CIE Spotlight: Fishing directly selects on growth rate via behaviour: implications of growth-selection that is independent of size

Peter B.

Peter B.

TitleFishing directly selects on growth rate via behaviour: implications of growth-selection that is independent of size.

AuthorsPeter A. Biro; Portia Sampson.

Source: The Royal Society Publishing: PROCEEDINGS B, Volume: 282. Issue: 1802, March 2015.

Brief summary of the paper: Size-selective harvest of fish and crustacean populations has reduced stock numbers, and led to reduced growth rates and earlier maturation.

In contrast to the focus on size-selective effects of harvest, here, we test the hypothesis that fishing may select on life-history traits (here, growth rate) via behaviour, even in the absence of size selection.

If true, then traditional size-limits used to protect segments of a population cannot fully protect fast growers, because at any given size, fast-growers will be more vulnerable owing to bolder behaviour.

We repeatedly measured individual behaviour and growth of 86 crayfish and found that fast-growing individuals were consistently bold and voracious over time, and were subsequently more likely to be harvested in single- and group-trapping trials.

In addition, there was some indication that sex had independent effects on behaviour and trappability, whereby females tended to be less active, shyer, slower-growing and less likely to be harvested, but not all these effects were significant.

This study represents, to our knowledge, the first across-individual support for this hypothesis, and suggests that behaviour is an important mechanism for fishing selectivity that could potentially lead to evolution of reduced intrinsic growth rates.

More information about the research can be found on: