Sardine (<em>Sardina pilchardus</em>) spawning in the light of fat content analysis

Abstract

Sardine samples from commercial catches obtained by purse seiners operating in Croatian fishing grounds (eastern Adriatic Sea) were collected monthly from March 2017 to February 2018 (excluding January due to a fishing ban). A total of 1085 sardines were analysed. Their total body length and mass ranged from 11.5 to 16.9 cm (mean±SD: 13.9±0.03 cm) and from 11.30 to 54.03 g (mean±SD: 20.31±0.161 g), respectively. Analysis of the length-mass relationship showed positive allometric growth (b=3.3573, r=0.948). Female specimens were predominant (m/f=0.404). According to the monthly gonadosomatic index values, spawning occurred from November to February, which was consistent with previous investigations. The monthly analysis of fat content in the gonads, liver and muscles indicated that the fat content in each studied tissue oscillated seasonally regardless of sex. These alternations were linked to the sardine’s reproductive cycle.

Seasonal Changes in Free Amino Acid and Fatty Acid Compositions of Sardines, Sardina pilchardus (Walbaum, 1792): Implications for Nutrition

“…As for most clupeids, the spawning season of European sardines from the Central Adriatic occurs between November and April, with a peak in winter, particularly in January and February, depending on a series of environmental factors such as temperature and salinity [ 33 , 34 ]. The low lipid content could be explained by a high energy demand during the spawning period [ 35 , 36 ]. The highest values of lipid content (>10%) were observed in the summer, which coincides with the feeding period of sardines, as there is a peak in primary production (planktonic blooms) during spring and summer.…”

A review of reproduction biology and spawning/ nursery grounds of the most important Adriatic commercial fish species in the last two decades

“…Those anchovies spawning and/or nursery areas were previously characterised as nutrient-enriched areas due to the river inputs or upwelling (MARASOVIĆ et al, 1988;REVELANTE & GLIMARTIN, 1992;GAČIĆ et al, 1997;MAURI & PAULAIN, 2001; KRŠINIĆ, 2010), hence occurrence of anchovy early life stages were expected there. As far as the southern Adriatic is concerned, somewhat lower values of anchovy eggs/larvae abundance were noted in the last two decades (ZORICA et al, 2019) as well as before (MORELLO & ARNERI, 2009), few favourable areas for early life stages were distinguished -the Gulf of Manfredonia (MALAVOLTI et al, 2018), area of Boka Kotorska Bay (MANDIĆ, 2011;MANDIĆ et al, 2011MANDIĆ et al, , 2013MANDIĆ et al, , 20152017;ZORICA et al, 2019) and the area in front of the northern Albania coastline (ZORICA et al, 2019).…”

“…Highest abundances of anchovy eggs/ larvae were noted during the July as it was expected considering the fact that at that month Adriatic anchovy reach its spawning peak. In the whole Adriatic, areas with the higher abundances of its early life stages are mostly placed northern, precisely in GSA 17 -the Gulf of Trieste (TIRELLI et al, 2013, HORVAT, 2017, the Gulf of Venice (TIRELLI et al, 2013), Kvarnerić area, area beyond the Island of Dugi otok, outer part of mid-Dalmatian islands (ZORICA et al, 2015(ZORICA et al, , 2018(ZORICA et al, , 2019 and Zrmanja River estuary (SINOVČIĆ, 2004, SINOVČIĆ & ZOR-ICA, 2006. Those anchovies spawning and/or nursery areas were previously characterised as nutrient-enriched areas due to the river inputs or upwelling (MARASOVIĆ et al, 1988;REVELANTE & GLIMARTIN, 1992;GAČIĆ et al, 1997;MAURI & PAULAIN, 2001; KRŠINIĆ, 2010), hence occurrence of anchovy early life stages were expected there.…”

“…According to ZORICA et al (2019) findings it seems that anchovy tend to shift its spawning centres during its protracted spawning linked to achieving favourable environmental conditions. Precisely, it seems that Adriatic anchovy population firstly starts to spawn in northern and shallower part of Adriatic, where favourable conditions are reached first, and as summer progress anchovy shift it spawning towards the southern areas.…”

“…Precisely, it seems that Adriatic anchovy population firstly starts to spawn in northern and shallower part of Adriatic, where favourable conditions are reached first, and as summer progress anchovy shift it spawning towards the southern areas. Furthermore, over the last two decades' analysis of ichthyoplankton samples reveal that anchovy for its spawning in the area of middle and southern Adriatic preferred the areas with sea depths from 70 m to 120 m (MALAVOLTI et al, 2018;ZORICA et al, 2019).…”