This study records length-weight relationships （LWRs） for eleven commercially important marine catfish species of the family Ariidae （sea catfishes） and Plotosidae （eel catfishes） from the northern Arabian Sea c...This study records length-weight relationships （LWRs） for eleven commercially important marine catfish species of the family Ariidae （sea catfishes） and Plotosidae （eel catfishes） from the northern Arabian Sea coast of Pakistan. The specimens were sampled from December 2014 to November 2015, using bottom trawls with various mesh sizes by commercial vessels. The species were Nemapteryx caelatus, Sciades sona, Arius gagora, Batrachocephalus mino, Neturna thalassina, N. bilineata, Osteogeneiosus militaris, Plicofollis dussumieri, P. tenuispinis, Plotosus limbatus, and P. lineatus. Of the eleven species, two species A. gagora and N. bilineata were recorded for the first time and LWRs for four species A. gagora, N. bilineata, S. sona, and B. mino still have no data in the FishBase database. In addition, new maximum length for each of the three species N. bilineata, O. militaris andB. mino was also found.展开更多
Cytogenetic studies have shown that the genus Astyanax has extensive karyotypic variability among species and many are the works developed about this group in different river basins in Brazil. The Tangara da Serra ar...Cytogenetic studies have shown that the genus Astyanax has extensive karyotypic variability among species and many are the works developed about this group in different river basins in Brazil. The Tangara da Serra area （Mato Grosso State, Brazil）, which contains tributaries of both Amazon and Upper Paraguay River basins is, therefore, a natural watershed. Thus, in this work, the karyotypes of three species of Astyanax from the Sepotuba River＇s tributary streams were analyzed by using conventional methods of chromosome analysis. Astyanax marionae presented 2n =48（12m＋ 10sm＋ 12st＋ 14a） and NF （fundamental number） = 82 with evident heterochromatin in several chromosomal regions. Astyanax cf. asuncionensis presented 2 n = 50 （20m ＋ 12sm ＋ 6st ＋ 12a）, NF = 94 chromosomes and with evident heterochromatin in few chromosomes and Ag-NOR in one chromosome pair. Astyanax cp. scabripinnis presented 2 n = 50 （12m ＋ 10sm ＋ 10st ＋ 18a）, NF = 82 with evident heterochromatin at most of the chromosomes in pericentromeric region and a strongly marked block on a telocentric chromosome pair. The Ag-NORs were observed near the heterochromatic region. The karyotypic differences found, probably occurred by chromosomal rearrangements, resulting in a heterogeneous model of chromosomal evolution who probably involved both Robertsonian chromosomal rearrangements to A. marionae, as not Robertsonian to other Astyanax species. This indicates that although these species share the same hydrographic basin （Upper Paraguay） are isolated in different microbasins and the absence in the gene flow may have allowed the establishment of independent rearrangements in each population.展开更多
Length-weight relationships （LWRs） were determined for fish species Diplodus vulgaris from the Benghazi coast along the eastern Mediterranean Sea coast of Libya. Samples were collected using trammel nets. The parame...Length-weight relationships （LWRs） were determined for fish species Diplodus vulgaris from the Benghazi coast along the eastern Mediterranean Sea coast of Libya. Samples were collected using trammel nets. The parameters a and b from the LWR formula W = aLb were estimated. The values of the exponent b of the length-weight relationships in all categories range between 2.295 in September to 3.208 in August. The total number of fish samples investigated were 290, from which 179 were males, 41 females and 70 fishes immature. The sex ratio male to female were 4.3：1. In January, August and Females the slope ＂b＂ close to equal 3, were the categories exhibited isometric relationship, in September, October and November were slope ＂b＂ not equal 3, which the categories exhibited negative allometric relationship. The mean observed length of male was 18.29 cm at mean observed weight 114.8 g, and mean observed length of female was 19.15 cm at mean observed weight 133.97 g.The general equation for the length-weight relationship for both sex was： W = 0.03835L277, for male was： W = 0.036 L274, for female, W = 0.016 L302.展开更多
文摘This study records length-weight relationships （LWRs） for eleven commercially important marine catfish species of the family Ariidae （sea catfishes） and Plotosidae （eel catfishes） from the northern Arabian Sea coast of Pakistan. The specimens were sampled from December 2014 to November 2015, using bottom trawls with various mesh sizes by commercial vessels. The species were Nemapteryx caelatus, Sciades sona, Arius gagora, Batrachocephalus mino, Neturna thalassina, N. bilineata, Osteogeneiosus militaris, Plicofollis dussumieri, P. tenuispinis, Plotosus limbatus, and P. lineatus. Of the eleven species, two species A. gagora and N. bilineata were recorded for the first time and LWRs for four species A. gagora, N. bilineata, S. sona, and B. mino still have no data in the FishBase database. In addition, new maximum length for each of the three species N. bilineata, O. militaris andB. mino was also found.
文摘Cytogenetic studies have shown that the genus Astyanax has extensive karyotypic variability among species and many are the works developed about this group in different river basins in Brazil. The Tangara da Serra area （Mato Grosso State, Brazil）, which contains tributaries of both Amazon and Upper Paraguay River basins is, therefore, a natural watershed. Thus, in this work, the karyotypes of three species of Astyanax from the Sepotuba River＇s tributary streams were analyzed by using conventional methods of chromosome analysis. Astyanax marionae presented 2n =48（12m＋ 10sm＋ 12st＋ 14a） and NF （fundamental number） = 82 with evident heterochromatin in several chromosomal regions. Astyanax cf. asuncionensis presented 2 n = 50 （20m ＋ 12sm ＋ 6st ＋ 12a）, NF = 94 chromosomes and with evident heterochromatin in few chromosomes and Ag-NOR in one chromosome pair. Astyanax cp. scabripinnis presented 2 n = 50 （12m ＋ 10sm ＋ 10st ＋ 18a）, NF = 82 with evident heterochromatin at most of the chromosomes in pericentromeric region and a strongly marked block on a telocentric chromosome pair. The Ag-NORs were observed near the heterochromatic region. The karyotypic differences found, probably occurred by chromosomal rearrangements, resulting in a heterogeneous model of chromosomal evolution who probably involved both Robertsonian chromosomal rearrangements to A. marionae, as not Robertsonian to other Astyanax species. This indicates that although these species share the same hydrographic basin （Upper Paraguay） are isolated in different microbasins and the absence in the gene flow may have allowed the establishment of independent rearrangements in each population.
文摘Length-weight relationships （LWRs） were determined for fish species Diplodus vulgaris from the Benghazi coast along the eastern Mediterranean Sea coast of Libya. Samples were collected using trammel nets. The parameters a and b from the LWR formula W = aLb were estimated. The values of the exponent b of the length-weight relationships in all categories range between 2.295 in September to 3.208 in August. The total number of fish samples investigated were 290, from which 179 were males, 41 females and 70 fishes immature. The sex ratio male to female were 4.3：1. In January, August and Females the slope ＂b＂ close to equal 3, were the categories exhibited isometric relationship, in September, October and November were slope ＂b＂ not equal 3, which the categories exhibited negative allometric relationship. The mean observed length of male was 18.29 cm at mean observed weight 114.8 g, and mean observed length of female was 19.15 cm at mean observed weight 133.97 g.The general equation for the length-weight relationship for both sex was： W = 0.03835L277, for male was： W = 0.036 L274, for female, W = 0.016 L302.
