Fishing Can Turn Big Fish Into Small Fish

People affect animals and plants all over the world. One example is by fishing. Fishing selects fish with unique traits. First, fishers take large fish out of the water. So, populations become small and have only small fish left in them. These fish have babies for the first time when they are younger and smaller. Second, different fishing methods can select fish with different behaviors. So, fishers might catch more timid fish or more active fish, depending on the method. Fishing makes fish populations less diverse and productive. Less diverse means there are only small fish or active fish, not a mix of big, small, active, and timid. Less productive means fewer fish to catch later. Small, less diverse populations are weaker and cannot respond to large changes in the environment. Weaker populations are more difficult to fish in a way that will allow the population to survive. So, fishing makes the fish populations less valuable to the fishers.