Due to growing population pressure, rapid economic growth and industrialization, there is an immense pressure on biodiversity and ecosystem services with the consequences of destruction, fragmentation, overexploitation of the natural habitats; shrinking genetic diversity; invasion of alien species…
Himanshi Shukla
India is one of the 12 mega diverse countries that account for approximately 8% of the total global biodiversity in the world. It is estimated that 70% of the Indian population is directly dependent on the biodiversity for livelihood and socio-economic growth and sustainable development, as per statistics from the National Biodiversity Authority. However, due to growing population pressure, rapid economic growth and industrialization, there is an immense pressure on biodiversity and ecosystem services with the consequences of destruction, fragmentation, overexploitation of the natural habitats; shrinking genetic diversity; invasion of alien species. The 2017-18 annual report from the National Biodiversity Authority duly recognises these factors, yet little is done to prevent threat to species that contribute to the biodiversity pool of India.
Take for instance, the newly discovered Dawkinsia Filament Barbs from the Western Ghats. Or the Trimeresurus salazar, a snake species discovered from the Arunachal Pradesh’s Pakke Tiger Reserve. Both the Western Ghats and the Indo-Burma Region (Arunachal Pradesh falls in the region of Indo-Burma) are declared to be biodiversity hotspots by the Conservation International. While they are home to richest biodiversity hotspots, yet they are the most threatened as well. The very fact that the most important species discoveries are being made in these hotspots remain a living testimony to this. The aforementioned threats hang like the Damocles sword over them.
What are Dawkinsia Filament Barbs and why is their discovery important?
Dr Unmesh Katwate, Scientist B, Bombay Natural History Society (BNHS), Mumbai, has led the recent discovery along with Dr Rajeev Raghavan, Assistant Professor, Department of Fisheries Resource Management, KUFOS and Dr Neelesh Dahanukar, Assistant Professor,
Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Delhi NCR. New research employing an integrative approach of evidence gathering using morphological and genetic analysis has resulted in the discovery of this new species from rivers of Ratnagiri and Sindhudurg districts of Maharashtra. The new species is named as Dawkinsia uttara, honouring Uttara Katwate, mother of the Dr Unmesh Katwate. The species name also epitomize the distribution of this species in northern part of the Western Ghats, and hence, the common name of ‘Northern Filament Barb’.
The scientific paper describing Dawkinsia uttara has been published in the international journal – Vertebrate Zoology, published from the Senckenberg Museum in Germany. This new species is currently known only from the upstream regions of the Kajali, Terekhol and Jagabudi rivers of the Ratnagiri and Sindhudurg districts of Maharashtra. Commenting on the importance of Filament Barbs, Dr Unmesh Katwate told TreeTake: “Filament barbs of genus Dawkinsia, endemic to peninsular India and Sri Lanka, are known for their stunningly beautiful colour patterns and a unique character of having filamentous extensions of the dorsal fin rays in mature males. They are like an aquatic version of pheasants in rivers of the Western Ghats. These medium-sized (80–120 mm standard length, SL) freshwater species are among the world’s most popular aquarium fishes. Owing to their stunning coloration, they share important place in the global ornamental-fish trade. Being some of the most common cyprinid fishes inhabiting the rivers, floodplains, brackish water lakes and reservoirs of peninsular India, they also form the basis of an important local fishery, particularly in the coastal wetlands and west-flowing rivers of Kerala.”
“Filament barbs are poorly known in terms of their species diversity and distribution. In previous studies on this group of fish carried out by Dr Rohan Pethiyagoda, one of Asia’s foremost ichthyologists and his team, suggested this group has comprises several undescribed species, which are unknown to science. To address these knowledge gaps and understand the true diversity, we carried out an extensive study across the west- and east-flowing rivers of the Western Ghats, from north of Mumbai to the southern tip peninsular India, exploring all possible habitats. The new knowledge generated on species diversity and distribution can help us in delineating important freshwater key biodiversity areas, and help prioritise conservation initiatives for Western Ghats freshwater biodiversity,” he added about the importance of the discovery.
Dr Neelesh Dhanukar told TreeTake: “Despite the more than 200 years of ichthyological surveys in Western Ghats, our knowledge about the fish diversity and distribution is highly limited. Further, the newer methods based on molecular analysis are providing fresh insights into the evolution, ecology, diversity and distribution of fishes. Our integrative taxonomic approach, which includes both morphological and molecular analysis, suggests that there are several new species of freshwater fishes in the Western Ghats of India that are hiding from the plain sight. When we applied the approach to filament barbs, we got new insights into the diversity and distribution of these fishes and this led to description of three new species of filamentous barbs from Western Ghats. Discovery of three new species highlights limitations in our understanding of fish diversity of this region. Understanding diversity is the first step towards its conservation so this study can help in understanding conservation status of organisms and designing and implementing conservation action plans.”
