Secondary impacts of harvest on wild populations and ecosystems

Cohort: 2017, 2018

Semester 1

Semester 2

Semester 3

Semester 4



Ecosystem based fisheries management
Galway Mayo Institute of Technology


Traditional approaches to harvesting largely assume a population exists in isolation and that harvesting acts to primarily change the size and or composition of the population. Increasingly, however, evidence suggests that failure to consider secondary effects of harvesting may lead to decreased productivity, population decline and in some cases extirpation.


Review of compensatory harvest theory
Harvesting populations within a community
Trophic interactions and Trophic cascades
Stable states
Evolutionary effects of fishing and hunting
Management trade-offs
Case studies


This module will provide an overview of the effects of harvesting on wild populations and the communities in which they exist. Through a combination of lectures, group discussions, case studies, presentations and practical exercises this module will address a key element of an ecosystem based approach to resource management


Demonstrate an understanding of the extant theory of harvesting
Discuss the latest research of secondary effects of population harvesting
Critically evaluate current methods to incorporate secondary effects
Explain implications of optimal population harvesting
Describe how to account for secondary impacts


Coltman, D.W, O'Donoghue, P., Jorgenson, J.T., Hogg, J.T., Strobeck, C. and Festa-
Bianchet, M. (2003). Undesirable evolutionary consequences of trophy hunting. Nature, 426, 655-658.

Allendorf, F.W., England, P.R., Luikart, G., Ritchie, P.A. and Ryman, N. (2008). Genetic effects of harvest on wild animal populations. Trends in Ecology and Evolution, 23(6), 327

Allendorf, F.W. and Hard, J.J. (2010). Human-induced evolution caused by unnatural selection through harvest of wild animals. Proceedings of the National Academy of Sciences, 106, p9987-9994.

Frank, K.T., Petrie, B., Choi, J.S. and Leggett, W.C. (2005). Trophic Cascades in a Formerly Cod-Dominated Ecosystem. Science, 308, 1621-1623.

Link, J.S. (2010). Ecosystem-Based Fisheries Management: Confronting Tradeoffs. Cambridge University Press, Cambridge, UK


All assessments are formative and summative, they contribute to the module grade. The module is 100% continuous assessment with no terminal examination. Practical assignments, group discussions and class presentations will be used to assess the learning outcomes on an ongoing basis.

Involved teachers

Dr Cóilín Minto, Dr Katie O'Dwyer, Dr Ian O'Connor

Contact hours

3 hours per week, lectures, group discussion, case study readings

3 - scenario role playing, presentations