or anti-protease activities. Ploidy had a significant effect on lysozyme activity at 21 days post-infection (while infection and time did not), although activity was within the ranges previously recorded for salmonids. Stock did not significantly affect any of the parameters measured. Based on the study results, it can be suggested that ploidy does not affect the manifestation or severity of AGD pathology or the serum innate immune response. Additionally, the serum immune response of diploid and triploid Atlantic salmon may not be significantly affected by amoebic gill disease.
... Currently, the only method available to sterilize commercial-scale numbers of salmon is triploidization [83,84]. However, triploid (infertile) salmon are generally more sensitive to suboptimal rearing environments, which can make them prone to deformities [85,86] and less tolerant to rising seawater temperatures [87]. ...
Article
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Aquaculture is the fastest growing food production sector and is rapidly becoming the primary source of seafood for human diets. Selective breeding programs are enabling genetic improvement of production traits, such as disease resistance, but progress is limited by the heritability of the trait and generation interval of the species. New breeding technologies, such as genome editing using CRISPR/Cas9 have the potential to expedite sustainable genetic improvement in aquaculture. Genome editing can rapidly introduce favorable changes to the genome, such as fixing alleles at existing trait loci, creating de novo alleles, or introducing alleles from other strains or species. The high fecundity and external fertilization of most aquaculture species can facilitate genome editing for research and application at a scale that is not possible in farmed terrestrial animals.
... Deformities were largely localised in vertebrae numbers 28-30, the cranio-caudal axis for mineralisation along the vertebral column (Grotmol et al., 2003), and 54-57 (region 4) where strong variations in vertebral parameters are typically observed (Kacem et al., 1998). Furthermore, with regards to pathology types observed, symmetry shifts (particularly Type 19) were the most commonly recorded in R2 and R4 in all treatments, as previously reported by Fjelldal and Hansen (2010). However, radio-dense/opaque (Type 11-13) were equally prevalent in triploid LP fish which may indicate under mineralisation and an attempt to strengthen vertebrae or excess cartilage density compared to the neighbouring vertebrae (Helland et al., 2006). ...
Article
In order to assess the effect of dietary phosphorus (P) in reducing vertebral malformations and improving freshwater (FW) performance in triploid Atlantic salmon (Salmo salar), both triploid and diploid Atlantic salmon were fed three different dietary P inclusion levels (low: 4.9, medium: 7.7, and high: 9.7 g available P kg⁻¹) from first feeding until smolt. Somatic and skeletal response was assessed at fry (~0.5 g), parr (~5 g) and smolt (~45 g) stages. Triploid parr initially grew faster on the high P diet, while groups fed low P resulted in a significantly higher weight at smolt. Image analysis of double stained Alcian blue and Alizarin red S fry revealed that low P fed triploid fish presented less well mineralised vertebrae, and significantly more malformed vertebrae in both parr and smolt stages following x-ray radiographic assessment. Triploid parr fed high and medium P had similar numbers of malformed vertebrae relative to their diploid counterparts but greater numbers than at smolt. Low P fed triploids had the highest prevalence of jaw and vertebral malformations as well as the highest number of deformed vertebrae in the central caudal vertebral region, which was more pronounced at parr than at smolt. Shorter vertebrae dorso-ventral lengths were observed throughout the spinal column (R1–R4) in parr fed low P and only in the caudal region (R3) at smolt. In parr, both ploidies showed reduced phosphate homeostasis protein fgf23 gene expression in vertebrae when fed low P diets, while triploids showed greater down-regulation of osteogenic factors (alp, opn and igf1r) between diets relative to diploids, suggesting possible greater active suppression of mineralisation and reduced osteogenic potential in triploids. No effects of diet or ploidy on gene expression were evident at smolt. Comparisons between development stages suggest early P supplementation in triploids is crucial for skeletal development. Ultimately, reducing vertebral deformities observed at smolt with higher P supplementation in triploids could contribute towards improving skeletal performance and welfare of the stocks in the marine phase.
... The occurrence of skeletal deformities has resulted in severe economic losses for the aquaculture industry due to the reduced market value of the affected products, as well as the additional labor cost of manual sorting out deformed fi sh (Hattori et al., 2003). In addition to the direct economic losses, skeletal deformities have also been related to high mortality (Puvanendran et al., 2009;Ben Alaya et al., 2011), limited feeding and swimming behavior (Le Vay et al., 2007;Davidson et al., 2011), reduced growth and feeding effi ciency (Eissa et al., 2009;Fjelldal and Hansen, 2010), and susceptibility to infectious disease (Davidson et al., 2011). The Japanese fl ounder, Paralichthys olivaceus , has been used for marine aquaculture and stock enhancement in China and Japan for the past three decades (Katayama and Isshiki, 2007;Lv et al., 2011). ...
Article
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The present study compared vertebral deformities of hatchery-reared and wild-caught juvenile Japanese flounder, Paralichthys olivaceus. A total of 362 hatchery-reared flounder (total length 122.5-155.8 mm) were collected from three commercial hatcheries located in Yantai, East China, and 89 wild fish (total length 124.7-161.3 mm) were caught off Yangma Island near Yantai City (37 degrees 27'N, 121 degrees 36'E). All the fish were dissected, photographed, and images of the axial skeleton were examined for vertebral deformities. Compared with wild-caught flounder in which no deformed vertebrae were detected, 48 (13.3%) hatchery-reared fish had deformed vertebrae. The deformities were classified as compression, compression-ankylosis, and dislocation-ankylosis. The vertebral deformities were mainly localized between post-cranial vertebra 1 and 3, with vertebrae number 1 as the most commonly deformed. The causative factors leading to vertebral deformities in reared Japanese flounder may be related to unfavorable temperature conditions, inflammation, damage, or rupture to the intervertebral ligaments under rearing conditions. Furthermore, no significant difference in the total number of vertebral bodies was observed between wild-caught (38.8 +/- 0.4) and hatchery-reared flounder (38.1 +/- 0.9) (P>0.05). However, the number of vertebral bodies of hatchery-reared and wild-caught flounder ranged from 35 to 39 and from 38 to 39, respectively.
... A higher prevalence of vertebral deformities in triploids than diploids has also been found in many other studies on salmonids (e.g. Fjelldal & Hansen, 2010;Leclercq et al., 2011;Taylor et al., 2014;Weber, Hostuttler, Cleveland, & Leeds, 2014). One possibility for the higher incidence of skeletal deformities in triploid fish might be associated with the standard feed used in this experiment, which was designed for diploids and may not have fulfilled the nutritional (especially phosphorus) requirements of triploids (see e.g. ...
Article
Three‐summers‐old all‐female triploid and diploid rainbow trout were compared after one on‐growing season in sea net cages. Slaughter traits of round weight, gutted weight, fillet weight, carcass% and fillet% were measured at three times in November 2017, January and April 2018. The triploid group had lower daily growth coefficient mean (4.25) and higher feed conversion ratio (1.18) than diploids (4.48 and 1.05, respectively) during on‐growing (June–November). In November, no difference of means was found between mature or immature diploids and triploids for any of the weight traits when the effect of vertebrae defects was statistically removed. However, the triploids had attained higher means than mature or immature diploids in gutted and fillet weight by January, suggesting that the loss of muscle mass during early winter was lower in triploids. Sexually maturing diploids (46%) had lower slaughter yield means compared to triploids or immature diploids at each measurement time, and these differences also increased during overwintering. Instead, the means of yield traits remained similar between the triploid and immature diploid groups through the winter. Likewise, fillet redness remained at equally high level in triploids and immature diploids, whereas in maturing diploids this attribute decreased substantially during overwintering. The triploid group had a higher incidence of vertebral defects (12.0%) than diploids (5.3%). The present results demonstrate the potential of triploid trout in producing large‐sized (>2 kg) fillet fish until spring markets. However, more detailed investigations are needed, particularly regarding the animal health and growth efficiency in triploids, relative to their diploid counterparts.
