gravimetric method fecundity|fish fecundity study pdf : trading Fecundity Definitions and Methods of Determination. The number of eggs produced per female has been variously defined in fisheries literature and different fe-cundity terms have been used .
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The gravimetric method involves dissecting and weighing a small subsample (typically 0.5–1 g) of the ovary, then preserving and counting the oocytes or embryos manually .
In this contribution, we review several methods currently used to estimate fecundity of marine fishes collected in the field in relation to their reproductive strategy.
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The gravimetric method involves dissecting and weighing a small subsample (typically 0.5 – 1 g) of the ovary, then preserving and counting the oocytes or embryos manually under a microscope.ovary (volumetric method). The gravimetric method is based on counting oocytes in weighed samples of ovarian tissue and relating the tissue samples to the total ovary weight. In the .
The gravimetric method involves dissecting and weighing a small subsample (typically 0.5–1 g) of the ovary, then pre-serving and counting the oocytes or embryos manu-ally under a .Fecundity Definitions and Methods of Determination. The number of eggs produced per female has been variously defined in fisheries literature and different fe-cundity terms have been used . Fecundity can be determined by tedious, complete oocyte counts. Researchers save time by counting a subsample of oocytes, measuring the subsample and total ova .
Measuring potential fecundity is most often accomplished by the gravimetric method (Burd and Howlett, 1974, Bagenal, 1978, Kjesbu and Holm, 1994). This procedure .
Gravimetric and autodiametric methods provide unbiased estimates of fecundity. • The autodiametric method proved to be faster because it took on average 61% and 73% less . In highly fecund spawners, like most teleosts, fecundity measurements are carried out in smaller fractions of ovarian tissue of known weight/volume and resulting oocyte densities are extrapolated to the total weight/volume of the ovary (gravimetric or .
Gravimetric method. 4.4.1.1. . The total number of eggs in an ovary is then calculated from the equation F = nG/g (where F = Fecundity, n= number of eggs in the subsample, G=total weight of the ovary and, g = weight of the subsample in the same unit.) Last modified: Monday, 19 December 2011, 8:43 AM.Early work (Kjesbu et al., 1991) used a gravimetric method to estimate fecundity and prepared histological sections to determine the proportion of the fecundity that was atretic and hence the standing stock of atretic oocytes. . Bluemouth, Helicolenus dactylopterus is zygoparous species with internal fertilization spawning multiple batches of early-celled embryos in gelatinous masses. Its unusual reproductive strategy required methodological adjustments to estimate potential annual fecundity. The present study applied an adaptation of the gravimetric method, estimated .
potential fecundity). Different methods exist but their use will depend on the species under investigation, re-sources and laboratory facilities available (Murua et al., 2003). Traditionally, potential fecundity is determined by a gravimetric or volumetric method (Bagenal, 1978; Kjesbu and Holm, 1994). Although these methods arefecundity) to measure the seasonal decline in the total fecundity of the population. G is measured on-ship using gross anatomical criteria to distinguish active (advanced yolked oocytes present) from inactive ovaries (no advanced oocytes present) and E is measured in the laboratory using conventional gravimetric fecundity methods.Early work (Kjesbu et al., 1991) used a gravimetric method to estimate fecundity and prepared histological sections to determine the proportion of the fecundity that was atretic and hence the standing stock of atretic oocytes. This approach has been shown to be biased (Kurita et al., 2003) and reduced the estimated proportion of atretic oocytes .
