Wyniki wyszukiwania

1

Fecundity of asp Aspius aspius [L., 1758] from Miedzyodrze waters

100%

Kompowski A., Neja Z.

Bulletin of the Sea Fisheries Institute

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2004

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nr 3

2

Variation in brown trout [ Salmo trutta L.] reproductive characteristics in the River Usk, South Wales

100%

Bembo D. G., Beverton R. J. H., Weightman A. J., Cresswell R. C.

Polskie Archiwum Hydrobiologii

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1995

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tom 42

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nr 3

3

Effect of an adult trematode, Proctoeces lintoni [Fellodistomidae], on the gonadosomatic index of Fissurella limbata [Archaeogastropoda]

86%

Oliva M. E.

Acta Parasitologica

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1993

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tom 38

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nr 4

The influence on the gonadosomatic index of the adult Proctoeces lintoni (Digenea), a parasite of the gonads of the key-hole limpet Fissurella limbata (Gastropoda), was analyzed. Parasitic biomass reached as much 34.9% of gonadic weight, with a maximum of 99.4%. The gonadosomatic index computed as: (gonadic weight x total length ⁻¹) x 100, shows significant differences when compared with a corrected gonadosomatic index that excludes the parasitic biomass. Thus, caution must be taken when the gonadosomatic index is considered as a valid parameter in parasitized gonads.

4

Annual ovarian cycle of Vimba vimba [L.] from the Drawienski National Park in Northwest Poland

72%

Hliwa P., Demska-Zakes K., Martyniak A.

Archives of Polish Fisheries

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2002

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tom 10

|

nr 1

Macroscopic and microscopic changes which occur during the annual ovarian cycle of vimba females from the Drawieński National Park (DNP) were studied. The study was carried out in 1997-1998 using 146 fish with an average body length (longitudo corporis) of 24.2 cm and an average body weight of 274.9 g.No abnormalities or pathological changes in the ovaries of the investigated fish were detected. The histological picture showed the clear asynchronicity of oocyte maturation. The following ovary maturity stages, characteristic for portion spawners, were distinguished: IV₂; V₂; IV₃; V₃. A relatively short post-spawning stage was also identified (VI/II). It was confirmed that in vimba from the Drawieński National Park (DNP) the longest the maturity stage is III, which starts in October and finishes in March or April of the next year.

5

Breeding characteristics of the sand goby [Pomatoschistus minutus] - one of the most abundant goby species in the coastal waters of the Gulf of Gdansk Region [Southern Baltic Sea]

72%

Waligora-Borek K., Sapota M. R.

Oceanological and Hydrobiological Studies

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2005

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tom 34

|

nr 4

6

Reproductive biology of two grey mullet species (Actinopterygii: Mugiliformes: Mugilidae) in a northern Aegean Sea estuarine system

58%

Koutrakis E. T.

Acta Ichthyologica et Piscatoria

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2011

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tom 41

|

nr 1

Background. Limited information is available on the reproductive biology of grey mullets mainly because it is very difficult to collect fully mature specimens. In the presently reported study the reproductive biology of two mugilid species, namely Liza saliens and Liza ramada, was studied in the Vistonis and Porto Lagos estuarine systems. Materials and methods. Gonadosomatic index (GSI) and standard length at first maturity (SL50) were calculated. In order to estimate which oocytes are going to mature, oocyte size-frequency profiles were constructed for each fish and only the most advanced yolked oocytes were considered. The fecundity estimates were obtained using the volumetric method. Results. The results indicated that the sex ratio was in favour of females for both species. The gonadosomatic index indicated that the spawning season of L. saliens extends from June through October and that of L. ramada—from September through January. L. ramada sexually matures at a greater size and older age than L. saliens. For a correct estimate of the fecundity, the smallest group of eggs in both species (<0.20 mm) was rejected. For L. saliens the absolute fecundity varied from 245 000 to 555 000 eggs, while for L. ramada from 150 000 to 685 000 eggs. Fecundity is probably more correlated with the weight of the fish for both species. Conclusion. For the estimation of fecundity the total number of the oocytes is often used. However, this can be misleading as shown from the frequency distribution of the oocytes in the two grey mullet species, where a large proportion of the oocytes will never mature and therefore they do not contribute to the reproduction process. The percentage of these oocytes can be high, as shown in the current study (3.9%–28.1%).

