[Show abstract][Hide abstract] ABSTRACT: Puntius) endemic to the Western Ghats Hotspot of India, are popular and highly priced freshwater aquarium fishes. Two decades of indiscriminate exploitation for the pet trade, restricted range, fragmented populations and continuing decline in quality of habitats has resulted in their 'Endangered' listing. Here, we tested whether the isolated RLTB populations demonstrated considerable variation qualifying to be considered as distinct conservation targets. Multivariate morphometric analysis using 24 size-adjusted characters delineated all allopatric populations. Similarly, the species-tree highlighted a phylogeny with 12 distinct RLTB lineages corresponding to each of the different riverine populations. However, coalescence-based methods using mitochondrial DNA markers identified only eight evolutionarily distinct lineages. Divergence time analysis points to recent separation of the populations, owing to the geographical isolation, more than 5 million years ago, after the lineages were split into two ancestral stocks in the Paleocene, on north and south of a major geographical gap in the Western Ghats. Our results revealing the existence of eight evolutionarily distinct RLTB lineages calls for the re-determination of conservation targets for these cryptic and endangered taxa.
[Show abstract][Hide abstract] ABSTRACT: The Malabar snakehead Channa diplogramma is one of the most enigmatic and least understood species within the family Channidae, which comprise one of the most important groups of freshwater food fish in tropical Asia. Since its description from peninsular India in 1865, it has remained a taxonomic puzzle with many researchers questioning its validity, based on its striking similarity with the South East Asian C. micropeltes. In this study, we assessed the identity of the Malabar snakehead, C. diplogramma, using morphological and molecular genetic analyses, and also evaluated its phylogenetic relationships and evolutionary biogeography.
The morphometric and meristic analysis provided conclusive evidence to separate C. diplogramma and C. micropeltes as two distinct species. Number of caudal fin rays, lateral line scales, scales below lateral line; total vertebrae, pre-anal length and body depth were the most prominent characters that can be used to differentiate both the species. Channa diplogramma also shows several ontogenic color phases during its life history, which is shared with C. micropeltes. Finally, the genetic distance between both species for the partial mitochondrial 16S rRNA and COI sequences is also well above the intra-specific genetic distances of any other channid species compared in this study.
The current distribution of C. diplogramma and C. micropeltes is best explained by vicariance. The significant variation in the key taxonomic characters and the results of the molecular marker analysis points towards an allopatric speciation event or vicariant divergence from a common ancestor, which molecular data suggests to have occurred as early as 21.76 million years ago. The resurrection of C. diplogramma from the synonymy of C. micropeltes has hence been confirmed 146 years after its initial description and 134 years after it was synonymised, establishing it is an endemic species of peninsular India and prioritizing its conservation value.
[Show abstract][Hide abstract] ABSTRACT: The diet composition of fingerlings and adults of Horabagrus brachysoma, a threatened, freshwater catfish, endemic to South India, collected from the Periyar River of Kerala in south India was studied using standard methods. The results of the stomach content analysis revealed that the species is an omnivore, predominantly feeding on animal matter in the young stage and plant matter in the adult stage. Based on the findings of the present study, it can be concluded that H. brachysoma collected from Periyar River is a benthophagic omnivore and that adults prefer dietary fractions of plant origin over animal tissues. An ontogenic diet shift from carnivorous to more pronounced omnivorous nature is exhibited by the fish. The fish is adapted for a wide spectrum of feeding habits including the ability to digest all major types of nutrients and these findings will help to formulate a more economically viable and nutritionally balanced diet for the artificial rearing of this cultivable catfish.
No preview · Article · Jan 2009 · Fish Physiology and Biochemistry
[Show abstract][Hide abstract] ABSTRACT: Damsel in distress'-The tale of Miss Kerala, Puntius denisonii (Day), an endemic and endangered cyprinid of the Western Ghats biodiversity hotspot (South India) ABSTRACT 1. Denison's Barb, Puntius denisonii (Day) is an endemic and endangered cyprinid fish of the Western Ghats biodiversity hotspot in peninsular India, which is the focus of an organized yet undocumented fishery targeting juveniles for the international aquarium trade. 2. Research on P. denisonii has been very limited and there has been no systematic effort to assess and monitor their abundance, distribution and populations. 3. Anecdotal and circumstantial evidence indicates a highly restricted distribution, low abundance, declining populations, low catch per unit effort and increasing market prices, providing evidence of an impending conservation crisis and the need for urgent management of wild stocks. 4. This paper reviews current knowledge, provides results from the authors' field study and suggests priorities for conservation and management actions for P. denisonii in the streams of Kerala.
