Vessel Strikes
Inadvertent vessel strikes can injure or kill blue whales. Vessel strikes have killed blue whales throughout their range, but the risk is much higher in some coastal areas with heavy ship traffic. 

Entanglement
Blue whales can become entangled in fishing gear, either swimming off with the gear attached or becoming anchored. Blue whales can become entangled in many different gear types, including traps, pots, or gillnets. Once entangled, whales may drag and swim with attached gear for long distances, ultimately resulting in fatigue, compromised feeding ability, or severe injury, which may lead to reduced reproductive success and death. 

Additional Threats
Additional threats include ocean noise, habitat degradation, pollution, vessel disturbance, and long-term changes in climate.