Article

Broodstock Management, Fecundity, Egg Quality and the Timing of Egg-Production in the Rainbow-Trout (Oncorhynchus-Mykiss)

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Abstract

The full potential of rainbow trout hatcheries can be attained only if the hatcheries can provide producers with regular supplies of high quality eggs and fry every week of the year. This review assesses aspects of brookstock management central to determining total number of eggs produced, quality of eggs, and timing of maturation and spawning. The effectiveness of hatchery programmes in supporting an expanding rainbow trout market is profoundly affected by the conditions under which the broodfish are maintained, their husbandry, and the stock selected for production. The paper examines factors that can critically affect fecundity, egg production, egg quality, spawning time, and maintenance of egg supplies. The discussion also outlines methods of manipulating spawning and areas requiring further advancement of knowledge if progress is to continue in optimising egg and fry production.

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... It is now well established that some female steelhead kelts remature after a summer of reconditioning, whereas other fish do not, and that plasma estradiol level from mid-August onward indicates maturation status. Evidence in both steelhead kelts and post-spawning rainbow trout suggests that the initial decision to remature is made early, before mid-July for kelts and before 10 weeks after spawning in rainbow trout (Bromage, et al. 1992;Caldwell et al. 2013b;Hatch, et al. 2013a;Jenkins et al. 2018b). Plasma estradiol levels in rematuring and non-rematuring kelts for 2018 at all sites were similar to previous years and were similar to those seen in other projects. ...
... Egg number and egg size were positively related to body condition in European plaice (Pleuronectes platessa; an income breeder) based on feed restriction during late vitellogenesis, indicating conditiondependent reproductive performance attributed to a relationship between feed availability and the rate of vitellogenesis (Kennedy, et al. 2008). In rainbow trout and lake charr (capital breeders), feed restriction reduced reproductive performance, but only for feed restriction during early oogenesis (Bromage et al. 1992;Henderson and Wong 1998). Condition impacted reproduction at different times during oogenesis for the two reproductive modes, likely due to the difference in funding strategies. ...
... These findings suggest that, among fish on the consecutive spawning trajectory, egg size is set first based on condition at approximately 10 weeks after spawning, and then fecundity (and consequently TEM) is set based on condition at approximately 20 weeks after spawning. A study in rainbow trout found that reproductive effort was impacted by feed restrictions in the period close to a year prior to spawning, but not at time periods approaching repeat spawning (Bromage et al. 1992). Similarly, feed restriction implemented prior to the theorized critical period for maturation negatively impacted reproductive investment in lake charr in terms of both ovarian lipid density and fecundity (Henderson and Wong 1998), which was not the case for feed restriction implemented later during oogenesis. ...
Technical Report
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Kelt Reconditioning and Reproductive Success Evaluation Research Project Number 2007-401-00 Report covers work performed under BPA contract # 76182 and 76548 Report was completed under BPA contract #76548 Report covers work performed from: January 2018 – December 2018 Douglas R. Hatch, Columbia River Inter-Tribal Fish Commission, Portland, OR
... However, these parameters showed an opposite trend to relative fecundity (Johnston et al., 2016). Interestingly, these trends are in accordance with data reported in several cultured rainbow trout populations (Springate and Bromage, 1985;Bromage and Cumaranatunga, 1988;Bromage et al., 1992;Estay et al., 1994aEstay et al., , 1994bKanyilmaz et al., 2016), which suggest that under natural conditions introduced populations of rainbow trout could maintain a similar trade-off pattern. Of note is that in other introduced salmonids, such as Atlantic salmon and brown trout, this relationship is not always constant since it can be affected by biotic factors, such as food availability (Jonsson et al., 1996;Fleming, 1999, 2000). ...
... This spawning time, which occurs mainly from winter to spring in the Northern Hemisphere, could be related to the underlying genetics of this trait which, in rainbow trout, is subjected to strong genetic control (Fishback et al., 2000;O'Malley et al., 2003). In rainbow trout is not rare to find variations in the spawning time of native (Ade, 1989) and cultured (Bromage et al., 1992;Ferguson et al., 1993) populations that could be determined by the same genetic factor. In addition, data on the survival rate registered at the early development stages indicate that this parameter may vary significantly in naturalized strains inhabiting the same river, for example, at the eyed stage (e.g., 81, 5% in steelhead and 66.6% in kamloops) (Negus, 1999). ...
... Total fecundity increasing with body weight in naturalized females of rainbow trout is not an unexpected result, since this trend has been observed in several naturalized populations of the Northern Hemisphere (Dubois et al., 1989;Johnston et al., 2016). This trend is also in accordance with data reported in cultured strains of rainbow trout (Springate and Bromage, 1985;Bromage and Cumaranatunga, 1988;Bromage et al., 1992;Estay et al., 1994aEstay et al., , 1994bKanyilmaz et al., 2016). Therefore, our results suggest that, under natural conditions, the introduced populations of rainbow trout from the Calafquén Lake follow a general reproductive trade-off pattern. ...
Article
Naturalized rainbow trout (Oncorhynchus mykiss) populations are an important recreational fishing resource in the Araucanian lakes of southern Chile, but few reproductive studies have been undertaken to assess their sustainability. It is important to address this issue, since this analysis may provide information for improving management activities. In this study we carried out a biometric and reproductive analysis of naturalized rainbow trout breeders to describe their performance and to explore the variables that could determine fecundity, fertilization in addition to egg survival and size. We collected naturalized rainbow trout breeders from six tributaries of Calafquén Lake, during 2006, 2007 and 2012 to record their biometric and reproductive traits. Spawning and incubation were performed under controlled conditions in a hatchery facility to improve the recording process. In each spawning season, total fecundity (TF, No. of eggs/female), relative fecundity (RF, No. of eggs/kg female), fertilization rate (FR, %), egg diameter (ED, mm) and eyed egg survival (EES, %) were modeled as a function of biometric and reproductive parameters, using general linear mixed models. We used this statistical tool to explore the relationships between these reproductive traits and other breeder traits in order to identify all the potential combinations that could be linked to TF, RF, FR, ED and EES. The spawning period ranged from September to November (i.e., spring spawning season), with a clear spawning peak in October in all reproductive seasons. Mean TF (from 2275.9 to 3438.7) and RF (from 1730.5 to 1909.8) fell within the range of, or were close to, data reported for other Araucanian lakes, respectively. Mean values of FR and EES were relatively high, ranging from 88.8% to 93.3% and between 83.4% and 88.8%, respectively. Models indicated that TF is significantly affected by the interaction between female body weight and egg weight, while RF is affected by the combination of female body length and egg weight. In addition, a positive correlation was observed between female body weight and total fecundity, while an inverse association was recorded between relative fecundity and female body length. This trend is in accordance with the trade-off pattern between egg number and fish size described for naturalized populations of rainbow trout from the Northern Hemisphere. However, regression equations output suggests that the reproductive performance of the Calafquén Lake population has a more depleted fecundity in comparison either with naturalized populations from the Northern Hemisphere, or with cultured stocks of this species. Models for ED revealed that this variable is affected by egg weight and also by body length or body weight, all with positive correlations. This result concurs with observations reported for other naturalized populations of rainbow trout from North America, further supporting evidence that larger females of this species produce larger eggs than smaller females. Models for EES revealed the significant positive effect of fertilization rate and relative fecundity, being the latter an unexpected result, given that insignificant correlations between these variables have been found in cultured stocks of this species. Overall, the population analyzed exhibited a regular spawning period, and an optimal reproductive performance in terms of egg survival. To promote the sustainability of the naturalized rainbow trout of Calafquén Lake, we recommend the use of hatchery propagation of wild adults to support the production of fry to be used in subsequent restocking activities. This management effort can benefit because the broodstocks have a short spawning period during their spring run.
... The control of egg quality (i.e., the ability of the egg to be fertilized and subsequently develop into a normal embryo) is of major importance for many, if not all, aquaculture fish species (Migaud et al. 2013). A regular supply of high-quality eggs is mandatory for rainbow trout hatchery sustainability (Bromage et al. 1992). Given the high cost of broodstock rearing, large variations in the quantity or quality of gametes can significantly impact the competitiveness and sustainability of fish farms and aquaculture companies (Bromage et al. 1992;Bobe 2015). ...
... A regular supply of high-quality eggs is mandatory for rainbow trout hatchery sustainability (Bromage et al. 1992). Given the high cost of broodstock rearing, large variations in the quantity or quality of gametes can significantly impact the competitiveness and sustainability of fish farms and aquaculture companies (Bromage et al. 1992;Bobe 2015). Hence, controlling egg quality is a major issue in aquaculture with important economic consequences. ...
... The egg size remains an interesting parameter to measure. Although the possible benefit effect of egg size on egg survival and alevins is still debated, especially under aquaculture conditions (Bobe and Labbé 2010;Bromage et al. 1992;Campbell et al. 1992;Jastrebski and Morbey 2009;Migaud et al. 2013;Springate and Bromage 1985b), it is established that larger eggs produce larger alevins (Springate and Bromage, 1985) with substantial fitness advantages over small alevins (Heath et al. 2003). While egg size is very often measured in studies on fish reproductive performance, it is unusual to measure egg size variability within the spawn. ...
Article
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Assessing female fish reproductive success requires a thorough evaluation of egg characteristics, including egg number, size, and variability as well as egg developmental potential through the monitoring of embryo survival after fertilization. While embryonic success relies, at least in part, on paternal contribution, some parameters are strictly related to egg characteristics, one of the main ones being the viability of the egg when released into the water at spawning. It is however not necessarily possible, at least in salmonid fish that lay nontransparent eggs, to separate the different causes of egg/embryo failure. In this context, our aim was (i) to develop a simple and rapid system to capture images of rainbow trout eggs combined with computerized processing of these images to perform a fully automatic individual characterization of egg features including number and size (ii) to estimate unfertilized egg viability through the monitoring of the percentage of eggs that will not survive to water hydration. To evaluate the VisEgg system, unfertilized eggs (approximatively 400 eggs per batch) originating from 105 different females were hydrated in water. After 24 h, a picture of the eggs was obtained using a dedicated shooting system consisting of a light source and a digital single-lens reflex (SLR) camera. An image processing algorithm was developed to allow the automatic detection and separation of the eggs and to perform automatic measurements of egg number and individual egg size. The presence of white egg was used as an indirect measure of egg integrity, the “whitening” being the result of water entry into the egg through the vitelline membrane. These white eggs were therefore considered nonviable, as a result of their lack of physical integrity. Fertilization assays were performed in parallel using a subsample of the same egg batch. Embryonic development was monitored and hatching rate was calculated. A significant correlation between white egg percentage after hydration and hatching rate was observed (Spearman coefficient = −0.557, p < 0.001), in consistency with the fact that nonviable egg will not allow successful embryonic development. In contrast, the percentage of eggs that do not successfully hatch includes egg/embryo failures of different nature including reduced egg viability. Using the VisEgg, we were able to quantify the lack of viability of the eggs separately from the different other events that may occur during fertilization and incubation. the VisEgg is a convenient and reliable tool to obtain individual measures on trout eggs. It can be used to assess not only egg size and egg number but also unfertilized egg viability before fertilization.
... Aquaculture has been widely used as an effective strategy to conserve endangered fish species through artificial propagation to produce viable offspring by in situ or ex situ conservation and captive breeding techniques are still used to conserve aquatic species stocks (Maitland, 1995;Philippart, 1995). In aquaculture, gamete quality is of great importance, and availability of high-quality gametes is necessary in order to obtain quality offspring (Bromage et al., 1992;Migaud et al., 2013). Egg quality can be defined as the ability of the egg to be fertilized and subsequently develop into a normal embryo and larvae (Bobe & Labbé, 2010). ...
... Many fish species have shown that relative fecundity decreased with increasing body weight, while total fecundity has shown an increasing trend with increasing body size as observed in our study (Adámek et al., 2004;Bromage et al., 1992;Hattori, 1995;Hislop et al., 1978;Mayer et al., 1990;Ridha & Cruz, 1989;Siraj et al., 1983). ...
... in accordance to what is reported from studies on other species (Bromage & Cumaranatunga, 1988;Bromage et al., 1992); however, reproductive parameters such as fertilization and hatching rate showed a negative correlation with increased egg size. The reliable production of high-quality offspring is principally dependant on egg quality, since production of low-quality eggs results in a greater number of deformed larvae and increased mortality it is a major obstacle in the advancement of aquaculture for both marine and freshwater species (Brooks et al., 1997;Migaud et al., 2013;Reading et al., 2018). ...
