Publication

2000-08

English

http://archimer.ifremer.fr/doc/2000/publication-485.pdf (0.45 Mo)

2000 International Council for the Exploration of the Sea. All rights reserved

IFREMER, Lab Maerha, F-44311 Nantes 03, France.

ICES Journal of Marine Science (1054-3139) (Elsevier), 2000-08 , Vol. 57 , N. 4 , P. 1160-1174

12

Fishing

Teleost fishes, Population dynamics, Life history, Density dependence, Biological reference points

Density dependence means that exploited fish populations exhibit earlier maturity, a faster growth rate, increased fecundity and reduced egg size. Here, the consequences of these effects on population dynamics, the estimation of spawning biomass per recruit and associated biological reference points are examined by a simulation model. The model is a self-regenerating model in which the population parameters (age at maturity, growth, fecundity, egg size) vary according to three classes of population abundance. Early life stages are characterized by a size-dependent growth and mortality model. It is concluded that spawning per recruit is an ambiguous concept because, if density dependence occurs in the adult population, the spawning biomass of a cohort is not proportional to the number recruited. This leads to significant level of uncertainty in the estimates of spawning biomass per recruit and the associated biological reference points such as F-low, F-med, F-high and VSPR.