Length-Frequency Distribution and Relative Condition Factor of Brycinus nurse in the New Calabar River, Niger Delta, Nigeria

<p><strong>ABSTRACT<br /> </strong><br />The anchovy  (Stolephorus sp.)  in  Muara  Sungsang  estuary South Sumatera  are  generally caught by stationary liftnet. Morphometric studies are essential to determine the growth form and growth rate of species, which is  very much important for proper  utilization  and management of the population of the species. This study aimed to determine the size structure and growth pattern of the  anchovy  caught  by  stationary  liftnet.  The   size  structure,  length -weight  relationship  and  the condition factor  of  anchovy were computed.  The anchovy samples were taken  in July 2013 (750 samples) and September 2013 (1950 samples).    Results  showed  that the population of anchovy was  dominated by length frequency distribution  of  65 mm during study on July 2013 and 75 mm during  study  on  September  2013.  Both  populations  were  dominated  by  weight  frequency distribution 2 gram.  The anchovy that caught on September 2013 were more allowable catch than on July 2013. The growth pattern of anchovy was negative allometric. The relative condition factor (Kn)  value  in  September  2013  was  higher  than  in  July  2013.  It  indicated  that  the  environmental conditions  at  Muara  Sungsang  estuary  are  suitable  for  growth  of  anchovy’s  and  still  safe  from fishing pressure.</p><p>Keywords: allometric, anchovy, condition factor, frequency distribution</p><p> <strong><br />ABSTRAK</strong></p><p>Ikan  Teri  (Stolephorus  sp.)  di  Muara  Sungsang  Sumatera  Selatan  umumnya  ditangkap menggunakan bagan tancap. Studi morfometrik berguna untuk menentukan bentuk pertumbuhan dan laju pertumbuhan spesies. Hal ini berguna untuk manajemen populasi dan sebagai informasi tentang stok atau kondisi organisme. Disamping itu, sebagai dasar dalam upaya pengelolaan dan pemanfaatan  ikan  teri  di  masa  akan  datang.  Penelitian  ini  bertujuan  untuk  mengetahui  struktur ukuran dan pola pertumbuhan ikan teri hasil tangkapan bagan tancap. Data ikan teri didapatkan pada  bulan  Juli  2013  (750  sampel)  dan  September  2013  (1950  sampel).  Hasil  penelitian menunjukkan bahwa populasi ikan teri didominasi oleh distribusi frekuensi panjang 65 mm pada bulan Juli 2013 dan 75 mm pada bulan September 2013. Distribusi frekuensi berat teri pada kedua bulan tersebut sama yaitu 2 gram. Penangkapan ikan teri pada bulan September 2013 lebih layak tangkap  dibandingkan  pada  bulan  Juli  2013.  Pertumbuhan  ikan  teri  bersifat  negative  allometric. Nilai Faktor kondisi (Kn) pada bulan September 2013 lebih tinggi daripada bulan Juli 2013. Hal ini mengindikasikan bahwa kondisi  lingkungan Muara Sungsang cocok untuk pertumbuhan ikan teri dan masih aman dari tekanan aktivitas penangkapan.</p><p>Kata kunci: allometrik, teri, faktor kondisi,distribusi frekuensi</p>

Penelitian ini dilakukan di Sungai Belumai Kabupaten Deli Serdang Provinsi Sumatera Utara pada Bulan Mei dan juni 2014 di empat lokasi yang berbeda dengan menggunakan metode sensus. Tujuan dari penelitian ini untuk mengetahui aspek pertumbuhan (sebaran frekuensi panjang, hubungan panjang bobot, faktor kondisi dan koefisien pertumbuhan). Jumlah ikan lemeduk yang tertangkap adalah 55 ekor. Hasil penelitian menggambarkan bahwa populasi ikan didominasi oleh sebaran ukuran kelas panjang 174-194 mm. Hasil hubungan panjang berat menunjukkan bahwa pola pertumbuhan ikan bersifat allometrik negatif (b=2,565) dimana pertambahan panjang lebih cepat dibandingkan pertambahan berat. Nilai faktor kondisi ikan lemeduk (Barbodes schwanenfeldii) berkisar 0,946-1,059.This research was done in Belumai River Deli Serdang District North Sumatera Province. This research was conducted in May until June 2014 in four different locations by using census method. The purpose of this research is to know the aspect of growt (length frequency distribution, length-weight relationship, condition factor and growth coefficient). The number of lemeduk fish which caught were 55 fish. Result shown that the population is dominate by length frequency distribution 174-194 mm. Result length-weight relationship shown that growth pattern was allometric negative (b=2,565) where the length is faster growth than the weight. The condition factor of lemeduk fish was around 0,946-1,059.

