Weight-length relationships of six endemic fish species of Greece

2014 ◽  
Vol 31 (1) ◽  
pp. 255-256
Author(s):  
O. Petriki ◽  
D. C. Bobori
Keyword(s):  
Fish Species ◽  
Endemic Fish ◽  
Of Greece

scholarly journals Length-weight Relations of 14 Endemic Fish Species from the Upper Yangtze River Basin, China

2013 ◽  
Vol 43 (2) ◽  
pp. 163-165 ◽  
Author(s):  
Jinming Wu ◽  
Lei Li ◽  
Hao Du ◽  
Hui Zhang ◽  
Chengyou Wang ◽  
...  
Keyword(s):  
River Basin ◽  
Fish Species ◽  
Yangtze River ◽  
Yangtze River Basin ◽  
Upper Yangtze River ◽  
Endemic Fish ◽  
The Upper Yangtze River

scholarly journals DINAMIKA POPULASI IKAN NILA (Oreochromis niloticus Linnaeus, 1758) DI DANAU PANIAI, PAPUA

2018 ◽  
Vol 23 (3) ◽  
pp. 193
Author(s):  
Samuel Samuel ◽  
Yoga Candra Ditya ◽  
Vipen Adiansyah
Keyword(s):  
Fish Species ◽  
Oreochromis Niloticus ◽  
Nile Tilapia ◽  
Lake Management ◽  
Nile Tilapia Oreochromis Niloticus ◽  
Average Maximum ◽  
Fish Samples ◽  
Information Research ◽  
Endemic Fish ◽  
Average Size

Introduksi ikan nila atau “serapia” (Oreochromis niloticus) di Danau Paniai bertujuan untuk meningkatkan diversitas hasil tangkapan dan mengurangi tekanan eksploitasi terhadap jenis ikan endemik. Pertumbuhan dan produksi ikan nila yang cepat tanpa diiringi upaya pengelolaan akan mengancam keberlanjutan ikan endemik di danau. Upaya pengelolaan sumberdaya ikan di suatu perairan membutuhkan informasi dinamika populasi. Penelitian dinamika dan pengelolaan populasi ikan nila dilakukan pada bulan Februari sampai Oktober 2016. Contoh ikan dikumpulkan dari hasil tangkapan nelayan dengan menggunakan jaring insang dengan berbagai ukuran mata jaring dan dari 4 (empat) enumerator pada tujuh stasiun pengamatan. Hasil penelitian menunjukkan populasi ikan nila di Danau Paniai didominasi ukuran panjang individu antara 15-25 cm sebanyak 67,24%. Pola pertumbuhan ikan jantan dan betina adalah isometrik, panjang maksimum rata-rata (L) adalah 37,28 cm dan koefisien pertumbuhan (K) adalah 0,50 per tahun. Mortalitas alami (M) dan mortalitas penangkapan (F) masing-masing sebesar 0,99 dan 0,54 per tahun. Tingkat eksploitasi (E) diperoleh nilai 0,35 lebih kecil dari nilai optimum (E=0,5). Ukuran rata-rata ikan nila tertangkap (Lc) adalah 20,55 cm lebih besar dari ukuran pertama matang gonad (Lm) sebesar 14,73 cm. Nilai Lc>Lm mengindikasikan sebagian besar populasi ikan nila di Danau Paniai sempat melakukan pemijahan sehingga pemanfaatan lebih atau sama dengan nilai optimum diharapkan dapat meningkatkan pemanfataan ikan nila di Danau Paniai. Introduction of nile tilapia (Oreochromis niloticus) in Lake Paniai known as “serapia” is aimed for improving the diversity of catches and reducing the exploitation pressure on the endemic fish species. The rapid growth, reproduction and production of nile tilapia without its management efforts is a new threat to the sustainability of the existence and utilization of endemic fish species in the lake. Management efforts of fish resources require population dynamics information. Research on the dynamics and management of nile tilapia populations was conducted from February to October 2016. Fish samples were collected from fishermen catches using nets with various mesh sizes and from four enumerators at seven observation stations. The results showed that the population of nile tilapia in Lake Paniai was dominated by individual length between 15-25 cm with frequency of 67,24%. The growth pattern of male and female fish were isometric, the average maximum length (L) was 37.28 cm and the growth coefficient (K) was 0.50 per year. Natural mortality (M) and fishing mortality (F) were 0.99 and 0.54 per year respectively. Exploitation rate (E) of 0.35 was smaller than the optimum value (E=0.5). The average size of nile tilapia captured (Lc) was 20.55 cm larger than the first size of gonad maturity (Lm) of 14.73 cm. The Lc value was higher than that the Lm value(Lc>Lm) indicating that most of nile tilapia population in Lake Paniai has spawned so that increasing the more or equal to the optimum value was expected to improve the of nile tilapia fish in Lake Paniai.