... The presence of 3 homologous chromosomes sets interferes with the correct pairing and segregation of the chromosomes in meiosis, impairing normal gametogenesis and causing total or partial sterility (Allen & Downing 1986, Purdom 1993 or producing unviable offspring (Lincoln 1981, Wong & Zohar 2015. Triploids have been used in several fish and shellfish species and are widely used in aqua culture (Beaumont & Fairbrother 1991, Beaumont et al. 1995, Maldonado et al. 2003, Arai 2001, Brake et al. 2004, Maldonado-Amparo et al. 2004, Piferrer et al. 2009, Fjelldal & Hansen 2010 because their sexual sterility prevents or reduces the expression of traits related to sexual maturation and reproduction that are unfavorable to aquaculture production (Allen & Downing 1986). ...
Article
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The use of artificially produced triploid (3n) organisms has been proposed as a strategy to produce total or partial sterility in a number of species in order to prevent the potential negative effects of escapees on the genetic structure and integrity of wild conspecific populations or to avoid having alien species become feral in a new environment. When infertility is incomplete, triploid organisms are able to produce gametes that compete with those produced by wild diploid populations or crops that share the same habitat during reproductive periods, which may adversely affect the reproductive success of the wild population. In the present study, a model was developed in order to estimate the effects of the production of gametes by triploid organisms on the reproductive efficiency of a sympatric diploid population of the same species. The chance of the production of balanced gametes by triploids rapidly reduced with the increase of haploid number of the species. It was concluded that, in most aquatic species, this effect depends on the relative contribution of gametes derived from triploid individuals (pet), which is determined by the proportion of triploids in the population and their relative fecundity relative to normal diploids. The variation of the reproductive efficiency in a mixed population of diploids and triploids will be directly proportional to pet if only one sex is fertile in triploids but will have a logarithmic relationship if both sexes are fertile.
... These anomalies may be a result of suboptimal (i.e. diet, high density, limited space availability) culture conditions, rearing conditions promoting fast growth (Witten et al., 2005; Deschamps et al., 2009; Gil-Martens, 2012), inbreeding depression (Aulstad & Kittelsen, 1971; Kincaid, 1976; Poynton, 1987), and triploidy (Sadler, Pankhurst & King, 2001; Fjelldal & Hansen, 2010), at least in salmonids (Boglione et al., 2013). ...
Article
Fish domestication is an evolutionary process arising in captivity through genetic and developmental mechanisms, producing organisms performing more poorly than wild conspecifics in the natural environment. Culture conditions could be suboptimal for fish at particular life cycle stages, presenting environmental disturbances leading to developmental instability. The limited size of captive lots, moreover, can result in the loss of genetic variation, and the resulting homozygosity (as well as hybridization and mutation) could have strong harmful effects on developmental stability. Rainbow trout are the most widely-cultured species in Europe and North America, having been in culture for more than a century. Prolonged artificial selection for desired traits and incidental effects of domestication has led to the development of a ‘farmed type’. Fluctuating asymmetry, variations in meristic counts, and skeletal anomalies were examined in several rainbow trout captive and wild clonal lines as indicators of developmental instability. Differences in developmental stability were identified among lines and correlated with different degrees of exposure to captivity. Some relationship between meristic counts and domestication level was found in the present study, with the number of vertebrae and of dorsal pterygiophores and rays being the strongest predictors of the domestication level. However, the occurrence of skeletal anomalies and fluctuating asymmetry were apparently not related to the level of exposure to captivity. The findings of the present study will facilitate the selection of clonal lines with divergent phenotypes for subsequent quantitative trait loci analyses aimed at identifying genome regions linked with morpho-anatomical and physiological adaptive responses to captivity. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 608–628.
... Farmed salmonids are vulnerable to skeletal deformities (Boglione et al., 2013) with numerous factors associated with vertebral deformity in Atlantic salmon (Salmo salar L.) (Sullivan et al., 2007;Fjelldal and Hansen, 2010;Fjelldal et al., 2012;Fjelldal et al., 2016;Witten et al., 2006;Fraser et al., 2015). Rainbow trout and other Pacific salmon species (Oncorhynchus spp.) display similar ranges of deformity (Boglione et al., 2014). ...
Article
The integrity and function of Type I collagen (Col-I), a fundamental structural molecule, is central to fish movement. Farmed Chinook salmon in New Zealand are reported to develop a late onset curvature syndrome, lordosis, kyphosis and scoliosis (LKS), associated with inflammation and fibrosis, which affects movement and product quality. To investigate if type I collagen integrity is associated with LKS, salmon from a farm with high LKS (Farm 1) were compared with a farm with low LKS (Farm 2). Representative salmon from Farm 1 and Farm 2 were harvested at 25 months of age and their physical metrics measured. Condition factor (K) was derived. White muscle samples from the abdominal and caudal regions were sampled and analysed. The properties of Col-I were determined using liquid chromatography-electrospray ionization mass spectrometry. The amount of Col-I in white muscle, inferred from hydroxy-proline [Hyp], was 0.071 and 0.130 ([Hyp (mg) / Dry sample (mg)]%) for Farm 1 and Farm 2 respectively. There was a significant (p < .0004) difference (~2-fold) in [Hyp] between farms and significant differences for all crosslinks reported below. Mature crosslinks histidinohydroxymerodesmosine (HHMD) were ~2.5-fold higher in Farm 1 salmon. Immature crosslinks were ~3-fold dihydroxylysinonorleucine (DHLNL) and >4-fold hydroxylysinonorleucine (HLNL) higher in Farm 1 salmon. Mature pyridinoline (PYR) crosslinks were readily detectable in salmon from Farm 2 but below the threshold for reliable detection in those from Farm 1. The mature crosslink of elastin, desmosine (DES), was ~1.5-fold higher in Farm 2 salmon. We have quantified Col-I in the white muscle compartment of farmed Chinook salmon and established methods to compare the crosslink profile. PYR and DHLNL crosslinks associated with myosepta were significantly different between the populations. Salmon from Farm 2 had both a higher proportion of mature PYR crosslinks and higher [Hyp], additive differences that may be of functional significance. Higher levels of crosslinks (HLNL, HHMD) associated with loose connective tissue and the extracellular matrix were seen in salmon from Farm 1 and also associated with condition factor. These results demonstrated differences in the amount of Col-I and crosslink profile of farmed Chinook salmon which could be linked with a population-based susceptibility toward LKS. The association between LKS and genetic and/or husbandry differences requires additional controlled experiments to determine these relationships more precisely.
... In some studies, deformity prevalence has been shown to be low (< 2%) at first feeding with no overall effect of ploidy (Benfey, 1999;Taylor et al., 2011), while other authors reported higher skeletal deformities in 3 N fish at the same stage of development (Sadler et al., 2001). Prevalence of lower jaw skeletal anomalies associated with 3 N has been reported by several authors at later developmental stages (Amoroso et al., 2016;Benfey, 2001;Fjelldal and Hansen, 2010;Fraser et al., 2015;Leclercq et al., 2011;Sadler et al., 2001;Taylor et al., 2015Taylor et al., , 2011. Shortening of one or both opercula also commonly and equally occur in both 2 N and 3 N Atlantic salmon (Amoroso et al., 2016;Sadler et al., 2001;Sutterlin et al., 1987;Taylor et al., 2012), with potentially important consequences for performance in sea cages and product saleability (Beraldo and Canavese, 2011;Boglione et al., 2013). ...
