The Steller sea lion population has been decreasing in parts of Alaska. New evidence suggests that Steller sea lions need herring as a part of their diet in order to survive. Pollock, another type of fish, also feed on herring. Which would most likely help the Steller sea lion population to increase?

Improving the habitats of herring thereby increasing their population.

Explanation:

First, two consumers (Steller sea lion and  Pollock) are both competing for common prey (herring). Since the question only asked what could be done to increase the decreasing Steller sea lion population of Alaska, the focus would be made only on the Steller sea lion.

The Steller sea lion population would increase if:

1. The herring population should be increased by improving the food available for them to feed on, and improving their reproduction capacities to enable them to reproduce efficiently.

2. Since there are 2 predators. If the population of the prey is fixed, then Pollock should be more hunted by farmers or other biological means to eliminate competition.