They eat small fish and have a migratory pattern similar to that of the mackerel, arriving a short time before the latter to spawn.They eat small fish and have a migratory pattern similar to that of the mackerel, arriving a short time before the latter to spawn.In the autumn, they return to the open sea, including the Atlantic west of Ireland and Great Britain.Spawning occurs in May and June among seagrass beds with the long sticky tendrils on the chorion adhering to the blades of the sea grasses.[5] The garfish is a predator which hunts in the open sea seeking out shoals of small fish such as Atlantic herring, sprats, sand eels, and even three-spined sticklebacks.