Assessing the sustainability of subsistence fisheries of small indigenous fish species: fishing mortality and exploitation of hill stream loaches in India

Abstract

Small, least conspicuous fish species are targeted through subsistence fisheries in many regions of the world, but little is known about their population dynamics or exploitation levels. In the Western Ghats of India, part of a global biodiversity hotspot and an exceptional region of freshwater fish diversity and endemism, several small species of loaches are caught and sold in the local markets by marginalized communities through an unmanaged fishery, resulting in high levels of exploitation. Of particular concern is the fishery for the spiny loach, Lepidocephalichthys thermalis whose exploitation rates at various sites in the northern part of the Western Ghats region were observed to be greater than their E 50 (exploitation rate where the stock is reduced to half its virgin biomass). A comparison of various fishing sites showed that populations in the high anthropogenic impact areas (located close to urban settlements with high human population density, and impacted by various threats, i.e. introduced species, pollution) are exploited at a rate greater than 86% of their E max (exploitation producing maximum yield). The first quantitative information on population dynamics and exploitation levels of small indigenous fish species in tropical rivers indicates their potential vulnerability to over fishing, and is an important starting point for further investigations into similar fisheries in other regions of Asia and Africa.

Contracaecum nematode parasites in hillstream loaches of the Western Ghats, India

“…In Maharashtra, where we discovered Contracaecum parasites and their third‐stage larvae, loaches are caught and sold in local markets, as well as consumed by members of the tribal community called Katkari (Keskar et al, 2017). The cooking method, which involves use of complete fish without degutting, might also include only partial cooking due to limited resources available to the tribal community.…”

“…One unit of SOD represents the enzyme required for 50% reduction in absorbance at 560 nm mg −1 protein, one unit of CAT represents mM H 2 O 2 decomposed mg −1 protein min −1 , one unit of POX represents μM tetraguaiacol formed mg −1 protein min −1 and one unit of GST represents μM S-(2,4-dinitrophenyl) glutathione formed mg −1 protein min −1 . Lipid peroxidation levels are represented as malondialdehyde (MDA) content mg −1 proteinIn Maharashtra, where we discovered Contracaecum parasites and their third-stage larvae, loaches are caught and sold in local markets, as well as consumed by members of the tribal community called Katkari(Keskar et al, 2017). The cooking method, which involves use of complete fish without degutting, might also include only partial cooking due to limited resources available to the tribal community.…”

Ichthyofaunal diversity in snow-fed Mardi Stream of Gandaki River, Central Nepal

“…Anthropogenic disturbances such as unscientific construction of roads in the watershed, extraction of boulders and sand mining, extensive fishing activities using electrofishing and lethal chemical, and construction of hydropower dams were few observed harmful activities. These practices contribute to natural habitat degradation, which eventually alters the composition of the riverine ecosystem (Morrongiello et al 2011;Sarkar et al 2012;(Keskar et al 2017;Liu, X. et al 2018).…”

Assessing the sustainability of lepidophagous catfish, Pachypterus khavalchor (Kulkarni, 1952), from a tropical river Panchaganga, Maharashtra, India

“…Nearly 30% of the species inhabiting the Western Ghats have been categorized as threatened in the IUCN Red list (Dahanukar, 2011;Dahanukar, Raghavan, Ali, Abraham, & Shaji, 2011;, Ramprasanth, Ali, & Dahanukar, 2018a). However, several endemic and threatened species continue to be harvested at unsustainable levels through artisanal and open-access fisheries throughout the Western Ghats (Das et al, 2017;Keskar, Raghavan, Kumkar, Padhye, & Dahanukar, 2017;Kharat & Dahanukar, 2013;Prasad, Ali, Harikrishnan, & Raghavan, 2012;Raghavan, Ali, Dahanukar, & Rosser, 2011;Raghavan et al, 2018a). According to Darwall et al (2018), another most important and fundamental cause for the freshwater biodiversity crisis is the insufficient consideration of impacts on freshwater ecosystems in decision-making and policy.…”