No preview · Article · Jan 2009 · Aquatic Conservation Marine and Freshwater Ecosystems
[Show abstract][Hide abstract] ABSTRACT: Common names: Gunther’s catfish, Yellow catfish. Vernacular: Manjeletta, Manjakoori. Conservation status: Endangered (Molur & Walker 2001). Identification: Described by Gunther (1864) as Pseudobagrus brachysoma placed into Horabagrus (Jayaram 1955). The only other species in the genus is Horabagrus nigricollaris. This species has a moderately elongated, compressed body with a large head and a wide sub-terminal mouth. Eyes are large, inferior, and visible in ventral profile. Dorsal with 5 – 7 rays and a large anterior spine; Pectoral fins with 8 – 9 rays and a large anterior spine serrated along its posterior edge with large antrorse teeth; adipose separated from dorsal fin by a broad gap; pelvic fins with six rays; anal fin long, 23 – 29 rays. Four pairs of barbels; 1 nasal 2 mandibular and 1 maxillary. Caudal fin forked or deeply emarginated. Lateral line complete and simple. Key character: A black ocellus extending from the humeral region of each side over the nape, bordered by light yellow ring. Distribution: Restricted to rivers (and occasionally lakes) in the southern region of the Indian subcontinent. Known from the Chalakudy, Periyar, Meenachil, Manimala, Pampa, Moovatupuzha, Achenkovil rivers and Vembanad Lake in the State of Kerala and Aghanashini and Kali rivers of Karnataka State. Abundance: Previously abundant in the rivers of Kerala, but have declined precipitously (60 – 70%) during the last few years (Molur & Walker 2001). Habitat and ecology: Benthic, primarily occupying lowland areas of rivers and backwaters with mud and sand substrate, but has also been recorded from the deep pools in hill streams. They are seen in high abundance at the beginning of southwest monsoon (June–August) and subsequently occur in lower profusion after the monsoon season. Reproduction: Spawning occurs during the pre-monsoon months and finishes by the southwest monsoon. Size at sexual maturity of the female fish is 21.5 cm and the fecundity varied between 1500 and 21,184 (Kurian & Inasu 2003). Threats: H. brachysoma is imperiled by the alteration of riverine habitats, aquatic pollution, and exploitation for food and ornamental purposes. Conservation action: National Bureau of Fish Genetic Resources and Regional Agricultural Research Station of the Kerala Agricultural University have conducted experimental trials on captive breeding of this species. The Kerala State Council for Science, Technology and Environment has granted a major research project to the Department of Zoology, University of Kerala to study the life history traits, captive breeding and culture of H. brachysoma. Conservation recommendations: Suitable sanctuaries for this species should be created in selected areas of the rivers. Surveys to determine the current status of wild populations are of highest priority. Since H. brachysoma is one of the most important food and ornamental species exploited in the inland waters of Kerala, this yellow catfish embodies the problems that must be resolved for sustainable management of the riverine fishery of this region. The species could be hence considered as a potential ‘‘flagship species’’, which can be used to increase the environmental profile of inland biodiversity, facilitate proper media attention and provide a focus for conservation action (Prasad et al. 2005). Remarks: H. brachysoma has aquaculture potential in both the food and ornamental trades. It is already established on the international market as a highly desired ornamental fish.
