Scientia Marina, Vol 79, No 1 (2015)

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

Andreia V. Silva
Instituto Português do Mar e da Atmosfera (IPMA) , Portugal

Isabel Meneses
Instituto Português do Mar e da Atmosfera (IPMA) , Portugal

Alexandra Silva
Instituto Português do Mar e da Atmosfera (IPMA) , Portugal


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.


daily age; otoliths; sardine; otolith weight; otolith diameter; northern Portugal

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Alemany F., Álvarez F. 1994. Formation of initial daily increments in sagittal otoliths of reared and wild Sardina pilchardus yolksac larvae. Mar. Biol. 121: 35-39.

Alemany F., Álvarez I., García A., et al. 2006. Post larvae and juvenile daily growth patterns of the Alboran Sea sardine (Sar- dina pilchardus, Walbaum): influence of wind. Sci. Mar. 70S2: 93-104.

Álvarez F., Alemany F. 1997. Birthdate analysis and its applica- tion to the study of recruitment of the Atlanto-Iberian sardine, Sardina pilchardus. Fish. Bull. 95: 187-194.

Baumann H., Voss R., Hinrichsen H.-H., et al. 2008. Investigating the selective survival of summer- over spring-born sprat, Sprat- tus sprattus, in the Baltic Sea. Fish. Res. 91: 1-14.

Bernal M., Stratoudakis Y., Coombs S., et al. 2007. Sardine spawning off the European Atlantic coast: Characterization of and spatio-temporal variability in spawning habitat. Prog. Oceanogr. 74: 210-227.

Campana S.E., Neilson J.D. 1985. Microstructure of fish otoliths. Can. J. Fish Aquat. Sci. 42: 1014-1032.

Coombs S.H., Smyth T.J., Conway D.V.P., et al. 2006. Spawning season and temperature relationships for sardine (Sardina pilchardus) in the eastern North Atlantic. J. Mar. Biol. Assoc. U. K. 86: 1245-1252.

Fey D.P., Linkowski T.B. 2006. Predicting juvenile Baltic cod (Gadus morhua) age from body and otolith size measurements. ICES J. Mar. Sci. 63:1045-1052.

Fletcher W.J. 1991. A test of the relationship between otolith weight and age for the Pilchard Sardinops neopilchardus. Can. J. Fish. Aquat. Sci. 48: 35-38.

Fletcher W.J. 1995. Application of the otolith weight-age relationship for the Pilchard, Sardinops sagax neopilchardus. Can. J. Fish. Aquat. Sci. 52: 657-664.

Fossen I., Albert O., Nilssen E. 2003. Improving the precision of ageing assessments for long rough dab by using digitalized pictures and otoliths measurements. Fish. Res. 60: 53-64.

Francis R.I.C., Campana S.E. 2004. Inferring age from otolith measurements: a review and a new approach. Can. J. Fish. Aquat. Sci. 91: 1269-1284.

Gago J., Cabanas J.M., Casas G., et al. 2011. Thermohaline measurements in the continental shelf zone of the NW Iberian Peninsula, 1994–2006. Clim. Res. 48: 219-229.

ICES 2011. Report of the Workshop on Age Reading of European Atlantic Sardine (WKARAS), 14-18 February 2011, Lisbon, Portugal. ICES CM 2011/ACOM: 42, 91 pp.

ICES 2014. Report of the Working Group on Southern Horse Mackerel, Anchovy, and Sardine (WGHANSA), 20-25 June 2014, Copenhagen, Denmark. ICES CN 2014/ACOM: 16, 532 pp.

INE 2014. Estatísticas da pesca 2013. Instituto Nacional de Estatística, I.P., Lisbon, Portugal, 135 pp.

Jones C.M. 1992. Development and application of the otolith increment technique. In: Stevenson D.K., Campana S.E. (eds). Otolith microstructure examination and analysis. Can. J. Fish. Aquat. Sci. 117: 1-11.

Kasapoglu N., Duzgunes E. 2013. The relationship between somatic growth and otolith dimensions of Mediterranean horse mackerel (Trachurus mediterraneus) from Black Sea. J. App. Ichthyol. 29: 230-233.

Kimura D.K. 1980. Likelihood methods for the Von Bertalanfy growth curve. Fish. Bull. 77: 765-776.

Lou D.C., Mapstone B.D., Russ G.R., et al. 2005. Using otolith weight-age relationship to predict age-based metric of coral reef fish populations at different spatial scales. Fish. Res. 71: 279-294.

Lou D.C., Mapstone B.D., Russ G.R., et al. 2007. Using otolith weight-age relationships to predict age based metrics of coral reef fish populations across different temporal scales. Fish. Res. 83: 216-227.

Megalofonou P. 2006. Comparison of otolith growth and morphology with somatic growth and age in young-of-the-year bluefin tuna. J. Fish Biol. 68: 1867-1878.

