Spatiotemporal Analysis Of The Daily Growth Traits Of The Prerecruits Of A Small Pelagic Fish In Response To Environmental Drivers

A comparative analysis of daily growth patterns was carried out for prerecruits (PR) of Engraulis ringens, collected from spring to summer (2015-2016) in northern (18 degrees 25'S-24 degrees 40'S) and southern nursery areas (32 degrees 40'S-41 degrees 00'S) off the Chilean coast. Prerecruits ranged from 2.2 to 7.3 cm TL (4.27 +/- 0.88) and from 27 to 102 days (54.68 +/- 15.92) of age and were hatched mainly in spring 2015. Growth traits were addressed through otolith microstructure analysis to determine the increment width profiles (IW), back-calculated growth rates (BIGR), and overall absolute growth rates (AGR), whereas the Chl-aand sea-surface temperature (SST) variations were assessed by analyzing satellite and field-based data. The IWs (5.42 +/- 1.94 mu m versus 1.02 +/- 0.37 mu m), BIGRs (1.02 +/- 0.37 versus 0.72 +/- 0.26 mm center dot day(-1)), and AGRs (0.93 +/- 0.15 versus 0.62 +/- 0.08 mm center dot day(-1)) were significantly higher in the northern than in the southern stocks. The SST ranged from 17 degrees C to 23 degrees C (19.42 +/- 1.45) and from 12 degrees C to 18 degrees C (14.81 +/- 1.31) and varied significantly between stocks and months, whereas the higher concentration of Chl-alpha (similar to 8 mg/m(3)), occurred close to the shallow coastal areas irrespective of stocks. A parabolic relationship between the recent otolith growth rates (ROGR) (as a proxy of recent daily somatic growth rates) and SST recorded at the date of capture estimated a maximum ROGR of 13.4 mu m center dot day(-1) at 18 degrees C. These results demonstrated that water temperature seemed to be an important daily growth controller for early juveniles of E. ringensin the Humboldt Current System and that the field-based growth-temperature relationship obtained will contribute to future potential bioenergetics models for this important forage species.