Age and growth characteristics of the thin-lipped Grey Mullet (Liza ramada) were investigated in Eastern coast of Libya. Aging was done by two methods: counting annuli on scales and by length frequency distribution, a total of 218 scales were studied for age determination, in addition of 334 fishes specimen for length frequency distribution reading. Four age groups were determined from scale reading, and five age groups from length frequency distribution methods, the parameters of the Von Bertalanffy growth equation for both sex of all individuals were estimated at 35.4 cm, 0.187 per year, -1.14 years and 2.4, for male were estimated at 35.7 cm, 0.17 per year, -1.367 and 2.3, for female were 38.6 cm, 0.156 per year, -1.383 and 2.4, for L∞, k and t0, and φ′, respectively.

Otoliths reading and length frequency distribution were used for age determination and growth estimation of Sardinella aurita (round sardinella) stock of Southern Atlantic coast of Morocco. Both otoliths' method for age determination and Bhattacharya’s method for length frequency analysis showed five age groups. The growth performance index revealed that there is significant accordance among method of length frequency distribution and otoliths reading for stock assessment studies of Sardinella aurita stock in the south of Morocco. The microscopic observation of female gonads using histology method was investigated for the first time in our study area and confirms the presence of five principal stages of ovary of sardinella aurita: immature, maturing virgin and recovering spent, mature (or pre-spawning phase), spawning, post-spawning or spent. In addition, our results of the fecundity showed that the mean relative fecundity obtained is estimated at 193 ± 98 oocytes/g which is lower compared to those obtained in other areas in the Atlantic coast.

AIM: The population biology of the freshwater shrimp Macrobrachium jelskii was investigated here emphasizing the length-frequency distribution, sex ratio, reproductive period and juvenile recruitment. In addition, the abundance of individuals was correlated with the abiotic factors. METHODS: Samples were collected on a monthly basis from July 2005 to June 2007 along the river margin in shallow water of Grande River, at Planura region, State of Minas Gerais, Brazil (20º 09' S and 48º 40' W), using a trawl net (1.0 mm mesh size, and 2.0 m × 0.5 m wide). The fishing gear was handled by two people along the marginal vegetation of the Grande River in a course of 100 m, covered for one hour. In the laboratory, the specimens were identified, measured and sexed. RESULTS: A total of 2,789 specimens was analyzed, which corresponded to 1,126 males (549 juveniles and 577 adults) and 1,663 females (1,093 juveniles, 423 adults non-ovigerous and 147 ovigerous). The sex ratio differed significantly in favor of the females of M. jelskii (1:1.48; χ² = 103.95; p < 0.0001). The mean size of carapace length (CL) of females (6.32 ± 1.84 mm CL) was statistically higher than of males (5.50 ± 1.07 mm CL) (p < 0.001). The length-frequency distribution of the specimens revealed an unimodal pattern and non-normal distribution for males and females (W = 0.945; p < 0.01). No significant relationship between the abundance of M. jelskii and the environmental variables was observed (p = 0.799). CONCLUSION: The presence of ovigerous females and juveniles in the population suggests a continuous reproduction pattern and recruitment for M. jelskii at Planura region.

Abstract The age and growth of Pseudoplatystoma corruscans, is analyzed on specimens landed in Puerto Antequera, Province of Chaco, Argentina. The study is based on length frequency distribution of 1192 individuals and growth marks of 293 pectoral spines. Previously to age assignation based on spines readings, we performed analyses that ruled out age-associated resorption of rings and corroborated the annual periodicity of mark formation. The average sizes of the radius of each ring were obtained, and the total length of fish were back-calculated to the time of the ring formation, by the regression model fitted between the total radius of the spines to the respective sizes of each fish. Such data showed a good fitting to growth models of von Bertalanffy, Gompertz and logistic for both sexes separately. Results indicate that the study of the species growth must be carried out for each sex separately and that the fishing regulations must consider this characteristic of the species since the current management guidelines could be promoting differential capture by sexes.

Abstract. A time series from 1977–1989 and 2000–2002 of scientific trawl surveys in the Porcupine Seabight and adjacent Abyssal Plain of the NE Atlantic was analysed to assess changes in demersal fish biomass and length frequency. These two periods coincide with the on-set of the commercial deep-water fishery in the late 1970s and the on-set of the regulation of the fishery in the early 2000's and allowed us to investigate changes in the relationship between total demersal fish biomass and depth between the pre- and post commercial fishing periods, changes in the biomass (kg km2) depth distribution and length frequency distribution of the most dominant fish species. Our results show a decline in total demersal fish biomass of 36% within the depth range of the commercial fishery (< 1500 m). Whilst there were significant declines in target (e.g. Coryphaenoides rupestris decreased by 57%) and non-target (e.g. Coryphaenoides guentheri and Antimora rostrata) species, not all species declined significantly. Changes in the overall length-frequency distribution were detected for 2 species (Coryphaenoides armatus, Synaphobranchus kaupii), but only at depths greater than 1800 m (outside the maximum depth for commercial trawling). This suggests that whilst there is evidence for likely fisheries impacts on the biomass distribution of the demersal fish population as a whole, species-specific impacts are highly variable. It is clear that changes in population structure can extend beyond the depth at which fishing takes place, highlighting the importance for also considering the indirect effects on deep-sea fish populations.