Meneses I. 2003. Estimação de factores que Condicionam a Variabilidade do Recrutamento de Peixes na Costa Atlântica da Península Ibérica. PhD Thesis, Portuguese Institute for Fisheries and Sea Research (IPIMAR), Lisbon, Portugal.

Moksness E., Rukan K., Ystanes L., et al. 1995. Comparison of somatic and otolith growth in North Sea herring (Clupea herengus L.) larvae: evolution of growth dynamics in mesocosms. In: Secor D.H., Dean J.M., Campana S.E. (eds), Recent Developments in Fish Otolith Research. University of South Carolina Press, pp. 119-134.

Nunes C., Silva A., Soares E., et al. 2011. The use of hepatic and somatic indices and histological information to characterize the reproductive dynamics of Atlantic Sardine Sardina pilchardus from the Portuguese coast. Mar. Coast. Fish. 3: 127-144.

Paiva V.H., Werner A., Geraldes P., et al. 2013. Overcoming difficult times: The behavioural resilience of a marine predator when facing environmental stochasticity. Mar. Ecol. Prog. Ser. 486: 277-288.

Pawson M.G. 1990. Using otolith weight to age fish. J. Fish Biol. 36: 521-531.

Preciado I., Velasco F., Olaso I. 2008. The role of pelagic fish as forage for demersal fish community in the southern Bay of Biscay. J. Mar. Syst. 72: 407-417.

Ramírez T., Cortés D., Garcia A. 2001. Growth of North Alboran Sea sardine larvae estimated by otolith microstructure, nucleic acids and protein content. J. Fish Biol. 59: 403-415.

R Development Core Team. 2008. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL

Ré P. 1984. Evidence of daily and hourly growth in pilchard larvae based on otolith growth increments, Sardina pilchardus (Walbaum, 1792). Cybium 8: 33-38.

Ré P. 1986. Otolith microstructure and detection of life history events in sardine and anchovy larvae. Ciênc. Biol. Ecol. Syst. 6: 9-17.

Relvas P., Luís J., Santos A.M.P. 2009. Importance of the mesoscale in the decadal changes observed in the northern Canary upwelling system. Geophys. Res. Lett. 36: L22601.

Ricker W.E. 1979. Growth rates and models. In: Hoar W.S., Randal D.J., Brett J.R. (eds) Fish Physiology, Vol III Bioenergetics an Growth. Academic Press, pp. 677-744.

Santos M.A., Peliz A., Dubert J., et al. 2004. Impact of a winter upwelling event on the distribution and transport of sardine, (Sardina pilchardus) eggs and larvae of western Iberia: a retention mechanism. Cont. Shelf Res. 24: 149-165.

Santos M.B., Gonzalez-Quiros R., Riveiro I., et al. 2012. Cycles, trends, and residual variation in the Iberian sardine (Sardina pilchardus) recruitment series and their relationship with the environment. ICES J. Mar. Sci. 69: 739-750.

Secor D. H., Dean J. M. 1989. Somatic growth effects on the otolithfish size relationship in young pond-reared striped bass, Morone saxatilis. Can. J. Fish. Aquat. Sci. 46: 113-121.

Secor D.H., Dean J.M., Laban E.H. 1992. Otolith removal and preparation for microstructural examination. In: Stevenson D.K., Campana S.E. Otolith Microstructure examination and analysis. (eds). Can. Spec. Publ. Fish. Aquat. Sci. 117: 19-57.

Silva A., Skagen D.W., Uriate A., et al. 2009. Geographic variability of sardine dynamics in the Iberian Biscay region. ICES J. Mar. Sci. 63: 663-676.

Steward C.A., DeMaria Karen D., Shenker J.M. 2009. Using otolith morphometrics to quickly and inexpensively predict age in the gray angelfish (Pomacanthus arcuatus). Fish. Res. 99: 123-129.

Stratoudakis Y., Coombs S., Lago de Lanzós A., et al. 2007. Sardine (Sardina pilchardus) spawning seasonality in European waters of the northeast Atlantic. Mar. Biol. 152: 201-212.

Templeman W., Squires H.J. 1956. Relationship of otolith length and weights in the haddock Melanogrammus aeglefinus (L.) to the rate of the growth of the fish. J. Fish Res. Board Can. 13: 467-487.

Wilhelm M.R., Painting S.J., Field J.G., et al 2005. Impact of environmental factors on survival of larval and juvenile Cape anchovy Engraulis encrasicolus (G.) in the southern Benguela upwelling region, determined from hatchdate distributions: implications for recruitment. Mar. Freshwater Res. 56: 561-572.

Wilson J.A., Vigliola L., Meekan M.G. 2009. The back-calculation of size and growth from otoliths: validation and comparison on models at an individual level. J. Exp. Mar. Biol. Ecol. 368: 9-21.

Wright P.J., Metcalfe N.B., Thorpe J.E. 1990. Otolith and somatic growth rates in Atlantic salmon parr, Salmo salar L.: evidence against coupling. J. Fish Biol. 36: 241-249.

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