7

Histological analyses of gonad development in female spin-cheek crayfish Orconectes limosus Raf.

58%

Juchno D., Chybowski L.

Archives of Polish Fisheries

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2003

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tom 11

|

nr 1

Histological analyses were preformed to investigate the annual cycle of the ovaries of female spiny-cheek crayfish Orconectes limosus Raf. (Crustacea). In May, the crayfish ovaries were filled mainly with oocytes in the initial stage of development (previtellogenic oocytes). The histological picture of the ovaries indicated the presence of empty follicles and mature oocytes undergoing resorption. In the summer months, the volume of the oocytes gradually increased and surplus substances material began to be synthesized (phase I or endogenous vitellogenesis). The histological picture of the ovaries in August was varied; some of them contained previtellogenic and vitellogenic oocytes in phase I, while others contained mainly oocytes in phase II of vitellogenesis when the cytoplasm fills with yolk and lipid globules. In fall, winter and spring the ovaries of crayfish O. limosus were filled mainly with oocytes in phase II of vitellogenesis; these were gradually increasing in volume. The annual gonadosomatic index (GSI) was calculated in the range of 0.41 to 5.83. The percentage of previtellogenic to vitellogenic oocytes prior to spawning was 23:77, and following spawning it was 70:30.

8

Age, reproduction, and fecundity of a population of Cobitis sp. (Actinopterygii: Cypriniformes: Cobitidae) from the Babolrud River in the southern Caspian Sea basin

44%

Mousavi Sabet H., Kamali A., Soltani M., Bani A., Esmaeili H. R., Rostami H., Vatandoust S., Moradkhani Z.

Acta Ichthyologica et Piscatoria

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2011

|

tom 41

|

nr 2

Background. Loach fishes, Cobitis sp., are found in the majority of streams in the southern Caspian Sea basin, but reproductive parameters of them are barely known. Reproductive conditions are key parameters of fish populations and their assessment is very important for several reasons. Therefore, the main aim of this study was to obtain reproductive characteristics of this fish which will be a first report for the basin. Materials and methods. Sampling was done at monthly intervals throughout the year and 226 individuals of Cobitis sp., were caught from the Babolrud River in the southern Caspian Sea basin, north of Iran. Age, sex ratio, fecundity, oocytes diameter, gonadosomatic- and modified gonadosomatic indices were estimated. Regression analyses were used to find relations between fecundity and fish size (length and weight), gonad weight, and age. Results. Sex ratio differed significantly from unity, and the percentage of females was greater than that of males. The mature females and males were longer than 45 and 35 mm in total length (+2 and +1 in age, respectively). The average egg diameter was 0.58 mm. The spawning took place from beginning of May to late July, when water temperature was between 19.1 and 24.6°C. Average GSI value at the beginning of the reproduction period was 8.93% and ranged between 4% and 26% in ripe, mature females. The average of absolute and relative fecundity was calculated 2172 and 590, respectively. The absolute fecundity was significantly related to body weight and gonad weight. Conclusion. Based on the pattern of gonadosomatic index, it was concluded that this fish has a prolonged active reproductive period. Their reproduction in this basin shows some differences from other reports, which might be related to different environmental conditions.

Ograniczanie wyników

Fecundity of asp Aspius aspius [L., 1758] from Miedzyodrze waters

Variation in brown trout [ Salmo trutta L.] reproductive characteristics in the River Usk, South Wales

Effect of an adult trematode, Proctoeces lintoni [Fellodistomidae], on the gonadosomatic index of Fissurella limbata [Archaeogastropoda]

Annual ovarian cycle of Vimba vimba [L.] from the Drawienski National Park in Northwest Poland

Breeding characteristics of the sand goby [Pomatoschistus minutus] - one of the most abundant goby species in the coastal waters of the Gulf of Gdansk Region [Southern Baltic Sea]

Reproductive biology of two grey mullet species (Actinopterygii: Mugiliformes: Mugilidae) in a northern Aegean Sea estuarine system

Histological analyses of gonad development in female spin-cheek crayfish Orconectes limosus Raf.

Age, reproduction, and fecundity of a population of Cobitis sp. (Actinopterygii: Cypriniformes: Cobitidae) from the Babolrud River in the southern Caspian Sea basin