Title: Otolith microstructure, age, and growth patterns of dolphin, Coryphaena hippurus, in the western Mediterranean
Abstract: The age and growth of dol- phin, Coryphaena hippurus, has been determined in wild specimens between 14.4 and 124 cm fork length (FL) caught off Majorca (Balearic Islands, western Mediterranean). Also, several methods have been applied to validate the re- sults obtained and to assess the aging techniques presently used. In accor- dance with the sexual dimorphism of this species, the length-weight rela- tionship showed negative allometry in females and isometry in males. The high correlation between increment counts and known age in 75 reared lar- vae from 0 to 38 days old (number of increments = 0.3894+0.9846·days of age; r=0.98) indicated that the daily deposition of growth increments in sag- ittal otoliths and regular incremental formation begins on day one. This cor- relation validated the use of otoliths in the aging of 176 juvenile specimens between 16.5 and 58.5 cm FL, in which the minimum and maximum ages ob- served were 47 and 176 days, respec- tively. Nevertheless, the progressive increase in complexity with the onto- genic development of these structures suggests that this method may under- estimate age in adult fish, probably owing to the loss of marginal zones of the otolith during the polishing process. Thus, from 150 specimens between 65 and 124 cm FL, the interpretation of annuli from scales gave ages up to 3 years old, whereas readings of otoliths in 36 specimens of the same size inter- val gave ages between 0 and 1 year old. Growth parameters were calculated from the age-length relationships of otolith and scale readings in juvenile and adult fish, respectively, and from the analysis of monthly length-fre- quency distributions, obtained in 1990 and 1991 during the exploitation of ju- veniles from 18 to 70 cm FL (n=4084). The values obtained for L∞ ranged from 72.4 cm FL in unsexed juveniles and 110.0 cm FL in females both juvenile and adult, whereas k ranged from 1.6/year in juvenile and adult females and 2.5/year in unsexed juveniles. Although the re- sults obtained were quite different ow- ing to the different length and age range considered, similar results were obtained by comparing the growth per- formance index (F), and showed the rapid growth of the species.
Publication Year: 1999
Publication Date: 1999-01-01
Language: en
Type: article
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Cited By Count: 26
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