The Mangroves of Aghanashini Estuary

Aghanashini meaning the “Remover of Sins” is one of the very few free-flowing rivers of the world. Flowing westward over 140 km distance and receiving rainfall up to 8000 mm at some places, most of the course is through forested gorges and valleys. Having no dams or noticeable industries nor major townships along its banks, the Aghanashini remains pristinethrough its course. The river joins the sea in the Aghanashini village of Kumta taluk. The estuary of the river is a flat expanse of water dotted with small islands and narrow creeks.

Aghannashini estuary is a highly productive and biologically rich waterscape with a significant livelihood dependence related to fishing, agriculture, collection of edible bivalves and crabs, shrimp aquaculture, traditional fish farming in the gazni rice fields, bivalve shell mining, salt production, sand removal, water transportation etc.

With more than 11 distinct species, the large tracts of mangrove found in the estuary contribute nutrients to the estuarine-marine ecosystem through litter fall that turn into soluble nutrients eventually. These nutrients contribute significantly towards the productivity of the coastal landscape. Further, mangroves act as a nursery for fishes and prawns and considered as important fish breeding and spawning areas. Several species of fish visit nutrient rich mangrove area for laying eggs so that the juveniles grow amidst abundance of food before they leave for the sea.

Resident estuarine fishes also take benefit of the mangrove areas for their food and breeding. The mangroves with their entanglement of roots making a dense impenetrable cover provide a safe place for fishes and prawns, ultimately securing them from predators. Moreover, fishermen do not cast their nets within the mangrove areas due to the physical obstacles created by the root network. Mangroves provide good roosting place for many species of birdsand also protect the mainland from erosion by trapping soil and debris that come along with the run-off during the rainy season.

In tropical coastal areas where land and sea perpetually compete with each other, mangroves perform the crucial task of stabilisation. Traditionally, local farmers planted mangroves alongside the earthen embankments of their gazni rice field cum fish farming arease to protect from tides, waves and torrential rains.Since the government built permanent embankments in the estuaries, the practice of planting mangroves by the locals almost waned out.

In the heart of the mangrove enriched estuarine centre of Aghanashini is a small uninhabited island which is the abode of ‘Babrudevaru’, the guardian deity of the estuary. The deity is worshipped in the estuarine landscape by villagers who have strong cultural bonds with the deity.

A stretch of mangrove forest dominated by the several ancient trees of Avicennia officinalis (Upatti in Kannada) is considered so sacred that no one should step inside it wearing footwear. Numerous birds, both migratory (during winter) and resident ones are associated with this sacred kan forest.

A recent study by scientists from IISc, Bangalore, concluded that annual revenue generated from Aghanashini estuary itself is about 4.12 billion Rupees. Aquaculture, fishing, bivalve and calms, oyster, mussels and other molluscs and shellfish collection contribute significantly to the revenue. Bulk of the bivalve harvest is from mudflats bordering the village Aghanashini, close to the mouth of the river. It is significant to note that so much of food production is without any investment or supply of feeds by humans.

This unique ecosystem is constantly threatened by industrialisation and heavy mechanisation of fisheries. However, no project has come up there so far despite many proposals being floated. This is mainly because the area is not viable for a manufacturing or energy project. Secondly, the local population favours keeping the area protected. This is evident from the public hearings and discussions that have been conducted here. It is important that all stakeholders understand the value of conserving this important estuarine-mangrove ecosystem.