No preview · Article · Feb 2007 · Environmental Biology of Fishes
[Show abstract][Hide abstract] ABSTRACT: Streams and rivers in the Kerala part of the Western Ghats are an exceptional hotspot of freshwater fish diversity 1 , having an immensely rich and diverse ichthyo-fauna of around 207 species 2 , including food, ornamental and sport fishes 3 . Among these, the native ornamental fishes form the most important component of the regio-nal biodiversity from an eco-biological and socio-economic perspective. The ornamental fish fauna of Kerala is contributed by 106 species 4 . Among these, no single species has received at-tention as much as the red-lined torpedo fish, Puntius denisonii Day, an endemic and endangered cyprinid 5 . Locally known as 'chorakanni', literally meaning bleed-ing eyes, and more popular as 'Miss Kerala', this native barb has become one of India's biggest exports in recent times 6 . Market studies have confirmed that P. denisonii is the most preferred ornamen-tal fish in the international trade and is being exported from India in consistent numbers 7 . The species was collected for the first time in 1996 and sent to Ger-many, and has been a regular among the native ornamental fishes exported from Kerala since then. The opening up of the Cochin International Airport in 1999 probably stimulated an increased trade, as the region became connected to Sin-gapore (the single largest market for na-tive ornamental fishes from Kerala) by daily flights. An alarming yet predictable increase in the export of P. denisonii, and an as-sociated decline in its wild population have been witnessed in recent years. Re-ports 8 have suggested that the wild stock of the species has dwindled at a rate of 70% during the period 2000–04. The catch per hour for P. denisonii in the various rivers of Kerala was found to be low, ranging from 0.002 to 0.042, proba-bly indicative of the extreme fishing pressure that the species is being sub-jected to 9 , resulting in its low abundance. Although there are no direct measures of the population status of the Denison's barb till date, there exists a general con-sensus among scientists and researchers in the region that the fish has become rare 2,4,9 and its population has declined precipitously. The fact that wild stocks have declined and the species has become scarce in the trade can also be confirmed by the sharp increase in its market price over the last few years. Saturation in market supply due to decline in catches has probably resulted in an increase in retail prices for this species from US$ 8 per piece at the start of the decade 10 to the current value 6,11 of US$ 20–30. This gradual in-crease in price witnessed over the last few years, has certainly driven the flow of more catches from the wild, turning the stock position into a downward spiral. Given the nature of marketing involv-ing various stakeholders like collectors (locals belonging to tribes and forest communities who survive on subsistence level), intermediaries, wholesalers and exporters, engaged in what can be descri-bed as a clandestine and surreptitious trade, it has been extremely difficult to track and precisely quantify the trade in P. denisonii. A large share of the exports is also channelled through non-conventional routes and is seldom documented and re-corded. Although P. denisonii is known to be found in as many as nine rivers in Kerala, its distribution is restricted to certain specific locales of these rivers and most stocks are known to be highly frag-mented. Pooyamkutty (Periyar River), Vettilapara (Chalakudy River) and Iritty (Valapatanam River) are the epicentres of mass-scale collection of this species in view of the comparatively large popula-tions that these locales sustain. However, as wild stocks in these sites are declin-ing, supply sources are changing and col-lectors are moving onto new locales for exploitation. Despite being the most celebrated and perhaps the most threatened native fish species, P. denisonii has not been well documented in the literature. Lack of any data on this species is also evident from Fishbase – the world's largest encyclo-paedia on fishes. Our current knowledge of the biology of the species is princi-pally in the form of grey literature, indi-cating that the species is herbivore and that its spawning season corresponds with the regional monsoon 12 . To the best of our knowledge, the only available peer-reviewed publication is on the length– weight relationship of this species from the Bharatapuzha River 13 . Even though captive breeding techno-logy has been standardized for thirteen native ornamental species of Kerala 14 , no breakthrough has yet been achieved with P. denisonii. High rates of female morta-lity and a skewed sex ratio favouring males are the major factors that have hampered the closing of its life cycle in captivity 8 . We believe that P. denisonii presents the most complex challenge to conserva-tion biologists of the Western Ghats in recent times. First, because the entire volume of exports for the last ten years (and also in the foreseeable future) has been based on collections from the streams of Kerala and subsequently by the fact that no scientific data are avail-able on aspects of its population, fishery or life history. The organized fishery for P. denisonii in the streams of the Kerala part of the Western Ghats is a 'boom and bust fish-ery' 15 , where a newly discovered popula-tion is being rapidly exploited for trade, resulting in its eventual collapse. In an open-access fishery devoid of any quotas or access restrictions, the race to exploit and market the product has no doubt led to a rapid collapse of the wild stock. In spite of being the focus of a flourishing trade, it is highly disappointing that the species has received rather poor attention from the concerned government authorities and conservationists. Additional worry is due to the fact that the government agen-cies are actively promoting the marketing and export of this fish without focusing on their resource characteristics. An urgent consideration is therefore needed from scientists, policy makers and relevant government agencies to take up the cause of this species, conduct baseline studies