Molecular evidence indicates the existence of multiple lineages of Sperata species in Indian Rivers

Sperata seenghala (Giant river-catfish) and Sperata aor (Long-whiskered catfish) are commercially important freshwater catfishes of India, belongs to family Bagridae. Due to high nutritional significance and the low number of intramuscular bones, both fishes have considerable demand in South Asian countries. Both of the Sperata species are morphologically close and well adapted to the same habitat. In this study, we have assessed the level of genetic diversity and differentiation of S. seenghala and S. aor in the Ganga River based on the mitochondrial DNA (mtDNA) control region and compared with the other major Indian rivers. We found high haplotypes diversity for both the species in the Ganga. However, it was comparatively low for S. seenghala in Mahanadi and Brahmaputra populations. The phylogenetic and median-joining network strongly indicated the presence of two distinct maternal lineages of S. seenghala from the Ganga river. Interestingly, the genetic differentiation between S. seenghala of Ganga-Brahmaputra was much higher (~25.3%) than the S. seenghala and S. aor (~17%), whereas it was comparatively low between Ganges-Mahanadi (~8.0%). Our finding provided evidence that all the three rivers: Ganga, Mahanadi, and the Brahmaputra sustain a highly diverse and genetically distinct stock of giant river catfish; therefore, all populations should be considered as a different management unit for the protection of stocks. Our findings indicated that Brahmaputra lineages qualify the species level variations. This study can be further used as a reference database for proper lineage identification of S. seenghala and S. aor that could formulate the appropriate conservation and management plans.

LENGTH-WEIGHT RELATIONSHIPS OF EIGHTEEN SPECIES OF FRESHWATER FISHES FROM PANCHET RESERVOIR IN GANGES BASIN, JHARKHAND, INDIA

The present study describes the length-weight relationships (LWRs) of 18 fish species from a large tropical reservoir, Panchet, in the Damodar River basin, one of the main tributary of the largest river Ganga in India. A total of 2419 individuals represented by 18 species belonging to 9 families were sampled between November 2014 and June 2016. The b values ranged from 2.469 for Trichogaster chuna to 3.428 for Ailia coila. All the regressions were highly significant (p<0.001). The results revealed positive allometric growth for seven species (b>3, p<0.05), negative allometric growth for seven species (b<3, p<0.05) and isometric growth for four species (b=3, p>0.05). This study represents the first reference on the length-weight relationship of Trichogaster chuna from a reservoir ecosystem. This is the first report on LWRs of five fish species viz., Puntius terio, Pethia conchonius, Sperata seenghala, Ailia coila and Trichogaster chuna from an Indian reservoir. This study provides basic data for future stock assessment studies and management programmes from Panchet Reservoir as well as for complementing the comparisons of LWRs from other ecosystems.

Genetic characterization and phylogenetic study of Indonesian indigenous catfish based on mitochondrial cytochrome B gene

Aim: This study aimed to determine the genetic characterization and phylogenetic structure of Indonesian indigenous catfish using cytochrome B (Cyt B) sequences. Materials and Methods: The genomes of 26 catfishes caught from nine rivers from nine different geographical locations around Indonesia were analyzed. The tissue isolation method was used to isolate the total genome of the fishes. Furthermore, polymerase chain reaction was done to amplify the mtDNA Cyt B using the CytBF and CytBR primers. Following sequencing, the analysis of genetic variation and the phylogenetic relationship was performed using MEGA version X software. Results: Cyt B gene sequencing attained a total of 1139 nucleotides encrypting 379 amino acids for all samples. The ClustalW alignment program using MEGA X software revealed 395 substituted nucleotides, which then translated into 63 amino acid variation sites among all 26 samples. No amino acids in catfish BB were different compared to catfish PM, MP, and KR2,3. Catfish MS had one modified amino acid; KR1 and KS had two different amino acids; BF had 38 different amino acids; EM had 31 different amino acids; and BSBJ had 26 different amino acids compared to catfish BB. The most significant alteration of amino acids was between catfish EM and BF (49 amino acids). Conclusion: Indonesian catfish were divided into five clades based on the Cyt B gene. Samples KR and MP (Sumatra); MS and BB (Kalimantan); and PM (Java) were clustered with Hemibagrus nemurus and Hemibagrus wyckioides (Bagridae family). Samples from Kalimantan (KS) and one sample of KR (KR1) from Sumatra were clustered with Sperata seenghala and Hemibagrus spilopterus (Bagridae family). Samples from Java (BSBJ) were clustered with Pseudolais pleurotaenia (Pangasiidae family). Samples EM (Java) were together with Mystus cavasius (Bagridae family). Samples from West Papua were clustered with Potamosilurus latirostris (Ariidae family).

