title: Fishing directly selects on growth rate via behaviour: implications of growth-selection that is independent of size.
abstract: 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.
authors.affiliation: Centre for Integrative Ecology, School of Life and Environmental Science, Deakin University, 75 Pigdons Road, Geelong, Victoria 3216, Australia pete.biro@deakin.edu.au.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Biro
authors.affiliation: Evolution and Ecology Research Centre, University of New South Wales, Sydney, New South Wales 2032, Australia.
authors.forename: Portia
authors.initials: P
authors.lastname: Sampson
mesh_terms: D000818:Animals; D003400:Astacoidea / Q000254:growth & development* / Q000502:physiology*; D001522:Behavior, Animal; D005260:Female; D005398:Fisheries / Q000379:methods*; D008018:Life Cycle Stages; D008297:Male; D010641:Phenotype; D012737:Sex Factors
keywords: behavioural syndromes; bias; boldness; catchability; life history; personality