Article
The Asian catfish, Clarias magur, is an endangered fish species, which is immensely important due to its high commercial value in India and other South‐East Asian countries. Various anthropogenic activities and natural habitat loss have greatly impacted the biodiversity of C. magur in natural water bodies, leading to the addition of this species to the endangered species list. The development of captive spawning and selection of an ideal broodstock size are critical steps to maximize the efficiency and robustness of conservation efforts for the catfish. An induced spawning experiment was conducted to ascertain the reproductive performance, egg and larval quality of catfish broodstock from fish with varying body weights. Five female C. magur broodfish from each of the following size ranges, F65 (65 ± 5.0); F130 (130 ± 7.9), F180 (180 ± 3.5) and F250 (253 ± 9.7g), were selected along with male broodfish with the same body weight range. The present study's results revealed that the stripping response was higher (F = 2.06; p = 0.15) for medium‐sized F180 magur female broodstock; however, no significant differences were observed for this group. Total (F = 20.79; p < 0.001) and relative fecundity (F = 3.09; p = 0.057) were found to be significantly higher for F250 and F65 broodfish respectively. Total fecundity had a strong significant positive correlation (r = 0.99; p = 0.012) and also had significant linear regression relation (R2 = 0.98; p = 0.012) to maternal size. Hatching rate was observed to be significantly higher (F = 7.82; p = 0.002) for the medium‐sized broodfish, F130. The medium‐sized broodstock of 130–180 g had strong positive influence on the growth and survival of the progeny, while F250 broodfish produced poor‐quality larvae, which resulted in reduced larval growth performance and survival. Specific growth rate (SGR) and thermal growth coefficient (TGC) were also found to be significantly higher for F130 female broodstock. Hence, the selection of medium‐sized (130–180) or 1‐ to 2‐year‐old female broodstock had a significant effect on the reproductive performance, egg and larval quality of magur in captivity. The results from this study can be utilized as helpful and practical information enhancing selection protocols for the hatchery operators to select ideal broodstock based on size, enabling the production of viable egg and larvae in indoor conditions and a scalable seed production system.
... Secondary oocyte development is characterized by bulk transfer of energy from soma to gonad during vitellogenesis (Lubzens, et al. 2010), during which oocyte number is not expected to significantly change, whereas oocyte volume will increase up to 98%, or >50-fold, with increasing gonadosomatic index (GSI) to approximately 20% of the soma (Tyler, et al. 1990). However, the relationship between the timing of energy reserve acquisition and the allocation of reserves to somatic and reproductive processes is not fully understood and is a key question in salmonid biology (Bromage, et al. 1992a;Campbell, et al. 2006a). ...
... Also, despite a reduction in proportional egg size in consecutive spawners as compared to maiden spawners, absolute egg size was not smaller. Larger egg size is expected to lead to greater survival in salmonids due to larger size at first feeding, larger gape for feeding, competitive advantage, and reduced surfacearea to volume ratio potentially reducing chances of contracting infection or disease (Bromage et al. 1992a). The benefit of egg size is difficult to quantify without a complex understanding of the contextual ecology and habitat (substrate size, conspecifics, nutrient availability for juveniles, etc.), though larger egg size has been empirically linked to environments of decreasing quality (Rollinson and Hutchings 2013). ...
... Rather, likely subfertility in skip spawners resulted from misidentification of ripeness and or undetected infection. Maiden and consecutive spawner averages exceeded 80% fertilization success, consistent with the mean survival to eyeing in O. mykiss, reported as early as 1953 (Bromage et al. 1992a). Below 80% success, spawners are referred to as "subfertile". ...
Technical Report
Full-text available
Kelt Reconditioning and Reproductive Success Evaluation Research Project Number 2007-401-00 Report covers work performed under BPA contract # 76182 and 76548 Report was completed under BPA contract #76548 Report covers work performed from: January 2017 – December 2017 Douglas R. Hatch, Columbia River Inter-Tribal Fish Commission, Portland, OR Report Created:
... The reproductive dysfunctions observed in culture range from the complete absence of reproductive development observed in freshwater eel Palstra et al., 2005;van Ginneken and Maes, 2005), to the absence of only gamete release (i.e., spawning) observed in cultured salmonids (Bromage et al., 1992). However, the most common dysfunctions include the production of lower quantity of milt and/or sperm during the spermiation period and the failure to undergo OM at the completion of vitellogenesis (Mañanos et al., 2008;Zohar, 2001b, 2007;Zohar and Mylonas, 2001b). ...
... This may be due to inappropriate tank size, lack of bottom substrate for the preparation of a nest or plant substrate for the adhesion of the eggs, and possibly other reasons that are not yet known. Therefore, for many species it is also necessary to employ artificial gamete collection and fertilization, using strip spawning (Billard et al., 2004;Bromage et al., 1992;Hurvitz et al., 2007;Manning and Crim, 1998;Marino et al., 2003;Suquet et al., 1995;Williot et al., 2005;Yaron, 1995). In addition, artificial insemination methods are worth developing for management reasons. ...
... Fish egg quality, measured through traits such as fertilization rate, oocyte yield and alive offspring number, is considered very important in accordance with European scientific criteria (AQUAEXCEL, 2013), including good survival and lack of abnormalities (Kjørsvik et al., 1990;Brooks et al., 1997). Gametes, both in terms of their quantity and quality, are closely associated with the competitiveness and sustainability of hatcheries and farms (Bromage et al., 1992;Migaud et al., 2013;Theodorou et al., 2016). ...
... The spawning quality of breeders depends of many factors related with nutrition, genetics, environmental conditions and any stress (Brooks et al., 1997;Fernández-Palacios et al., 1997;Almansa et al., 1999;Bobe and Labbé, 2010;Scabini et al., 2011;Jerez et al., 2012;Migaud et al., 2013;Bobe, 2015). Many traits related to reproduction, survival, morphology and growth (Kjørsvik et al., 1990(Kjørsvik et al., , 2003Bromage et al., 1992;Fernández-Palacios et al., 1995;Brooks et al., 1997;Shields et al., 1997;Patarnello, 2004, 2005;Lahnsteiner et al., 2008;Bobe and Labbé, 2010;Migaud et al., 2013;Bobe, 2015) have been proposed for the characterization of spawning quality in different species. At the industrial level it is important to start fattening a suitable quantity and quality of animals. ...
Article
Full-text available
Fish egg quality is strongly related with the ability of the egg to be fertilized and develop a normal embryo with good survival and a lack of abnormalities. Large variations in the spawning quantity or quality impact directly in the competitiveness and sustainability of hatcheries, which create an overly large broodstock in order to satisfy the on-growing companies’ demand for undeformed fry. The present study reports, for the first time in relation to gilthead seabream, the effect of the genetic background of breeders for presence or absence of deformity on their spawning quality and the importance of considering this when creating broodstock. The spawning quality of crosses of breeders with genetic background for presence or absence of deformity (EBVdef), were evaluated during a whole spawning season, through study of the following traits: oocyte yield, fertilization rate, viability rate, hatching rate, larval survival rate, fertilized eggs, viable eggs, hatched eggs, and number of alive larvae. Breeders with a genetic background for deformity and a normal phenotype had shorter spawning periods, lower oocyte yield and, consequently, produced a lower number of alive larvae. In these two traits, the genetic background of breeders was of greater importance during intermediate spawning periods, when spawning is generally considered optimal for the industry, while environmental factors were more important at the beginning and end of the spawning season. In conclusion, these results demonstrate the importance of controlling the breeders’ genetics when creating broodstock.
... It is now well established that some female steelhead kelts remature after a summer of reconditioning, whereas other fish do not, and that plasma estradiol level from mid-June onward indicates maturation status Trammell, et al. 2016). Evidence in both steelhead kelts and post-spawning rainbow trout suggests that the initial decision to remature is made early, before mid-July for kelts and during the 10 weeks after spawning in rainbow trout (Bromage, et al. 1992;Caldwell et al. 2013;Hatch, et al. 2013;. Plasma estradiol levels in rematuring and non-rematuring kelts for 2020 at all sites were similar to previous years and were similar between projects. ...
... However, the timing of the critical period for gonadal recrudescence in steelhead kelts is not known in detail. In first-time spawning rainbow trout, energy restriction during the first third of the year prior to spawning resulted in a reduced proportion of maturing fish (Bromage et al. 1992). In repeat spawning rainbow trout, energy restriction to a maintenance ration after spawning resulted in reduced plasma estradiol (E2) levels within 10 weeks after spawning and resulted in no fish maturing as consecutive spawners . ...
Technical Report
Full-text available
Kelt Reconditioning and Reproductive Success Evaluation Research Project Number 2007-401-00 Report covers work performed under BPA contract # 73354 REL 27 and 73354 REL 45 Report was completed under BPA contract #73354 REL 45 Report covers work performed from: January 2020 – December 2020 Douglas R. Hatch, Columbia River Inter-Tribal Fish Commission, Portland, OR
... It is now well established that some female steelhead kelts remature after a summer of reconditioning, whereas other fish do not, and that plasma estradiol level from mid-June onward indicates maturation status . Evidence in both steelhead kelts and post-spawning rainbow trout suggests that the initial decision to remature is made early, before mid-July for kelts and during the 10 weeks after spawning in rainbow trout (Bromage, et al. 1992;. Plasma estradiol levels in rematuring and non-rematuring kelts for 2019 at all sites were similar to previous years and were similar between projects. ...
... However, the timing of the critical period for gonadal recrudescence in steelhead kelts is not known in detail. In first-time spawning rainbow trout, energy restriction during the first third of the year prior to spawning resulted in a reduced proportion of maturing fish (Bromage et al. 1992). In repeat spawning rainbow trout, energy restriction after spawning resulted in reduced plasma estradiol (E2) levels within 10 weeks after spawning . ...
Technical Report
Full-text available
Steelhead Kelt Reconditioning in the Yakima and Snake River basins.
... Due to this, several studies have identified the effect of distinct factors on fish gamete quality (Arslan et al., 2016;Bromage & Roberts, 1995;Huang et al., 2010;Vassallo-Agius et al., 2001). Broodstock nutrition is a key factor that can affect fecundity, gametogenesis and gamete quality (Bobe & Labbé, 2010;Izquierdo et al., 2001), and is known to influence fish reproduction, larval quality and survival (Bromage et al., 1992;Izquierdo et al., 2001). Dietary lipids play a vital role in broodfish nutrition as it is preferentially utilized in meeting energy requirements throughout embryogenesis, and is a major determiner of reproductive success and larval development (Migaud et al., 2013;Sargent et al., 1989Sargent et al., , 2002. ...
Article
Full-text available
The present study evaluated the effects of dietary fish oil replacement with linseed or sesame oil on sperm quality and reproductive performance in rainbow trout (Oncorhynchus mykiss) during a 7‐month feeding trial. Male (≈ 970 g) broodfish were fed three isonitrogeneous and isolipidic formulated diets containing fish oil (FO diet), linseed oil (LO diet) and sesame oil (SO diet). Commercial trout broodfish diet was fed to another group to serve as control (CD). Growth performance was not affected by diet. Slight variations in volume, pH and density were recorded in the semen produced by rainbow trout subjected to the different dietary treatments (p > 0.05). Similarly, motility and kinematic parameters were not influenced by diets (p > 0.05). However, osmolality differed in the dietary groups, with semen from SO and LO fed fish having comparatively higher values (p < 0.05). Fatty acid (FA) profile of fish spermatozoa reflected dietary FA composition. FA profile of spermatozoa showed evidence of de novo biosynthesis of eicosapentaenoic acid, docosahexaenoic acid and arachidonic acid. Dietary treatments did not significantly affect reproductive performance (fertilization, eyeing and hatching rates). This may be suggestive of the ability of male rainbow trout to synthesize HUFA in vivo to meet their reproductive needs in the event of low dietary n‐3 HUFA supplementation.
... While the number and size of the eggs are important criteria for determination of gamete quality of the female broodstock, the rate of fertilization and eyed egg ratio are also important for the quality. During the incubation, survival rates of Salmonid eggs may vary 0-100% (Bromage et al., 1992). The survival of eggs during the incubation period and hatching larvae recorded in the present study was lower than previously reported for some salmonids species (Pennell and Barton 1996). ...
Article
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In this study, the quality and reproductive success of wild Black Sea Trout (Salmo trutta labrax) were investigated. In total 32 wild trout (27.3±13.6 g and 13.9±2.3 cm) from the Bıçkı Stream in Kocaeli Province in the Marmara Region were kept in circular fiberglass outdoor flow-through tanks (1.5m ø) at the mean water temperature of 11.8±4.5 °C. In November 2016, when the water temperature was 8.4 °C, the first spawning of wild trout occurred. Sperm volume (ml), Motility (%) and VCL (µm/ sec) values were determined to be 7.5±2.5, 70.42±0.83 and 70.35±3.98, respectively. The weight (g), total fecundity and egg diameter (mm) values of female fish were listed to be 513.75±78, 1.171±171, and 3.84±0.02, respectively. In the experiment, 5.859 wild Black sea trout eggs were fertilized. The eyed-egg stage occurred 24 days (288 day-degree) post fertilization and the survival rate from fertilization to the eyed-stage was 28%. Wild Black Sea trout larvae from P1 (Paternal Generation) hatched 48 days after fertilization with the hatching rate of 7%.
... To obtain quality seeds in future, the aquaculture production and development chiefly depend on the control of reproduction of aquatic species. In captivity, management of the technologies to increase gamete production is one of the primary steps that would ensure the growth and development of aquaculture sector (Bromage et al. 1992). Moreover, the reproductive potential could be modulated to enhance the fish production by reducing the excess energy used for breeding purposes like gonadal development in some prolific breeders like tilapia. ...