Population genetics of Indian giant river-catfish, Sperata seenghala (Sykes, 1839) using microsatellite markers

The giant river-catfish Sperata seenghala is one of the commercially important freshwater catfishes of India with wide distribution in all major rivers and reservoirs. This fish has huge demand in domestic market due to high nutritional value and low number of intramuscular bones. Conversely, the culture practices for this fish have not yet been standardized and capture fisheries is the only source to meet the demand. This may lead to over exploitation of resources and subsequent population reduction. Knowledge on genetic structure of populations is prerequisite to formulate sustainable management and conservation measures. In the present study, 15 microsatellites were used to characterize population genetics of S. seenghala collected from river Brahmaputra, Ganga, Godavari, Mahanadi and Narmada. Locus-wise, the number of alleles varied from 8 to 19 with an average of 12 alleles per locus. The mean observed and expected heterozygosity values varied from 0.622 to 0.699 and 0.733 to 0.774, respectively. Several loci have shown deviation from Hardy–Weinberg equilibrium and no significant linkage disequilibrium between pairs of loci was detected. Pair-wise FST values between populations ranged from 0.135 (Brahmaputra–Ganga) to 0.173 (Brahmaputra–Narmada) and confirmed the moderate to high genetic differentiation among the populations. AMOVA, Structure and Principal Co-ordinate analyses showed significant genetic differentiation among the sampled populations of S. seenghala. A total of 65 private alleles were recorded across populations. This study confirmed the distinctiveness of each population of S. seenghala from five major rivers of India. These populations could be treated as distinct management units (MUs) for assessment and management purpose.

Risking lives for living: a study on underwater fishing in the Padma River, Bangladesh

A variety of methods and gears are being employed across the globe including Bangladesh. This study describes the underwater fishing method in the Padma River- one of the three largest rivers in Bangladesh. Standardised efforts have been made for collecting data of interest between September 2016 and May 2017. Two types of underwater fishing, with or without using oxygen cylinders, were recorded. Mean duration of fishing per effort was higher (by 382%) when fishermen used oxygen cylinders. Mean water depth of fishing sites was also higher when oxygen cylinders were used. Three species of finfish (Rita rita, Sperata seenghala and Labeo calbasu) and one freshwater prawn species (Macrobrachium dayanum) have been identified in the catch. The catch was dominated by M. dayanum in both fishing types (27 ± 9.3 [with oxygen] and 15 ± 5.2 [without oxygen]). However, all the number of caught fish species varied significantly among different sampling months in both fishing methods (P < 0.001) except L. calbasu in fishing with oxygen cylinder. A number of health issues of the fishermen were also recorded.

Morphological variation in an anopthalmic specimen of Sperata seenghala (Sykes, 1839) from Brahmaputra River, Assam, India

The present investigation reports the variation observed in morphological traits of an anopthalmic specimen of Sperata seenghala (Sykes, 1839) (168.9 mm in standard length) from Assam. Thirty morphometric and six meristic characters of the abnormal specimen were studied and compared with normal specimens to observe variation in the morpho-meristic traits, if any. The proportionate pre-pectoral length (28.5 mm), length of dorsal fin base (15.0 mm), pelvic fin length (15.5 mm), distance between urino-genital openings and anal fin base (14.0 mm) and body depth at pectoral fin base (12.0 mm) of the abnormal specimen was found to be higher compared to that of the normal specimens (23.8 – 26.5 mm; 12.2 – 14.1 mm; 11.1 – 14.7 mm; 10.9 – 12.4 mm and 8.9 – 9.9 mm, respectively); while the dorsal to adiposedistance (12.8 mm) and body width at cleithrum (41.5 mm) was lower than the normal specimens (13.7 – 16.7 mm and 44.0 – 50.0 mm, respectively). No marked variation was observed in the meristic characters. Pollution due to urban runoff, sewage discharge and oil spill from inland water transport facilities adversely affecting the river water quality could be the reason for such deformity. The overall growth performance of the fish does not seem to be affected by these anomalies.