2. What are the threats faced by Filament Barbs and other such endemic species in Western Ghats in India?
Dr Neelesh Dhaunkar told TreeTake: “Various threats are affecting the populations of Filament Barbs in the Western Ghats of India. First, Since the various species in Dawkinsia have beautiful coloration, they are famous in the aquarium trade. Unfortunately, most individuals are caught from the wild for aquarium trade. It is for this reason, fish collection for aquarium trade is a threat to the species. It is essential to note that there are some species of Dawkinsia that are highly restricted in their distribution and if their population is continuously exploited for aquarium trade, such exploitation will be unsustainable. Secondly, some species of the fish grow quite big and are often found in local fish markets for consumption. Although quantitative data are not available, studies in the Western Ghats have shown that such exploitation even at subsistence level can become unsustainable. Third, habitats of several species of Dawkinsia are threatened by modifications due to organic and inorganic pollution, habitat modification, sand mining, and other anthropogenic activities. Another major threat to the populations of Dawkinsia are the introduction of exotic species such as Tilapia (Oreochromis mossambicus), African catfish (Clarias gariepinus), etc. that compete for the resources and can also actively decrease the populations through predation.”
Dr Unmesh Katwate told TreeTake: “Freshwater fishes of the Western Ghats, including filament barbs are highly threatened because of habitat degradation and modification. Multiple anthropogenic stresses contribute to habitat degradation such as pollution, deforestation, mining, dynamite fishing and the construction of irrigation and hydroelectric dams which has profoundly altered the aquatic ecology and river hydrology upstream and downstream. Overfishing is also a problem in several coastal rivers of Karnataka and Kerala. Furthermore, spread of alien invasive species poses a big problem to native fish fauna through resource competition. Unmanaged and illegal exploitation of wild fish to meet the heavy demand of filament barbs in global aquarium trade pose a big threat to endemic species which are restricted to not more than one or two river systems.”
Exploitation at the behest of Aquarium Hobbyists
Commenting on the exploitation faced by the species at the behest of Aquarium Hobbyists, Dr Neelesh Dhanukar told TreeTake: “Quantitative data are not available, however, species of Dawkinsia are sold in aquarium markets where they fetch good price. Since the organisms are caught from wild, aquarium trade can adversely affect wild populations due to unsustainable harvest. In the paper published in biological conservation in 2013 we suggested that at least two threatened species of Dawkinsia, namely Dawkinsia arulius and Dawkinsia rohani were exported during 2005–2012 for aquarium trade. This is in addition to other species of Dawkinsia for which the threat statuses are not known.”
Dr Unmesh Katwate commented: “Most importantly species such as Apsara Barb Dawkinsia apsara, Assimilis Barb D. assimilis, Exclamatio Barb D. exclamatio, Rohani Barb D. rohani, Tambraparni Barb D. tambraparniei and almost all other species of filament barbs have a high demand in the international aquarium trade, as they are among the world’s most beautiful tropical fish. The growing demand of Filament barbs in hobby and ultimately in the international aquarium trade, is worrisome. Almost all fish in the trade currently originates from the wild threatening several local populations. Attempts need to be made to develop captive breeding and mass scale seed production technology to ease pressure on wild collection for the pet trade. Since, so far, there is not much information available on population trends and biology of these species, there is a need to generate baseline data on its life history and demography, which can aid in managing wild collection and captive breeding practices. Furthermore, following “The Wild Life (Protection) Amendment Bill, 2021” a bill recently introduced in the Parliament to further amend the Wild Life (Protection) Act, 1972, it is now illegal to transport any threatened and endemic/native fish species outside India, following the Biological Diversity Act, 2002 and regulation of international trade in endangered species of wild fauna and flora as per CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) treaty, unless, and until it is approved.”
What steps can be taken for the protection of Endemic Dawkinsia species?