... Precisely 37 min and 30 s after initiation of fertilization at 8°C, eggs were subjected to hydrostatic pressure of 655 bar for 6 min and 15 s. This procedure has been extensively used in this facility to produce triploid salmonids [40,[67][68][69][70]. Eggs were thereafter incubated in single family trays fed by running water at 6°C. ...
Article
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Background: Triploid organisms have three sets of chromosomes. In Atlantic salmon, hydrostatic pressure treatment of newly fertilized eggs has been extensively used to produce triploids which are functionally sterile due to their unpaired chromosomes. These fish often perform poorly on commercial farms, sometimes without explanation. Inheritance patterns in individuals subjected to pressure treatment have not been investigated in Atlantic salmon thus far. However, work on other species suggests that this treatment can result in aberrant inheritance. We therefore studied this in Atlantic salmon by genotyping 16 polymorphic microsatellites in eyed eggs and juveniles which had been subjected to pressure-induction of triploidy. Communally reared juveniles including fish subjected to pressure-induction of triploidy and their diploid siblings were included as a control. Results: No diploid offspring were detected in any of the eggs or juveniles which were subjected to hydrostatic pressure; therefore, the induction of triploidy was highly successful. Aberrant inheritance was nevertheless observed in 0.9% of the eggs and 0.9% of the juveniles that had been subjected to pressure treatment. In the communally reared fish, 0.3% of the fish subjected to pressure treatment displayed aberrant inheritance, while their diploid controls displayed 0% aberrant inheritance. Inheritance errors included two eyed eggs lacking maternal DNA across all microsatellites, and, examples in both eggs and juveniles of either the maternal or paternal allele lacking in one of the microsatellites. All individuals displaying chromosome aberrations were otherwise triploid. Conclusions: This is the first study to document aberrant inheritance in Atlantic salmon that have been subjected to pressure-induction of triploidy. Our experiments unequivocally demonstrate that even when induction of triploidy is highly successful, this treatment can cause chromosome aberrations in this species. Based upon our novel data, and earlier studies in other organisms, we hypothesize that in batches of Atlantic salmon where low to modest triploid induction rates have been reported, aberrant inheritance is likely to be higher than the rates observed here. Therefore, we tentatively suggest that this could contribute to the unexplained poor performance of triploid salmon that is occasionally reported in commercial aquaculture. These hypotheses require further investigation.
... Generally, genome manipulated and normal diploid brook trout studied in the present paper showed the same body disorders however, triploids and gynogenotes had higher prevalence of deformations what is in agreement with already published results (Fjelldal and Hansen, 2010;Fraser et al., 2013;Jagiełło et al., 2018;among others). The increased ratio of individuals with skeletal deformities among chromosome set manipulated brook trout may be caused by the low egg quality, side effects of the HHP shock, nutritional and genetic factors, and their interactions. ...
Article
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In the present research we produced triploid, mitogynogenetic (doubled haploid; DH) and meiogynogenetic brook trout (Salvelinus fontinalis) to examine efficiency of these technologies and potential susceptibility of chromosome set manipulated individuals for the spinal disorders. Triploidy was induced by shocking (High Hydrostatic Pressure – HHP) of fertilized eggs 30 min. after insemination. In turn, gynogenetic development was induced by activation of eggs with UV-irradiated sperm. Activated eggs were then exposed to HHP shock applied 30 and 420 minutes after insemination to provide meiogynogenotes and gynogenetic DHs, respectively. When compared to non-manipulated diploids, the highest survival rates was observed among triploid brook trout while DHs showed the highest mortality. Malformation rates in the diploid larvae from the control groups did not exceed 7.0% while percentage of malformed triploid individuals equaled 19.1%. Drastically increased number of deformed larvae (> 30%) was observed in both, DH and meiogynogenetic individuals. Intensification of kyphosis and scoliosis was clearly demonstrated in the gynogenetic and triploid brook trout. Genetic factors such as increased number of sets of chromosomes in triploids and expression of lethal alleles in the gynogenetic fish plus side effects of HHP shock utilized for retention of the second polar body or inhibition of the first cell cleavage when induced triploid and gynogenetic development have been discussed to affect survival rates and prevalence for the skeletal deformities in the chromosome set manipulated brook trout.
... Several new studies also show that triploid salmon generally grow faster than diploids in freshwater under moderate temperatures (e.g. Fjelldal and Hansen, 2010;Fjelldal et al., 2011;Fraser et al., 2013;Leclercq et al., 2011;Taylor et al., 2011). ...
Article
Sterilization by triploid induction prevents interbreeding between escaped farmed salmon and wild stocks, but reduced performance of triploids at high seawater temperatures has been reported. As high temperature may be followed by limited oxygen (O2) supply in net cages, this study compared the effect of reducing O2 from 100% to 70% of air saturation (termed hypoxia) on parameters of production performance (feed intake, growth, feed conversion ratio, mortality), and physiological status (plasma K+, Cl−, Na+, osmolality, glucose, creatinine (Cr), bilirubin, triacylglycerol (TAG) and alkaline phosphatase (ALP) concentrations) in triploid versus diploid Atlantic salmon kept at high seawater temperature (19 °C). Two triplicate groups of diploid and two triplicate groups of triploid Atlantic salmon post-smolts were acclimated to 10 °C and 100% O2 before experiment start up. During the experiment, temperature was maintained at 10 °C for 10 days, increased to 19 °C over 9 days and kept stable at 19 °C until the experiment ended (day 51). From day 22 to 51, the O2 level was reduced from 100% O2 to 70% O2 in one diploid and one triploid group. The abbreviated group names are 2N100, 2N70, 3N100 and 3N70. Triploidy led to reductions of feed intake and growth, and this effect was amplified by reducing O2 from 100% to 70% O2. Analyses from blood samples drawn on day 51 show that plasma levels of Cl−, TAG, ALP and bilirubin were lowered in triploids in general, and that plasma Cr levels trebled and plasma K+ levels dropped in triploids subjected to 70% O2 for 29 days. Mortality was also significantly higher in the 3N70 group. According to these effects, the following order of production performance is suggested at high seawater temperature (best to worst): 2N100 > 2N70 ≥ 3N100 > 3N70. An interesting difference in the behavior between diploid and triploid fish was observed during the experiment: triploids generally moved against the tank water current, ram ventilating, as opposed to diploids, which displayed normal gill ventilation and were in part moving along with the current. The inability of triploid Atlantic salmon to withstand high temperature in combination with moderate hypoxia could set limitations to the geographical distribution of triploid salmon farming.
... The incidence of cranial deformities and kyphosis was significantly higher in intensively cultured P. pagrus. In addition, a higher number of fish from the intensive system had an extra vertebra (Roo et al., 2010).Interestingly, several studies did not find any connection between the occurrence of skeletal deformities and rearing circumstances (Gjerde et al., 2005;McCrimmon and Bidgood 1965;Boglione et al., 2014), contradictory, other studies verified that some deformities such as fusion and compression of vertebral spines and displacement of spinal column and degrading bone quality could be linked to rearing condition of fast-growing fish(Fjelldal & Hansen, 2010;Gil-Martens et al., 2005). There were significant differences in the occurrence of skeletal abnormalities in rainbow trout reared either in organically or intensively reared systems, fish reared in intensively system showed 12.5% of the individuals with anomalies (Boglione et al., 2014). ...
