Quantifying environmental effects on the recruitment of the Brazilian sardine (<i>Sardinella brasiliensis</i>), 1977-1993

Abstract

SUMMARY:The recruitment process for Brazilian sardine (Sardinella brasiliensis) from 1977 to 1993 was investigated by taking into account the effects of spawning stock biomass (SSB), the intensity of the wind and the sea surface temperature (SST). Nonparametric models were applied. Best fits resulted from relating recruitment to a combination of SSB and Ekman transport. Transformation of Ekman transport is nearly dome-shaped, with lower and upper limits of 520 and 700 kg s -1 m . SST transformations also follow an apparent dome-shaped curve optimising around 24.75 and 25.5ºC. Inclusion of SST as a third predictor variable led to the loss of the dome-shaped relationship, as shown by the transformations with two predictor variables. Biomass curves are almost logarithmic, their critical point oscillating around 200,000-250,000 t, below which value the stock becomes more dependent on recruitment. The biomass range is greater than previous estimates. [1977][1978][1979][1980][1981][1982][1983][1984][1985][1986][1987][1988][1989][1990][1991][1992][1993]. -El reclutamiento de la sardina brasileña (Sardinella brasiliensis) fue investigado, en el periodo de 1977 a 1993, teniendo en cuenta los efectos de la biomasa del stock frezante, la intensidad del viento y la temperatura de la superficie del mar (TSM). Se aplicaron modelos no parámetricos. Los mejores ajustes fueron obtenidos considerando las variables de biomasa frezante (SSB) y el transporte de Ekman. Para la transformada del transporte de Ekman fue observada una forma aproximada de "domo" con límites inferior y superior, respectivamente, de 520 y 700 kg s -1 m -1 . La fracción de la variabilidad del reclutamiento explicada por el ajuste fue de 94%. Fueron evidenciadas regiones de máximo con lími-tes, respectivamente, de 0,035 y 0,045 N m -2 para el "stress" del viento; y 30 y 45 m 3 s -3 para el índice de turbulencia. Esos valores corresponden a vientos con intensidad entre 3,0 y 4,5 m s -1 . Las transformadas para la TSM muestran, también, un efecto con forma de domo alrededor de 24,75 a 25,5ºC. La inclusión de la TSM como una tercera variable independiente llevó a la 'perdida' de la forma "domo", observada en las curvas de las transformadas para dos variables. Para la biomasa, se observan curvas próximas a la logarítmica, con un valor de cerca de 200 a 250 mil toneladas como límite por debajo del cual el stock pasa a depender mas estrictamente del suceso del reclutamiento. Ese intervalo es superior a las estimativas obtenidas en estimaciones anteriores.

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

“…Previous studies have also shown the importance of spawning quantity and wind intensity to the survival in the initial stages of live. Jablonski and Legey (2004) discussed the importance of SST and wind intensity to the success of Brazilian sardine recruitment, but cited the quantity of spawning as the most important factor. They argue in favour of an optimum interval of wind intensity, between 3 and 4.5 m s -1 , as stronger winds could disrupt plankton distribution and reduce larva survival.…”

“…In another study, Sunyé and Servain (1998) suggest that the seasonal landings of the Brazilian sardine are influenced by the cold and low salinity coastal water flowing along the inner shelf of the SBB. It has been also suggested that low wind velocity and the size of the spawning stock biomass are important factors influencing recruitment variability (Jablonski and Legey, 2004). Paes and Moraes (2007) discussed the influence of El Niño and La Niña events on the variability of the Brazilian sardine yields, and suggested that during El Niño episodes the Subtropical Jet is intensified, blocking the evolution of frontal systems and therefore affecting their reproductive habitat.…”

Fish assemblages on the southeastern Brazilian Bight, sampled by midwater trawl during spring and summer seasons: species composition, abundance, and environmental drivers

“…The growth of pelagic fish larvae occurs at a higher rate in specific temperature ranges, and those ranges differ among species (e.g., Matsuura, 1998). Therefore, this observed fidelity to habitat (water mass) may ensure suitable food supply within optimal temperature conditions for higher larval growth, survival, and recruitment, in turn, ensuring reproductive success (Matsuura, 1998;Jablonski and Legey, 2004). For example, the body condition of larvae of Argentine anchoita was highest in the SACW upwellings (Clemmesen et al, 1997).…”

“…For example, the body condition of larvae of Argentine anchoita was highest in the SACW upwellings (Clemmesen et al, 1997). Results from studies based on observational data (Matsuura, 1998;Jablonski and Legey, 2004) and simulated data (Dias et al, 2014) have indicated that the reproductive activity and larval growth rates of Brazilian sardinella were higher at higher temperatures (~21-27°C) of CW in the SBB.…”