Seasonal and spatial variability in condition of age‐0+ Argentine hake Merluccius hubbsi Marini, 1933, in the San Jorge Gulf (Argentina): A bottom‐up perspective

Abstract

Fish survival at early life stages depends on the temporal and spatial overlap with prey resources, following the match-mismatch hypothesis (Cushing, 1990). In temperate ecosystems, variability in physical and biological features such as the onset of stratification, light availability and the occurrence of phytoplankton blooms affects the seasonal and spatial patterns of zooplankton abundance, which further influences the feeding success of planktivorous fish. Adequate feeding translates into energy reserves stored within individuals, which reflect their well-being or physiological condition to accomplish essential biological processes such as growth and reproduction

Cold offshore area provides a favorable feeding ground with lipid‐rich foods for juvenile Japanese sardine

“…Fish generally store lipids as various deposits in the body such as mesenteric, muscle, and liver fat (Sheridan, 1988). The liver fat has a major role in bottom‐dwelling (lean) fish (Lambert & Dutil, 1997; Temperoni et al, 2020), whereas mesenteric and muscle fat are important as lipid deposits in more active fish (Sheridan, 1988). The temporal scale of lipid changes is different from deposits.…”

“…From fluctuations in these indexes, we might be able to deduce that food availability in the offshore area is superior to that in the coastal area, while the feeding opportunities for the sardine vary with small spatiotemporal scales within each area. For dynamic and heterogeneous feeding environments, the combination of multiple body condition indices to investigate fish body parameters would be desirable (McPherson et al, 2011; Temperoni et al, 2020) and may help our understanding of fish feeding conditions.…”

Who let the young‐of‐the‐year (YOY) up? The pelagic habitat as a nursery and feeding ground area for the YOY Argentine hake Merluccius hubbsi Marini, 1933

“…Seasonal diet shift, with more consumption of the Euphausiid Euphausia spp. and the hyperiid amphipod T. gaudichaudii during the warm season, would be related to the abundance of these zooplankton prey which reach their annual maximum during summer (Pérez Seijas et al ., 1987; Sabatini & Alvarez‐Colombo, 2001), and this was in accordance with a bottom‐up effect on condition of YOY hake previously suggested, manifested as lower condition values in winter, the less productive season (Temperoni et al ., 2020).…”

“…Seasonal differences with high cannibalism rate during the warm season than during the cold one were also herein reported, and it was in accordance with the vertical distribution of YOY pelagic hake, located at larger distances from the bottom during the cold season, probably reducing natural mortality by cannibalism. Moreover, the YOY hake condition indices showed significant seasonal variations, with minimum values in winter (percentage of lipids: 4.7 ± 1.4), intermediate in summer (percentage of lipids: 10.6 ± 5.1) and maximum in spring (percentage of lipids: 17.2 ± 5.2) (Temperoni et al ., 2020), so they would be better as prey in terms of lipid contribution, during the warm season. The present paper provides crucial information about the biology and ecology of early life cycle stage of the Argentine hake M. hubbsi , to understand the processes involved in the recruitment and the success of a cohort.…”

Reclutamiento de la merluza argentina, Merluccius hubbsi, del stock patagónico: una revisión de las principales características que afectan el potencial reproductivo y la supervivencia durante las primeras etapas de la vida

“…First studies to assess the condition of YOY hake were carried out by Prenski and Angelescu (1993) using the Fulton index. In more recent analyses, information on lipids stored in the liver (hepatosomatic index HSI, and lipid percentage %L) was incorporated as a proxy of condition (Temperoni et al 2018(Temperoni et al , 2020a. Both indices showed significant seasonal and spatial variations, being maximum in spring and minimum in winter, with intermediate values in summer, associated with variations of Chl-a concentration from satellite measures.…”