Chapter
Reproduction is arguably the most vital process in animals including fish that is being controlled by the brain through hypothalamic-pituitary-gonadal (HPG) axis. Several bioactive compounds from plants were recognized to be having a great role in promoting a variety of biological activities such as growth, immunomodulation, feed consumption and antioxidant activity or can act as antiviral agents. Moreover, phytochemicals have been used for several hundred years as additions to energize, vitalize and eventually curb the male and female reproductive functions. There can be different approaches to administer the plant-based bioactive compounds such as oral, immersion or injection methods. However, the nanodelivery approach forms an effective way to achieve the delivery to target tissues with less or no impediment. The nanodelivery approach improves the efficiency of targeted delivery of plant-based bioactive compounds. The phytochemicals can also be involved in phenotypic sex manipulations that sometimes become necessary in fisheries and aquaculture. The aim of this chapter is to provide an overview of available studies on the reproductive control via HPG axis along with different phytochemicals and their delivery approaches for reproductive modulation.
... Egg quality can be generally defined as the egg's potential to produce viable fry 8 , whereas good quality eggs for the fish farming industry www.nature.com/scientificreports/ have been defined as those exhibiting low mortalities at fertilization, hatching, and first feeding 33 . For this reason, NH success is widely accepted as the ultimate measures of egg quality in aquaculture species 34 . ...
Article
Full-text available
Closed-cycle aquaculture using hatchery produced seed stocks is vital to the sustainability of endangered species such as Pacific bluefin tuna (Thunnus orientalis) because this aquaculture system does not depend on aquaculture seeds collected from the wild. High egg quality promotes efficient aquaculture production by improving hatch rates and subsequent growth and survival of hatched larvae. In this study, we investigate the possibility of a simple, low-cost, and accurate egg quality prediction system based only on photographic images using deep neural networks. We photographed individual eggs immediately after spawning and assessed their qualities, i.e., whether they hatched normally and how many days larvae survived without feeding. The proposed system predicted normally hatching eggs with higher accuracy than human experts. It was also successful in predicting which eggs would produce longer-surviving larvae. We also analyzed the image aspects that contributed to the prediction to discover important egg features. Our results suggest the applicability of deep learning techniques to efficient egg quality prediction, and analysis of early developmental stages of development.
... The rainbow trout (Oncorhynchus mykiss) is a carnivorous Salmonid species, very demanding in terms of water quality, which must be relatively cold (6-20°C), clear, transparent, free of pollutants and well oxygenated (O 2 ≥ 5-6 mg/L) (Cataudella et al., 2001). The spawning season, in wildlife, occurs between late autumn and early winter months, with each female producing eggs over a 6-8 week period (Bromage et al., 1992). Under farming conditions, oocytes and semen (both obtained by manual abdomen pressing) are incubated in small water tanks for about 10-15 minutes (Pennell and Barton, 1996). ...
Article
In aquaculture, the many chemicals used as therapeutics, prophylactics and growth promoters, can accumulate in fish and spread in the environment through effluent water. Nowadays, the focus of zootechnical productions has shifted towards the search for possible natural alternatives, considered safer for animals and consumers, with lower environmental impact. Herbal products are made of natural compounds, but “natural” is not necessarily synonymous of harmless, thus toxicity needs to be tested for each composition at different doses. Indeed, since herbal products' action is often dose-dependent, negative effects may be prevented by studying the posology according to the species and life stage. In this study, the effects of two different doses (0.05 and 0.1 mL/L) of a natural-based complementary feed, Gill Fish®, were assessed on the early stages of life of farmed rainbow trout (Oncorhynchus mykiss). The product was added daily to tanks containing rainbow trout eggs during the pre-hatching period, from 30 to 36 days post fertilization. Embryos mortality (evaluated three times during the six days of treatment; t0-t2) and zootechnical indices such as biomass, weight, length and number of alevins (all evaluated 3 and 4 weeks after the end of treatment; t3-t4), were analysed to assess both direct and indirect toxicity. Furthermore, whole body cortisol (from embryos and alevins; t0-t4) was measured to highlight potential stressful effects of the treatment. For each parameter, time was a statistically significative factor, while no differences were noticed between the three groups within the same time point. These results demonstrate that Gill Fish® had no harmful nor stressful effects, both immediately and short term; this herb-based product could therefore be a good candidate for future studies with different doses and/or longer administration, to evaluate its possible beneficial effects as an alternative to chemicals in aquaculture.
... The third set of dysfunctions leads to failures to spawn in the breeding season; sometimes E. aeneus, M. saxatilis, and Dentex dentex (common dentex) females may release eggs after ovulations without exhibiting characteristic breeding behavior [7,62]. Under some circumstances, cultured salmonids fail to complete the reproductive cycle and eggs in the abdominal cavity are reabsorbed over the following months [63]. These are examples of failures among female broodstocks that do not appear to be accompanied by reproductive problems that can be attributed to male fishes. ...
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Fish represent an excellent source of animal protein as well as a biomedical research model as a result of their evolutionary relatedness and similarity with the human genome. Commercial and ornamental fish culture has achieved popularity, but reproductive dysfunctions act as a limiting factor for quality fry production, interfering with the sustainability of the aquaculture industry. Fish reproduction is crucial for any species' existence, and reproductive performance can potentially be improved through applications of epigenetics and probiotics. Epigenetics is a highly sensitive molecular approach that includes chromatin structure and function alteration, DNA methylation, and modification of non-coding RNA molecules for the transfer of desired information from parents to offspring. DNA methyltransferase improves reproductive cyp11a1, esr2b, and figla gene expression and feminizes zebrafish (Danio rerio). Moreover, epigenetics also contributes to genome stability, environmental plasticity, and embryonic development. However, methylation of specific genes can negatively affect sperm quality, resulting in poor fertilization. Probiotic administration is able to induce responsiveness of incompetent follicles to maturation-inducing hormones and can change oocyte chemical composition during vitellogenic development. The positive role of probiotics on testicular cells is validated by upregulating the transcription levels of leptin, bdnf, and dmrt1 genes facilitating the spermatogenesis. This review not only discusses the effects and mechanism of epigenetics and probiotics for improving fish reproduction, but also presents an overview of the causal factors and current techniques used to eradicate dysfunction. Moreover, key genes and hormones related to fish reproduction along with research gaps and future prospects are also considered. This review provides an overview of necessary information for students, scientists, researchers , and breeders to resolve fish reproduction-related problems to ensure profitable and sustainable aquaculture.
... Valores altos en viabilidad y eclosión de los huevos, como los obtenidos en este trabajo, han sido considerados por Bromage et al. (1992) como factores de buena calidad del huevo. Gutiérrez-Sigeros, Ibarra-Castro & Álvarez-Lajonchére (2018), con Ocyurus chrysurus, obtuvieron adecuados desarrollos larvales con 87,3 % de huevos flotantes de los cuales el 90 % eran transparentes con embriones vivos. ...
Article
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The technological foundation of the Lutjanus guttatus aquaculture was developed in Costa Rica in 2002 by Parque Marino del Pacífico. The first juvenile mass production was obtained in 2005; small scale commercial farms were established in 2006; and the first technology transfer to the private sector began in 2008. Based on these advances, the need to optimize the production of juveniles was identified. With this objective, three larval crops obtained from natural spawning of second generation (F2) breeders were evaluated and biologically described. Three families n = 8 each: 1.45 ± 0.21 kg, 1.33 ± 0.12 kg, and 1.28 ± 0.10 kg from an aquaculture farm were acclimatized in the laboratory until they spawned. A total of 100,000 eggs were incubated per spawning (density: 520 eggs mL-1). Larvae (90 thousand/tank) were seeded with an initial total length (TL) equal to 2.25 mm and fed with enriched rotifers, microalgae produced in helical photobioreactors, and artemia nauplii. Growth, survival, cannibalism, size variability, and deformities obtained were registered. A total of 22,837 juveniles were harvested on day 60 after spawning. During harvest, the juvenile’s total length (TL) was 57.8 ± 7.82 mm, Absolute Growth Rate (AGR) was 0.93 mm d-1 , Specific Growth Rate (SGR) was 5.41% d-1, Condition Factor (K) was 1.089, average survival was 8.4 % and total eye deformities were 6.3 %. Methodologies used to obtain natural quality spawning, improvement of live food produced by photobioreactors, and separation by size were effective aspects for the larval culture of the species, although starvation in the first days of exogenous feeding, metamorphosis, and cannibalism continue to be factors affecting final survival.
... The lower deformity of C. falco larvae was found among temperature 24-26 • C, but the relative lower hatching at 24 • C were observed. Bromage et al. (1992) indicated the optimal hatching temperature was similar to spawning temperature. From the previous discussion, the highest hatching (95.56 ± 2.94%), lowest deformity (0.00%), highest survival (78.97 ± 15.22%) and SAI (10.26 ± 2.05) were observed at 26 • C, which approximately equal to spawning temperature (26-27 • C) in our study. ...
Article
The dwarf hawkfish, Cirrhitichthys falco is one of the popular species in the aquarium trade. However, the limited breeding resources nowadays available represent a clear limitation towards the rearing of this species. The aim of this study was to report the successful results on natural spawning of C. falco, a description of embryonic and larval development stages and appropriate rearing condition (temperature, salinity and initial prey) for the larviculture. Natural spawning of C. falco in captivity from 31 July 2014 to 31 July 2015 was describe d. A single male dominated a harem of eight females, spawning with each at dusk 30 min after sunset. Over a 365-d period, the females produced 357 spawns, 76.6 ± 0.9% of which resulted in fertilized eggs. The average fecundity per spawn was 1348 ± 712 eggs. Newly hatched larvae were 1.99 ± 0.09 mm in total length (LT) and had an oil globule in the ventroanterior area of the yolk sac. At 2 days post hatch (d ph), the larvae me asured 3.04 ± 0.03 mm LT , with the yolk sac and oil globule being completely absorbed. First feeding took places at 2 dph which is marked by the widening of the gut. On the scanning electron microscope observations, the fertilized egg membrane was smooth and lack surface sculpturing. The distribution density of pores was 2.8 pores μm −2. The micropyle was circular, and the diameter was 5.60-5.62 μm. At 2 dph, several neuroma sts were found on the head, body surface and caudal fin membrane. At 18 dph, the larvae measured 5.22 ± 0.02 mm LT , dorsal and anal fin rays were formed. Consider the hatch, survival, deformity, and survival activity indices, the water temperature 26°C and salinity 27-30 psu may be a suitable rearing condition for the larvae. In the first feeding experiment, the survival was not significantly in feeding treatment B (Euplotes sp. 20 ciliates mL −1), C (Euplotes sp. 10 cili-ates mL −1 + Brachionus ibericus 10 rotifers mL −1) and D (Euplotes sp. 10 ciliates mL −1 + B. ibericus 5 ro-tifers mL −1 + Mi crosetella sp. 5 nauplii mL −1), but all higher than treatment A (starved control) in 3-4 dph of C. falco larvae. The results indicate that Euplotes sp. may be an important initial prey for the first feeding larvae. These findings provide a basis for further studies to determine the successful captive breeding of C. falco and other valuable ornamental hawkfishes.
... The fecundity of Liza parsia was observed to be less in the specimens of Vizag harbor waters than those of the relatively unpolluted waters [42]. Variation in fecundity between two different populations was very common affairs and also found that the total number of eggs by an individual female fish was dependent on different factors such as age, size, space, food availability, season, climatic conditions, environmental factors, habitat changes, nutritional status and genetic potential [43,44]. In our study, insignificant result was found in case of fecundity for the female C. punctatus with same body weight in same water body but significant variation was found in different water bodies. ...
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The present study was carried out to compare gonad development, oocyte maturation and fecundity of the spotted snakehead (Channa punctatus) fish during January to November 2015 in different water bodies (such as pond, Joghati baor and Bhairab river) in Jashore, Bangladesh. Mean GSI (gonadosomatic index) values of the female C. punctatus during January, March, May, July, September and November were significantly highest in pond, followed by those in Joghati baor and the lowest in Bhairab river. Absolute fecundity during the month of July in pond, baor and river was 30,006±2,027, 23,629±2,356 and 16,659±2,486, respectively, and the relative fecundity was 5064±183, 4865±106 and 4641±138 eggs, respectively. Mean ova diameter in pond, baor and river in March was 0.25±0.04 mm, 0.16±0.02 mm and 0.21±0.03 mm; in May was 0.36±0.03 mm, 0.29±0.03 mm and 0.23±0.04 mm; in July was 1.06±0.06 mm, 0.95±0.05 mm and 0.87±0.03 mm; and in September was 0.84±0.04 mm, 0.82±0.03 mm and 0.72±0.05 mm, respectively. Mean GSI values of the male C. punctatus during January, March, May, July, September and November were significantly higher in pond than those in baor and river, respectively. The mean highest GSI for female was found to be 6.06±0.11 in pond during the month of July, while the lowest GSI of 0.30±0.08 was in Bhairab river during November. The highest GSI value for male was obtained to be 0.70±0.16 in pond during the month of July, while the lowest GSI of 0.12±0.03 was found in Bhairab river during January. However, significant differences (P<0.05) were found in GSI values, absolute fecundity, relative fecundity and ova diameter of C. punctatus during different months in pond, Joghati baor and Bhairab river. The findings from the present research would immensely be useful for captive breeding and seed production techniques of C. punctatus for aquaculture production, sustainable management and species conservation.
... Discharge, DO, turbidity, and SPC were measured three times per week with a multiparameter water quality sonde (2018: n = 10; 2019: n = 10). Daily water temperature is the average hourly water temperature of the stream measured with a Hobo data logger during each day of RSI deployment (2018: n = 17 d; 2019: n = 23 d (Bromage et al. 1992). The mortality rate of eggs from first-year spawning adults was greater in the hatchery, which was the reason we received one-third of the eggs in 2018 that we received in 2019. ...
