Fisheries-Induced Selection & Evolution

There is increasing that intense commercial fishing pressure can not only reduce fish stocks but also cause evolutionary changes to fish populations. However, the mechanisms which underlie these changes remain largely unknown. This research theme investigates the role of animal physiology in fisheries induced evolution. Within a given species, variation in physiological traits among individuals – and especially those related to energy balance (e.g. metabolic rate) and swimming performance (e.g. aerobic scope) – could make some fish more vulnerable to capture or more likely to suffer mortality after discard.

Our work to date has shown that, depending on the exact type of fishing gears being used, different traits may be under selection by fishing. One common trend is that fish social behaviours seem to influence capture likelihood via a number of mechanisms. For passive gears such as traps, for example, social cohesion causes individuals to follow each other into traps and be retained. For active gears such as trawls, social interactions allow some fish to follow others toward escape routes. Notably, environmental factors such as temperature and hypoxia can modulate the strength of selection on physiological and behavioural traits by fishing gears. Perhaps most surprisingly, population density alters the heretability of traits under selection by fishing and can even alter the underlying genes that are targeted.

Our most recent work in this area is examining whether wild fishing practices in the ornamental fish trade may select for specific phenotypes. This work is being carried out with wild fisheries in the Brazilian Amazon basin, in collaboration with Dr Daiani Kochhann.