Removing the mud, uncovering gravel beds where fish spawn, and finding suitable salmon types to rebuild the population is a daunting task.

清除淤泥，发现鱼类产卵的砾石层，找到合适的鲑鱼种类来重建种群是一项艰巨的任务。

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"These are the habitats that provide really valuable places for the fish to get together, to aggregate,to spawn, so they are the bases of the fisheries."

VOA: standard.2010.05.26

The boats of both countries take fish returning to spawn in the rivers of either.

ECONOMIST: Canada

The Angling Trust said it was disappointed after none of 72 fish electronically tagged negotiated the barrage to migrate up river to spawn.

BBC: Fears over Tees Barrage impact on fish

Coral-reef fish tend to grow slowly, take many years to reach reproductive age, and then spawn in only a few localised sites.

ECONOMIST: What price coral?