Employment of morphometric variables to assess nutritional condition of Argentine anchovy larvae Engraulis anchoita Hubbs & Marini, 1935

Abstract

Most important causes of larval mortality are predation and starvation. The latter can be assessed by the measurement of the nutritional condition. The objective of the present study was to evaluate the nutritional condition of E. anchoita larvae employing morphometric techniques in three different hydrographic areas of the Argentine sea in order to establish regional and interpopulation variability: El Rincón coastal area, Outer-shelf and Península Valdés tidal front. Sampled larvae from El Rincón coastal area showed a higher growth rate (growth curve slope = 3.575) but had lower weight, and thus low Fulton (15.71 ± 3.58, n = 41) and Le Cren (0.63 ± 0.13, n = 41) condition indices, in comparison to specimens from the other two areas (P < 0.001). The Principal Component Analysis, employing morphometrical variables and weight, separated larvae from El Rincón from larvae captured in the other areas. These results could be explained as a consequence of an increase in density dependent mortality or food competition in El Rincón due to a year with an exceptional high larvae production. Our results showed that the use of morphometrical variables and weight allow to find differences in growth rate and nutritional condition among anchovy larvae collected in areas characterized by dissimilar oceanographic scenarios.

Larval population structure of Engraulis encrasicolus in the Strait of Sicily as revealed by morphometric and genetic analysis

“…Several previous studies (Bembo et al ., ; Işmen, ; Magoulas et al ., ; Pollar et al ., ; Diaz et al ., ; Viñas et al ., ) have demonstrated that these methods represent a useful tool for studying the population structure of small pelagic species such as Engraulis encrasicolus .…”

“…(), the larvae were individually placed in the binocular stereo microscope and photographed. Morphometric parameters were acquired by software Image Pro Plus 6.0 (Image Cybernetics, RoperIndustries, SilverSpring, MD, USA; image analysis and processing): total length (TL), standard length (SL), body diameter (BD), head length (HL), eye diameter (ED) and mouth length (ML) (Diaz et al ., ).…”

“…The aim of the present study was to investigate the population connectivity of E. encrasicolus by studying the early life stage using an integrated approach, comprising morphometric variation, growth and mtDNA sequence analysis in the Strait of Sicily. The use of genetic analysis may account for the hypothetical presence of different unit and the morphometric parameters and the larval otolith readings can be a good tool for the evaluation of larval survival and thus the subsequent recruitment in relation to environmental variability (Ré, ; Diaz et al ., ).…”

Potential zooplankton preys (Copepoda and Appendicularia) for <i>Engraulis anchoita</i> in relation to early larval and spawning distributions in the Patagonian frontal system (SW Atlantic Ocean)

“…In terms of the carbon contribution of these four groups to the mixed waters of the front, 60% and 50% of the total biomasses corresponded to cyclopoids and calanoids in the northern and southern transects respectively. Moreover, Diaz et al (2009) found highly propitious nutritional conditions for the anchovy larvae collected in this frontal system, including the first-feeding larvae. Viñas and Ramirez (1996) analyzed the stomach contents of anchovy larvae (2.5 to 5.5 mm standard length), and found that nauplii, eggs and small copepods (<500 µm) were the main food items.…”

Nutritional condition of Argentine anchovy Engraulis anchoita larvae in connection with nursery ground properties

“…They had found better condition indices off Argentinean Patagonia than off Brazil, but they could not relate this fact with hydrographical conditions or prey densities. Later, Diaz et al (2009) demonstrated that the use of morphometrical variables and weight allow to find differences in growth rate and nutritional condition among anchovy larvae collected in areas with different oceanographic scenarios of the Argentinean Sea.…”