Human alteration of predation risk

By looking through the lens of prey behavior, we try to understand and predict the role that predator-prey relationships play in shaping marine food webs and ecosystems. This work explores how fishing may impact marine ecosystems in ways that might otherwise go unnoticed. Understanding these consequences is important because it provides insight into how fishing – whether recreational, commercial, or subsistence – can havesurprising consequences for coral reefs and other marine ecosystems.

For example, fishing is one of the most critical threats facing ocean ecosystems worldwide, but a puzzling dichotomy remains: why does fishing cause cascading effects through some ecosystems but not others? My colleagues and I have found evidence that one of the keys to this puzzle may lie in the behavior of fish. As sharks and other predators disappear from the ocean from fishing, the small fish – who would otherwise be their prey – are getting bolder. So bold, in fact, that humans are unwittingly changing the way seascapes look by changing where small fish graze for seaweed. Seaweeds are important because areas of lush seaweed growth inhibit growth of corals, the critically important “engineers” of the reef. By changing where seaweed grows, fishing may inadvertently also be changing where coral can grow.


Madin, E.M.P., L.M. Dill, A.D. Ridlon, M.R. Heithaus, and R.R. Warner. 2015. Human activities change marine ecosystems by altering predation riskGlobal Change Biology.

Madin, E.M.P., S.D. Gaines and R.R. Warner. 2010. Field evidence for pervasive indirect effects of fishing on prey foraging behavior. Ecology 91: 3563–3571.

Madin, E.M.P., S.D. Gaines, J.S. Madin and R.R. Warner. 2010. Fishing indirectly structures macroalgal assemblages by altering herbivore behavior. American Naturalist 176(6): 785-801.

Madin, E.M.P., S.D. Gaines, J.S. Madin, A.K. Link, P.J. Lubchenco, R.L. Selden and R.R. Warner. 2012. Do behavioral foraging responses of prey to predators function similarly in restored and pristine foodwebs? PLoS One 7(3): e32390. DOI: 10.1371/journal.pone.0032390.

Madin, E.M.P. and J.S. Madin. 2011. Predators, facilitators, or both? Re-evaluating an apparent predator-prey interaction. Marine Ecology Progress Series 431: 299-302.

Madin, E.M.P. 2011. Genetically engineered salmon pose environmental risks that must be considered. Bioscience 61(1): 6.

Madin, E.M.P. 2010. Effects of fishing on prey foraging. Bulletin of the Ecological Society of America 91(3): 339-341.

Relevant collaborative projects

McCauley, D.J., Micheli, F., Young, H.S., Tittensor, D.P., Brumbaugh, D.R., Madin, E.M.P., Holmes, K.E., Smith, J.E., Lotze, H.K., DeSalles, P.A., Arnold, S.N. and Worm, B. 2010. Acute effects of removing large fish from a near pristine coral reef. Marine Biology 157: 2739-2750.

Selected media coverage & press releases