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A Small Fish With A Big Mission: An Introduction To The Small Pelagics Of The Pemba Channel

The small pelagic ring-net fishery, in its current form dates back to 1961, when it was introduced by Greek fishery entrepreneurs and it was initially known as the Greek Method.

Artisinal fishing vessels, dhows and so-called boti, are plank-built and typically range in length from ~7m to 15m, and are powered by either inboard or outboard engines. Non-motorised dugout canoes are also used in the very small-scale nearshore gillnet component of the fishery.

Fishermen, on Dhows and boti, fix lamps (kerosene, on-board generator and/or battery powered) to the gunwales of their vessels to attract shoals of fish and use large ring-nets to capture the fish. Although the light-aggregation technique has been widely used throughout the world and across many fisheries for millennia, the reason why it works is still debated, and is likely to be a combination of behavioural responses of both fish and plankton.

Seine nets, scoop nets, cast nets, traps and (illegal) beach seines are also used in certain shallow, near-shore habitats. Some enterprises also use ngwanda, which are similar vessels to the boti but are deployed without nets; they act as light boats to attract fish before a dhow or boti with a net (usually part of the same enterprise) is called over to catch the fish. Crews of 10-20 fishers are employed, depending on the size of the vessel.

Small pelagic fishing is largely scheduled around the cycle of the moon. Night fishing using the lights takes place mostly during the 15-20 darkest nights of the lunar cycle, when the marginal effect of the lights is at its highest. A few smaller vessels may operate throughout the lunar cycle.

Further Reading:

Anderson, J. and Samoilys, M. 2016. Chapter 2: The small pelagic fisheries of Tanzania. In: Case studies on climate change and African coastal fisheries: a vulnerability analysis and recommendations for adaptation options, edited by Jim Anderson and Timothy Andrew. FAO Fisheries and Aquaculture Circular No. 1113. Rome, Italy.

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Ocean Science in Action: Addressing Marine Ecosystems and Food Security in the Western Indian Ocean

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