Article
The successful use of remote site incubators (RSIs) to rear Arctic Grayling Thymallus arcticus eggs along Montana streams has sparked interest to reestablish the species in Michigan. As a preparatory step, we assessed the efficacy of RSIs by deploying them along three Michigan streams during two years using surrogate eggs from Rainbow Trout Oncorhynchus mykiss. Our objectives were to: (1) compare hatching success between two different RSI designs (19‐L vs. 265‐L RSIs), (2) test whether the removal of dead eggs (“picking”) from 19‐L RSIs affected hatching success, and (3) develop a simple model to predict fry yield and its uncertainty. Overall survival was 41.3% in 2018 and 52.4% in 2019. Differences in survival between unpicked 19‐L and 265‐L RSIs tended to be small, with mean differences from 4.82% (95% CI, ‐0.60 to 10.25%) in 2018 to 0.08% (95% CI, ‐0.14 to 0.30%) in 2019. On average, picked 19‐L RSIs had greater survival—although not always statistically significant—than unpicked 19‐L RSIs during both years (mean difference = 1.6% [2018] and 10.4% [2019]). We documented a significant positive correlation between survival and RSI flow rate. Survival abruptly declined in unpicked 19‐L RSIs when RSI flow rates dropped below ~0.3 L/min, suggesting removing dead eggs from 19‐L RSIs likely increased survival when RSI flow rates were <0.3 L/min. The most notable result from our fry yield model was that increasing the number of RSIs reduced the coefficient of variation in fry yield following a pattern of diminishing returns, suggesting two or three RSIs usually will be a good choice. We showed that 19‐L and 265‐L RSIs can be used successfully in Michigan streams with our model providing a tool for managers to explore the relative importance of several properties of RSI design and operation on fry yield and uncertainty.
... And on other fish species (Rheman et al., 2002;Rahman et al., 2016;Olusegun et al., 2019). Absolute fecundity often has a direct proportion with the size and age of the fish (Bromage et al., 1992;Adamek et al., 2004). ...
... The development and success of fish farming depend upon the supply of good-quality eggs because eggs that exhibit low mortality at fertilization, eyeing, hatching and at first feeding are highly desirable (Bromage et al. 1992). Survival and hatching rates are usually considered as the ultimate measures of egg quality, but these parameters do not provide sufficient information about the factors that influence its quality. ...
Article
Aims: This study describes the effect of phage therapy on hatching of longfin yellowtail (Seriola rivoliana) eggs challenged with Photobacterium damselae subsp. damselae. Methods and results: A lytic phage (vB_Pd_PDCC-1) against P. damselae subsp. damselae was isolated and characterized. The use of phage vB_Pd_PDCC-1 increased the hatching rate of eggs, and reduced presumptive Vibrio species to non-detectable numbers, even in non-disinfected eggs. High-throughput 16S rRNA gene sequencing analysis revealed that phage vB_Pd_PDCC-1 caused significant changes in the composition and structure of the associated microbiota, allowing that members (e.g., those belonging to the family Vibrionaceae) of the class Gammaproteobacteria to be displaced by members of the class Alphaproteobacteria. Conclusions: To our knowledge, this represents the first study evaluating phage therapy to control potential negative effects of P. damselae subsp. damselae during hatching of longfin yellowtail eggs. Significance and Impact of the Study: The Seriola genus includes several important commercial fish species due to its rapid growth and easy adaptability to confinement conditions. However, bacterial infections (especially those caused by Vibrio and Photobacterium species) are among the main limiting factors for the intensification of marine fish aquaculture, particularly during early development stages. Therefore, the use of phages, which are natural killers of bacteria, represents a promising strategy to reduce the mortality of farmed organisms caused by pathogenic bacteria.
... The development and success of fish farming depend upon the supply of good-quality eggs because eggs that exhibit low mortality at fertilization, eyeing, hatching and at first feeding are highly desirable (Bromage et al. 1992). Survival and hatching rates are usually considered as the ultimate measures of egg quality, but these parameters do not provide sufficient information about the factors that influence its quality. ...
Article
Aims: This study describes the effect of phage therapy on hatching of longfin yellowtail (Seriola rivoliana) eggs challenged with Photobacterium damselae subsp. damselae. Methods and results: A lytic phage (vB_Pd_PDCC-1) against P. damselae subsp. damselae was isolated and characterized. The use of phage vB_Pd_PDCC-1 increased the hatching rate of eggs, and reduced presumptive Vibrio species to non-detectable numbers, even in non-disinfected eggs. High-throughput 16S rRNA gene sequencing analysis revealed that phage vB_Pd_PDCC-1 caused significant changes in the composition and structure of the associated microbiota, allowing that members (e.g., those belonging to the family Vibrionaceae) of the class Gammaproteobacteria to be displaced by members of the class Alphaproteobacteria. Conclusions: To our knowledge, this represents the first study evaluating phage therapy to control potential negative effects of P. damselae subsp. damselae during hatching of longfin yellowtail eggs. Significance and Impact of the Study: The Seriola genus includes several important commercial fish species due to its rapid growth and easy adaptability to confinement conditions. However, bacterial infections (especially those caused by Vibrio and Photobacterium species) are among the main limiting factors for the intensification of marine fish aquaculture, particularly during early development stages. Therefore, the use of phages, which are natural killers of bacteria, represents a promising strategy to reduce the mortality of farmed organisms caused by pathogenic bacteria.
... The development and success of fish farming depend upon the supply of good-quality eggs because eggs that exhibit low mortality at fertilization, eyeing, hatching and at first feeding are highly desirable (Bromage et al. 1992). Survival and hatching rates are usually considered as the ultimate measures of egg quality, but these parameters do not provide sufficient information about the factors that influence its quality. ...
Article
Aims: This study describes the effect of phage therapy on hatching of longfin yellowtail (Seriola rivoliana) eggs challenged with Photobacterium damselae subsp. damselae. Methods and results: A lytic phage (vB_Pd_PDCC-1) against P. damselae subsp. damselae was isolated and characterized. The use of phage vB_Pd_PDCC-1 increased the hatching rate of eggs, and reduced presumptive Vibrio species to non-detectable numbers, even in non-disinfected eggs. High-throughput 16S rRNA gene sequencing analysis revealed that phage vB_Pd_PDCC-1 caused significant changes in the composition and structure of the associated microbiota, allowing that members (e.g., those belonging to the family Vibrionaceae) of the class Gammaproteobacteria to be displaced by members of the class Alphaproteobacteria. Conclusions: To our knowledge, this represents the first study evaluating phage therapy to control potential negative effects of P. damselae subsp. damselae during hatching of longfin yellowtail eggs. Significance and impact of the study: The Seriola genus includes several important commercial fish species due to its rapid growth and easy adaptability to confinement conditions. However, bacterial infections (especially those caused by Vibrio and Photobacterium species) are among the main limiting factors for the intensification of marine fish aquaculture, particularly during early development stages. Therefore, the use of phages, which are natural killers of bacteria, represents a promising strategy to reduce the mortality of farmed organisms caused by pathogenic bacteria.
... The reliable production of good quality eggs is a well-known bottleneck plaguing much of the aquaculture industry [1][2][3]. Indeed, generating high quality eggs from captivity-reared eels is an increasingly urgent necessity for the development of eel propagation practices world-wide [4,5]. The well-documented gonadal arrest of captive eels demands that fish must be frequently manipulated with fertility drugs in order to advance oocytes past the early vitellogenic stage. ...
Article
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Our previous work documented significant advancements in steroid-induced progression of oogenesis, demonstrating that co-treatment of female eels with 11-ketotestosterone (11KT) and estradiol-17β (E2) successfully induced uptake of vitellogenin by oocytes. Here we evaluate the effects of this steroid co-treatment on subsequent time to ovulation and egg quality in shortfinned eels artificially matured by hypophysation. Co-treatment with 11KT (1 mg) and E2 (0.2 or 2 mg) significantly reduced time to ovulation and therefore, the amount of pituitary homogenate required, without any detrimental effects on gonadosomatic index, oocyte diameter or the total weight of stripped eggs. E2 treatment resulted in promising increases in fertilization rates. These indicators suggest that co-treatment with 11KT and E2 holds promise for future artificial maturation practices in terms of minimising fish handling and stress, and of reducing the need for expensive pituitary preparations.
... The reduced size of eggs is also in agreement with a reduction in egg yolk diameter and volume. Good quality eggs often display low levels of mortality at fertilization, eying, hatch and first-feeding (Bromage et al., 1992). While there is no agreement as to what levels of mortality constitute a good quality egg, asip1-Tg embryonic mortality at 24 h was higher than that of WT thus suggesting asip1-Tg eggs to have lower quality. ...
Article
In two swordtail species of the genus Xiphophorus, onset of puberty in males and females, fecundity in females, and adult size in males are modulated by sequence polymorphism and gene copy-number variation at the P locus affecting the type 4 melanocortin hormone receptor (Mc4r). The involvement of Mc4r in regulating the onset of puberty outside the genus Xiphophorus remains unclear. In this study we used a transgenic line overexpressing asip1 (asip1-Tg), an endogenous antagonist of both type 1 melanocortin hormone receptor (Mc1r) and Mc4r, to investigate the relevance of the melanocortin system on the onset of puberty and adult reproductive performance in zebrafish (Danio rerio). Comparison of growth, puberty and reproductive performance between wild-type (WT) and asip1-Tg zebrafish revealed that a decreased activity of the melanocortin system did not change the timing of puberty but significantly delayed early growth of transgenic animals. Hatching time was postponed in asip1-Tg fish and they were significantly smaller than their WT siblings at 75 dpf, despite showing enhanced linear growth after having completed puberty. asip1-Tg females produced 1.38 times more eggs but spawned less frequently, and their eggs had showed a 0.89-fold smaller diameter but a 1.04-fold increase in larvae body length at hatching. Therefore, we demonstrate that asip-tg zebrafish do not reach puberty earlier than WT counterparts as it could be expected considering the enhanced length and weight growth during early adulthood. This is so because the effects of transgene on growth are noticeable from an umbral length when puberty has already been reached. Data show that the inhibition of melanocortin system via asip overexpression is an excellent strategy to promote growth, in absence of obesity, by enhancing food efficiency but without accelerating puberty timing. Data are crucial to provide a stepwise ahead in the characterization of the phenotype induced by the decreased activity of the melanocortin system in fish thus providing an excellent strategy for future aquaculture especially because U.S. Food and Drug Association has recently approved transgenic fish trading.
... The size and oil droplet are usually considered as the evaluation indicators of the quality of pelagic oocyte (Bromage et al., 1992;Lahnsteiner and Patarnello, 2005;Bozkurt and Secer, 2006;Mansour et al., 2007). However, neither the biochemical nor the molecular composition of the oocyte are reflected by such measures. ...
... Egg yield and size of fish are affected by various factors. The most important of these are broodstock size, age, genotypic structure, and feeding conditions (Bromage et al. 1990(Bromage et al. , 1992. In salmonids, larger females generally produce larger eggs especially in the culture environment (Sargent et al., 1987;Hatcher et al., 1995). ...
Article
Full-text available
This study aimed to improve some culture characteristics of Black Sea salmon (Salmo labrax) culture generations through a classical selective breeding program. Thus, the success of the applied program was examined by comparing the reproduction time and proportional distribution of the wild broodstock (F0 ) individuals with the F1 , F2 , F3 and F4 generation broodstocks adapted to the culture conditions. According to the results, gamete uptake from the new generations occurred between October and February. The highest egg uptake was determined for all generations in December. While the difference between wild (F0 ) broodstock and F1 , F2 , F3 , and F4 generations was statistically significant in favor of new generations (P<0.05), the difference was insignificant between hatchery origin-new generations. Mean egg diameters were low in F2 and F3 generations, and F0 , F1 and F4 generations were found to be higher than the others (P<0.05). It was calculated that the fertilization rate was higher in F3 and F4 generations, similar in F1 and F2 generations, and lower in F0 generation than the others (P<0.05) at the end of the study. Through the selection program, it was determined that the adaptation of the species to the culture conditions improved, the reaction to human activities declined, and homogeneous distribution in tanks/ponds was relatively achieved from the F2 generations. As a result, it has been determined that F4 generation broodstock have higher culture performance than other generations. Producers of this species should use F4 broodstock for efficient and economical production.
... Different species that exhibit this problem undergo normal vitellogenesis, maturation, and ovulation but the ovulated eggs are not released. These eggs remain in the abdominal cavity and are reabsorbed [78] or can be released at some point after ovulation even without spawning behavior [79]. In captivity spotted wolffish females often fail to release the eggs and become egg bound or release overripe eggs. ...
