Reproductive biology characteristics of red mullet (Mullus barbatusL., 1758) in Southern Adriatic Sea and management implications

Abstract

The main important reproductive aspects of Mullus barbatus, one of the most important target species for the fishery in the Mediterranean basin, have been studied on the basis of MEDITS trawl survey and sampling of commercial landing. The total length (TL) of females has been demonstrated to be positively correlated with egg sizes and plasmatic concentration of vitellogenin. The possible implications of these aspects on the management of red mullet resources are discussed in this work. Moreover, the relationship between TL and fecundity follows an exponential pattern with a temporal trend during the spawning season. These results represent an important input for more effective management measures, such as the seasonal closure of fishery in summertime. The frequency distribution of the oocytes' diameters showed an asynchronous ovarian organization with batch spawning pattern. Monthly variations in the gonadosomatic index and maturity stages percentage showed that males spawn during almost the entire year showed an increasing trend from November to June and a decreasing trend from July to October, while females in spawning phase are recorded from April to July, with peaks in May and June. The length at 50% maturity (L50) estimated respectively for females and males are 12.1 cm (±0.083) and 10.1 cm (±0.073).

A holistic approach to the age validation of Mullus barbatus L., 1758 in the Southern Adriatic Sea (Central Mediterranean)

“…According to reproductive patterns, the theoretical birthday was set at 1 st July 20 . The age estimation scheme utilized is reported in Table 1.…”

The MEDITS maturity scales as a useful tool for investigating the reproductive traits of key species in the Mediterranean Sea

“…germinal vesicle migration) are also considered to be in the mature/spawner stage (stage 3). In M. barbatus, as in other batch spawners, the presence of all stages of oocytes (i.e., PG, CA, Vtg 1, Vtg 2, Vtg 3 and OM) is observed (Carbonara et al 2015), whereas in total spawners Vtg3 or early OM and PG are the only oocytes present. The evidence that batch spawner fish, in stage 3, have already spawned in a previous event could be detected by the presences of post-ovulatory follicles.…”

“…In general, the more or less rapid growth as a result of the different hatching season leads specimens to reach sexual maturity at different sizes, thus justifying the variability of data recorded in the geographical areas investigated. Generally, when maturity data are used for maturity ogive estimation, one important issue should be taken into consideration: the possible macroscopic misclassification of resting females as immature (ICES 2015, Carbonara et al 2015. Specifically in teleosteans, the difference between resting and recovery is sometimes unclear, and apparently means the same thing for researchers who consider recovering (or regenerating) or resting as a single stage.…”

“…For the red mullet, the immature specimens are rare/ lacking during the spawning period because they reach the first maturity in the first years of life (Carbonara et al 2015). This pattern of maturing/growth makes it difficult to estimate SFM 50 only with data collected during the spawning period.…”

“…Mullus barbatus Linnaeus, 1758 (red mullet) for Osteichthyes -iteroparous and batch spawner (Carbonara et al 2015);…”