Harikrishnan Mahadevan

A trend on unethical and unsustainable use of resources to meet the high demand in the trade of indigenous ornamental fishes is widespread. This increased exploitation calls for regulation. Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), an apex body having a central role in regulating the trade of any living organisms including indigenous ornamental fishes and preventing the species from being left as extinct. To enlist a species in trade by CITES, formulation of baseline data on its biology, population size, length-weight relations, condition factor, and habitat ecology are necessary. This paper looks into one such consideration on Sahyadria chalakkudiensis inhabiting Western Ghat rivers of Kerala. The length-weight relationships in respect of males and females inhabiting Chalakudy river are expressed as Log W = -3.800 + 2.43 Log L and Log W = -4.333 + 2.69 Log L while the same in males and females inhabiting Pooyamkutty river are Log W = -...

Abstract: Based on the annual length frequency data collected from three major fish landing centres along the River Periyar, draining the southern Western Ghats, the von Bertalanffy growth function (VBGF) estimates of Horobagrus brachysoma were worked out as asymptotic length (L a)= 422mm total length, growth co-efficient (K)= 0.55 yr-1 and growth performance index (ø)= 4.99. The total mortality rate (Z) was estimated at 5.64 yr-1, natural mortality rate (M) at 1.04 yr-1, fishing mortality (F) at 4.60 yr-1, and exploitation rate (E) at ...

Based on the annual length frequency data collected from three major fish landing centres along the River Periyar, draining the southern Western Ghats, the von Bertalanffy growth function (VBGF) estimates of Horobagrus brachysoma were worked out as asymptotic length (La) = 422mm total length, growth co-efficient (K) = 0.55 yr-1 and growth performance index (ø) = 4.99. The total mortality rate (Z) was estimated at 5.64 yr-1, natural mortality rate (M) at 1.04 yr-1, fishing mortality (F) at 4.60 yr-1, and exploitation rate (E) at 0.82 yr-1. Yield per recruit (expected lifetime yield per fish recruited in the stock at a specific age) analysis showed an excessive fishing effort. Using the analysis of probability of capture of each length class, the length at first capture (Lc) of H. brachysoma was estimated to be 110mm. An indication of both growth and recruitment fishing is provided by the dominance of year 1 class in the exploited population and the capture of immature individuals bel...

Four embryonic bigeye thresher sharks Alopias superciliosus (126–158 cm total length) were collected from two females caught by bottom set gillnet and hook and line (operating in 120–800 m depth) caught from off Kanyakumari area and landed in Cochin Fisheries Harbour on 11-06-2012. Detailed morphometric measurements are provided. The ratio of size at birth (L b) and maximum observed length (L max) in this study was 0.36, the largest when compared to earlier reports available till date. The bigeye thresher shark (Alopias superciliosus) is listed as Vulnerable globally because of declining population (IUCN 2007, Amorim et al. 2009). The production of a large neonate at parturition has the advantage of increased survival rate because of enhanced prey capturing and predator escaping abilities.

River Pampa is one of the longest river systems of Kerala. Out of the 60 species of fishes reported from the river, 26 species, belonging to 5 orders and 21 genera contributed to the exploited fishery. The landings were represented by one endangered (Gonoproktopterus curumca), two each vulnerable (Horabagrus branchysoma and Channa diplogramma) and near threatened (NT) fish species (Wallago attu and Ompok bimaculatus). The annual average landings from this river was estimated to be 394.22 t. Highest landings were recorded during pre-monsoon season (194.48 t) and lowest in monsoon (38.97 t). Labeo dussumieri (75.98 t), Puntius sarana subnasutus (39.61 t), W. attu (37.65 t), Channa striatus (36.34 t) and Amblypharyngodon microlepis (34.32 t) were the dominant fishes in the landings. Catla catla (17.28 t) and Clarias gariepinus were the exotic species observed in the landings. Macrobrachium rosenbergii was the most priced species used for export. Among the landing centers, Parumala acco...

Genus Macrobrachium includes freshwater prawns which inhabit most diverse habitats ranging from low saline areas to inland hill streams and impounded water bodies. Being morphologically conserved, this genus has been exposed to severe disputes related to their taxonomy, systematics and phylogeny. Macrobrachium striatum and M. equidens represent two morphologically related congeneric species within this genus. Earlier, M. striatum was considered as a striped form of M. equidens. Though these species are now well-described morphologically and differentiated into two species, no molecular level investigation has been carried out in support of their speciation. We report a study on M. striatum and M. equidens with emphasis to their molecular data through mitochondrial markers (16S ribosomal RNA and cytochrome oxidase subunit I). Results obtained from developed molecular markers of the two species revealed considerable genetic differentiation between them. Phylogram generated using Minim...

ABSTRACT Labidocera madurae A. Scott, 1909, belonging to the family Pontellidae, may easily be mistaken for Labidocera pavo Giesbrecht 1889 or Labidocera bataviae A. Scott, 1909. L. madurae is distinguishable from its congeners by the presence of a moderately large and asymmetrical genital segment, with the middle of the right side considerably inflated and with a short anal segment in females, and a short, curved, thumblike process on the proximal outer margin of the first joint of the right exopodite of the fifth pair of feet, the apical joint of left exopodite elongate and ovate, and twice as long as broad in males. Since Labidocera individuals exhibit close proximity in morphology, there exists the potential for misidentification. Intraspecific distance of L. madurae sequences developed in the present study ranged from 0.2 to 0.9 %, which was adequate to confirm the genetic congruence of the same. This study also supported the differentiation of Labidocera madurae from other individuals of the genus Labidocera. A point of major confusion concerning L. madurae and Labidocera sp. from the Hawaiian region was resolved in this study, as is evident from the molecular inference that L. madurae and Labidocera sp. individuals were the descendants of a common ancestor and close relatives to other individuals within the genus. The present database represents the first molecular data for L. madurae, which will be adaptable for resolving taxonomic ambiguities and inferring phylogenetic relationships of the genus Labidocera.

Genus Glyphocrangon, the only representative of Family Glyphocrangonidae, comprises about 89 species. According to previous records, this species is known to inhabit a depth range of 145-410 fathoms in Bay of Bengal. A thorough scrutiny of literature revealed a detailed morphological description of G. investigatoris and little molecular database. As part of an exploratory research survey conducted in Bay of Bengal, specimens of this species were collected from trawl catches off Paradeep, Orissa. In our present study, an attempt was made to develop its DNA barcode based on mitochondrial Cytochrome oxidase subunit I (mtCOI) and to establish its phylogenetic relationship with other species of genus Glyphocrangon. The developed mtCOI sequences of G. investigatoris exhibited its genetic identity favoring its morphological description.