Transition period from larva to juvenile in anchoveta Engraulis ringens. Length or age related?

Abstract

To determine the beginning and end of the transition period from larvae to juveniles in anchoveta Engraulis ringens, seven morphometric measurements were carried out in 333 laboratory-reared and 324 field-caught larvae. Measurements of body morphometrics were employed to calculate the six body ratios selected to show transition changes described in this study. The analysis was carried out with 'dummy variables' (variables that take only one of two possible values: 0 or 1) because a single model was used to indicate the point at which the slope changes in piecewise linear regressions. The regression coefficients of the relationship between ratios of morphometric measurements and body length were not significant in any case (P > 0·05) and, accordingly, a discrete length at which the slope changes could not be estimated. The ratio of the measurements according to the age showed two inflections, corresponding to the beginning and end of the transition period. The first inflection occurred between 32 and 64 days (average 46 days); the second inflection occurred between 81 and 149 days (average 107 days). Therefore, the transition period lasted c. 61 days, starting with a high growth rate, continuing with a slower growth phase, and ending with the onset of a new high growth rate period that corresponded to the start of typical juvenile growth. On the basis of these results, it is hypothesized that the transition from larvae to juveniles in E. ringens is determined more by age than body size.

Growth and mortality of larval anchoveta Engraulis ringens, in northern Chile during winter and their relationship with coastal hydrographic conditions

“…In this scenario, the growth differences among cohorts that live in upwelling zones may reduce intraspecific competition for food (Hernández & Castro, ). Studies on E. japonicus larvae indicate that faster growth rates result in higher survival in the adult stages compared to slow‐growing individuals (Takahashi & Watanabe, ; Takasuka, Aoki, & Oozeki, ) even though age would be a determinant factor compared to body length in the transition from larva to juvenile (Moreno et al., ). To conclude, even though the environmental conditions in northern Chile can markedly change over a short period, the first hatching larvae will have a faster growth rate as well as a higher probability of escape from predators due to the higher energy delivered by their parents.…”

“…Studies about larval anchoveta development have been conducted mostly in south‐central Chile and along Peruvian shores (Bustos, Landaeta, & Balbontín, ; Castro & Hernández, ; Castro et al., ; Cubillos et al., ; Hernández & Castro, ; Landaeta & Castro, ; Landaeta, Ochoa‐Muñoz, & Bustos, ; Lett, Penven, Ayón, & Freón, ; Soto‐Mendoza, Castro, & Llanos‐Rivera, ). Nevertheless, in northern Chile (Moreno, Claramunt, & Castro, ), which is an area characterized by coastal upwelling throughout the year, there have been few studies aimed at analyzing the early life history of this species and its relation to oceanographic dynamics. In northern Chile, winter upwelling conditions should generate higher mortality rates because of the increase in offshore transport but also high growth rates due to increased temperature.…”

Climate change scenarios experiments predict a future reduction in small pelagic fish recruitment in the Humboldt Current system

“…Each day of the simulations, 5000 individuals were evenly spawned (released) over the continental shelf (from the coast to the 500 m depth isobath) from 4 °S to 38 °S and from the surface to 50 m depth (see Supplementary methods for details). Individuals were then tracked for 30 days, covering most of the anchovy larval phase (Moreno et al ., ) during which their swimming capability is limited and advection by currents is the main factor of horizontal motion.…”

Embryonic development and effect of temperature on larval growth of the Peruvian anchovy Engraulis ringens

“…During the 1970s and 1980s, studies on larval diet (De Mendiola, 1974) and behaviour of first‐feeding larvae (Walsh et al ., 1980; Ware et al ., 1981) were published, and Pauly (1987) pointed out the correlation between the abundance of anchovy larvae and high phytoplankton concentrations in the HCS, referring to it as a “recruitment window.” Since the 2000s, the number of studies on anchovy eggs and larvae collected in Chilean coastal waters has increased (Contreras et al ., 2017; Hernandez & Castro, 2000; Llanos‐Rivera & Castro, 2004; Yañez‐Rubio et al ., 2011), and among them, Moreno et al . (2011) reported the successful rearing of E. ringens larvae and juveniles until an age of 163 days post‐hatch (dph). Nonetheless, very few laboratory studies have focused on the ontogeny and behaviour of this species (Llanos‐Rivera & Castro, 2006; Tarifeño et al ., 2008).…”