Predicting the age of sardine juveniles (<em>Sardina pilchardus</em>) from otolith and fish morphometric characteristics

Abstract

Summary: An age prediction model based on individual morphometric characteristics (total length; weight) and otolith morphometric characteristics (diameter; weight) was investigated for juvenile sardine, Sardina pilchardus (Walbaum, 1792). Juveniles were collected from northern Portugal between May 2004 and January 2005. Daily growth rings were counted on the otoliths of 114 juveniles of 7-16 cm total length. The sample was divided into a training sample used to develop the age prediction model and a test sample used to evaluate the predictive ability of the model. The best model for predicting the logarithm of age was a linear regression with otolith diameter. The prediction of daily age was more accurate for younger (<200 days) juveniles. Overall, ages predicted from the model were unbiased in relation to ages determined from otolith microincrement counts. Moreover, predicted daily ages reproduced the overall shape of the observed age distribution and provided comparable growth estimates (0.041 cm day -1 ). The back-calculated birthdate period ranged from 29 September 2003 to 22 July 2004, with a peak in January 2004, which is consistent with the spawning season. The model presented here could be used as a method for increasing the volume of juvenile daily age data. Since growth and survival varies spatially and temporally, relationships between age and otolith/fish morphometry should not be extrapolated outside sampled periods, areas and fish size/age.

Maturation of the European sardine Sardina pilchardus under experimental conditions strengthens bioenergetic estimate

“…The birth date determined in December 2013 in the present study is consistent with observations for S. pilchardus in the wild. Our estimates of age-length relationship based on this birth date determination are in the range of the age-length relationship previously proposed by Silva et al (2015) for the same species.…”

“…It was, however, well under what was previously estimated using Von Bertalanffy growth model in the Alboran sea (Alemany et al, 2006) and in the Gulf of Lions (Van Beveren et al, 2014), with 24 cm and from 18.38 cm to 33.57 cm, respectively. Using a Gompertz growth model, Silva et al (2015) estimated an even lower theoretical maximum length (14.3 cm) than us for sardines from the northwest coast of Portugal. The narrow range of observations in total length or weight in the present study certainly prevented from getting realistic estimates of the asymptotic weight and total length although the temperature forcing was included in the model.…”

Stock discrimination of two insular populations of Diplodus annularis (Actinopterygii: Perciformes: Sparidae) along the coast of Tunisia by analysis of otolith shape

“…In the same way, Silva et al (2015) made the prediction of the age of juveniles of sardine, Sardina pilchardus (Walbaum, 1792), from otolith and fi sh morphometric characteristics. The authors revealed that morphometric variables examined, otolith weight, diameter, fi sh total length and weight, were linearly related to the logarithm of age in sardine juveniles being 109-280 days old.…”

Kısa (Chihuahua köpek) ve Uzun (Asya fili) Ömürlü Hayvanlarda Artan Yaş İle Birlikte Telomerik Yıpranma

“…Unfortunately, age determination is difficult for most species, especially on living animals. Some methods involve using age-specific characteristics like tooth eruption and dental wear [1,2] , skeletal morphology [1,3] , body morphometrics [4] and bone ossification [5] , although most of these are applicable only after death. In addition, radiocarbon dating and aspartic acid racemization can serve as a tool for age estimation [6,7] , but again, not for living animals.…”