84 resultados para Gender relationships


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Parameters a and b of the power body weight (W) - fecundity (F=a W super(b)) are presented for 25 populations comprising 15 species of Nigerian fishes. Estimates of b varied between 0.511 (Parauchenoglanis akin) and 1.654 (Periophthalmus barbarus) with a mean of 1.087 (s.d.=0.520). The maximum weight of populations examined did not significantly influence the relative magnitude of b. The parameters proportional to and beta of the linear weight-fecundity relationship (F= proportional to + beta W) are also presented for 27 fish populations from 22 species. Estimates of beta ranged from 4.22 (Chromidotilapia guntheri) to 2,062.94 (Pellunula min), with a mean of 243.80 (s.d.=477.89). The magnitude of beta declined with increasing maximum weights of fishes examined.

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Length-weight relationships were calculated for nine fish species from Lake Volvi (Macedonia, Hellas), caught with gillnets of five different mesh sizes between October 1995 and October 1996. In addition, length-weight relationships for 24 Greek freshwater fish species and one hybrid were also obtained from the literature. The values of the exponent of the length-weight relationships for all fish species examined ranged between 2.14 and 3.70 (mean = 3.12; SE=0.0321), and the median value was 3.19.

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Length-weight relationships of 335 species of fish of New Caledonia, belonging to 65 families of coral reef fishes, were computed (80%) or assembled from the literature (20% of all cases) to facilitate, among other things, estimation of coral reef fish biomass from visual census.

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The present study reports the length-weight relationship of 11 species of baitfish from the pole and line fishery at Minicoy and S. delicatulus from the fishery at Agatti, Bangaram and Perumal Par.

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Slopes and intercepts of length-weight relationships obtained from 37 populations from the rivers Oti, Pru and Black Volta in Ghana were compared using a one way analysis of covariance with fixed effects. Although no significant differences were obtained from this analysis, an ANOVA comparing the magnitudes of mean condition factors (Wx100/SL3) found 9 out of 37 populations significantly different at the 0.05 level. A two-way nested ANOVA using all populations combined, however, did not yield any significant differences between the three rivers. Thus, pooling the data to obtain the results presented in Part I (see Entsua-Mensah et al. Naga 1995) is justified here.

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Parameters a and b of the length (L)-weight (W) relationship W = a · Lb are presented for 17 commercial bivalve species collected from the southwest coastal waters of Korea. Estimates of b varied between 2.44 (Atrina pinnata japonica) and 3.31 (Scaphara broughtonii) with a mean of 2.891 (± 0.212). A total of 2 107 specimens were analyzed for this study. The length-weight relationship was isometric in most of the species.

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The results of a study on length-weight relationships of Penaeus monodon, reared in fertilized ponds in Kerala, India, and fed three different supplementary feeds are presented.

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The length-girth relationships of Javanese carp (Barbodes gonionotus) and hampal carp (Hampala macrolepidota) in the Jatilujur Reservoir, Indonesia were examined. The equations derived from estimating the maximum girth of Javanese carp are G sub(m) = -1.19 + 0.80L, and for the hampal carp, G super(m) = -0.47 + 0.62L. Models relating head girth to total length are also given. The relationship between G sub(m) (maximum girth) of fish caught and gillnet mesh size is also briefly discussed.

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The diet of marine animals is usually determined by stomach content analysis. Although partially digested prey fragments can often be identified to species level, it is difficult to estimate the original mass of the prey organism. This information, however, is essential for calculating both the total food intake as well as the relative contribution of each prey item. In this study we present regression equations that can be used to estimate the original mass of 18 common South African crustaceans from various indigestible fragments such as the carapace (length and width), chelae (length and width of left and right dactylus) and eye (length and width).

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The parameters a and b of the length-weight relationship of the form W=aL super(b) were estimated for 24 species of soft bottom demersal fishes caught on the continental shelf off Jalisco and Colima states, Mexico. The estimates of b ranged from 2.74 to 3.33. The mean of the b values is 3.02 with a standard deviation of 0.15.

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Length-weight relationships are presented by sex and by country for five species of the family Sparidae (Pugrus caeruleostictus, Pagellus bellottii, Dentex canariensis, Dentex congonensis, Dentex angolensis) sampled in April 1990 during the Guinea '90 trawling survey off Sierra Leone, Liberia, Cote d'Ivoire and Ghana.

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This paper presents 649 length-weight relationships gathered from literature pertaining to 83 fish species, belonging to 34 families, throughout Greek marine waters. The value of the slope b ranged from 1.667 for Cepola macrophthalma to 3.707 for Mullus barbatus. The mean value of b was 2.989 (SD=0.339) and did not differ significantly from 3(t-test, p<0.05). The median value of b was 3.058 and 50% of the b values ranged between 2.900 and 3.186.

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Biological/fisheries parameters (L sub(oo) M, F) are presented for four fish species (Gadiculus argenteus; Gaidropsarus mediterraneous; Symphurus ligulatus; Lepidorhombus boscii) as well as body length-weight and length-height relationships for 11 and 12 fish species, respectively, estimated from trawl samples collected using three different cod-ends (stretched mesh size: 14 mm and 20 mm diamond-shaped and 20 mm square-shaped) during 1993-1994, in the western Aegean and North Euboikos Gulf, Greece. The fisheries paramaters, estimated from length-frequency using the ELEFAN approach and software, are discussed in the light of recent information on the selectivity of the presently used trawl cod-end (14 mm diamond shaped)

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The parameters a and b of the length-weight relationship of the form W = aL super(b) were computed for 40 species from tables/graphs presented in E. Balon's Fishes of Lake Kariba, Africa.