Article
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The first artificially fertilized spotted wolffish (Anarhichas minor) eggs hatched in Norway in the mid-1990s as this species was considered by Norwegian authorities to be a top candidate species for cold-water aquaculture in the North Atlantic regions. Previous research conducted in Norway (since 1992) and Canada (since 2000), focused on identifying key biological parameters for spotted wolffish cultivation which led, respectively, to the rapid establishment of a full commercial production line in northern Norway, while Québec (Canada) is witnessing its first privately driven initiative to establish commercial production of spotted wolffish on its territory. The control of reproduction can be viewed as a major requirement to achieve the development of performant strains using genetic selection tools and/or all-year-round production to bring about maximal productivity and synchronization among a given captive population. Although the basic reproduction aspects are more understood and controlled there are still some challenges remaining involving broodstock and upscaling of operations that limit the achievement of a standardized production at the commercial level. Quality of gametes is still considered a major constraint and it can be affected by multiple factors including nutrition, environmental conditions, handling practices, and welfare status. Internal insemination/fertilization and the protracted incubation period are challenging as well as the establishment of a health monitoring program to secure large-scale operations. The profound progress achieved in the control of reproduction, sperm handling, and cryopreservation methods for this species is presented and discussed. In this review, we also go into detail over the full range of up-to-date cultivation practices involving broodstock and identify areas that could benefit from additional research efforts (i.e., broodstock nutrition, health and welfare, scaling-up egg and larval production, genetics, and development of selective breeding programs).
... In general, during early stages of oogenesis, animals focus on somatic growth which is mediated by a variety of metabolic factors, and these metabolic factors are likely to also affect oocyte physiology during this period (Thorpe et al. 1984;Bromage et al. 1992;Zakes and Demska-Zakes 1996;Campbell et al. 2006). Eels have a prolonged somatic growth phase (up to 25 years for New Zealand shortfinned eels, c.f., Arai et al. 2004) during which levels of hormones involved in metabolism are likely to be elevated. ...
Article
Full-text available
Pituitary gonadotropins, metabolic hormones, and sex steroids are known factors affecting the advanced stages of ovarian development in teleost fish. However, the effects of these hormones and of the interactions between them on the growth of previtellogenic ovarian follicles are not known. In order to address this void in understanding, previtellogenic ovarian fragments from eel, Anguilla australis, were incubated in vitro with recombinant Japanese eel follicle-stimulating hormone (rec-Fsh), human chorionic gonadotropin (hCG), or 11-ketotestosterone (11-KT) in the presence or absence of recombinant human insulin-like growth factor-1 (IGF1). The results of long-term in vitro culture (21 days) demonstrated that rec-Fsh and 11-KT, rather than hCG, caused significant increases in the diameter of previtellogenic oocytes. Meanwhile, only 11-KT induced a significant increase in lipid accumulation. Moreover, a greater effect on oocyte growth was observed when IGF1 supplementation was combined with 11-KT rather than with rec-Fsh or hCG. For short-term culture (24 h), treatment with 11-KT in the presence or absence of IGF1 had no significant effects on mRNA levels of target genes (lhr, cyp19, cyp11b, lpl, and ldr) except for upregulation of fshr. There were no significant effects of rec-Fsh on expression of any target gene, whereas hCG downregulated the expression of these genes. There was no evidence for any interaction between the gonadotropins and IGF1 that resulted in growth of previtellogenic oocytes. Taken together, these results suggest that hormones from both the reproductive and the metabolic axes regulate the growth of previtellogenic oocytes in Anguilla australis.
... In finfish hatcheries, morphological egg quality is mainly assessed by monitoring various parameters during embryonic development. Fertilization rate, embryonic and larval mortalities [1][2][3], egg size [4], the buoyancy of the pelagic eggs [5][6][7], distribution of lipid vesicles [8] and their shape, yolk uniformity [9,10], early cleavage patterns and blastomere morphology [2,[11][12][13], as well as macroscopically evident malformations during early ontogeny, have been considered as appropriate morphological descriptors of the quality of fish eggs and embryos. Furthermore, the need for early, precise, reliable, and simple to use biomarkers applicable to the industry has increased interest in molecular components that can be considered key role players in regulating egg quality parameters [13][14][15][16][17][18]. ...
Article
Identifying early egg-quality predictors is a major challenge in finfish hatcheries, and relevant research is now focused on the development of molecular markers. In our study, we examined whether fertilization rates and early morphological abnormalities in sea bream egg batches of high (HQ) and low quality (LQ) are associated with mRNA levels of cathepsin D, cathepsin Z, cyclin-A2, and glucocorticoid receptor. Additionally, we examined whether these early quality descriptors were associated with the development of skeletal abnormalities during the larval period. HQ egg batches were characterized by significantly higher rates of normal embryos (95.8 ± 2.3%) and lower rates of unfertilized (2.8 ± 1.0%) and abnormal eggs (1.3 ± 1.4%), compared to LQ (84.2 ± 0.8% normal embryos, 12.3 ± 12.3 unfertilized eggs, and 3.5 ± 1.4% abnormal eggs) (p < 0.05, Mann–Whitney U test). Relative expression of cyclin-A2 and glucocorticoid receptor was found to be significantly higher in HQ embryos compared to those of LQ (respectively, p < 0.01 and p < 0.05, Mann–Whitney U test). No statistically significant differences were observed in the mRNA transcripts of cathepsin D and cathepsin Z (p > 0.05, Mann–Whitney U test). Differences in the rate of skeletal abnormalities between the two quality groups of larvae were not significant (p > 0.05, G-test), indicating that cyclin-A2 and glucocorticoid receptor may serve as reliable molecular markers for early prediction of fish egg quality but not for later larval stages.
... The developing phase is a period of gonad growth prior to entry into the spawning capable phase, when gamete development advances enough such that spawning may occur. For females, partial follicular atresia-the resorption of ovarian folliclescan occur during the developing phase and can be an important determinant of fecundity (Bromage and Cumaranatunga 1988;Bromage et al. 1992;Grier et al. 2007;Corriero et al. 2021). Once fish become spawning capable, outcomes are to (1) successfully undergo oocyte maturation, ovulation, and oviposition; or (2) undergo mass follicular atresia (Figure 1). ...
Article
Rainbow Trout Oncorhynchus mykiss have been intensively studied and gametogenesis has been described, but the use of reproductive indices in field studies has not been widely applied when assessing variability in growth or recruitment dynamics. We integrated descriptions for gametogenesis within the framework of standardized terminology for reproductive development in teleosts to develop sex‐specific criteria for assignment of reproductive phases. We used these descriptions and histological analysis of gonad tissue collected from Rainbow Trout in the Colorado River downstream from Glen Canyon Dam to quantify season‐, size‐, and sex‐specific variation in population reproductive structure. The accuracy of nonlethal methods (manual expression and ultrasonography) was evaluated for assigning sex by comparing estimates with those determined by histology. Rainbow Trout were sampled through an annual spawning cycle from October 2018 to April 2019. Spawning capable males were available across the entire period, with a higher proportion earlier in the season compared to later. Females were spawning capable in October, with a peak in February; by April, they were in the early developing phase, indicating that spawning had ended. Elevated levels of atresia (19% for fall spawners) and evidence for delayed maturation were identified, suggesting energetic limitations on the reproductive potential of the population. For both sexes, the probability of being spawning capable increased with fork length, with minimum sizes of ≥283 mm for females and ≥187 mm for males. Sex assignment using ultrasonography was more accurate (46%) than manual expression of gametes (9%), as only a small proportion of males and females expressed gametes. Probabilities of correct sex assignment using ultrasonography were strongly influenced by reproductive phase, with spawning capable fish (females: 100%; males: 77%) having significantly higher probabilities of correct sex assignment compared to immature fish. Furthermore, probabilities of correct sex assignment increased with fish size and were higher for females than for males. Results provide a framework for quantifying spawning capability and population reproductive structure in ongoing research to better understand the drivers of recruitment variability in aquatic ecosystems.
... Although the growth rate of fish larvae increases as temperature increases, the higher survival is not necessarily attained at higher temperatures (Akatsu et al., 1983;Johnson and Katavic, 1986). Bromage et al. (1992) indicated the optimal hatching temperature was similar to spawning temperature. From the previous discussion, the optimum hatch rate (85.1%), higher survival (78.9-97.8%) ...
Article
Bluestreak cleaner wrasse, Labroides dimidiatus, is one of the top ten most exported fish to the global trade in marine aquarium fish and a key species for reef fish diversity. However, knowledge on reproduction and early ontogeny of this species in captivity are scarce and incomplete. Daily spawning, early development and appropriate rearing condition (temperature and salinity) for the larviculture of L. dimidiatus were studied for the first time. We raised wrasse larvae by using an inorganic fertilization method to produce natural assemblages of phytoplankton and zooplankton, and compared it to the higher N: P ratio group and traditional rotifer-fed group. A single male dominated a harem of three females, spawning between late afternoon and dusk. L. dimidiatus spawned 305 times from 1 May 2011 to 30 April 2012, 86.9 ± 10.1% of which resulted in fertilized eggs. Fecundity ranged from 53 to 25,108 eggs per spawn with average hatching rate of 72.2 ± 22.6%. Fertilized eggs were spherical, buoyant and had a diameter of 0.68 ± 0.02 mm. Embryonic development lasted 19 h at 27.3 °C. Newly hatched larvae were 1.81 ± 0.06 mm in total length (LT) and had an oil globule in the ventroanterior area of the yolk sac. First feeding took places at 3 days post hatch (dph) which is marked by the widening of the gut. At 41 dph, transformation of larvae to the juvenile stage was completed at 12.60 ± 0.98 mm LT. On the scanning electron microscope observations, the fertilized egg membrane was smooth and lack surface sculpturing. The distribution density of pores was 61 pores 100 μm⁻². The micropyle was circular or oval-shaped, and the diameter was 6.90–7.13 μm. Several neuromasts were found on the head and body surface of newly hatched larvae. The results showed that unicellular algae, zooplankton within the size ranges of 48–150 μm and larval survival of L. dimidiatus were all significantly (P < 0.05) higher in the fertilized treatment (maintaining the inorganic nitrogen and phosphorus concentrations of 700 μg N L⁻¹ and 100 μg P L⁻¹, respectively) compared with the others. These results indicated that the optimal conditions for embryo incubation and larval rearing of L. dimidiatus were combinations of temperature 27 °C and salinity 33 psu. Our results of this study may provide a keystone for further studies to determine the successful mass-scale production of juvenile L. dimidiatus.
... Eggs from wild fish are usually considered of better quality (Srivastava and Brown, 2011), and fertilization rates, hatch rates, survival and size at hatch are usually higher than in eggs produced in captivity. Aside factors such as water chemistry (Bromage et al., 1992), photoperiod (Carrillo et al., 1989), or overripening of eggs the main driver of egg quality seems to be the mothers nutrition (Brooks et al., 1997). The most discussed biochemical group in relation to mothers' nutrition and egg quality are lipids (Izquierdo et al., 2000), a vast group of molecules fulfilling many roles in living organisms. ...
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Ballan wrasse (Labrus bergylta) is in the limelight of aquaculture research due to the species role as cleaner fish in salmon aquaculture. A major drawback is that the salmon industry still depends on wild caught fish as there are still many unsolved challenges in ballan wrasse aquaculture, amongst them the determination of egg quality. We measured a range of different egg quality markers on 6 different batches of eggs from ballan wrasse. Additionally, we performed lipidomics on these eggs to test whether their lipid profiles relate to, and can be thereby used as, a predictor for egg quality. We identified relationships between several lipid species and physiological and morphological egg quality markers, and the lipids grouped into two groups. The first group consisted of a diverse blend of 32 lipids, and was positively correlated with size related measures while it was negatively related to measures describing metabolic activity. It consisted of phosphatidylcholines (PC), lysophosphatidylcholine (lysoPC), and triacylglicerids (TAG) and three different sphingomyelins (SM). The second group consisted of 24 lipid species, and showed the inverse pattern, positive relationships with metabolic activity and negative relationships to size related measures. This group of lipid species contained several phosphatidylethanolamines (PE) and free fatty acids. These lipid species may be proposed as key egg quality markers which ultimately can be used by the aquaculture industry to select high quality egg batches in hatcheries.
... 2) in the larger and the smaller egg groups, respectively (Fig. 1) As a result, the larger egg group tended to show higher SL and BW values in the early period, and the smaller egg group tended to show higher SL and BW values in the later period. The phenomenon observed in several salmonids suggested that individuals from large eggs showed larger body size than individuals from small eggs in the early life stage, and the body size difference disappeared with growth approximately 100 to 150 days after hatching (Ohkuma 2005;Bromage et al. 1992). This phenomenon is thought to be caused by different metabolic rates between groups. ...
... Valores altos en viabilidad y eclosión de los huevos, como los obtenidos en este trabajo, han sido considerados por Bromage et al. (1992) & Álvarez-Lajonchére (2018), con Ocyurus chrysurus, obtuvieron adecuados desarrollos larvales con 87,3 % de huevos flotantes de los cuales el 90 % eran transparentes con embriones vivos. El diámetro del huevo, la longitud inicial de la larva y el porcentaje de eclosión se encontraron dentro del rango de valores normales reportados para la especie por varias investigaciones (rango del diámetro del huevo 650 a 900 μm; longitud total entre 2,1 y 2,7 mm; eclosión ≥80 %), mientras que el porcentaje de fecundación estuvo por encima del rango del 90 % (Abdo-de-la- Parra et al., 2015). ...
