Age-structure, growth and reproduction of the introduced pumpkinseed (lepomis gibbosa, l. 1758) in a tributary of the Guadalquivir river (southern Spain)

Abstract

The age structure, growth and reproduction of Lepomis gibbosa (L. 1758) (= L. gibbosus) was studied from March 1993 to September 1994 in a tributary stream of the Guadalquivir River. The maximum age observed was 5+ years both in males and females. In the O+ group, seasonal growth began in February and lasted 8 months. Males and females matured during their second year of life (l+). There were no significant differences in the overall sex-ratio, which was 1: 1.1 (677 males to 745 females). Reproductive activity started in MarcWApril and lasted until AugusUSeptember. During this period, females spawned 2 batches of eggs. The relationship between fecundity (F) and fork length (&, mm) was: F=5.09 % 279 (1993) and F=85.81 L, ' 56 (1994). The maximum contribution to the fecundity of the population was observed in the 4+ female group. The reproductive effort was maximun in the 3+ group. Compared with the American pumpkinseed populations that have been studied, the lifehistory patterns of this stock are characterized by low annual growth, early maturity, reduced longevity and low fecundity.