Putting the pieces together: Recent growth, nutritional condition, and mortality of Engraulis anchoita larvae in the Southwest Atlantic

Abstract

Dynamics of clupeiform fish populations such as anchovy are frequently impacted by environmental variations which can affect the success of the species recruitment. Herein, we have analyzed recent otolith growth rate, RNA/DNA nutritional condition index (sRD), and mortality rate of argentine anchovy larvae Engraulis anchoita from three different nursery areas in the Southwest Atlantic. We have evaluated the relationship between the environmental variables (abundance of copepod nauplii, temperature, chlorophyll‐a concentration, and abundance of E. anchoita larvae) and larval endogenous variables (size, weight, age, and otolith radius) to sRD and recent growth rate. Fast larval growth rates were observed toward the northern sector of the studied area, characterized by higher temperature. High values of sRD were associated with higher nauplii abundance in the proximity of coastal fronts. The larvae with the lowest growths and lowest minimum values of nutritional condition coincided with the area where there was less abundance of nauplii and higher larval mortality. Larval size and nauplii abundance were positive explanatory factors for both recent growth rate and sRD index. Temperature had a positive effect on recent growth rate and a negative effect on sRD index. This condition index was poorly explained in terms of model fit in comparison with the growth model. The results herein provided could be significant to better understand the recruitment of the species, as to determining favorable areas for the growth and survival of anchovy larvae.

Evaluating the role of endogenous and exogenous features on larval hake nutritional condition

“…While a positive relationship between larval growth rate and temperature may be expected, the relationship between sRD indexes and the temperature is complex and should be established for each fish species (Buckley et al., 1999). Negative relationships were also observed in other fish larvae species (Do Souto et al., 2019; Esteves, Pina, Chícharo, & Andrade, 2000). This phenomenon may be a consequence of compensatory mechanisms, due to the reduced activity of ribosomes at lower temperatures, and the higher content of RNA required to maintaining the same activity level (Buckley et al., 1999; Bulow, 1987).…”

Body condition of larval roundherring,Gilchristella aestuaria(family Clupeidae), in relation to harmful algal blooms in a warm-temperate estuary

“…Moreover, biochemical condition analyses have the added advantage of responding to conditions that a larval fish experienced 3–4 days prior ( Clemmesen, 1994 ). These indices are advantageous to assessing the effects of the nursery environment on larval growth ( Theilacker et al ., 1996 ; Do Souto et al ., 2019 ; Cohen et al ., 2021 ).…”