Article
Skeletal deformities in fish are abnormal transformations of normal bony and/or cartilaginous structures into abnormal skeletal structures that are histologically and anatomically different from their normal prototype. Such deformities are diverse in their location, morphology and impact. The three main topographic regions of a fish (head, trunk and tail) could be affected by several types of deformities with various degrees of severity depending on the cause, age and histology of the affected tissue, regardless of whether it is bony or cartilaginous. The degree of skeletal deformity could impact physiological processes, including swimming, reproduction, growth, resistance to diseases and susceptibility to predation, as well as being the direct or indirect cause of low body weight gain or even death in young fish. Skeletal deformities are commonly recorded from wild and cultured fish, with high incidence in fish hatcheries. Skeletal deformities are responsible for considerable economic damage to the sector of aquaculture by making fish unsightly and affected fish consequently remain unsold. Such deformities are also proposed as biological indicators of aquatic environmental pollution and defaults in aquaculture management. Several diagnostic techniques, such as radiography, ultrasonography and magnetic resonance imaging, have been used for detecting and defining skeletal deformities in fish. Here, the present review summarizes the incidence, classification, aetiological factors, diagnostic procedures and prevention of the most common skeletal deformities in fish.
... Skeletal deformities in triploids have long been seen as a bottleneck to their commercial acceptance (Taranger et al., 2010). We found no ploidy effect on vertebral deformities, in contrast to numerous previous studies (Fjelldal and Hansen, 2010;Leclercq et al., 2011;Fraser et al., 2013). This is most likely explained by the relatively high dietary phosphorus content throughout the study (≥15.5 g/kg total phosphorus), the requirement for which is known to be higher in triploids compared to diploids (Fjelldal et al., 2016), especially during the very early stages of development . ...
Article
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Sterile triploid Atlantic salmon (Salmo salar) show inconsistent seawater grow-out, but the reason why remains unclear. The purpose of this study was to determine the salinity optima of triploid post-smolts. Diploids and triploids were assessed for smoltification status during an underyearling smolt regime before being transferred to one of four different salinities, 0, 11, 23 and 35 ppt at 12 °C and under 24 h continuous light for 83 days. During this period, fish growth, plasma biochemistry, and production traits (vertebral deformities, ocular cataracts, sexual maturation) were monitored. Molecular biomarkers in the gill (nkaα1a, nkaα1b, nkcc1a) suggested triploids reached peak smolt earlier than diploids and began the desmoltification process before the start of the salinity treatments, however this was not reflected in gill Na⁺/K⁺-ATPase enzyme activity. At the initiation of the salinity treatments triploids were significantly larger than diploids (mean weight g ± SE: 71 ± 0.7 and 87.2 ± 0.8 for diploids and triploids, respectively) and there was a ploidy effect on post-smolt growth, with body weight showing a clearer positive trend with salinity in diploids (0 < 11 = 23 = 35 ppt) than in triploids (0 < 11 < 35 = 23 ppt) (final mean weight g ± SE: 255.2 ± 7.4, 303.9 ± 9, 313.9 ± 9 and 342.4 ± 12 for diploids and 322.9 ± 9.7, 361.7 ± 10.7, 425.9 ± 12.1, 415.2 ± 12.2 for triploids at 0, 11, 23, and 35 ppt, respectively). Plasma Na⁺ and Cl⁻ increased, but plasma pH decreased, with increasing salinity in both ploidy. However, ploidy only had transient effects on plasma biochemistry depending on the salinity treatment. There was no ploidy effect on vertebral deformities (21% of both ploidy had one or more deformed vertebra). In contrast, triploids had a significantly higher prevalence of ocular cataracts (84 vs 98% in diploids and triploids, respectively) with a higher mean cataract score (mean ± SE: 1.93 ± 0.1 and 2.78 ± 0.1 for diploids and triploids, respectively), but a significantly lower prevalence of pubertal male post-smolts (15 vs 2% in diploids and triploids, respectively). Salinity treatment had no effect on vertebral deformities, cataracts, or post-smolt sexual maturation. In summary, there was a ploidy mismatch for smoltification biomarkers in the gill and salinity had a strong effect on post-smolt growth, but the effects were ploidy dependent.
... By contrast TG/DIP fish showed enhanced growth rates compared to their NTG counterparts, which is in agreement with previous results reported by Tibbetts et al. (2013). Conventional triploid salmonids demonstrate inconsistent growth performance showing inferior (Carter et al., 1994;O'Flynn et al., 1997), equal (Cotter et al., 2002;McGeachy et al., 1995;Taylor et al., 2011) or superior (Burke et al., 2010;Fjelldal and Hansen, 2010;Galbreath et al., 1994;Galbreath and Thirgaard, 1995;Jungalwalla, 1991;Taylor et al., 2011Taylor et al., , 2012 growth rates than their NTG/DIP siblings in freshwater culture. The discrepancy in these results is most likely related to large variations in strain, growth phase, diet formulation, methodology and environmental conditions of different studies. ...
Article
This study assessed the capacity of non-transgenic (NTG) and growth-hormone transgenic (TG; gene construct EO-1α) Atlantic salmon (Salmo salar L.), comprised of conventional diploid (DIP) and reproductively-sterile triploid (TRIP) fish, to utilize a diet containing relatively high amounts of plant protein (PP) concomitant with lower levels of fish meal (FM) protein. Triplicate groups of full-sibling NTG/DIP, NTG/TRIP, TG/DIP and TG/TRIP salmon (initial weight, 27–35 g) were held in freshwater and fed two experimental diets until they exceeded 400% growth. Two isonitrogenous (50% crude protein), isolipidic (21% lipid) and isoenergetic (22 MJ/kg gross energy) experimental diets were tested. The control diet (FM) contained 64 and 36%, while PP diet contained 32 and 68% of total dietary protein from FM and PP, respectively. TG and NTG fish achieved the target (> 150 g) weight in 89 and 206 days, respectively. TG fish exhibited significantly higher specific growth rates (SGR) (2.48 vs 0.7%/day) and thermal growth coefficient (TGC) (3.04 vs 0.79) than NTG, regardless of ploidy or diet. TG/TRIP fish had significantly lower growth rates than DIP due to lower feed intake, while no ploidy effect was observed within the NTG group. Feed conversion ratio (FCR) was significantly better in TG/DIP and TG/TRIP fish having achieved the same target weight with 20–25% less feed due to improved protein utilization and retention efficiency compared to NTG fish. NTG fish had higher digestibility of protein (93% vs 89%), lipid (95% vs 94%) and energy (89% vs 85%) relative to their TG siblings, and was similar between DIP and TRIP fish. Nutrients' digestibility was significantly lower in TG fish fed PP diet than those fed FM diet, regardless of ploidy. At the end of the study, TG fish had significantly lower whole-body protein (56% vs 59%) and higher lipid (36% vs 34%) and energy (2746 vs 2694 kJ/100 g) content than NTG fish. However, as a result of the rapid growth rate and efficient feed utilization, nutrient gain and retention efficiencies were significantly higher in TG than NTG fish. DIP and TRIP TG Atlantic salmon have the ability to maintain accelerated growth even when fed a high PP diet (68% of dietary protein), which may have important benefits for the production of growth hormone transgenic Atlantic salmon.
Article
Different levels of pressure were investigated to see if it was possible to induce triploidy at a lower pressure than previously used (600 bar) for Atlantic cod (Gadus morhua). Newly fertilized eggs were exposed to different levels of pressure: 400, 500, and 600 bar, and one control group (no pressure). Induction of triploidy occurred at each pressure level used in this experiment. Mean weight and length at the termination of the trial period was significantly lower, in the 400 bar group, compared to the other treatment groups. Microsatellite loci analysis revealed over 90% triploid outcome in each experimental group. Lower incidence of deformities was seen in the 400 bar group compared to the 500 and 600 bar groups. Overall this study demonstrated successful triploid induction at both low (400 bar) and medium (500 bar) pressures.
