Spatial analysis of egg distribution and geographic changes in the spawning habitat of the Brazilian sardine Sardinella brasiliensis

Abstract

This paper establishes the spawning habitat of the Brazilian sardine Sardinella brasiliensis and investigates the spatial variability of egg density and its relation with oceanographic conditions in the shelf of the south-east Brazil Bight (SBB). The spawning habitats of S. brasiliensis have been defined in terms of spatial models of egg density, temperature-salinity plots, quotient (Q) analysis and remote sensing data. Quotient curves (Q(C)) were constructed using the geographic distribution of egg density, temperature and salinity from samples collected during nine survey cruises between 1976 and 1993. The interannual sea surface temperature (SST) variability was determined using principal component analysis on the SST anomalies (SSTA) estimated from remote sensing data over the period between 1985 and 2007. The spatial pattern of egg occurrences in the SBB indicated that the largest concentration occurred between Paranaguá and São Sebastião. Spawning habitat expanded and contracted during the years, fluctuating around Paranaguá. In January 1978 and January 1993, eggs were found nearly everywhere along the inner shelf of the SBB, while in January 1988 and 1991 spawning had contracted to their southernmost position. The SSTA maps for the spawning periods showed that in the case of habitat expansion (1993 only) anomalies over the SBB were zero or slightly negative, whereas for the contraction period anomalies were all positive. Sardinella brasiliensis is capable of exploring suitable spawning sites provided by the entrainment of the colder and less-saline South Atlantic Central Water onto the shelf by means of both coastal wind-driven (to the north-east of the SBB) and meander-induced (to the south-west of the SBB) upwelling.

Morphometry and relative growth of the Brazilian sardine, Sardinella brasiliensis (Steindachner, 1879) in the southeastern Brazilian bight

“…The diet varies according to prey availability, which is conditioned by area and season (Goitein, 1978;Schneider & Schwingel, 1999;Kurtz & Matsuura, 2001). The productivity of the SEBB affects the development of the fish, primarily in the larval phase (Matsuura, 1996;Jablonski & Legey, 2004Gigliotti et al, 2010, Moraes et al, 2012. Productivity is more pronounced primarily during spring and summer, consistent with our results and environmental conditions (CARTON-GIESE SODA, 2013).…”

Oceanic and atmospheric patterns during spawning periods prior to extreme catches of the Brazilian sardine (<i>Sardinella brasiliensis</i>) in the southwest Atlantic

“…However, we contend that the quality of the spawning habitat and the interannual catch variability are likely to be a consequence of specific oceanatmosphere linkages rather than the sole choice of a stable environment. There is strong evidence indicating that the spawning habitat expands and contracts along the SBB according to the interannual variability of the horizontal and vertical mesoscale structure of the ocean (Gigliotti et al, 2010). Also, our results on wind stress, Ekman transport and mixing index show a better representation of the contrasts between the southern and northern SBB sectors (Fig.…”

“…Following a physical reasoning proposed in a numerical study performed by Chaves and Nobre (2004), the increased cloudiness (Fig. 6e) in the region is likely to be the cause of the ob- Gigliotti et al (2010) demonstrated that the spawning habitat of the Brazilian sardine expands over the SBB when the SSTA during the spawning period is zero or slightly negative, leading to increased sardine catches in the following year. In contrast, the spawning habitat contracts when SSTA is positive, leading to reduced sardine catches.…”

“…Recently, Gigliotti et al (2010) established for the first time the spawning habitat of the Brazilian sardine on the basis of survey data, spatial modelling and a 23-year-long SST time series from satellite data. Spawning areas are mostly coastal, with the largest one located to the south of the SBB and the patches becoming smaller to the northeast.…”

Modeling the spawning strategies and larval survival of the Brazilian sardine (Sardinella brasiliensis)

“…It has been suggested that this decline is related to overfishing of the Brazilian sardine population (Cergole et al, 2002). However, some studies showed that, besides overfishing, the interannual variation of the Brazilian sardine landings may be partially related to climate patterns and the thermodynamic control of the ocean-atmosphere system (Bakun and Parrish, 1990;Jablonski and Legey, 2004;Gigliotti et al, 2010;Soares et al, 2011).…”