What primarily governs the movement and direction of ocean currents?

The movement and direction of ocean currents are primarily governed by wind patterns and Earth's rotation. Wind is a significant factor because it exerts friction on the ocean's surface, leading to the movement of water. As wind blows across the surface, it drags the water along, creating currents.

Earth's rotation plays a crucial role in this process as well. The Coriolis effect, which arises from the spinning of the Earth, causes currents to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This deflection influences the overall direction of ocean currents, creating systems like gyres in the major oceans.

While gravity is a force that affects water movement, it does not solely dictate the direction of currents. Temperature does influence water density and, therefore, can affect vertical currents (such as thermohaline circulation), but it is not the primary driver of surface current movement. Fish migration patterns do not have a significant impact on the broader currents in the ocean, as they are driven primarily by ecological factors rather than physical forces.