to estimate fecundity using the gravimetric method, but were then used to develop an entirely new method which they termed the ‘auto-diametric’ method. Within the ovary of developing Atlantic cod, vitellogenic oocytes are packed together in a very uniform way. Thorsen and Kjesbu (2001) assessed the uniformity of this packing using Volumetric and gravimetric methods have been widely used for the estimation of fecundity in diverse crustacean species, such as Aratus pisonii (Díaz et al., 1983), Callinectes sapidus (Prager et .The weight-based gravimetric method is currently one of the most widely used methods to determine fecundity (Murua et al. 2003). The gravimetric method involves dissecting and weighing a small .Batch fecundity was determined using the gravimetric method (Hunter et al. 1985) to count numbers of hydrated but unovulated oocytes in weighed subsamples of formalin-fixed ovaries. Each subsample consisted of a wedge of tissue extend ing from the periphery to the lumen of the ovary. In order to
Typically, fecundity has often been estimated using the gravimetric method, in which fecundity is the product of the number of oocytes per gram of ovary tissue (oocyte density) and the weight of . The mean difference between total oocyte count and extrapolated count based on the gravimetric method was 111.2 (SD ± 154.0) and 165.9 (SD ± 279.0) for the volumetric method. Gravimetric and volumetric fecundity estimates were closely correlated with total oocyte counts, although both were positively biased. Traditionally, potential fecundity is determined by a gravimetric or volumetric method (Bagenal, 1978; Kjesbu and Holm, 1994). Although these methods are simple, inexpensive and give reliable results, the work is time-consuming and .
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gravimetric fecundity method because too few of the specimens contained all developing oocytes in stage 5 or beyond. However, enough samples were suitable for the stereological method. This study provides a fecundity estimate based on stereological and gravimetric techniques for shortspine thornyhead off Alaska. Benefits and limitations of the
Fecundity was estimated using the gravimetric method (Zweicker 1967; Murua et al. 2003) and Image-Pro Plus version 10.0 (Media Cybernetics, Rockville, Maryland) to Batch fecundity was estimated by the gravimetric method for females with late stage migratory nucleus or hydrated oocytes. For each fish, a core subsample of between 0.05–0.09 g was taken from the middle region of .Currie et al. (2010) noted that the mean percent difference between traditional gravimetric estimates of fecundity and this non-invasive method was 3.68%, thus concluding that the method was . The results indicated that the fecundity increased over time (Portugal) were processed for histology and observed applying the histometric method (Emerson et al., 1990) and 65 pre-spawning ovaries .
The problem of estimating fecundity depends upon several factors such as: the absolute numbers of eggs produced the total or partial spawning nature of the fish and the immature eggs present which will be carried over to the next spawning season. The methods used in fecundity studies fall into three sections: (1) Random sampling of fish, (2) estimating the number of eggs . The most common and widespread method to estimate fecundity is the gravimetric method, proposed by McGregor, 1922, Raitt, 1933, which uses whole mounts samples of gonad tissue. Begenal and Braum (1978) summarizes most of these methods based on counting the number of mature oocytes in whole mounts preparations, assuming that all the oocytes . The gonadosomatic index (GSI) is widely used as a simple measure of reproductive capacity, but its validity has often been questioned. This study showed the inter-spawning variation in the predicted GSI of Japanese anchovy using the gravimetric oocyte packing density method. Time course sampling showed that final oocyte maturation and subsequent ovulation . Typically fecundity is assessed through the use of gravimetric methods, entailing the measurements of either the whole or a sample of the ovary and subsequent counting and re-weighing of a subsample of oocytes to determine overall fecundity (Kraus et al., 2002; Miller and Kendall, 2009). This method is both labour-intensive and costly.
Fecundity (F) = _____ x number of mature ova in subsample. . Gravimetric method. This is based on weight of the ovary. After liberating the ova from the ovarian tissues, the ova should be thoroughly washed and spread on a blotting paper to dry in air. The number of eggs present in the each subsample can be counted using compound microscope.Gravimetric analysis and volumetric analysis are two common methods used in analytical chemistry to determine the concentration or amount of a substance in a sample. Gravimetric analysis involves the measurement of mass, where the analyte is precipitated and then weighed to determine its concentration.Bay. Stereological sampling methods were used to determine if environ-mental changes in the Chesapeake Bay watershed over the last 60 years have altered average fecundity of this species. These methods were compared with automated gravimetric meth-ods to determine the efficacy of using stereological fecundity sampling for white perch. An adaptation of the gravimetric method, estimated batch fecundity based on different spawning fraction criteria (gestation, early-celled, and blastula females), and compared these estimates with the number of developing oocytes (NDOR) in the beginning of spawning to clarify the oocyte development pattern suggests vitellogenic oocyte .
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gravimetric method fecundity|fish fecundity study pdf