Dr Unmesh Katwate commented: “When it comes to implementation of freshwater conservation policies, it is always a tricky job in India. Freshwater ecosystems are governed by multiple stakeholders, ministries, state departments and investors - these include the Ministry of Environment, Forest and Climate Change, Ministry of Fisheries, Animal Husbandry & Dairying, Ministry of Power, Ministry of New and Renewable Energy, irrigation departments of different states, fisheries and forest departments, fishing communities and national and international investors. Our future policies should support research and management that enhance the interactions between these different stakeholders and ecological integrity for freshwater biodiversity conservation. For better policies, we need a better and a common pathway to improve communication between all stakeholders. We also need to see how better our riverine conservation policies can cope up with growing anthropogenic pressure, as it is always going to be a quite complicated multi-aspect problem in developing countries, especially in the world’s most populous biodiversity hotspot such as the Western Ghats. Specifically talking about Filaments barbs of the Western Ghats, since they are more vulnerable to over-exploitation as a result of the aquarium trade, we need better investment towards capacity building for captive breeding programs. Such ornamental fish breeding and ranching units can ease the trade pressure on wild stock. Since the 2021 amendments in Wild Life (Protection) Act, 1972 is currently being proposed state forest departments must also think about on ground policies which can curb an illegal trade and transport of native and endangered fishes outside India, including that of filament barbs.” In this connection, Dr Neelesh Dhanukar commented: “There needs to be some check on the collection of Dawkinsia from the wild. Captive breeding technology can be developed for some species for aquarium trade. For species that are highly restricted in distribution, there is a need to do site area protection. There is also a need to keep the freshwater ecosystems healthy by proper waste management and avoiding runoffs from urban and rural areas, industries and agricultural lands. There is also need for exotic species management.”
Not the only case
Unfortunately, Dawkinsia is not the only species that faces threat. The same fate is shared by the Trimeresurus salazar that was discovered by Harshal Bhosale, Scientist at Bombay Natural History Society, Zeeshan A. Mirza from National Centre for Biological Sciences and others. Interestingly, the snake has been named after Salazar Slytherin, a fictional character from the fan favourite Harry Potter series. “The new species belongs to the group of green pit vipers from which it differs from its closely related species in bearing a rusty red or orange lateral stripe along the head and the entire body. Comparison of DNA sequences and skull morphology of closely related species highlight the distinctness of the new species,” Harshal Bhosale told TreeTake.
While the authors are happy about discovering a new species of pit viper but worried at the same time. The proposed 49-km Seijosa-Balukpong road will cut through the habitat of the new species, that is, through the Pakke Tiger Reserve. Roads take a heavy toll on wildlife and data from various studies have highlighted high mortality of snakes due to vehicular movement. The 49-km Seijosa-Balukpong road has been designed as an elevated corridor near the border of Arunachal Pradesh with Assam. If built, it will destroy at least 160 hectares of forest land and fracture a continuous jungle corridor between Pakke and the Nameri Tiger reserve in Assam, an important tiger and elephant passage in the region. The Seijosa-Balukpong road constitutes phase I of an ambitious East-West Industrial Corridor (EWIC), a 539-km double-lane state highway planned between Pasighat in central Arunachal Pradesh to Bhairabkund in the west. When faced with backlash from environmentalists, Arunachal Pradesh state forest and environment department withdrew the permission it had given to the PWD highway on 7 April, 2021 “for survey and investigation within the Pakke Tiger Reserve (PTR) for preparation of detailed project report (DPR) of proposed East-West Industrial Corridor (EWIC) road.” Still, uncertainties remain as the entire project has still not been called off. Forests across northeast India have not been well-explored for their biodiversity, especially reptiles, amphibians and most invertebrate groups, the authors state that “anthropogenic pressures like road widening, construction of dams and hydropower plants threaten the forest and biodiversity across Arunachal Pradesh”.
Suggestions and way forward
Dr Unmesh Katwate concluded with regards the Filament Barbs: “Even after coming up with a brief revision of Filament barb, I still think, quite affirmatively that these group of endemic fish are still least studied and least understood in terms of extant diversity, distribution and biology. To further explore the diversity and distribution of filament barbs we need more such taxonomic sampling, surveys and studies throughout the east- and west-flowing rivers of Western Ghats and parts of Eastern Ghats. I would also like to mention, many of newly described (4 in the current study) and resurrected species of filament barbs and other fish species in Western Ghats are not yet evaluated for the IUCN Red List of threatened species. Because global conservation status informs and catalyse the actions for biodiversity conservation and policy change, critical to protecting the natural resources, there is an urgent need to address this knowledge gap through systematic assessment of conservation status of the filament barbs and other endemic fish species.”
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