Effect of ENSO on the distribution and concentration of catches and reproductive activity of anchovy Engraulis ringens in northern Chile

Abstract

Anchovy makes up 90% of pelagic fishery catches in northern Chile. For the present work, anchovy (Engraulis ringens, Jenyns 1842) catches between 1997 and 2016 were analyzed to determine changes in distribution, concentration, and reproductive behavior before, during, and after ENSO events, using spatial indexes: gravity center (GC), inertia, coverage (CI), Gini index, and gonadosomatic index (GI). At the start of ENSO, anchovy catches increased and concentrated along the coast (rising Gini index), while CI decreased. During ENSO, Gini decreased, registering a southward displacement of the GC and smaller catches. In the long run, anchovy occupied lesser area (<CI) starting from 2008, concentrating in coastal areas. It developed a size structure composed mainly of specimens smaller than 17.0 cm. In addition, specimens < 12.0 cm were positively correlated with thermal anomalies, CI and MEI, reaching more than 60% of the catches during the 1997–1998 and 2015–2016 ENSO cycles. Results suggest that the warm phase of ENSO alters the anchovies’ reproductive activity, delaying its onset up to 4 weeks, and reducing GI intensity to 50%, due to increased participation in the reproductive process of individuals 12.0–13.5 cm. Therefore, large‐scale environmental processes, such as ENSO, significantly affect size structure and contribute to reduction of occupied area and higher reproductive activity of small‐size anchovies.

AnchovetaEngraulis ringensalong the Chilean coast: Management units, demographic units and water masses: Insights from multiple otolith‐based approaches

“…While early stages seem to be retained nearby spawning areas, older anchoveta acquire an increasing ability to escape from anomalous El Niño conditions by moving horizontally to the SE and vertically to deeper waters, as observed at both the Peruvian (Bertrand, Segura, Gutiérrez, & Vásquez, ; Gutiérrez, Castillo, Segura, Peraltilla, & Flores, ; Swartzman, Bertrand, Gutiérrez, Bertrand, & Vasquez, ) and the northern Chilean coast (Blanco, Barria, Castillo, & Atkinson, ; Hernández‐Santoro, Landaeta, & Castillo Pizarro, ). It has been hypothesized that these movements are directed to reach Cold Coastal Water (CCW), which are characterized by a salinity range of 34.8–35.05 and a temperature range of 15–19°C (Bertrand et al, ).…”

Assessing Granger-Causality in the Southern Humboldt Current Ecosystem Using Cross-Spectral Methods

“…Examples include, (1) distribution of anchovy changes in space and depth during warm conditions such as El Niño; (2) after 2002 female length classes showing a positive trend of the gonadosomatic index (GSI), indicating favorable development of anchovy gonads coinciding with the period of prevailing cool conditions without strong, warm events (i.e., El Niño 1997–98); and (3) cool conditions will favor the presence of cold coastal water, a shallower thermocline, stronger upwelling and higher productivity [ 4 ]. Differences could be related to how anchovies synchronize reproductive dynamics with local environmental conditions to foster survival of offspring [ 5 ]. These dynamics are ultimately influenced by other long-term climatic processes, such as mild temperature changes [ 6 ].…”

“…This is due to warm/cool phase changes produced by environmental changes associated with sea surface temperature (SST) which affects upwelling habitat conditions. Thus, regional factors could reduce the horizontal upwelling habitat, leading to more anchovy abundance on the coast [ 4 , 5 ].…”

Spatiotemporal analysis of the daily growth traits of the prerecruits of a small pelagic fish in response to environmental drivers

“…One of the forage species that supports substantial fishery activity but has high recruitment variability in the Humboldt Current System (HCS) in the southeast Pacific Ocean (SPO) is the anchoveta Engraulis ringens , which is distributed from 4º30'S to 42º30'S (Bertrand et al., 2008; Hernández‐Santoro, Landaeta, & Pizarro, 2018). In this area, intense fishery activity has caused anchoveta landings to reach the highest levels in recent decades, with 4.3 and 3.1 million tons landed by Peru and Chile, respectively, between 2015 and 2016 (Pikitch et al., 2012).…”

“…The extensive Chilean coast offers a marked latitudinal gradient, where sea surface temperatures can vary between 14 and 24°C in more northern areas (18–24°S) and 10–16°C toward more extreme southern areas (38–42 o S) (Hernández‐Santoro et al., 2018; Pinochet, Garcés‐Vargas, Lara, & Olguín, 2019; Thiel, Macaya, & Acuña, 2007). Furthermore, throughout this long distribution area, E. ringens is influenced by the dynamics of upwelling events, which trigger high productivity conditions but differ from the northern areas to southern ones (Thiel et al., 2007).…”