Density-dependent growth as a key mechanism in the regulation of fish populations: evidence from among-population comparisons.
It is generally assumed that fish populations are regulated primarily in the juvenile (pre-recruit) phase of the life cycle, although density dependence in growth and reproductive parameters within the recruited phase has been widely reported. Here we present evidence to suggest that density-dependent growth in the recruited phase is a key process in the regulation of many fish populations. We analyse 16 fish populations with long-term records of size-at-age and biomass data, and detect significant density-dependent growth in nine. Among-population comparisons show a close, inverse relationship between the estimated decline in asymptotic length per unit biomass density, and the long-term average biomass density of populations. A simple population model demonstrates that regulation by density-dependent growth alone is sufficient to generate the observed relationship. Density-dependent growth should be accounted for in fisheries' assessments, and the empirical relationship established here can provide indicative estimates of the density-dependent growth parameter where population-specific data are lacking.
Lorenzen
Kai
K
Department of Environmental Science and Technology, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BP, UK. k.lorenzen@ic.ac.uk
Enberg
Katja
K
D000375:Aging / Q000502:physiology; D000818:Animals; D018533:Biomass; D004777:Environment; D005399:Fishes / Q000254:growth & development / Q000502:physiology*; D008954:Models, Biological; D011155:Population Control; D011156:Population Density; D011158:Population Growth