How brown mussels sustain livelihoods along Thiruvananthapuram’s coast

Brown mussels are edible shellfish with brown shells and soft, fleshy meat. Scientists identify them as Perna indica or Perna perna. They matter because they support coastal diets, fishing livelihoods and a growing seafood trade in southern Kerala.

Their range runs from Kollam district in Kerala to Tiruchendur in Tamil Nadu. In Thiruvananthapuram, divers pull them from rocks between September and February. They use broad metal knives and carry the catch ashore in cloth sacks or wicker baskets.

The species is increasingly valuable. More than 280 people harvest and trade brown mussels in Vizhinjam alone. Prices have risen as more people eat them and roadside vendors and restaurants buy them. The ICAR-CMFRI is also testing open-sea longline farming to produce more mussels and train fisherfolk.

Vizhinjam’s brown-mussel economy involves more than 280 harvesters and traders. The figure comes from the Diving Workers Welfare Society. Divers, auction buyers, vendors and suppliers all depend on the daily catch, making mussels an important coastal livelihood.

Balu Kovalam, a veteran diver with 20 years of experience, earns ₹2,000 daily collecting mussels. At the harbour, baskets are auctioned within seconds. One lot fetched ₹15,000, showing how much value can move through a single morning’s catch.

Income is not guaranteed. Divers can work only when the sea is safe enough, and the society limits them to two baskets per day. Demand from roadside vendors, restaurants and households has increased prices. Farming could eventually provide another income source when wild harvesting is restricted by weather or sustainability rules.

Mussel prices and availability change because supply depends on nature, while demand is rising. More people now eat mussels, and roadside vendors are the biggest auction buyers, followed by seafood restaurants. Greater competition for the catch pushes prices upward.

Rain can affect availability and price, according to restaurant owner Salim S. Rough seas create another shortage because divers cannot enter the water when waves are high. They usually collect mussels from 6am to 10am, so a short weather window can determine the day’s supply.

These forces are visible in markets and restaurants. Nirmala buys three baskets for ₹12,500 and sells 100 pieces for ₹1,000 or ₹1,200. Growing demand makes wild harvests more valuable, but weather and harvesting limits keep supply uncertain. Open-sea farming may make supplies more dependable.

Mussel harvesting is direct and physically demanding. Fishers collect shellfish between 6am and 10am, during the September-to-February peak. They dive underwater and use broad metal knives to pry mussels from rocks. Some leave from boats, while others dive directly from shore rocks.

Babu Sukumaran, who has harvested mussels since age 15, emerges with a cloth sack tied around his waist. Divers may suffer bleeding cuts while working among rocks and shells. At the harbour, labourers carry baskets to the market, where buyers auction the catch.

The sea controls the workday. Balu Kovalam says his job depends on whether the water is peaceful or turbulent. High waves prevent entry and make collecting dangerous. This uncertainty affects daily earnings and market supply. The society’s two-basket limit also encourages divers to avoid exhausting the mussel beds.

Kerala has two mussel types with different habitats and textures. Brown mussels, Perna indica or Perna perna, occur from Kollam to Tiruchendur. Green mussels, Perna viridis, are found elsewhere. Brown mussels are soft and fleshy, while green mussels are firmer.

Green mussels can tolerate low-salinity water, so they are cultivated in lakes in Kannur, Kozhikode and Kasaragod. Construction of sea walls has also been linked to more green mussels appearing in Thiruvananthapuram and Kollam. Brown mussels are gathered from rocky coastal waters and are central to Vizhinjam’s fishery.

The article describes active farming development for mussels, including brown mussels in an open-sea longline unit at Vizhinjam. It does not compare the two species’ profitability directly. The contrast shows that farming methods must match each mussel’s habitat and local water conditions.

Open-sea longline farming grows mussels on lines suspended in the sea. It matters because wild collection depends on waves, rain and limited daily harvesting. A farm can create a more planned source of mussels while opening another livelihood for coastal workers.

The ICAR-CMFRI unit at Vizhinjam launched its first full-fledged open-sea mussel longline unit. Its goals are to produce more seeds and extend cultivation into the sea. Mussels mature there in six to eight months, faster than the two years reported for Europe and Australia because of tropical temperatures.

The unit builds on an earlier Kanyakumari trial that withstood the monsoon. Researchers aim to deploy more units and train additional fisherfolk. If expanded, the method could support rising demand and reduce pressure on wild mussel beds. Its success will still depend on the sea and farming conditions.

Mussels require relatively little feed because they use food already present in the water. According to ICAR-CMFRI scientist MK Anil, they feed on phytoplankton, microscopic organisms drifting in water, and other organic matter. Farmers therefore do not need to provide the same regular feed used in many fish or prawn systems.

This natural feeding mechanism also reduces supervision. Mussels remain attached to farming lines while filtering available food from the surrounding water. The article links this lower-input system with greater profitability than rearing prawns or fish, though it does not give comparative earnings.

That advantage supports the move toward open-sea farming at Vizhinjam. The unit aims to produce seeds, grow mussels in the sea and train fisherfolk. Farming could increase supply as demand rises, while wild harvesting remains limited by rough weather and sustainability rules.