S. Lo Brutto

The stock genetic structure of two Sparidae species, Diplodus vulgaris and Lithognathus mormyrus, in the Mediterranean Sea

Abstract Polyacrilamide gel electrophoresis (PAGE) of allozymes was used to investigate the intraspecies genetic variation and the genetic stock structure of Diplodus vulgaris and Lithognathus mormyrus captured from eight localities in the Mediterranean Sea. Twenty-two and 20 putative enzyme-coding loci were examined, respectively, in D. vulgaris and L. mormyrus . Polymorphic loci at the 95% level were used to assess the allozyme variability in D. vulgaris ( AAT-2 ∗ , EST-1 ∗ , GLDH ∗ , PEPB-2 ∗ , PGI-2 ∗ , PGM ∗ , SDH ∗ ) and L. mormyrus ( AAT-2 ∗ , EST-1 ∗ , GLDH ∗ , MDH-2 ∗ , PGI-2 ∗ , PGM ∗ ). The proportion of polymorphic loci in both species ranged from 0.31 ( D. vulgaris ) to 0.30 ( L. mormyrus ), and the observed and expected mean heterozygosity varied between 0.082 and 0.093 ( D. vulgaris ) and between 0.069 and 0.072 ( L. mormyrus ). The mean value of observed heterozygosity in D. vulgaris showed a deficit of heterozygosites, thereby indicating a Wahlund effect in the samples examined. Significant genetic differentiation (mean value of θ =0.013, p D. vulgaris indicating an intraspecific genetic substructure among the samples examined, whereas the mean value of θ =0.001, p >0.05 found in L. mormyrus showed a high degree of genetic homogeneity. The results showed the presence of distinct subpopulations of D. vulgaris among the sampled sites, and suggested that analysis of allozymes may provide important information on the genetic stock structure of these two sparids to ensure sustainable management of these species.

Growth Parameters and Population Structure of Aristeus Antennatus (Decapoda, Penaeidae) in the South Tyrrhenian Sea (Southern Coast of Italy)

The blue and red shrimp Aristeus antennatus (Risso, 1816) is one of the most important fishery resources in the Mediterranean Sea. Monthly samplings of blue and red shrimp from June 2006 to May 2007 were landed by the trawl fleet in two northwest Sicilian fishing harbours (San Vito Lo Capo and Terrasini). The carapace length (CL) frequency distribution of females ranged between 15.00 and 59.00 mm, whereas male CLs ranged between 17.00 and 34.00 mm. The estimated parameters of the Von Bertalanffy growth function (VBGF) for San Vito lo Capo females and males were: CL∞ = 65 mm, K = 0.58 y–1 and CL∞ = 41 mm, K = 0.71 y–1, respectively; while for Terrasini females and males these were: CL∞ = 69 mm, K = 0.65 y–1 and CL∞ = 37 mm, K = 0.8 y–1, respectively. In this study, we update the information on stock structure and growth parameters of the blue and red shrimp in two northwest Sicilian fishing grounds and compare these results with other data recorded in the Mediterranean Basin.

Growth and Reproduction Data of Plesionika Narval (Decapoda, Caridea, Pandalidae) Off the Island of Ustica (Southern Tyrrhenian Sea)

[We here report some data on the biology and population structure of Plesionika narval (Fabricius, 1787) captured along the coast of the island of Ustica in the southern Tyrrhenian Sea. Specimens were collected monthly from January to October 2000 using commercial traps at depths ranging from 15 to 100 metres. The carapace length (CL) of females ranged between 7.0 and 26.0 mm, and between 7.0 and 17.0 mm for males. Three modes were identified in the cumulative frequency distribution for females but only two for males. In females, the third modal value was observed only at the deeper sample sites. The Von Bertalanffy growth parameters and performance index p were K = 0.65 y–1, CL∞ = 27.4 mm CL and p = 2.62 for females, and K = 0.71 y–1, CL∞ = 17.8 mm CL and p = 2.28 for males. Ovigerous females were found during the entire period of the investigation, indicating that this species spawns all year round. We compared our results with other data recorded in the literature., We here report some data on the biology and population structure of Plesionika narval (Fabricius, 1787) captured along the coast of the island of Ustica in the southern Tyrrhenian Sea. Specimens were collected monthly from January to October 2000 using commercial traps at depths ranging from 15 to 100 metres. The carapace length (CL) of females ranged between 7.0 and 26.0 mm, and between 7.0 and 17.0 mm for males. Three modes were identified in the cumulative frequency distribution for females but only two for males. In females, the third modal value was observed only at the deeper sample sites. The Von Bertalanffy growth parameters and performance index p were K = 0.65 y–1, CL∞ = 27.4 mm CL and p = 2.62 for females, and K = 0.71 y–1, CL∞ = 17.8 mm CL and p = 2.28 for males. Ovigerous females were found during the entire period of the investigation, indicating that this species spawns all year round. We compared our results with other data recorded in the literature.]