Article
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The technological foundation of the Lutjanus guttatus aquaculture was developed in Costa Rica in 2002 by Parque Marino del Pacífico. The first juvenile mass production was obtained in 2005; small-scale commercial farms were established in 2006; and the first technology transfer to the private sector began in 2008. Based on these advances, the need to optimize the production of juveniles was identified. With this objective, three larval crops obtained from natural spawning of second-generation (F2) breeders were evaluated and biologically described. Three families n = 8 each: 1.45 ± 0.21 kg, 1.33 ± 0.12 kg, and 1.28 ± 0.10 kg from an aquaculture farm were acclimatized in the laboratory until they spawned. A total of 100,000 eggs were incubated per spawning (density: 520 eggs mL-1). Larvae (90 thousand/tank) were seeded with an initial total length (TL) equal to 2.25 mm and fed with enriched rotifers, microalgae produced in helical photobioreactors, and artemia nauplii. Growth, survival, cannibalism, size variability, and deformities obtained were registered. A total of 22,837 juveniles were harvested on day 60 after spawning. During harvest, the juvenile’s total length (TL) was 57.8 ± 7.82 mm, Absolute Growth Rate (AGR) was 0.93 mm d-1, Specific Growth Rate (SGR) was 5.41% d-1, Condition Factor (K) was 1.089, average survival was 8.4 % and total eye deformities were 6.3 %. Methodologies used to obtain natural quality spawning, improvement of live food produced by photobioreactors, and separation by size were effective aspects for the larval culture of the species, although starvation in the first days of exogenous feeding, metamorphosis, and cannibalism continue to be factors affecting final survival.
... The ovarian fluid was sampled at ovulation. Reproductive stages were estimated based on existing data on rainbow trout reproductive cycle [77]. Ovulation was checked once a week and fish were sampled 2 days after ovulation was detected. ...
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Background Circulating miRNAs (c-miRNAs) are found in most, if not all, biological fluids and are becoming well-established non-invasive biomarkers of many human pathologies. However, their features in non-pathological contexts and whether their expression profiles reflect normal life history events have received little attention, especially in non-mammalian species. The aim of the present study was to investigate the potential of c-miRNAs to serve as biomarkers of reproductive and metabolic states in fish. Results The blood plasma was sampled throughout the reproductive cycle of female rainbow trout subjected to two different feeding regimes that triggered contrasting metabolic states. In addition, ovarian fluid was sampled at ovulation, and all samples were subjected to small RNA-seq analysis, leading to the establishment of a comprehensive miRNA repertoire (i.e., miRNAome) and enabling subsequent comparative analyses to a panel of RNA-seq libraries from a wide variety of tissues and organs. We showed that biological fluid miRNAomes are complex and encompass a high proportion of the overall rainbow trout miRNAome. While sharing a high proportion of common miRNAs, the blood plasma and ovarian fluid miRNAomes exhibited strong fluid-specific signatures. We further revealed that the blood plasma miRNAome significantly changed depending on metabolic and reproductive states. We subsequently identified three evolutionarily conserved muscle-specific miRNAs or myomiRs (miR-1-1/2-3p, miR-133a-1/2-3p, and miR-206-3p) that accumulated in the blood plasma in response to high feeding rates, making these myomiRs strong candidate biomarkers of active myogenesis. We also identified miR-202-5p as a candidate biomarker for reproductive success that could be used to predict ovulation and/or egg quality. Conclusions Together, these promising results reveal the high potential of c-miRNAs, including evolutionarily conserved myomiRs, as physiologically relevant biomarker candidates and pave the way for the use of c-miRNAs for non-invasive phenotyping in various fish species.
... In teleost fishes, vitellogenin provides essentially most of the nutrients required for embryonic development and then directly determines the subsequent embryonic development and larval growth (Tong et al., 2013). Accordingly, many maternal factors including the age, feeding scheme and reproductive cycle of broodstock, maturation of the oocyte, and maternal-originated mRNAs encoding digestive enzymes and hormones all produced great impacts on performance of egg and embryo (Bobe & Labbé, 2010;Bromage et al., 1992;Carnevali et al., 1999). Among them, feeding scheme for broodstock played a key role. ...
Article
The ontogenesis of catabolic abilities and energy metabolism during endogenous nutritional periods of tongue sole was investigated. In this work, trypsin-like proteases (TRY) and triglyceride lipase (LIP) activities were measured to assess the capacities to catabolize proteins and lipids respectively. Meanwhile, specific enzymes including pyruvate kinase (PK), glutamic oxalo acetic transaminase (GOT) and glutamate dehydrogenase (GDH), and hydroxyacyl CoA dehydrogenase (HOAD) as well as their ratios were assayed to evaluate the abilities to use energy substrates of carbohydrates, amino acids and fatty acids respectively for energy production. In addition, activities of citrate synthase (CS) and lactate dehydrogenase (LDH) and LDH/CS ratio were calculated to analyze the evolution of aerobic and anaerobic pathways. The study found that hatching occurred at 38.8 hours after fertilization (HAF), mouth-opening day of eleuteroembryo appeared at 3 days after hatching (DAH), and the most rapid embryonic growth was observed in blastula stage before hatching. Enzymatic assay revealed that except for PK which appeared in cleavage stage onwards, all the other enzymes functioned after fertilization, preparing well for the coming embryogenesis of tongue sole. By comparing the average specific activity of enzyme in each period, it can be found that the highest value occurred at 3 DAH (for TRY, LIP, PK, LDH), 2 DAH (for GDH), fertilized egg (for GOT) and segmentation stage (for HOAD, CS), and the lowest value occurred at fertilized egg (for HOAD, CS, GDH), cleavage stage (for TRY, PK, LDH), gastrula stage (for GOT ) and hatching day (for LIP). Based on the changeable patterns of metabolic enzymatic activities and ratios, it is concluded that metabolic capacities on three energy substrates displayed stage-specific traits, and the dominant energy substrate was fatty acids before segmentation stage, amino acids until hatching day, and carbohydrate during eleuteroembryo period. As for energy production mode, aerobic pathway appeared to increase greater in fertilized egg and gastrula stage, whereas anaerobic pathway played a predominant role during cleavage stage, blastula stage, segmentation stage and eleuteroembryo stage. These results are valuable to elucidate the nutritional requirements of embryonic stages in tongue sole and to further understand their energy metabolic mechanisms. This article is protected by copyright. All rights reserved.
... Valores altos en viabilidad y eclosión de los huevos, como los obtenidos en este trabajo, han sido considerados por Bromage et al. (1992) & Álvarez-Lajonchére (2018), con Ocyurus chrysurus, obtuvieron adecuados desarrollos larvales con 87,3 % de huevos flotantes de los cuales el 90 % eran transparentes con embriones vivos. El diámetro del huevo, la longitud inicial de la larva y el porcentaje de eclosión se encontraron dentro del rango de valores normales reportados para la especie por varias investigaciones (rango del diámetro del huevo 650 a 900 μm; longitud total entre 2,1 y 2,7 mm; eclosión ≥80 %), mientras que el porcentaje de fecundación estuvo por encima del rango del 90 % (Abdo-de-la- Parra et al., 2015). ...
Article
Full-text available
The technological foundation of the Lutjanus guttatus aquaculture was developed in Costa Rica in 2002 by Parque Marino del Pacífico. The first juvenile mass production was obtained in 2005; small-scale commercial farms were established in 2006; and the first technology transfer to the private sector began in 2008. Based on these advances, the need to optimize the production of juveniles was identified. With this objective, three larval crops obtained from natural spawning of second-generation (F2) breeders were evaluated and biologically described. Three families n = 8 each: 1.45 ± 0.21 kg, 1.33 ± 0.12 kg, and 1.28 ± 0.10 kg from an aquaculture farm were acclimatized in the laboratory until they spawned. A total of 100,000 eggs were incubated per spawning (density: 520 eggs mL-1). Larvae (90 thousand/tank) were seeded with an initial total length (TL) equal to 2.25 mm and fed with enriched rotifers, microalgae produced in helical photobioreactors, and artemia nauplii. Growth, survival, cannibalism, size variability, and deformities obtained were registered. A total of 22,837 juveniles were harvested on day 60 after spawning. During harvest, the juvenile’s total length (TL) was 57.8 ± 7.82 mm, Absolute Growth Rate (AGR) was 0.93 mm d-1, Specific Growth Rate (SGR) was 5.41% d-1, Condition Factor (K) was 1.089, average survival was 8.4 % and total eye deformities were 6.3 %. Methodologies used to obtain natural quality spawning, improvement of live food produced by photobioreactors, and separation by size were effective aspects for the larval culture of the species, although starvation in the first days of exogenous feeding, metamorphosis, and cannibalism continue to be factors affecting final survival.
... Valores altos en viabilidad y eclosión de los huevos, como los obtenidos en este trabajo, han sido considerados por Bromage et al. (1992) & Álvarez-Lajonchére (2018), con Ocyurus chrysurus, obtuvieron adecuados desarrollos larvales con 87,3 % de huevos flotantes de los cuales el 90 % eran transparentes con embriones vivos. El diámetro del huevo, la longitud inicial de la larva y el porcentaje de eclosión se encontraron dentro del rango de valores normales reportados para la especie por varias investigaciones (rango del diámetro del huevo 650 a 900 μm; longitud total entre 2,1 y 2,7 mm; eclosión ≥80 %), mientras que el porcentaje de fecundación estuvo por encima del rango del 90 % (Abdo-de-la- Parra et al., 2015). ...
Article
Water salinity is an important environmental factor known to have detrimental effects on salmonid reproduction, mostly when migrating female broodfish are held in sea water. In contrast, data obtained in freshwater are scarce and the impact of low water salinity, and more specifically of low water concentrations in sodium, chloride and potassium, during reproduction in freshwater is currently unknown. For this reason, and because ion and water fluxes are critical for the final steps of the female gamete formation, including oocyte hydration and ovulation, the aim of the present study was to investigate the impact of low salinity water on final oocyte maturation, ovulation and, ultimately, on egg quality, using rainbow trout as a physiological model and relevant aquaculture species. Fish from the same commercial strain were raised either in a site characterized by low concentrations of Na+, K+, and Cl- ions in the water or in a closely located control site exhibiting higher concentration in these elements. Egg quality and duration of final oocyte maturation were investigated using innovative phenotyping tools such as automatic assessment of egg viability using the VisEgg system and non-invasive echograph-based monitoring of final oocyte maturation duration, respectively. Oocyte hydration during final oocyte maturation and after ovulation was also investigated. Finally, molecular phenotyping was performed using real-time PCR-based monitoring of several key players of final oocyte maturation and ovulation associated with ion and water transport, inflammation, proteolytic activity, and coagulation. Oocyte hydration and gene expression data were analyzed in the light of the duration of final oocyte maturation. Here we show that low water salinity (i.e., low water concentration in chloride, sodium and potassium) negatively influences final oocyte maturation, ovulation and, ultimately, egg quality. Low water salinity triggered delayed ovulation and lower oocyte viability. When investigating the impact of low water salinity on final oocyte maturation duration, individuals presenting the most severe phenotypes exhibited impaired oocyte hydration and abnormally reduced gene expression levels of several key players of the ovulatory process. While the under expression of water (i.e., aquaporins) and ion (i.e., solute carriers) transporters is consistent with impaired oocyte hydration, our observations also indicate that the overall ovulatory gene expression program is disrupted. Our results raise the question of the mechanisms underlying the negative influence of low salinity water on the dynamics of the preovulatory phase, on the control of the oocyte homeostasis, including hydration, and on the overall success of the maturation-ovulation process.
Thesis
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TESIS Que para obtener el grado de Doctor en Ciencias Uso, Manejo y Preservación de los Recursos Naturales P r e s e n t a (Orientación Acuicultura) CICLO REPRODUCTIVO Y COMPOSICIÓN BIOQUÍMICA DE LA CABRILLA SARDINERA, Mycteroperca rosacea (STREETS), EN EL MEDIO NATURAL
Chapter
The ultimate goal of broodstock management, to provide sufficient high-quality, genetically improved larvae for reliable production on grow-out farms, is currently achievable only for relatively few fish species. This is primarily because (a) broodstock, except in the case of mature industries, are typically acquired from the wild, or a few generations removed from the wild, (b) insufficient information is available about the environmental and social cues regulating spawning, (c) inadvertant hatchery stressors negatively impact gametogenesis and (d) inadequate, species-specific hormone-induction regimes and reliable markers for gamete quality are currently available. The purpose of this chapter is to review the physiological mechanisms that regulate gonadal development and spawning in fishes and how these processes can be manipulated to ensure successful reproduction in captivity, through volitional spawning or the collection of gametes for in vitro fertilization. As excellent, thorough, reviews are available, we will only briefly review the reproductive processes involved in broodstock development and reproduction (sexual differentiation, puberty, gametogenesis and gamete release), and instead identify control points important for broodstock management in the aquaculture industry.
Article
Migration timing has evolved in many animals, allowing them to maximize breeding and feeding success by matching seasonal changes in abiotic conditions and resource pulses. These seasonal changes can shift with the climate, resulting in mismatches between migrations and resource availability unless the populations respond through phenotypic plasticity or evolutionary adaptation. It is common, however, for factors unrelated to climate to affect phenology. Salmon are an exceptionally well-studied group of fishes whose breeding migrations can serve as a template to consider the complex factors affecting migration phenology. In this paper, hypotheses for explaining changes in adult salmon migration phenology are reviewed. Pathways through which climate change may influence migration timing are first summarized, including shifting migration cues, limiting freshwater conditions, changes in distribution and conditions at sea, and alterations in embryo development. Alternative causes of phenological change in salmon are then explored including anthropogenic modifications of river habitat, demographic effects, hatcheries, and fisheries. The effects of these factors on phenology can mimic and mask climate effects, making it challenging to disentangle the causal basis of observed patterns. Instead of inferring shifts from trends in timing data (as is often done), it is suggested that specific mechanistic hypotheses be proposed and tested rigorously, and alternative causes systematically ruled out. Overall, it is challenging to attribute causation to phenological change, but salmon exemplify the many ways in which migration timing can change, including shifts due to climate and other processes.
