Influence of female age, body size and environmental conditions on annual egg production of the bullhead

Authors: Abdoli, A.; Pont, D.; Sagnes, P.

Source: Journal of Fish Biology, Volume 67, Number 5, October 2005 , pp. 1327-1341(15)

Publisher: Wiley-Blackwell

Abstract:

A population of bullhead Cottus gobio inhabiting a mountainous river network, was examined for the influence of maternal condition (total length, L_T, and age class in years) and environmental factors (water temperature and fish density) on fecundity, egg size and net annual reproductive effort (E_R, defined as the ratio of total egg production mass to body mass) within several stocks. Regardless of location within the drainage network, bullhead reproduction was synchronous, with only a single batch and fecundity ranging from 69 to 896 eggs per female. As with L_T fecundity increased with age, although the difference between age classes 5 and 6 years was smaller than between other age classes. Egg diameter also increased with age from age classes 2 to 4 years, but then tended to decrease for age classes 5–6 years. Multiple stepwise regression was used to examine the effect of female L_T, water temperature and fish densities on bullhead egg production for each of the four age classes (2, 3, 4 and 5–6 years) separately. When statistically significant, water temperature always had a positive effect and fish densities a negative effect, on fecundity and egg size. The L_T always had a positive effect on fecundity for all the age classes. In contrast, L_T had a positive effect on egg size and E_R only for female reaching maturity (2 years), whereas intermediate aged females (3–4 years) were insensitive and the oldest fish showed a negative response.

Keywords: allocation to reproduction; Cottus gobio; density-dependent; egg size; fecundity; temperature

Document Type: Regular paper

DOI: http://dx.doi.org/10.1111/j.0022-1112.2005.00829.x

Affiliations: 1: CNRS UMR 5023, Ecologie des Hydrosystèmes Fluviaux, Université Lyon 1, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France and

Publication date: 2005-10-01

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