Do the Brazilian sardine commercial landings respond to local ocean circulation?

Mainara B Gouveia,Douglas F M Gherardi,Daniela F Dias,Paula C Campos,Carlos A D Lentini,Guoqi Han

doi:10.1371/journal.pone.0176808

Mainara B Gouveia, Douglas F M Gherardi + Show 4 more

Open Access

https://doi.org/10.1371/journal.pone.0176808

Copy DOI

Abstract

It has been reported that sea surface temperature (SST) anomalies, flow intensity and mesoscale ocean processes, all affect sardine production, both in eastern and western boundary current systems. Here we tested the hypothesis whether extreme high and low commercial landings of the Brazilian sardine fisheries in the South Brazil Bight (SBB) are sensitive to different oceanic conditions. An ocean model (ROMS) and an individual based model (Ichthyop) were used to assess the relationship between oceanic conditions during the spawning season and commercial landings of the Brazilian sardine one year later. Model output was compared with remote sensing and analysis data showing good consistency. Simulations indicate that mortality of eggs and larvae by low temperature prior to maximum and minimum landings are significantly higher than mortality caused by offshore advection. However, when periods of maximum and minimum sardine landings are compared with respect to these causes of mortality no significant differences were detected. Results indicate that mortality caused by prevailing oceanic conditions at early life stages alone can not be invoked to explain the observed extreme commercial landings of the Brazilian sardine. Likely influencing factors include starvation and predation interacting with the strategy of spawning “at the right place and at the right time”.

Highlights

In eastern boundary current systems (EBC), interdecadal variability of sardine populations can be related to both sea surface temperature (SST) anomalies and flow intensity [1]
Surface temperatures inside the South Brazil Bight (SBB) are roughly homogeneous, a reflection of Tropical Waters dominated by the southward flow of the Brazil Current (BC) warm waters
Local heating is known to be an important factor, the orientation of the isotherms suggests that an increase in surface temperature is primarily due to the advection of warm waters from lower latitudes [31]

Summary

Introduction

In eastern boundary current systems (EBC), interdecadal variability of sardine populations can be related to both sea surface temperature (SST) anomalies and flow intensity [1]. During periods of weaker flow, the residence time of larvae in the EBC and reproduction success increase, whereas that during periods of stronger flow, larval survival is restricted to coastal waters and productivity is relatively low. Mesoscale ocean processes, such as current meandering, eddies and thermal fronts can potentially influence sardine production. Biological, behavioral and multispecies interactions play an important role in population variability through mechanisms like undetermined fecundity, temperature. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Methods

Results

Discussion

Conclusion