Fish is a significant aquatic animal which had developed and modified reproductive strategies and characters to ensure its survival of the species under unfavorable circumstances1. These characteristics include age and size fecundity, time duration and frequency of spawning, size at first maturity and reproductive behaviour1,2, crucial to manage fisheries3. The Sardinella is a marine pelagic fish extensively found in tropical and subtropical seas of the world, including the entire Mediterranean and the Black sea4. Production of Sardinella exhibited variations from 1990 to 2014 and the biomass of showed fluctuations (associated with the migrations of the species).
Deep investigation regarding the reproductive biology of round Sardinella has been done in the Western5,6 and Eastern Atlantic7,8. Conversely, knowledge was less about the Atlantic Moroccan coast and study has been accomplished across its Mediterranean distribution. Including research about reproduction of Sardinella aurita in Algerian9,10, Tunisian waters11 and Egyptian12 waters. Ayoub Baali and team conducted an experiment to evaluate the reproductive biology of Sardinella aurita and Sardinella maderensis in the Southern Moroccan Atlantic including the time and duration of the spawning, the annual reproductive cycle, in terms of monthly changes in maturity stages, the sex-ratio, sex-ratio variation on the size and the size at first sexual maturity.
Scientists collected the monthly samples between February, 2015 and January, 2016 in the area between Cape Boujdor and Cape Blanc to calculate the aspects mentioned above. The χ2 test was used to compare the differences between both sexes and the data variation was analyzed by adopting ANOVA test. Ayoub and companion researchers noted that Sardinella sp. is a gonochoristic fish. The overall female to male ratio didn’t varied statistically for both species (χ2 = 0.68 for Sardinella aurita and χ2 = 1.04 for Sardinella maderensis), even though it fluctuated according to the length of the fish and seasonally.
It was also observed that the monthly changes in the gonadosomatic index and the macroscopic traits of gonads exhibited that round Sardinella in the South of Morocco spawns between February and July and between November and December with a spawning peak on April. While in case of flat Sardinella, spawning happens between February and March and in July with a peak point in July. Females round Sardinella reach first sexual maturity at a smaller size than males (26.17 and 26.78 cm, respectively). Conversely, case was contradictory in flat Sardinella. While, males reaching sexual maturity are smaller than females having sizes 20.75 and 21.76 cm, respectively. Conclusively, the spawning of S. aurita exhibits a pick in April and for S. maderensis in July. Consequently, as a shared stock this investigation will pave a way for stock assessment in the North West Africa area.
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17 November, 2019