How is the trophic cascade, specifically related to fish populations in the rivers and streams, affected by increased Northern Rocky Mountains wolf (Canis lupus irremotus) populations at Yellowstone National Park?

Most national parks around the world are tri-trophic ecosystems with predators, plants and prey.  It has been determined by various researchers that predators in the ecosystems directly or indirectly influence existence and behavior of plants and prey. Different states have different views about the continued existence of predators in parks. In Yellowstone National Park, wolves have been a subject of discussions over the past century. In early 20th century, U.S. Fish and Wildlife Service proposed elimination of wolves as the primary way of protecting other species in the park. This was strongly opposed by many wildlife scientists, who valued wolves as wildlife hence they should be allowed to continue their existence. In the late 20th century, proposal of reintroducing or increasing northern Rocky Mountain Wolf in Yellowstone National Park was passed .

Trophic cascade is an interaction which controls ecosystems in ecosystems such as national parks. For many years, wolves have been killed than any other animal in many countries around the world due to the belief that it negatively affects the ecosystem. However, this is not the case in the Yellowstone in reference to fish population. In the trophic cascade, the increase of Northern Rocky Mountain Wolf in the park has enhanced the survival of animals in the lower trophic levels. Wolves are the main predators hence they reduce the density and limit the behavior of the prey thus enhancing survival of the lower trophic level. Increasing their number leads to reduction in large herbivores, a situation which causes positive grazing effects in the long run. A huge number of domestic livestock leads to heavy grazing of streamside vegetation and this adversely affect the quality of life of the habitats for terrestrial biota or aquatic. More wolves results in the protection of streamside vegetation in the Yellowstone National Park. This is a positive change in channel morphology that favors the survival of the aquatic life, which is constituted largely by fish population. It also positively affects the quality of the fish population in the park.

Past studies on trophic cascades conducted were against the presence of predators in the ecosystem. Top predators play vital and inevitable regulatory functions in their ecosystem engagement. Therefore, government’s plan of restoring wolves in Yellowstone National Park is fundamental in protecting the fish population.