Article
Triplicate groups of triploid and diploid Atlantic salmon were fed diets with a low (LP, total P: 7.1 g kg−1), medium (MP, total P: 9.4 g kg−1) or high (HP, total P: 16.3 g kg−1) phosphorous (P) level from first feeding (0.18 g) to transfer to sea water (~50 g, duration: 203 days) and subsequently fed a commercial diet in sea water for 426 days (~3 kg). This study examined the short- and long-term effects of dietary P on freshwater performance (mortality, growth), vertebral deformities (radiology), bone cell activity (ALP and TRACP enzyme activity in vertebrae and scales, and fgf23, bgp and igf-I relative gene expression in vertebrae), bone mineralization (ash content) and some parameters related to fish condition (heart and liver size). Irrespective of ploidy, at seawater transfer, fish fed the MP diet had significantly highest length and weight and those fed the LP diet significantly lowest length and weight, while those fed the HP diet had intermediate lengths and weights. Increased dietary phosphorus reduced deformities in both ploidies at seawater transfer; however, triploids fed the LP and MP diets had more deformities than diploids fed the respective diets, while there was no ploidy effect observed for fish fed the HP diet. The vertebral bone ash content at seawater transfer was significantly higher in diploids than in triploids when fed the MP diet only. Alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRACP) enzyme activities and relative gene expression of bone hormones involved in metabolism of plasma phosphate (fgf23) and bone growth (bgp) were not affected by ploidy at seawater transfer, but by dietary P level; LP increased ALP activity and reduced TRACP activity and fgf23 and bgp expression levels in vertebral bone. In scales, LP increased both ALP and TRACP activity. At the termination of the seawater period, the group-wise pattern in occurrence of vertebral deformities was the same as at seawater transfer. The present results on mortality, growth, bone mineralization and development of skeletal deformities all demonstrate that triploids have a higher P requirement than diploids in fresh water. This study shows that an optimalization of P nutrition for triploid Atlantic salmon can improve health and welfare and reduce down-grading of triploid salmon.
Article
Artificial triploid salmonids are sterile and therefore commercially bred to prevent genetic interactions between wild and domestic fish strains. The full biological effects of having an extra chromosome set are largely unknown, but triploids are considered to be more sensitive to sub-optimal environmental conditions and to be stressed by the presence of diploid conspecifics. Brain serotonergic and dopaminergic activity are known to regulate the stress response in vertebrates, but monoamine systems in diploid and triploid fish have yet to be compared. Here we study monoamine neurochemistry in the telencephalon and brain stem of juvenile diploid and triploid Atlantic salmon (Salmo salar) in response to stress (unstressed vs stressed individuals) and holding (separate- vs mixed-ploidy) conditions. Both diploids and triploids showed an increase in serotonergic activity following stress, but the increase was significantly greater in the telencephalon of triploids compared to diploids. Furthermore, while telencephalic dopaminergic activity was significantly increased in diploids following stress, there was no response in triploids. Holding conditions had a significant effect on dopaminergic activity in the brain stem of diploids only, with lower values in mixed- compared to separate-ploidy conditions. These results suggest artificially produced triploids experience increased reactivity and monoaminergic dysregulation following stress that may impede their welfare and performance. Copyright © 2015. Published by Elsevier Inc.
Article
Using germ cell-free (GCF), sterile, dnd-knockout salmon for farming could solve the problems associated with precocious maturation and genetic introgression of farmed breeds into wild populations. However, prior to using GCF fish in the salmon farming industry, it is crucial to understand if, or how, the GCF phenotype differs from wild type (WT) counterparts in terms of growth and welfare. To characterize the GCF phenotype throughout a production cycle, we reared GCF and WT salmon in indoor common garden tanks for 3 years, until harvest size. Regarding body size, smoltification markers (mRNA levels of gill Na⁺/K⁺-ATPase [NKA] subunits), plasma stress indicators (pH, glucose, sodium, chloride, calcium), relative heart size, prevalence of vertebra deformities and fillet proximate composition, GCF fish could not be distinguished from WTs. Transient differences were detected in plasma concentrations of lactate and osmolality, and only a few genes were differentially expressed in WT and GCF transcriptomes of muscle and pituitary. At harvest, fillets from GCF and WT salmon contained the same amount of omega-3 fatty acids, however the relative content of omega-3 fatty acids was higher in GCF compared to WT males. Towards harvest size, body growth rate, condition factor and relative liver size were significantly higher in WT than in GCF fish, probably relating to initiation of puberty in WTs. Since GCF salmon never become sexually mature, it is possible to postpone the time of harvest to exploit the growth potential uninhibited by sexual maturation. In conclusion, GCF salmon performed to a large extent similarly to their WT counterparts but had the clear advantage of never maturing.
Article
Diploid (2N) and triploid (3N) sibling post-smolts were divided between six sea pens and fed: a standard commercial nutrient package diet (2 × 2N SP, 2 × 3N SP), or an iso-energetic nutrient boosted (higher dietary protein and phosphorous) package (2 × 3N BP) until market size. 3N groups initially grew significantly faster than 2N, and by harvest, 3N BP weighed significantly more (3210 ± 87 g) than 2N SP or 3N SP (3007 ± 64 g; 2965 ± 88 g), while there was no significant difference in weight between ploidy in SP diet. Higher visible vertebral (9.6 ± 0.4%) and jaw deformities (10.6 ± 1.2%) were observed in 3N compared to 2N (0.9 ± 0.1%; 1.3 ± 0.5%). However, x-ray radiography revealed that 3N BP and 2N SP had comparable levels of severely affected individuals at time of sea transfer, while 3N SP showed a 3 fold increase in the severity of malformed individuals. The tail region (R3) in 3N SP fish had both the lowest vertebral strength and stiffness and the highest number of deformed vertebrae. Fillet quality attributes were comparable between diet and ploidy. These findings show that triploid growth rate can be sustained until harvest throughout the seawater phase, and more importantly the progression of spinal deformity beyond that at sea transfer can be stabilised by increasing dietary P during the marine phase. Statement of relevance Tailored triploid specific aquafeeds must be formulated to support growth and prevent deformity in order to minimise welfare implications and allow exploitation of faster growth potential of triploid salmon within industry.
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The effect of a dietary phosphorus regime in freshwater on vertebra bone mineralisation was assessed in diploid and triploid Atlantic salmon Salmo salar. Fish were fed either a low phosphorus (LP) diet containing 10.5 g kg‐1 total phosphorus or a normal phosphorus (NP) diet containing 17.4 g kg‐1 total phosphorus from ∼3 to ∼65 g (day 126) in body weight. Two further groups were fed the NP diet from ∼3 g in body weight, but then switched to the LP diet after 38 (∼10 g in body weight) or 77 (∼30 g in body weight) days. Growth, vertebral ash content (% ash), and radiologically detectable vertebra pathologies were assessed. Triploids were initially smaller than diploids, and again on day 77, but there was no ploidy effect on day 38 or 126. Vertebral ash content increased with increasing body size and those fish fed the NP diet had higher vertebral ash content than those groups fed the LP diet during the intervening time period, but this diet effect became less apparent as fish grew with all groups having relatively equal vertebral ash content at termination. In general, triploids had lower vertebral ash content than diploids on day 38 and this was most evident in the group fed the LP diet. On day 77, those triploids fed the LP diet during the intervening time period had lower vertebral ash content than diploids. At termination on day 126, the triploids had the same vertebral ash content as diploids, irrespective of diet. There was a ploidy × diet interaction on vertebral deformities, with triploids having higher prevalence's of fish with ≥1 deformed vertebra in all dietary groups except continuous NP. In conclusion, between days 0 and 77 (3 to 30 g body size), triploids required more dietary phosphorus than diploids in order to maintain similar vertebral ash content. A possible link between ‘phosphorus feeding history' and phosphorus demand is also discussed. This article is protected by copyright. All rights reserved.
