Establishing length-at-age references in the red mullet, Mullus barbatus L. 1758 (Pisces, Mullidae), a case study for growth assessments in the Mediterranean Geographical Sub-Areas (GSA)

Length at age data are a fundamental tool for the assessment of exploited fish populations, their use requiring the identification of the ‘unit stock’. At the present, however, the spatial reference for stock assessment in the Mediterranean Sea is based on a grid of 30 arbitrary Geographical Sub Areas (GSA). Since older data rarely respect the GSA borders, the authors propose to reconstruct the historical data within a common frame and to assess a single reference length at age, together with the corresponding von Bertalanffy growth parameters, to be used as a broad benchmark for analyses inter and intra GSAs. This approach was tested using, as a case study, the red mullet (Mullus barbatus L. 1758), one of the most investigated fish of the whole Mediterranean basin. Published and grey literature was browsed, to get direct and/or indirect length at age estimations. To establish a common baseline and maximize the use of partial information, a vBGF (L∞, total length in mm, and Ky-1) was fitted to length at age data whenever possible. 56 Mediterranean sets were utilized; an overall reference growth line was estimated by sex, discussing its adequacy to the life traits of the species

Age determination of illex coindetii from the strait of sicily by statolith increment analysis

A total of 649 short-finned squid Illex coindetti caught in the Strait of Sicily (Central Mediterranean) was examined to investigate statolith microstructure and estimate the number of growth increments. Two different methods of analysis were employed to count increments, the conventional method by eye and an automatic image-analysis system (IAS). Age estimates (based on the assumption of daily deposition of increments) obtained with the two methods were compared. Maximum ages estimated by eye were 230 and 240 days for males and females respectively. Average IAS estimates were significantly higher (2 days more for males and 5 days more for females) than the conventional ones. Size-at-age relationships were computed from both sets of age estimates using three size indicators: mantle length, body mass and an index calculated as the ratio between the logarithmic values of body mass and mantle length. Size-at-age relationships were similar for both methods of counting increments. Best fits were obtained using the quadratic, power and von Bertalanffy models applied to mantle length, body mass and the new index respectively

Estimating the girth of fish by applying an elliptic model

A new method for estimating the maximum girth of roundfish is proposed as illustrated; this is based on an elliptic approximation of the cross sections of the fish body. Results derived from a small sample horse mackerel, Trachurus trachurus, suggest that maximum girth estimates based on the elliptic model are more precise than the values estimated by applying a conventional method

Distribution and biology of the Blackmouth catshark Galeus melastomus in the Strait of Sicily (Central Mediterranean Sea)

The Blackmouth catshark, Galeus melastomus, Rafinesque, 1810 (Carcharhiniformes; Scyliorhinidae), is a common, although at present discarded, by- catch of the bottom trawl fisheries in the Strait of Sicily. Given its ecological interest, data gathered in experimental bottom trawl surveys were analysed in order to describe its distribution and main biological traits. The Blackmouth catshark was sampled almost exclusively on the upper slope (200-800), showing the highest frequency of occurrence (69-100%), biomass (BI; 10-85 kg*km-2) and density (DI; 54-506 N*km-2) indexes in the deeper (501-800m) grounds. Individual size (total length, TL, mm) were between 70-590 and 90-510 in females and males, respectively. The sex ratio (SR) was around 0.5. The SR by size showed a gradual decrease till 450 mm class size, followed by an increase up 1 after 500 mm. Virginal/immature specimens represented the bulk of the samples in both females (77%) and males (65%); the length at 50% of sexual maturity (Lm50%) and corresponding maturity range (Lm25% - Lm75% ) was 433 (423-443) and 380 (366-394) mm, respectively

Ablation of atrial tachycardias in children by non fluoroscopic 3-D mapping

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Enterprising students: a values-driven, competency-based framework for embedding enterprise in the HE curriculum

To explore the topic of what enterprise and entrepreneurship education can add to the experiences of students., the Embedding Enterprise in the Arts, Humanities and Social Sciences project was developed in collaboration with Advance HE, SFEDI, the UK Government recognised Sector Skills Organisation for enterprise and business support, and higher education providers across the sector. The project was designed to promote collaboration, sharing good practice, and developing innovative approaches to embedding enterprise and entrepreneurship education. This collection of case studies from project participants explore how to embed enterprise and entrepreneurship education within a range of different academic disciplines. In so doing, the case studies will support experience exchange amongst educators wishing to add value through enterprise and entrepreneurship education

Batoid abundances, spatial distribution, and life history traits in the strait of sicily (Central mediterranean sea): Bridging a knowledge gap through three decades of survey

Batoid species play a key role in marine ecosystems but unfortunately they have globally declined over the last decades. Given the paucity of information, abundance data and the main life history traits for batoids, obtained through about three decades of bottom trawl surveys, are presented and discussed. The surveys were carried out in two areas of the Central Mediterranean (South of Sicily and Malta Island), in a timeframe ranging from 1990 to 2018. Excluding some batoids, the abundance trends were stable or increasing. Only R. clavata, R. miraletus, and D. oxyrinchus showed occurrence and abundance indexes notable enough to carry out more detailed analysis. In particular, spatial distribution analysis of these species highlighted the presence of two main hotspots in Sicilian waters whereas they seem more widespread in Malta. The lengths at first maturity (L50) were 695 and 860, 635 and 574, and 364 and 349 mm total length (TL), respectively, for females and males of D. oxyrinchus, R. clavata, and R. miraletus. The asymptotic lengths (L∞) and the curvature coefficients (K) were 1365 and 1240 (K = 0.11 and 0.26), 1260 and 1100 (K = 0.16 and 0.26), and 840 and 800 mm TL (K = 0.36 and 0.41), respectively, for females and males of D. oxyrinchus, R. clavata, and R. miraletus. The lack of detailed quantitative historical information on batoids of Sicily and Malta does not allow to analytically judge the current status of the stocks, although the higher abundance of some species within Malta raises some concern for the Sicilian counterpart. In conclusion, suitable actions to protect batoids in the investigated area are recommended