Littoral habitat loss caused by multiyear drought and the response of an endemic fish species in a deep desert lake

2019 ◽  
Vol 64 (3) ◽  
pp. 421-432 ◽  
Author(s):  
Hayley Corrine Glassic ◽  
Jereme William Gaeta
Keyword(s):  
Habitat Loss ◽  
Fish Species ◽  
Littoral Habitat ◽  
Endemic Fish ◽  
Desert Lake

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 Broad and fine-scale threats on threatened Brazilian freshwater fish: variability across hydrographic regions and taxonomic groups

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Murilo Luiz e Castro Santana ◽  
Fernando Rogério Carvalho ◽  
Fabrício Barreto Teresa
Keyword(s):  
Freshwater Fish ◽  
Habitat Loss ◽  
Fish Species ◽  
Threatened Species ◽  
Environmental Changes ◽  
Anthropogenic Impacts ◽  
Conservation Status ◽  
Fine Scale ◽  
Hydrographic Regions ◽  
Taxonomic Groups

Abstract: Anthropogenic environmental changes are the main cause of species extinction during the Holocene. Species have been exposed to major source of threats, such as habitat loss and fragmentation, pollution, introduced species, and harvesting, many of which are derived from specific anthropogenic activities, such as urbanization, agriculture, and damming (i.e. fine-scale threats). However, the importance of these threats on the species conservation status in a given region depends on the type of impacts they are exposed to and the susceptibility of species to these impacts. In this study, we used a database of threatened Brazilian freshwater fish species to test whether the major source of threats and the specific anthropogenic impacts to species vary across hydrographic regions and taxonomic groups. Our results showed that habitat loss is a ubiquitous major threat jeopardizing the conservation status of the Brazilian fish species. However, different fine-scale threats mediate this process across hydrographic regions and taxonomic groups. The combination of impacts from agriculture, deforestation, and urbanization affects most of the threatened species in the basins of the Northeast, South, and Southeast, including the species of the most threatened order, the Cyprinodontiformes. Damming is the main human activity affecting threatened species of Siluriformes, Characiformes, Gymnotiformes, and Cichliformes, especially in northern basins (Amazon and Tocantins-Araguaia). Therefore, we found that specific fine-scale threats influencing threatened species vary across hydrographic regions and taxonomic groups, probably due to geographic variability in the incidence of human activities and differential niche requirements and vulnerability of species to these activities.

Sign in / Sign up

Export Citation Format

Share Document