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Background and Objectives: Determining the age and growth of fish is vital in fisheries management and biology. This information is the foundation for modeling aquatic population dynamics and is employed to analyze fishing data. The relationship between length and weight and some other growth indices of Caspian Vimba persa was studied from autumn 1996 through spring 1997 on the southwestern coasts of the Caspian Sea (Astara, Anzali and Kiashahr). Methods: Sampling was carried out seasonally using beach seine net at three fishing regions e.g., Kiashahr, Astara and Anzali. Each season 8 samples were taken at designated sampling stations (a total of 24 fish each season) except for 9 samples at Anzali stations in the autumn (25 samples in total). In total 73 specimens of Caspian Vimba persa were collected from the sampling stations. Findings: Fish age varied in the range of 0+- 3+ in both females and males. The highest length frequency was observed in the length group of 14-25cm. Mean total length in the whole population, females and males were 18.05± 2.38; 18.61± 2.73 and 17.14±1.29 respectively. Mean total weight in the whole population, female and male were 65.62 ±33.98; 73.89± 39.43 and 52.32±15.78 respectively. Mean fork lengths in the whole population, female and male were 16.05± 2.66; 16.68±2.49 and 15.46± 1.17 respectively. Mean gonadosomatic index was 6.88 ± 4.23. Mean hepatosomatic index and obesity coefficient were 0.98±0.51 and 1.04±0.10 respectively. Conclusion: Analysis of the obesity coefficient showed that the species upholds ‘good’ growth rate. The Length-weight relationship for the whole population was W = 0.3403L3.403, female W= 0. 003 L3.365 and male W= 0.0047L3.2719. The t test showed that the obtained bvalue was greater than 3 thus the species has a positive allometric growth pattern. Since within the whole sampled fish the W> L3 and CF = K> 1 (obesity coefficient was greater than 1) relationship was applied, it can be concluded that the Caspian Vimba persa are more obese than usual which indicates good feeding condition of fish in the southwestern part of the Caspian Sea.
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The climbing perch Anabas testudineus, the most demanded indigenous fish species of India, were used for the evaluation of reproductive strategy and gonadal development at first maturation under the controlled laboratory condition. In both sexes, four distinct gonadal developmental stages namely preparatory, pre-spawning, spawning, and post-spawning were identified based on the gonadosomatic index (GSI), hepatosomatic index (HSI), gonadal morphology, and the levels of serum sex hormones. The spawning stage was identified from July and August and the fecundity ranged from 6500-11000 eggs. The GSI exhibited a significant increase from preparatory to pre-spawning and spawning stages, and maintained high until August. The HSI was maintained the same during preparatory, pre-spawning, and spawning stages while increased in post-spawning stage in both sexes. Serum estrogen and testosterone levels increased significantly during pre-spawning, and spawning stages in both sexes. Fecundity showed a positive correlation with the length, weight, and ovary weight. Histological sections showed that male A. testudineus were group-synchronous spawners. Both sexes showed discrete reproductive cycles characterized by distinct changes in gonadal size, sex hormones and gonadal indices. This study will bridge the gap of insufficient knowledge to support the best practices suitable for the A. testudineus culture and survival under captivity.
Article
Maturation of salmonid species reduces growth, flesh quality and immunocompetency and has inhibited, in part, the commercial production of brook trout in Tasmania. Photoperiod manipulation is routinely used to inhibit or reduce the incidence of maturation in salmonids, so an experimental adaptation of this approach was trialled experimentally for brook trout. Mixed-sex fish (age = 14 months) were subjected to simulated natural photoperiod (NP), advanced photoperiod (AP) and continuous photoperiod (CP) to investigate the response of endogenous circannual rhythm upon sexual maturity in this species. Light treatments commenced on the first day of the last month of the southern hemisphere’s winter and concluded towards the end of autumn when fish were ovulating. Maturation was observed in 100% of females and 96% of males held under NP. Fish exposed to AP corrected their maturation cycle by advanced phase shift of their endogenous rhythm for eight weeks and achieved final maturation during March–April. Plasma profiles of testosterone and oestradiol-17β were also adjusted according to advancement of photoperiod. Exposure to AP inhibited maturation by 6% and 8% in males and females, respectively. CP treatment for 10 consecutive months failed to inhibit gonadal development; however, this regime did delay or inhibit spermiation and ovulation.
Article
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.
Thesis
The lumpfish (Cyclopterus lumpus) has been proposed as a sustainable solution to sea lice infestations in Atlantic salmon (Salmo salar) aquaculture. Current production is reliant on wild caught broodstock and closed life cycle management is essential to improve sustainability and allow for stock improvement. This thesis aimed to address knowledge gaps in the broodstock management of the species. Holding temperature for broodstock during the spawning season should be kept below 10° C to improve egg quality and spawning performance. In order to extend the spawning season, temperatures can be safely lowered to 6° C without impeding egg quality. Oocyte histology and distribution data suggests that lumpfish are a batch spawning species and provided the first histological oocyte development scale for the species. Subsequent research, aimed to address challenges associated with gamete management to improve artificial fertilisation protocols. Ex vivo egg ageing suggested that the window of overripening for lumpfish is 24 hours before significant reduction in egg quality. Sperm concentration was also affected by high broodstock holding temperature for this species. Research into milt quantification and storage identified two extender solutions and two rapid methods for assessing sperm concentration to aid milt management. Research into egg quality determinants identified several candidates within egg composition which strongly associated with hatching success within lumpfish. Increased levels of essential fatty acids such as EPA and DHA as well as minerals such as calcium and total levels of pigment within eggs correlated with high hatching success. Analysis of the lumpfish ovarian fluid proteome also identified several protein biomarkers for egg quality through analysis of wild, captive “good” and “bad quality eggs, it also Identified several potential biomarkers for overripe eggs in lumpfish. Overall, this research provides important baseline data on the management of broodstock and the optimisation of hatchery protocols to close the life cycle of the species. URI- http://hdl.handle.net/1893/32611
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A study of the early life history of triploid rainbow trout (Salmo gairdneri Richardson) showed that the mean embryonic development time was significantly shorter in triploid fish (381°C × days) than in the control group (384°C × days; P < 0.01). Hatching speed (slope of the hatching curves) was identical in both groups. Triploid survival rates from fertilization to eyed stage, hatching and swim-up were 84.7, 95.0 and 97.9% respectively, relative to the controls, resulting in a total reduction of survival rate associated with triploidy of 21.3% at start feeding. Absorption of water by the yolk reserves was similar for both genotypes, but at swim-up, triploids were significantly lighter (95% of the controls) than their diploid full-sibs (P < 0.01). Starvation resulted in an increase in water content and a decrease in wet weight that were significantly greater for triploids (P < 0.01) until all animals died 3 weeks after swim-up. As soon as feeding started, differences between diploids and triploids increased rapidly. Thus, at day 106, triploid wet weights represented 91% of the control. A 10-day delay in start feeding did not modify this scheme.
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Thesis (Ph. D.)--Dept. of Biology, Stanford University.
Article
The number and weight of eggs stripped from a female, and the weight of an egg were measured for 133 rainbow trout (body length, 28.5~55.0 cm; body weight, 461~3430g) reared at the Oizumi Trout Hatchery and 28 fish (body length, 36~52 cm; body weight, 755~2156g) raised at the Nagano Prefectural Trout Hatchery. The relations between the values above mentioned and the size of those fish, as well as the same between values and condition factor were examined. The results obtained were as follows: 1) The number of eggs (EN) shows a curvilinear relation with the body length (to the last scale) (L, cm) and shows a linear relation with body weight (W, g) (Figs. 1 and 2). The equations are Log EN = 2.25483 log L-0.33071, EN = 1.1042 W+739.86 for the Oizumi trout and log EN = 1.38970 logL+1.15993, EN=1.1248 W+1206.3 for the Nagano. The number of eggs varies greatly among fish of nearly the same size. 2) The weight of eggs (EW, g) shows a curvilinear relation with body length (Fig. 3) as shown by equations; for the Oizumi fish, log EW = 3.05644 log L-2.73171, and for the Nagano, log EW = 2.02782 log L-0.95194. 3) The ratio of weight of eggs to body weight (10² × EW / W) and gonad index (10⁵ × EW/ L³) are calculated 13.80±0.357 and 236.2±8.11 respectively on the fish from the Oizumi, and these ratios, found in wide range, do not show sign of correlations referred to body length. Whereas, the same ratios for the Nagano fish, 17.20±0.988 and 289.5±26.27 respectively, show a slight reverse correlation to the body length. 4) The weight of an egg (Ew,mg) increases curvilinearly with the body length, expressed by equations, logEw = 0.68872 logL + 0.79911 for the Oizumi, and logEw = 0.57181 logL + 0.99851 for the Nagano (Fig. 4). 5) The 2-year-old fish which experiences spawning for the first time is featured by a ighter weight of an egg, a lower value of 10² × EW/W, and a higher value of condition factor as compared with those in the 3-year-old of nearly same size (Fig. 9). There is a tendency that the number of eggs of the 2-year-old fish is slightly larger than that of the 3-year-old, but not different in the weight of eggs. The difference in the number of eggs between the two year classes is lesser than the variation recognized in each class, it may be, thus, stated that the number of eggs does change greatly with the size of fish more than due to age. 6) Among the fish of nearly the same size, there is a tendency that the heavier the av-erage weight of an egg is weighed, the lower the number of total eggs are counted (Fig. 5). But no definite relationship is recognized between the average weight of an egg and the weight of total eggs. 7) Among the fish of approximately the same size, the condition factor (10³ × (W-EW)/L³) of fish increases with both weight and number of eggs (Figs. 7 and 8). 8) Relation between condition factor of fish and the number of eggs are not so clear as shown in the case of the total weight of eggs. This is believed to have derived from the fact that the number of eggs relate conversely to the weight of an egg, still the weight of an egg is not positively related to the condition factor (Fig. 6). 9) It may be suggested that nutritional factor encountered on brood fish will actually affect the weight and number of eggs produced. Following these factors and interpretations enumerated above discussion were made on the meaning of “gonad index “, and basis to select brood fish and their strains referred to fecundity. © 1963, The Japanese Society of Fisheries Science. All rights reserved.
Article
The rainbow trout Salmo gairdneri Richardson, which originates from the west coast of North America, was first described by Richardson in 1836 from specimens collected in the Columbia river. Initially, the rainbow trout was native to the coastal areas of the United States and Canada extending from Alaska as far south as Mexico. Aside from the head waters of the Peace and Athabaska Rivers in Canada and the Rio Cisa Grandes in Mexico it was not indigenous to areas east of the Continental Divide (MacCrimmon, 1971, 1972; Behnke, 1972, 1979).
Article
In the previous paper it was reported that the contents of iron and a kind of carotenoid-violaxanthin, were low in the eggs sampled from poor hatching broods. The present work was carried out to see if a similar relation held also for the samples of another source. The samples were supplied from the Fuji Trout Hatchery together with the data of thier hatching rates (Table 1). A part of the eggs of each sample was analyzed of thier chemical composition immediately after fertilization, while the remainders were reared at the Hatchery to observe the developing process. Also for the present samples, the content of iron was found to be proportional to the hatching rates (Table 2). There is a tendency that vitamin B2 content in the eggs of high hatching rate is slightly larger than those of low hatching rate (Table 4.). It should be noted that the yellow pigment in the present samples seems to be different from the one previously reported (violaxanthin), and that the amount of the pigment in the eggs is likely independent of the hatching rate (Tables 3, 4). © 1955, The Japanese Society of Fisheries Science. All rights reserved.
Article
This review of vertebrate placental structure attempts to integrate some of the considerable body of work done using electron microscopic and other techniques since Amoroso’s classic 1952 chapter. The reference list concentrates on the most recent work. Mossman (1987) provides the best comprehensive list of placental references. This chapter is mainly concerned with providing data to facilitate broad comparisons of structures and secretions both during development and in their final form with a view to relating them to the functional activity of the placenta. The remarkably wide variety of structures in the mature placenta develops from a basically similar repertoire of extraembryonic membranes as typified in the amniote egg, and the diversity can be further simplified by use of straightforward structural criteria. The major problem is to relate those criteria to the wide range of functions served by the placenta. A few non-amniotes have developed analogous structures which serve similar functions to the extraembryonic membranes, and these offer further insights into the requirements for successful fetal development (Hagan, 1951; Woollacott and Zimmer, 1975; Amoroso et al., 1979; Bone et al., 1985).
