Size at first sexual maturity in Zidona dufresnei (CAENOGASTROPODA: VOLUTIDAE) of the south-western Atlantic Ocean (Mar del Plata, Argentina)

Abstract

Size at sexual maturity was studied in Zidona dufresnei through analysis of gonadal tissue samples and secondary sexual characters. Individuals were sampled during two reproductive seasons (austral spring–summer) in the Mar del Plata area, Argentina. Gonadosomatic index was estimated for males and oocyte size frequency was used to estimate the stage of gonadal development in females. Gonadal maturity occurred prior to the development of secondary sexual characters. Size at first gonadal maturity in females was 12·8 cm shell length and in males 12·0 cm shell length, but size at which 50% of the population was mature was 15·7 cm in females and 15·0 cm in males. The results of this study could help to establish a minimal catching size.

Reproductive cycle and biochemical composition of Hexaplex trunculus (Gastropoda: Muricidae) from Bizerte lagoon, northern Tunisia

“…Differences in the size at first sexual maturity of males and females might be due to differential growth between the sexes (Power & Keegan 2001) or to a delay in sexual maturation of females (Cledón et al 2008). Sexual maturation at smaller sizes in males than in females has also been reported for other gastropod species, including Adelomelon brasiliana (Cledón et al 2008), Buccinum cyaneum (Miloslavich & Dufresne 1994), Buccinum isaotakii (Ilano et al 2003), Odontocymbiola magellanica (Bigatti et al 2008) and Zidona dufresnei (Giménez & Penchaszadeh 2003).…”

“…Differences in the size at first sexual maturity of males and females might be due to differential growth between the sexes (Power & Keegan 2001) or to a delay in sexual maturation of females (Cledón et al 2008). Sexual maturation at smaller sizes in males than in females has also been reported for other gastropod species, including Adelomelon brasiliana (Cledón et al 2008), Buccinum cyaneum (Miloslavich & Dufresne 1994), Buccinum isaotakii (Ilano et al 2003), Odontocymbiola magellanica (Bigatti et al 2008) and Zidona dufresnei (Giménez & Penchaszadeh 2003).Environmental factors influence the quantity and quality of available food and regulate metabolic activities, and therefore play a decisive role in the storage cycle (Gabbott 1983, Carrasco et al 2006. In addition, the species' reproductive cycle and particularly the processes associated with gonad maturation also determine the events of accumulation and depletion of stored energetic reserves (Ansell 1972).…”

Age, growth, and mortality of the prosobranch Zidona dufresnei (Donovan, 1823) in the Mar del Plata area, south-western Atlantic Ocean

“…2) and the growth function (Fig. 4) (Gime´nez and Penchaszadeh 2003). According to our growth model (Fig.…”

“…6). About 50% of all individuals are mature at this age (Gime´nez and Penchaszadeh 2003); that is, only a very small part of the reproductive population is not under exploitation pressure. Both the sharp fall in landings over the last 5 years (2,300 to 1,000 tons in Argentinean and Uruguay fishery) as well as the decrease in maximum size (>190 mm SL in 1999-2000, <190 mm SL in 2001, personal observation) point towards continuous overexploitation of the Mar del Plata stock of Z. dufresnei.…”

“…Over the last 5 years, however, landings in Argentina fell from 1,300 to 500 metric tons per year. At present this fishery is not regulated and the development of management strategies is difficult, as most basic information on population dynamics of Z. dufresnei is missing, except for the reproductive cycle (Gime´nez and Penchaszadeh 2002) and size at first maturity (Gime´nez and Penchaszadeh 2003). Our study provides first estimates of individual growth, production, and mortality in this species.…”