Evolusjonær økologi


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hands-on learning

Teaching by experience

What can free candy teach us about fisheries-induced evolution?

A bowl of candy fish
Beatriz Diaz Pauli


Beatriz Pauli and Mikko Heino have recently published a paper that engaged random groups of people in a selection study that revealed behaviour patterns that are relevant to discussions of the ecological and evolutionary effects of fisheries.

The experimental design was driven by the need to simplify the challenge of understanding sustainable fisheries management. This is important in teaching as well as in communicating science to a broader audience.

Simplified the experiment involved two types of candy fish, which were made available in 11 different office settings. Dishes containing a mix of the 2 types were made available for 2 experimental periods of 2 weeks each. The candy stock “reproduced” overnight in relation to the population left at the end of each day. A card with the following instructions accompanied the candy dish (There will be candy fished supply for 2 weeks, as long as you manage to “harvest” it in a sustainable way. These fish reproduce once each day. Enjoy!). While all the experiment participants worked in academic environments, only some groups had fisheries biology experience.

Among other things, the results showed:

  • Participants learned by experience: there was fewer extinctions in the second 2-week study were better than the first.
  • The groups with fisheries biology experience did not fare better: knowledge from one field does not necessarily transfer to another.
  • Short-term benefits out-weighed long-term benefits.
  • Selection can drive “genetic” change (the strawberry fish populations were much more exploited than the liquorice ones)
  • Common resources present complex management issues.

Interestingly, in 4 of the groups a person spontaneously emerged as a “resource manager”. The “good governance” in these groups resulted in lower population decline.

Read “Food for Thought - Ecological and evolutionary effects of harvesting: Lessons from the candy-fish experiment” published in the ICES Journal of Marine Science.