Temperature and Somatic Growth Effects on Otolith Growth of Larval Atlantic Menhaden, <I>Brevoortia Tyrannus</I> (Actinopterygii: Clupeiformes: Clupeidae)

Abstract

Background. If a link exists between somatic and otolith growth, otolith size and microstructure analysis can be a useful tool in studies of larval fish growth and condition—methods like growth back-calculation or marginal increment width analysis can be employed. Because significance of that link may vary among species and can be additionally modified by temperature, the aim of the present paper is to evaluate how sagittal otoliths of Atlantic menhaden responded to somatic growth and temperature. Materials and methods. Larval Atlantic menhaden, Brevoortia tyrannus (Latrobe, 1802) (age range: 20–120 days; length range: 14–35 mm SL), collected during 3 years were evaluated for length-at-age and groups of the shortest and longest-at-age individuals (8% of sampled population in each group) were used in the analyses. Similarly, otolith size-at-age estimated from sagittae length was evaluated and then compared with the earlier estimated growth indices of larvae. Results. Otolith growth rate (OGR) indicated growth differences among analysed larvae. Additionally, temperature effect on OGR independent of somatic growth was detected for larvae that were short-at-age (i.e., the slow growth group). For the fast grow group, temperature effect on OGR was insignificant. Conclusion. Back-calculation of growth from otoliths of larval and early juvenile Atlanticmenhaden is justified but less accurate estimates can be expected for the slowest growing individuals due to the independent temperature effect on otolith growth.