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Triploid Atlantic salmon Salmo salar is commercially available and ideal means of achieving sterility in fish. The expression patterns of triploid parr and smolt were described before. However, little is known about the gene expression and fatty acid composition of triploid alevins at endogenous nutritional stage, which is an important period for their survival and development. In this study, the development of the diploid and triploid Atlantic salmon embryos and hatched alevins before feeding was compared, and the results showed that there was no obvious morphological difference between them. And then, the transcription profiles of the triploid and diploid alevins on 3, 23 and 33 days post hatching (dph) were investigated by using RNA-seq after the yolk sacs were removed. There were more differentially expressed genes (DEGs) on 3 dph (2,925) than those on 23 (589) and 33 dph (606). Compared with the diploid groups, the up-regulated genes in the triploid groups at the three sampling times were 1,189, 339 and 340, respectively, while 1,736, 250 and 266 genes were down-regulated. There were 2,088 and 5,215 DEGs on 23 and 33 dph compared with on 3 dph in the diploid groups, while 6,533 and 9,340 DEGS on 23 and 33 dph compared with 3 dph in the triploid groups. The functional enrichment analysis showed that the DEGs were mainly enriched to digestion and metabolism function, especially on 33 dph when the larvae were about to feeding. Meanwhile, 15 out of 22 kinds of fatty acids of alevins on 33 dph showed significant differences (P < 0.05), in which all the fatty acids contents in the triploid were lower. The results indicated the specific nutritional requirement in the triploid was represented as early as yolk sac stage. The present study gave an important vision in triploid Atlantic salmon breeding.
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The study investigated the effects of a temperature shift during embryogenesis on diploid and triploid Atlantic salmon (Salmo salar L.) embryo development and juvenile skeletal deformities. From fertilization, sibling populations were incubated under one of three temperatures (6, 8 or 11°C) until 400 °days when all fish were then reared under a common temperature until smolt. Survival was negatively impacted by increasing temperatures irrespective of ploidy. There was no effect of incubation temperatures on growth in diploids, but triploids incubated at 6°C had improved growth rates (thermal growth coefficient, TGC: 6°C: 1.05, 8°C: 0.94, 11°C: 0.48). Fish from 11°C in both ploidies showed increased jaw and vertebral deformity prevalence. In response to the temperature change at 400 °days post fertilization, upregulation of bmp2, bmp4, col2a1, mmp13, opn and sparc, and downregulation of ocn further suggest that bone and cartilage formation is compromised after experiencing a thermal shift. The data show that temperature profile during embryogenesis strongly influences future growth and deformity prevalence. Triploids appear to require a lower incubation temperature than the current industry standard of 8°C to promote better overall performance; however, a thermal shift during embryogenesis was shown to impact expression of important developmental genes.
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Skeletal deformities and ocular cataracts have limited the farm performance of sterile triploid salmonids, but have not been assessed in Arctic char (Salvelinus alpinus). We repeatedly radiographed mixed-sex diploid and triploid char (n = 110/ploidy) of Hammerfest (Norway) origin reared on a natural photoperiod and temperature in freshwater over a 3-year period and assessed cataracts at termination. At the population level, triploids were significantly (p < 0.001) heavier at tagging, but lighter at harvest (mass (g) ± SE; tagging, 48 ± 2 vs 67 ± 3; harvest, 2015 ± 83 vs 1639 ± 71, in diploids and triploids, respectively). These growth differences were mainly related to sex and life history, as immature fish were generally smaller than those that matured, and triploids showed lower levels of sexual maturation throughout (mature (%); diploid males, 20 and 65; diploid females, 12 and 83; triploid males, 2 and 40; triploid females 0 and 0, after 2 and 3 years, respectively). In addition, males grew quicker than females, irrespective of ploidy. When comparing fish of the same sex and life history, there was no significant growth disadvantage of triploidy. However, survival was significantly lower in triploids (p < 0.001: 94 vs 86% from tagging to harvest in diploids and triploids, respectively) and they had a significantly higher incidence of fish with one or more deformed vertebra throughout (p < 0.001, 99 vs 71% in 3 year-old diploid and triploids, respectively). Cataract prevalence was high (>90% in both ploidy), but severity was low (on average, <10% of the lens shrouded) and not affected by ploidy (p > 0.1). Based on the average wet body mass of immature fish and losses due to sexual maturation and mortality, mono-sex stocks of male triploid fish gave the highest return per 100 juveniles stocked, followed by diploid males, diploid females, and triploid females (87.5, 83.0, 80.8, and 69.3 kg, respectively) at the earliest opportunity to harvest (i.e. when the fish first reached 0.7–1.0 kg). Therefore, all-male triploids may provide benefits to char aquaculture although their skeletal health should be addressed.
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A batch of experimental rainbow trout was found to have a high level of spinal deformities. An equal deformity level was found in fish from the same batch, but reared at the fish farm from where the fry originated, suggesting that the all-female triploid status of the rainbow trout might account for the high level of deformity.
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Manipulation of fish chromosomes dates back to the early part of this century. The earliest experiments involved induction of gynogenesis with sperm inactivated by radiation or chemical treatments. Temperature or pressure shocks applied soon after fertilization resulted in the retention of the second polar body and reconstitution of diploidy; triploidy resulted from shocks to fish ova fertilized with normal sperm. More recently, it has been possible to suppress the first mitotic division offish eggs with high-pressure or -temperature treatments applied at the time of first cleavage to produce mitotic gynogenetic diploids and tetraploids. Androgenesis has been successfully induced in fish by irradiation of ova, fertilization of eggs with normal sperm, and suppression of the first mitosis with high-pressure treatments. Gynogenetic diploids have been used for cytogenetic studies of meiotic phenomena and gene mapping. The general finding to date is that the arrangement of genes on chromosomes is highly conserved in fish genomes. Inbreeding in successive generations of gynogenetic diploids is not as rapid as was anticipated, due to extensive gene-centromere crossing-over and chiasmata interference. However, isogenic lines can be produced more rapidly from gynogenetic diploids than from inbred lines of normal diploids, which require many generations of sibmating. Mitotic gynogenetic diploids and androgenetic diploids are completely homozygous and similar to inbred or isogenic lines; they can be used to study genetic versus environmental effects on fish. Triploids are of interest because they are expected to be sterile, to grow faster than diploids as they reach the age of sexual maturity, and to live longer than diploids because of the biological costs associated with reproduction; however, results on the performance of adult triploidy have been equivocal. For some species, adult triploidy outperformed diploids in growth and other production characters, whereas the triploidy of other species did not possess superior performance traits.