Article
For the purpose of examining the viability of over-ripened ova, eggs were periodically stripped in small quantities at 5 day intervals in 1966 and at 3 day intervals in 1967 from female rainbow trout immediately after ovulation and subjected to treatment by artificial fertilization. Embryonic and larval developments were subsequently evaluated on the basis of certain criteria which included the percentage of eyed eggs, hatching rate and incidence of abnormal alevins (deformed and/or moribund) in relation to the over-ripening process. The results indicated that the percentage of eyed eggs and hatching rate exceeded 70% in those eggs which had been stripped by the 10th day after ovulation. These values, however, gradually decreased to 0% one month following ovulation, at which time typical over-ripened ova were recognized. Eggs classified as of the stage I type (normal eggs) showed a high percentage of eyed eggs and a hatching rate of 80% or more. Accompanying advancement toward the over-ripened condition, however, the percentage of eyed eggs and hatching rate exhibited a gradual decrease and fell below 10% for those eggs which were of the stage II-III type. Paralleling these tendencies, the percentage of abnormal alevins increased as a function of the progress of the over-ripening process. The evidence brought forth in this study supports the recommendation that viability of over-ripened ova, as assessed by those criteria stated above, is greatest when suitable females are sorted within 5 to 7 days after ovulation for artificial stripping. Furthermore, estimation of artificial fertilization success and ensuing embryo and larval viability is possible at the time of stripping on the basis of observation of egg stage. © 1975, The Japanese Society of Fisheries Science. All rights reserved.
Article
It has been frequently observed that during the stripping operation of the female rainbow trout, some eggs known as “over-ripened ova” contain oil globules which form into a lump. Furthermore, the yolk of such egg is characterized by a semi-transparency. It was confirmed from the present study that these eggs are not the products of abnormal ovarian function, but instead characterize a condition caused by an extended in situ existence within the body cavity following ovulation. This process of over-ripening could be divided into four stages according to the following description: normal ova immediately following ovulation (stage I) early stage of over-ripening (staeg II), followed by over-ripened ova (stage III), which then transform into the irregularly shaped ova with considerable decrease in their material content (stage IV). The progressive formation of over-ripened eggs, stage II, III and IV eggs could be generally recognized at about the 10th, 30th and 35th day following ovulation, respectively. During this process of over-ripening, partial collapse of the cortical alveoli and formation of a blastoderm-like structure permiated with oil globules occured. In the course of water-induced activation of eggs, the collapse of the cortical alveoli was restricted and bipolar differentiation was retarded in over-ripened eggs.
Article
The present work investigates the importance of circadian and circannual rhythms in the photoperiodic control of reproduction in the rainbow trout. Maintenance of groups of 20–30 female trout under continuous light (LL), constant long (18L:6D) or short (6L:18D) days and conditions of constant temperature (8.5–9.0°C) and feeding rates (0.5% body weight, day−1), starting in February, produced markedly different spawning periodicities during the first and subsequent years of treatment. At the end of the first year, spawning was advanced by up to 2 months in the fish under LL and 18L:6D and delayed by up to 5 months in those under 6L:18D when compared with the December spawning of control fish under ambient light. Continued exposure of the fish to the same photoperiod regimes produced cycles of spawning and peak levels of testosterone, oestradiol-17β and calcium (as an index of vitellogenin) at intervals of 150–170 days under LL and 18L:6D and 320–420 days under 6L:18D. The functional importance of these spawning cycles and their relationship to circannual rhythms and the control of reproduction is discussed. Exposure of fish to skeleton (6L:4D:2L:12D, 6L:6D:2L:10D and 6L:8D:2L:8D) and resonance (6L:42D, 6L:48D and 6L:54D) procedures produced ranges of spawning times up to two months in advance of control fish. Results with the resonance regimes, where fish received only a half the light-dark cycles and a quarter of the total daylight hours of those on ambient light cycles show that trout do not measure daylength and time by counting daily cycles or by hour-glass mechanisms. Collectively, these data support the proposition that rhythmic processes of photosensitivity are involved in the modulation of reproductive development in the rainbow trout and that circadian and circannual rhythms cooperate in the timing and entrainment of this cycle.
Article
Batches of eggs (1 batch/female) from 17 rainbow trout in their first spawning season were stripped and reared separately, and the percentage which hatched and the percentage which reached the stage of first feeding were determined. The fertilised egg batches were analysed for egg wet weight, egg dry weight, chorion weight and levels in the eggs of free, bound and total lipid, precipitable protein, protein phosphorus, lipid phosphorus, calcium and iron. All determinations were made on single eggs, and six eggs from each batch were analysed for each variable. Results were expressed in absolute terms (as weight of component per egg) and as percentage of egg dry weight. Highly significant variations in all these aspects of egg composition were shown to occur between parent females. However, there was no significant correlation between the percentage of the original number of eggs which hatched and any one aspect of egg composition, except for a weak positive correlation (P<0.05) with the percentage of protein phosphorus in the eggs. Similarly, there was no significant correlation between the percentage of the original number of eggs which reached first feeding and any one aspect of egg composition except for weak positive correlations (P<0.05) with egg wet weight and with both the absolute level and the percentage of protein phosphorus in the egg. There was significant positive correlation (P<0.05) between the percentage of hatched eggs (alevins) surviving to first feeding and each of the following: egg wet weight, egg dry weight and absolute levels in the egg of bound lipid, precipitable protein and protein phosphorus. Egg batches with higher hatching percentage (>50%) differed significantly from those with zero hatching percentage in having (in absolute terms) higher egg weight, chorion weight, protein phosphorus (all P<0.001), egg dry weight, bound lipid and precipitable protein (all P<0.01) and (percentages) higher chorion weight (P<0.05) and protein phosphorus (P<0.001), and lower free and total lipid (both P<0.01) and iron (P<0.05). In a separate experiment to investigate the effects of allowing the eggs to be retained by the female within the abdominal cavity for increasing periods of time after ovulation, eggs were obtained from three females on three or four successive occasions 2–11 days apart. Although the above aspects of egg composition remained almost constant when the eggs were held in the female for up to 18 days after ovulation, the hatching percentage declined sharply within this period, in two females falling from over 90% to near zero. These results together indicate that the time of stripping of the eggs in relation to the date of ovulation is a much more significant determinant of egg quality than any of the chemical and physical aspects of egg composition which were investigated.
Article
Brood stock rainbow trout (Salmo gairdneri) were fed diets low, intermediate, and high in energy and protein over a 3-year period. At the end of the study fish fed diets high in energy and protein weighed more and produced a greater number of larger eggs than did fish fed diets intermediate or low in energy and protein. The average total number of eggs produced by 3-year-old spawners were significantly less than that produced by either 4- or 5-year-old fish; numbers produced by the two older groups of fish did not differ. There was no significant difference in percentage of eyed eggs of 3-, 4-, or 5-year-old fish fed different diets; but the percentage of eggs that reached the eyed stage tended to decrease as age of the fish increased. Number of eggs produced per kilogram of body weight was greatest in 3-year-old fish fed a low-energy, low-protein diet; numbers did not differ between 4- and 5-year-old fish. No significant differences existed in weight of eggs per kilogram of body weight between fish as 3-, 4-, or 5-year-olds fed any of the diets. Fish fed high-energy, high-protein diets reduced their food intake to about 50% of that of fish fed the low-energy, low-protein diet. Mortality (primarily of males) was somewhat greater in 3-year-old fish fed the high-energy, high-protein diets.
Article
A selection program to improve the growth rate of rainbow trout (Salmo gairdneri) was begun in 1967 with random samples of fall-spawning fish from the Manchester and Wytheville National Fish Hatcheries. All matings were made as one male to one female, and selection was based on family mean fish weight of the progeny at 147 days post-fertilization. The selected families in each year class were mated in all combinations at 2 years of age (age II) and 3 years of age (age III). Selection was applied only to the age II progeny. A control group was established in 1971 from the base population and carried through the remaining portion of the study. All families were reared under standardized rearing conditions.
Article
Counts of eggs stripped from brown and rainbow trout show that over a sufficiently large size range the relationship to fish length is curvilinear. A direct relationship exists between egg numbers and fish weights. Brown trout from the Great Lake do not yield the expected number at larger sizes. The yield from rainbow trout is higher than that from brown.
Article
Under simulated natural conditions female sea bass (Dicentrarchus labrax) in eastern Spain (latitude 40° N and longitude 0°) spawned over a 6–8-week period in February and March, with each female spawning on more than one occasion. Generally, male fish began spermiation up to 2 months before, and continued for at least 1 month after the spawning period of the female fish.Exposure of fish to 1 month of long days (LD ) from either 2nd May (Group C), 3rd June (Group D) or 3rd July (Group E) in an otherwise constant short day (LD ) photoperiod regime, speeded up the rates of maturation, thus increasing the proportions of oocytes entering exogenous vitellogenesis during October and November, and also brought forward the timings of ovulation and spawning. In contrast, constant long days from 2nd May (Group B) delayed maturation and spawning time by 2–3 months. Fish maintained under constant short days throughout the experiment (Group A) spawned up to 6 weeks in advance of the control fish, suggesting that endogenous timing mechanisms may operate in this species.Spawning occurred naturally in all the experimental and control fish without the necessity for induction with pituitary or hypothalamic hormones.For the control fish, egg quality (defined as the proportion of eggs spawned which were floating and viable), hatching rate and survival to first feeding (both expressed as percentages of the numbers of floating or good quality eggs) averaged 78.3±7.7% (mean±s.e), 84.8±3.3% and 54.6±20% respectively. With the exception of the eggs and fry from Group B, these measures of quality and survival appeared unaffected by the photoperiod treatments. The eggs and fry produced by the fish maintained under long days (Group B) towards the end of their spawning period (i.e. in May), showed much more variable egg quality and survivals through hatch and first-feeding, possibly because of the higher sea water temperatures which prevailed at the time of their delayed spawning.Fecundities expressed as numbers of eggs per kg of post-spawning fish weight ranged from 247–305 000/kg for Groups A, C, D and E and the controls, but were significantly reduced in Group B fish. Egg sizes, which ranged from 1.147–1.176 mm in diameter, were unaffected by the photoperiodic manipulations of spawning time.It is concluded that artificial control of daylength can improve the supply of eggs and fry for commercial on-growing without any adverse effects on the fecundity of the broodstock or the quality and survival of the eggs and fry.
Article
The effects of egg size on the subsequent growth and survival of developing eggs and fry from rainbow trout were examined. Eggs, whose size varied from 3.36 to 5.63 mm in diameter, were stripped from six 2-year-old and seven 3-year-old ripe females, selected at random from a large group of commercially-maintained broodstock, and after fertilization the survival rates to eying, hatch and swim-up, and the growth and survival of the fry determined.At the time of first feeding (8 weeks post-fertilization) there was a positive correlation between the size of the water-hardened egg and that of the fry, with the largest eggs from both ages of broodstock producing the largest fry. Four weeks after first feeding the relationship between egg size and fry weight was lost, suggesting that genetic and environmental influences exert greater effects on growth after this time. This was also supported by the finding that the specific growth rates of the fry up to 26 weeks post-fertilization were not correlated with the initial size of the eggs irrespective of whether they had been derived from 2- or 3-year-old parental fish.Survival rates to eying, hatch and swim-up and as 3-month-fed fry also showed no correlation with initial egg size, indicating that under the generally favourable conditions found in commercial hatcheries egg size has no direct implications as far as overall egg quality and fry survival are concerned.
Article
Progeny from 2- and 5-year-old brood stock of rainbow trout (Salmo gairdneri) were studied for 324 days after spawning to evaluate the effects of female age and egg size on hatchability, mortality, and growth of fry. The 5-year-old brood stock produced larger eggs with better hatchability, which resulted in larger, faster growing fry and fingerlings with lower mortalities.
Article
Female rainbow trout were given half- (0.35%) or full-ration (0.7% body weight per day) of a commercial trout pellet for a period of 1 year prior to spawning. During development of the eggs produced by each group of trout, samples of the eyed eggs, yolk-sac and swim-up fry were analysed for proximate, elemental, amino acid, fatty acid and enzyme composition.The eggs produced by the half-ration fish were significantly smaller than those of the full-ration trout. A number of small differences were also found between the composition of both groups of eggs. However, the data obtained suggested that ample supplies of the materials essential for successful embryo production were present in eggs from both half- and full-ration fed rainbow trout.
Article
In a sample of 73 females of winter steelhead, Salmo gairdneri Richardson, from the 1965–66 spawning run in the Alsea River, Oregon, egg size and egg number were correlated with body length. Alsea steelhead produced approximately 32% fewer eggs than females from Trinity River, California, and 51% less than fish of similar size from Scott Creek, California.
Article
Counts were made of the number of developing ova during the secondary growth phase of the oogenetic cycle in several groups of brook trout. An adjustment was made for the growth of the females since they increase appreciably in length during the secondary growth phase of the ova. Fecundity counts were then corrected to fish of a mean adjusted length. The results indicate that there is no major reduction in the number of developing ova during the secondary growth phase.
Article
Studies of histology and development of rainbow trout ovaries indicate that the degree of follicular atresia is associated with degree of starvation during the maturation period. Experimental stocks raised under varying starvation regimes showed that the greater the starvation, the higher the proportion of maturing follicles which regressed. Thus the result was a lower number of eggs brought to maturity in starved fish.Observations on natural populations indicate wide differences in egg size, with corresponding inverse differences in egg number at maturity. Egg size is apparently not effected by diet, but rather through natural selection depending on intraspecific competition. There appeared to be little correlation between egg size and fish size, but some difference did exist between age classes. Variations in egg number are therefore attributable to fish size, egg size and adequacy of diet. Starvation has also a lasting effect on the proportion of a given age-class which matures.