Length-weight relationships for four endemic fish species from the Yalu River, China

2018 ◽  
Vol 34 (5) ◽  
pp. 1212-1213
Author(s):  
Yu-Yong Zhang ◽  
Qing-Li Bai ◽  
Zhi-Ying Jia ◽  
Cheng-Xue Ma ◽  
Yong-Yi Jia
Keyword(s):  
Fish Species ◽  
Yalu River ◽  
Endemic Fish

scholarly journals Population structure and reproductive biology of Astyanax gymnodontus (Characiformes: Characidae), a poorly known endemic fish of the Iguaçu River basin, Brazil

2016 ◽  
Vol 64 (1) ◽  
pp. 69 ◽  
Author(s):  
Matheus Tenorio Baumgartner ◽  
Pedro Rogério Leandro da Silva ◽  
Gilmar Baumgartner
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
River Basin ◽  
Reproductive Biology ◽  
Body Length ◽  
Fish Species ◽  
Energy Allocation ◽  
Influence Area ◽  
Endemic Fish ◽  
Iguaçu River

Success in fish breeding depends on reproduction intensity, periodicity and the place where it occurs. Information about fish species reproduction is important to assist managers, and to determine conservation and management strategies. The fish assemblage of the Iguaçu River basin is already known for its high endemism, and despite this privilege, the large number of dams built along it, threat this particular biodiversity. Astyanax gymnodontus is an endemic fish species and studies on its population structure and reproductive biology are important, since they represent the first step for further community studies. Our objective was to evaluate some aspects of the population structure and reproductive biology of A. gymnodontus in the influence area of Salto Santiago dam, Iguaçu River, Paraná State, Brazil. Sampling was made monthly from July 2003 to June 2005, and bimonthly from July 2005 to March 2013, at five sites in the influence area of Salto Santiago dam. Fishes were collected using 10 m length gillnets with meshes ranging from 2.5 to 6.0 cm between non-adjacent knots and trammel nets with inner meshes of 6.0 cm between non-adjacent knots. Nets were arranged on surface, bottom and margins of each site, exposed for 24 h. Additional drags on littoral areas were performed from January to March and October to December from 2009 to 2011, with 50.0 m nets, 0.5 cm mesh size, for juveniles capture. We captured and analyzed 21 932 individuals, being 9 249 females and 12 683 males, representing 42.2 % and 57.8 %, respectively. The average body length was 8.8 cm for females and 8.3 cm for males. The average weight was 18.8 g for females and 16.0 g for males. Sex ratio calculated for the entire period was 1.8 males/female. Males were more abundant than females in 73.2 % of samples and significant differences were observed in 35.3 % of samples. The estimated length at first maturity (SL50) was 6.4 cm for females and 6.2 cm for males. We suggest that sexual differences in body length and weight, and sex ratio occurred as a result of sexual differences in energy allocation. Females spend more energy on body growth, which means more eggs production and higher fecundity. As an integrated response, males spend more energy on sperm production, in competition with other males, leading to a smaller body size. Differences in estimated SL50 might be an indicator of this sexual difference in energy allocation. The reproduction period was from September to February, with greater intensity at the beginning of this period, and the sites of highest reproductive intensity were those immediate downstream from dams, and therefore with more riverine characteristics.

scholarly journals Modelling critical factors affecting the distribution of the vulnerable endemic Eastern Iberian barbel (Luciobarbus guiraonis) in Mediterranean rivers

2015 ◽  
Vol 17 (1) ◽  
pp. 264 ◽  
Author(s):  
E. J. OLAYA-MARIN ◽  
F. MARTÍNEZ-CAPEL ◽  
R. GARCÍA-BARTUAL ◽  
P. VEZZA
Keyword(s):  
River Basin ◽  
Fish Species ◽  
Model Parameters ◽  
Physical Habitat ◽  
Mediterranean Rivers ◽  
Exotic Fish ◽  
Gradient Descent Algorithm ◽  
River Basin District ◽  
Endemic Fish ◽  
Exotic Fish Species

Luciobarbus guiraonis (Eastern Iberian barbel) is an endemic fish species restricted to Spain, mainly distributed in the Júcar River Basin District. Its study is important because there is little knowledge about its biology and ecology. To improve the knowledge about the species distribution and habitat requirements, nonlinear modelling was carried out to predict the presence/absence and density of the Eastern Iberian barbel, based on 155 sampling sites distributed throughout the Júcar River Basin District (Eastern Iberian Peninsula). We used multilayer feed-forward artificial neural networks (ANN) to represent nonlinear relationships between L. guiraonis descriptors and variables regarding the physical habitat and biological components (macroinvertebrates, fish, riparian forest). The gradient descent algorithm was implemented to find the optimal model parameters; the importance of the ANN’s input variables was determined by the partial derivatives method. The predictive power of the model was evaluated with the Cohen’s kappa (k), the correctly classified instances (CCI), and the area under the curve (AUC) of the receiver operator characteristic (ROC) plots. The best model predicted presence/absence with a high performance (k= 0.66, CCI= 87% and AUC= 0.85); the prediction of density was moderate (CCI = 62%, AUC=0.71 and k= 0.43). The fundamental variables describing the presence/absence were; solar radiation (the highest contribution was observed between 2000 and 4200 WH/m2), drainage area (with the strongest influence between 3000 and 5.000 km2), and the proportion of exotic fish species (with relevant contribution between 50 and 100%). In the density model, the most important variables were the coefficient of variation of mean annual flows (relative importance of 50.5%) and the proportion of exotic fish species (24.4%). The models provide important information about the relation of L. guiraonis with biotic and abiotic variables, this new knowledge can help develop future studies and management plans for the conservation of this species in the Júcar River Basin District and, potentially, for the conservation of other endemic fish species of Barbus and Luciobarbus in Mediterranean rivers.

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