- Tuna eat fish
- If an animal eats other animals for food , then the animal is the predator
- Therefore, tuna is a kind of predator

- Tuna is a kind of predator
- Tuna is a kind of fish
- Hence, tuna is a kind of predatory fish

- Tuna is a kind of predatory fish
- Commercial harvesting from the ocean has caused populations of large predatory fish to decrease
- Hence, commercial harvesting from the ocean has caused the populations of tuna to decrease

So, commercial harvesting from the ocean has caused the populations of tuna to decrease
Q: A recent study concluded that about 90% of all large predatory fish such as tuna have disappeared from the world's oceans in the past 50 years. Which of these is most likely the direct cause of this loss?
Context:
- Commercial harvesting from the ocean has caused populations of large predatory fish to decrease 
- Tuna is a kind of fish 
- Tuna eat fish 
- If an animal eats other animals for food , then the animal is the predator