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A quantitative study of morphological and histological changes in the skeleton (cranial bones and vertebrae) of adult Atlantic salmon Salmo salar during its anadromous migration was performed in order to specify various aspects of its skeletal biology in relationship to this migration. At the beginning of the ascent, there was no morphological difference in the cranial bones between males and females. As the spawning season approached, males showed marked secondary sexual characters particularly allometric breeding growth of some bones of the skull. The histological analysis of the vertebral bone tissue along the vertebral axis showed that bone compacity and number of trabeculae vary depending on their localization on the vertebral axis. Moreover, bone compacity decreased significantly with the sexual maturation of the fish whereas the number of trabeculae grew in both sexes. Thus, the vertebrae (like scales) represent an important source of calcium and other elements during anadromous migration in Atlantic salmon.
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Developmental stability as measured by fluctuating asymmetry is reported to be greater in interspecific salmonid hybrids than in the pure parental species. We have examined FA in Atlantic salmon, Salmo salar and European trout, Salmo trutta and in hybrids between them. FA is significantly greater in meristic traits (number of gill rakers, pectoral fin rays and pelvic fin rays) in hybrids but not in morphometric traits (length of maxilla, length of head, opercular length and eye diameter) in which the hybrids show intermediate values. Triploidisation of salmon had no statistically significant effect on meristic FA. Triploidisation of hybrids significantly reduced meristic FA to values close to those of diploid salmon, thereby reversing the hybridization effect. Triploidisation had little effect on morphometric FA in any of the samples.We conclude that FA in meristic and morphometric traits must be considered separately, and the increased meristic FA in hybrids represents a break-down of coadaptation as mediated by relational genic balance between chromosomes or chromosomal segments.
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Muscle development and growth were investigated in diploid populations of normal-sex-ratio and all-female Atlantic salmon (Salmo salar L.) and their triploid counterparts produced by high-pressure treatment. Somites were formed at the rate of 6 h-1 in both diploids and triploids at 6 degrees C. The rostral-to-caudal development of myotubes, myofibrils and acetylcholinesterase staining at the myosepta was slightly more advanced in triploid than in diploid fish, although the differences were smaller than among individual families. The c-met receptor tyrosine kinase was used as a molecular marker for the satellite cells involved in postembryonic muscle growth. Satellite cell nuclei comprised 17.5 % of total myonuclei in smolts and they were 24 % more abundant in diploid than in triploid fish. Cells expressing the myogenic regulatory factor myf-6, a marker of satellite cells committed to differentiation, represented 14.8 % of total myonuclei in diploids and 12.5 % in triploids. At ambient temperatures, the number of white muscle fibres in normal-sex-ratio fish increased more than 30-fold between the alevin and smolt stages, and approximately 3.5-fold further during the first year of seawater growth. The rate of muscle fibre recruitment in seawater stages was significantly greater in diploid than in triploid fish, reaching 1162 fibres day-1 and 608 fibres day-1, respectively, in all-female groups 800 days post-hatching. For 42 cm fork-length fish, there were approximately one-third more muscle fibres per myotome in diploid than in triploid groups, 649 878 and 413 619, respectively, for all-female fish. The probability density function of muscle fibre diameters in each fish was estimated using non-parametric smoothing techniques, and the mean densities for diploids (fD) and triploids (fT) were calculated. The peak fibre diameter was approximately 20 (micro)m in all age classes, irrespective of ploidy. Distinct bimodal distributions of muscle fibre diameter were evident in all groups 775 days and 839 days post-hatching, reflecting seasonal cycles of fibre recruitment. fD and fT were compared using a non-parametric bootstrap technique and the reference band representing the null-hypothesis indicated that there was no difference with ploidy. Reference bands for normal-sex-ratio fish at 315 days and 470 days indicated that diploids had a higher percentage of smaller-diameter fibres and that triploid distributions had a thicker right-hand tail. Similar differences in fD and fT of muscle fibre diameters were found for all-female fish, although the statistical evidence was less strong. Reference bands indicated differences in the middle range of the distributions of muscle fibre diameter in fish 620-775 days post-hatch, with triploids having a thicker right-hand tail. Thus, a lower density of satellite cells was associated with reduced rates of fibre recruitment but a compensatory increase in muscle fibre hypertrophy in triploid compared with diploid fish.
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In several terrestrial vertebrates, heat shock (HS) during somitogenesis causes vertebral deformities. To determine if vertebral deformities can occur due to sudden temperature changes during early development in fish, Atlantic salmon embryos were HS treated during somitogenesis. Ten months later these individuals displayed a high prevalence of caudal vertebral column condensations (27-34%). The defects were located caudally of the abdominal cavity, displaying an even distribution in this region independent of time of HS. To determine if HS disturbed vertebral development during somitogenesis, two genes coding for markers of skeletal development were identified, namely, the secreted protein Shh (Sashh) and the transcription factor Twist (Satwist). These proteins are involved in the proliferation and specification of presumptive skeletal cells (sclerotome) in vertebrates. The spatial expression pattern of sashh and satwist in salmon indicated a functional conservation of these proteins. Furthermore, HS embryos displayed expressional disturbance in both sashh and satwist, indicating an effect of HS on sclerotomal cell patterning. However, the HS-protecting ability in embryos seems to be individually regulated because reduction in gene expression was not detected at all stages; in addition, HS did not induce somitic disturbance and vertebral deformity in all embryos.
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Anterior/posterior (a/p) compression of the vertebral column, referred to as 'short tails', is a recurring event in farmed Atlantic salmon. Like other skeletal deformities, the problem usually becomes evident in a late life phase, too late for preventive measures, making it difficult to understand the aetiology of the disease. We use structural, radiological, histological, and mineral analyses to study 'short tail' adult salmon and to demonstrate that the study of adult fish can provide important insights into earlier developmental processes. 'Short tails' display a/p compressed vertebrae throughout the spine, except for the first post-cranial vertebrae. The vertebral number is unaltered, but the intervertebral space is reduced and the vertebrae are shorter. Compressed vertebrae are characterized by an unchanged central part, altered vertebral end plates (straight instead of funnel-shaped), an atypical inward bending of the vertebral edges, and structural alterations in the intervertebral tissue. The spongiosa is unaffected. The growth zones of adjacent vertebrae fuse and blend towards the intervertebral space into chondrogenic tissue. This tissue produces different types of cartilage, replacing the notochord. The correspondence in location of intervertebral cartilage and deformed vertebral end plates, and the clearly delimited, unaltered, central vertebral parts suggest that the a/p compression of vertebral bodies is a late developmental disorder that may be related to a metaplastic shift of osteogenic tissue into chondrogenic tissue in the vertebral growth zone. Given the lack of evidence for infections, metabolic disorders and/or genetic disorders, we propose that an altered mechanical load could have caused the transformation of the bone growth zones and the concomitant replacement of the intervertebral (notochord) tissue by cartilaginous tissues in the 'short tails' studied here. This hypothesis is supported by the role that notochord cells are known to play in spine development and in maintaining the structure of the intervertebral disk.
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In August 1998, 3000 Atlantic salmon Salmo salar L. parr were divided into 7 groups with 2 replicates. Every 6 wk until March of the following year 1 group was vaccinated. One group was held as an unvaccinated control. The fish were transferred to seawater in May 1999, and slaughtered in February 2000. Temperature, fish size and photoperiod at vaccination, and the time between vaccination and sea transfer thus varied among the groups. In all vaccinated groups, growth was reduced for 1 to 2 mo following vaccination. Intra-abdominal lesions developed faster, and stabilised at a higher level in the groups vaccinated early at the highest temperature and the smallest fish size. Growth in seawater was influenced by the time of vaccination. At the end of the experiment, the group vaccinated last (MAR) was the heaviest of the vaccinated groups (4.0 kg), and the group vaccinated first, i.e. in August (AUG) was smallest (3.2 kg). Growth rate in seawater differed only in the summer when specific growth rate was above 1.45 in all groups. There was a correlation between adhesion, condition factor and number of weeks from vaccination to sea transfer. The AUG group had the highest condition factor, with a top level of 1.64 in autumn, and this group also displayed the highest incidence of deformed vertebra. The experiment shows that side effects of vaccination can be significantly reduced when planning the vaccination strategy, by taking environmental factors and fish biology into consideration.
