What is the independent variable in this experiment?

I am doing a project in Science class and I already found the dependent variable, but I don't understand what the independent is.

Here is the experiment....(we are not doing this, we just had to design an experiment)

We will put some Steller sea lions in a simulated environment and give them a supply of both Pollock and Herring over a weeks course, and see which species the sea lions prefer over the other.What is the independent variable in this experiment?
The independent variable is the part of the experiment that you control. Like for example, how much food to give them. What kind of food to give them. What time of day to feed.

Anything that you control. Now the dependent variable is related to the I V. That's the part you cant control as a result of the IV. Here is a good ex. Lets say u put 2 plants out and give one 8 hrs of light and the other 4 hrs of light. Water the same. Now the light is what u control. But u cant control the growth of the plants....that's the dependent V. The growth will vary depending on the amount of light. Understand now???What is the independent variable in this experiment?
independent variable: different foods (the pollock and herring)



independent variable is always the variable with two or more different things involved if tht makes sense lol.What is the independent variable in this experiment?
The independant variable is the thing that you change in an experiment (So in this case the fish type)