fish trap
魞 centers on a device for catching fish: a fish trap. The meaning is specific to this tool and does not extend to other trapping or fishing concepts.
魞 combines 魚 (fish) with 入 (enter), suggesting a device that fish enter and cannot easily leave. The exact historical development is uncertain, but the component logic fits the meaning of a fish trap.
A fish 魚 enters 入 a trap and cannot get out. Picture a woven basket with a narrow opening that fish swim into but cannot escape.
For えり, imagine a fish trap made of woven reeds at the edge of a river. The word 'edge' sounds like え, and the reeds (り) complete the reading: edge + reeds -> えり.