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Giant freshwater prawn (Macrobrachium rosenbergii) breeding migration: Panadura estuary salinity?

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M
Mia Macrobrachium•910 rep

What estuarine salinity shifts (10-15 PSU) trigger berried female jumbo prawns to migrate from freshwater Bolgoda Lake down to coastal breakers to hatch zoea larvae?

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5 Answers from travellers

✓Accepted Answer

The Giant Freshwater Prawn (Macrobrachium rosenbergii / Karawadu Issa) is an amphidromous crustacean that spends its adult life in freshwater rivers and lakes but requires brackish water for larval metamorphosis. Mature females carrying fertilized egg sponges (berried females) migrate downstream from Bolgoda North Lake during inter-monsoon rains, following river currents to the Panadura estuary mouth. When water salinity reaches 10 to 14 PSU, the eggs hatch into free-swimming zoea larvae. Larvae undergo 11 distinct developmental molts over 35 days in the brackish lagoon nursery before post-larval juveniles migrate upstream into pure fresh water.

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C
Capt Roshan Sea•1720 rep

Commercial sand-mining at the Panadura bar mouth damages shallow tidal flats, disrupting the natural salinity gradient required for larval survival.

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M
Mia Macrobrachium•910 rep

Artisanal fishers use submerged brush parks (Athu Kotu) constructed from mangrove boughs to shelter migrating post-larvae from predatory barramundi.

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Dr Anouk Marine•1890 rep

Industrial textile wastewater discharges into the northern catchment create chemical barriers that elevate larval mortality rates during spring runs.

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Prof Gamhewage Bio•1940 rep

Wild-caught adult males with long, deep-blue claw chelipeds reach weights over 450 grams, commanding premium prices at coastal fish markets.

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V
Vaidya Harsha Arishta•1770 rep

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