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The growth of worldwide aquaculture has been sustained and rapid, and the explosion of research in genetic biotechnology has made significant impact on aquaculture and fisheries, although potential for much greater progress exists. Aquaculture and Fisheries Biotechnology: Genetic Approaches covers topics essential to the study of fish genetics, including qualitative and quantitative traits, crossbreeding, inbreeding, genetic drift, hybridization, selection programs, polyploidy, genomics and cloning. This fully updated second edition also addresses environmental risk, food safety and government regulation of transgenic aquatic organisms, commercial applications of fish biotechnology and future issues in fish genetics.
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A large number of farmed Atlantic salmon escape from sea cages and hatcheries annually. Selection programmes and domestication have changed the genetic composition of farmed salmon to improve their performance in the culture environment, which apparently occurs at the cost of their fitness in the natural environment. Therefore, gene flow from farmed salmon to wild salmon populations may have altered the genetic composition of wild salmon populations. To investigate the temporal genetic stability in seven wild Norwegian salmon populations, genetic profiles were produced from historical and contemporary scale samples. Historical and contemporary samples of salmon from the Namsen, Etne, Opo, Vosso, Granvin, Eio, and Hå Rivers were genotyped at the following eight microsatellite loci: Ssa13.37, Ssa28, SsOSL85, Ssa197, Ssa20.19, SsaF43, Ssa202, and Ssa85. A significant change in genetic profiles was observed over time in the Opo, Vosso, and Eio Rivers, but no changes in genetic profiles were observed in the Namsen, Etne, Granvin, and Hå Rivers. A small reduction in FST values and genetic distances among populations was observed in the contemporary samples compared with the historical samples, indicating a eduction in population differentiation over time.
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Heat shocks of 5 min at 32°C or hydrostatic pressure shocks of 3 or 6 min at 7.0 × 104 kPa (10 150 p.s.i.), when completed within 20 min of fertilization at 10°C, were found to induce 100% triploidy with 70–90% survival (relative to controls) in landlocked Atlantic salmon (Salmo salar L.). The identical heat shock yielded substantially lower numbers of triploids when applied 25 to 45 min after fertilization. Pressure shocks of longer duration (9 to 15 min at 7.0 × 104 kPa) or higher magnitude (6 min at 7.9 × 104 to 10.5 × 104 kPa) resulted in 100% mortality prior to hatching. Possible applications of these techniques to salmonid aquaculture are discussed.
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Experiments were conducted on triploidy induction and effects of triploidy on growth and survival of embryos, larvae, and juveniles of pejerrey, a freshwater atherinid fish. Eighty minutes of cold shock (0.5–0.8°C) starting 6 min after egg activation at 18.5°C consistently induced 100% triploidy, as assessed by chromosome counting of juvenile offspring from five different females. Cold-shocked groups had mean relative survival rates of 94.26, 84.15, 53.16, 65.97, and 68.60% at 20 h and 6–7 d after egg activation, at hatching, and at 2 and 20 d after hatching, respectively. Cumulative mortality among cold-shocked groups up to 20 d after hatching exceeded 80%. Critical mortalities were encountered between the eyed-egg stage and a week after hatching. Triploids showed higher rates of embryo and larval abnormalities (ocular malformation, dilation of the pericardial cavity, bulges in the head, and curling or bending of the body). Triploid larvae and juveniles had variable performance in short-term survival and growth trials. A simple and efficient method for triploid induction was demonstrated; however, the superiority of triploid pejerrey has yet to be ascertained.
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Upwards of 95% triploidy was induced in landlocked, anadromous and hybrid (landlocked female × anadromous male) Atlantic salmon using heat shocks (5 min at 32°C, 20 min after fertilization and incubation at 10°C). On average, 23% of the treated eggs died within 24 h of fertilization. Most of the subsequent mortality occurred prior to hatching. In all cases, triploid hybrids had better survival rates than triploids of either pure form; triploid hybrids had survival rates comparable to those of diploid hybrids, whereas the survival rates of triploid pure forms were substantially lower than their respective diploid pure forms.Two types of morphological abnormalities were apparent in underyearling parr derived from control and heat shocked groups. Short gill covers were present in both diploid and triploid groups, and were not associated with the heat shock. Protruding lower jaws, however, were found almost exclusively in triploid fish, but were not present in all triploid fish within any particular treated group. No diploid fish originating from previously heat shocked eggs had protruding jaws, so the predisposition to this abnormality seems to depend on the triploid condition and not the heat shock.
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The impact of escaped farmed salmon on wild populations may have potentially negative genetic and ecological effects. There is widespread evidence that farmed salmon interact with wild salmon. The use of sterile fish in culture has been proposed as a means of eliminating genetic interaction and minimising the ecological effect of farmed salmon. In this study, the migration behaviour of groups of triploid salmon were investigated through the controlled release of microtagged triploid and diploid stocks on the western coast of Ireland. Mixed-sex and all-female stocks of ranched grilse origin were triploidised using hydrostatic pressure. Smolts were ranched from the hatchery of origin and two groups of post-smolts were released from cages in a marine site. The return of adult salmon from these experimental release groups to coastal and freshwater capture sites was monitored as part of the Irish national coded wire tag recovery programme. The return of triploid salmon from each of the release groups, both to the coast and to fresh water, was significantly reduced compared to diploid salmon. The highest percentage return to fresh water (2.25%) was in the ranched mixed-sex diploid group. In contrast, no salmon from the cage release groups returned to the hatchery location on the Burrishoole river system and recoveries in other freshwater systems were low (
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The use of sterile, triploid salmon for aquaculture would be an effective method of preventing genetic interactions between cultured and wild salmon. The studies presented in this paper compare the performance of six year classes of triploid and diploid salmon in freshwater and seawater stages of commercial production. Freshwater growth was comparable between triploids and diploids. Freshwater survival was also similar between triploids and diploids except that survival was lower in the triploids for the developmental interval between fertilization and first feeding. In sea water, triploids performed better than diploids in terms of growth. However, survival was lower in triploids and they showed a higher incidence of jaw deformities. In summary, the overall yields of triploids was lower than diploids under culture conditions.
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Eggs from nude common carp females heterozygous for the scale cover gene N (ssNn) were used for induction of mitotic gynogenesis and triploidy by heat shock. The type of scale cover for reared fingerling progeny was identified. Among gynogenetic progeny, 99.8% of fish were scattered (ssnn) and 0.02% were nude (ssNn). As the N gene has a very high frequency of recombination relative to the centromere, the occurrence of homozygous nn scattered fishes (NN homozygotes are inviable) proved the mitotic character of induced gynogenesis. In the triploidy experiment, eggs from nude females were inseminated with sperm collected from scattered males. In progeny produced with heat shock, the ratio of nude and scattered fishes was 13:1 instead of 1:1 usually observed at crossing between nude and scattered carp. Such a shift in the ratio in experimental progeny was explained as being due to the high recombination frequency for gene N artificially suppressing the second meiotic division, resulting in triploids with genotype Nnn. All scattered fingerlings karyologically investigated were diploids. It was found that nude triploid Nnn and nude diploid Nn fish differed in the rate of reduction of scale cover and soft rays in the anal fin. This provides an opportunity to identify triploids simply by means of external examination.