DNA barcoding of threatened fishes of Bangladesh

The ichthyofaunal diversity of Bangladesh is declining dramatically due to various anthropogenic factors. For authentic identification at species level, approximately 655 bp of the mitochondrial cytochrome c oxidase subunit I (COI) gene of 29 threatened fish species were amplified and a barcode dataset was generated. Among these species, 7% were categorized as Critically Endangered (CR), whereas 55% and 38% were categorized as Endangered (EN) and Vulnerable (VU), respectively. K2P genetic distances were evaluated and found to be increasing with higher taxonomic rank—1.01% to 13.09% within species and 17.42% to 41.57% between species with a DNA barcode gap of 4.33%. The average %GC content of the fish species was 44.7 ± 0.49. On the other hand, the %GC values for the 6 orders—Cypriniformes, Siluriformes, Synbranchiformes, Syngnathiformes, Perciformes and Osteoglossiformes were 44.8 ± 0.81, 45.6 ± 0.61, 44.8 ± 0.85, 47 ± 0.99, 46.3 ± 0.89, 47 ± 0.90, respectively. The %GC content was highest in the first codon followed by the second and third codons for both the individual species and the Orders (1st>2nd>3rd). It was also observed that the most synonymous mutations occur at the 3rd codon position followed by the 1st and the 2nd codons. Finally, genetic variations were identified in Raiamas bola (at position 101), Ompok bimaculatus (at position 396) and Cirrhinus reba (at positions 108, 273, 310, 345, 420, 462, 495, 540 and 591) including 3 incidents of transversion (A instead of C). Thus, two different groups of C. reba emerged in the phylogram. This study, for the first time, focuses on COI based molecular characterization of the threatened fish species of Bangladesh and therefore, might work as a referral study for their authentic identification and in-situ conservation. Bioresearch Commu. 7(2): 990-998, 2021 (June)

Population genetics of three threatened catfish species in heterogeneous environments of the Cauca River, Colombia

ABSTRACT Neotropical catfishes Ageneiosus pardalis, Pimelodus grosskopfii and Sorubim cuspicaudus are migratory fishes of commercial importance that exhibit decreasing populations due to overfishing and other anthropic interventions. This study used species-specific microsatellite loci to test the hypothesis that threatened fish populations show genetic vulnerability signs and are genetically structured in the middle and lower sections of the Cauca River. The studied species exhibit genetic diversity levels higher than the average values reported for Neotropical Siluriformes; however, they seem to have suffered recent bottlenecks and they present significant endogamy levels that are higher for the critically endangered catfish P. grosskopfii. Furthermore, both Ageneiosus pardalis and S. cuspicaudus are each formed by one genetic group, while Pimelodus grosskopfii comprises two coexisting genetic groups. The information obtained in this study is useful for the decision making in management plans that are appropriate for the sustainability of these three species populations within the proposal for the expansion of the hydroelectric development and other anthropic activities.

Study on the Present Status of Endangered Fishes and Productivity of Teesta River Closest to Barrage Region

This study was conducted to monitor the present condition of endangered fishes and productivity of Teesta river closest to Teesta barrage situated in the Lalmonirhat district of Bangladesh. Water and sediment samples were collected twice in a month during the study period from six different (3 upstream and 3 downstream) sites with three replications for each. Required information about threatened fishes was collected from the sampling region associated fishermen and fish markets. The study disclosed over 50 threatened fish species in Teesta river including several threatened fishes namely Bagarius bagarius, Sisor rabdophorus etc. The commonly available endangered fishes were Macrognathus aculiatus, Mastacembelus armatus, Barilius tileo, Raiamas bola, Botia dario, B. lohachata etc. which are rarely available in nationwide. Planktonic flora and fauna determination revealed that comparatively higher density of plankton (n >11500 per liter) as well as more number of planktonic flora (>21 nos.) and fauna (>9 nos.) were monitored in the early monsoon and monsoon season (April-September) and comparatively lower planktonic density (n<10000 per liter) and less number were found in premonsoon season (January-February). The investigation of benthic fauna showed that the riverine ecosystem near to barrage contained 16 species of macro-benthos from different groups. Lastly, it can be noticed that it is very essential to take all effective necessary actions to provide good productivity and conserve the ichthyo diversity of Teesta river that will help to conserve the commonly available endangered and critically endangered fishes of Teesta river. Res. Agric., Livest. Fish.7(3): 577-589, December 2020

Sensitive species in a bad habitat – species richness of ichthyofauna in the strongly anthropogenically transformed Uszwica River (southern Poland)

The Uszwica River is a 67 km long right-bank submountain tributary of the Vistula. From the beginning of the 20th century the Uszwica was subjected to strong anthropopressure. The water course was disrupted at km 37 + 300 with a 5.3-meter-high dam in the town of Brzesko. Strong pollution of water in this town and numerous hydrotechnical alterations along almost the entire course of the river have negative influence on the river habitats. Despite this, the Uszwica is characterized by relatively rich ichthyofauna composed of 26 species, including 6 species which are legally protected in Poland and 7 species regarded threatened according to the Polish Red List of fish and lampreys [1]. The composition of ichthyofauna was determined on the basis of electrofishing along the entire river in 2004 and 2015, and on selected reaches in 2014 and 2018. The results show that even heavily anthropogenically transformed rivers may provide habitats for threatened fish species and should not be excluded from nature protection plans and projects.

Over 90 endangered fish and invertebrates are caught in industrial fisheries

Industrial-scale harvest of species at risk of extinction is controversial and usually highly regulated on land and for charismatic marine animals (e.g. whales). In contrast, threatened marine fish species can be legally caught in industrial fisheries. To determine the magnitude and extent of this problem, we analyze global fisheries catch and import data and find reported catch records of 91 globally threatened species. Thirteen of the species are traded internationally and predominantly consumed in European nations. Targeted industrial fishing for 73 of the threatened species accounts for nearly all (99%) of the threatened species catch volume and value. Our results are a conservative estimate of threatened species catch and trade because we only consider species-level data, excluding group records such as ‘sharks and rays.’ Given the development of new fisheries monitoring technologies and the current push for stronger international mechanisms for biodiversity management, industrial fishing of threatened fish and invertebrates should no longer be neglected in conservation and sustainability commitments.