The primary cause of declining fish stocks in oceans is overfishing, driven by increased demand for seafood and unsustainable fishing practices. Additionally, habitat destruction and pollution further exacerbate the situation, leading to diminished fish populations and disrupted marine ecosystems. Lack of effective regulation and enforcement contributes to this crisis, as many fisheries operate without adequate management. To combat this, implementing sustainable practices, establishing marine protected areas, and promoting responsible consumption are crucial steps to restore fish stocks and ensure the long-term health of ocean ecosystems.