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

2009 ◽  
Vol 10 (1) ◽  
pp. 55 ◽  
Author(s):  
S. RAGONESE ◽  
G. NARDONE ◽  
D. OTTONELLO ◽  
S. GANCITANO ◽  
G.B. GIUSTO ◽  
...  
Keyword(s):  
Sexual Maturity ◽  
Bottom Trawl ◽  
Biological Traits ◽  
Central Mediterranean ◽  
Strait Of Sicily ◽  
By Catch ◽  
Trawl Fisheries ◽  
Individual Size ◽  
Trawl Surveys ◽  
Upper Slope

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.

scholarly journals Rapid-response indicators of changes in resource state based on Mediterranean bottom-trawl surveys

2005 ◽  
Vol 62 (3) ◽  
pp. 511-515 ◽  
Author(s):  
Sergio Ragonese ◽  
Gaia Morizzo ◽  
Alberto De Santi ◽  
Marco L. Bianchini
Keyword(s):  
Sex Ratio ◽  
Multivariate Techniques ◽  
Target Species ◽  
Median Length ◽  
Central Mediterranean ◽  
Strait Of Sicily ◽  
Dimensional Scaling ◽  
Multi Dimensional Scaling ◽  
Trawl Surveys ◽  
Resource State

Abstract The authors propose a method for developing operational indicators of resource state, with an example based on a set of eight variables (mean abundance index in weight, mean body weight, median length, sex ratio, sex ratio by selected length class, mean and median female length-at-maturity, and percentage of females at maturity) derived from surveys conducted in the Strait of Sicily (central Mediterranean Sea, 1994–2002) for six target species. The method combines univariate (kite diagrams, sphere displacement plots) and multivariate techniques (multi-dimensional scaling).

A comparison between acoustic and bottom trawl estimates to reconstruct the biomass trends of sardine and anchovy in the Strait of Sicily (Central Mediterranean)

2013 ◽  
Vol 147 ◽  
pp. 290-295 ◽  
Author(s):  
Fabio Fiorentino ◽  
Bernardo Patti ◽  
Francesco Colloca ◽  
Angelo Bonanno ◽  
Gualtiero Basilone ◽  
...  
Keyword(s):  
Bottom Trawl ◽  
Central Mediterranean ◽  
Strait Of Sicily

scholarly journals Distribution characteristics of pandalid shrimps (Decapoda: Caridea: Pandalidae) along the Central Mediterranean Sea

2004 ◽  
Vol 5 (2) ◽  
pp. 35 ◽  
Author(s):  
E. FANELLI ◽  
F. COLLOCA ◽  
A. BELLUSCIO ◽  
G.D. ARDIZZONE
Keyword(s):  
Spatial Distribution ◽  
Mediterranean Sea ◽  
Shelf Break ◽  
Distribution Characteristics ◽  
Central Mediterranean ◽  
Bathymetric Distribution ◽  
Spatial Differences ◽  
Study Population ◽  
Trawl Surveys ◽  
Upper Slope

The genus Plesionika is represented in the Mediterranean Sea by eight species, six of which,Plesionikaacanthonotus, P. antigai, P. edwardsii, P. gigliolii, P. heterocarpus and P. martia, are very common on muddy bottoms of the continental slope. During nine experimental trawl surveys a total of 29,038 individuals of these six pandalid species, was collected off the central western coasts of Italy (central Mediterranean) in order to study population structure and spatial distribution. P . antigaiinhabits the shelf break and upper slope; P. heterocarpus shows a wide bathymetric distribution, from the shelf-break to the upper slope; P. edwardsii and P. gigliolii occur in the upper slope. P. acanthonotus and P. martia occur in the deepest depths investigated. Segregation by size is revealed for the species that inhabit the same bottoms. The non-homogenous spatial distribution of Plesionikaspecies in the study area was probably related to the spatial differences in the magnitude of primary production in the area.

scholarly journals 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

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2189
Author(s):  
Michele Luca Geraci ◽  
Sergio Ragonese ◽  
Danilo Scannella ◽  
Fabio Falsone ◽  
Vita Gancitano ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Life History ◽  
Life History Traits ◽  
Current Status ◽  
Distribution Analysis ◽  
Central Mediterranean ◽  
Strait Of Sicily ◽  
Abundance Trends ◽  
First Maturity ◽  
Trawl Surveys

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.

scholarly journals A new record of a great white shark, Carcharodon carcharias(Chondrichthyes: Lamnidae) in the Strait of Sicily, Central Mediterranean Sea

2020 ◽  
Vol 61 (2) ◽  
pp. 231-238
Author(s):  
Danilo Scannella ◽  
Sergio Vitale ◽  
Federico Di Maio ◽  
Fabrizio Serena ◽  
Bruno Zava ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
White Shark ◽  
Central Mediterranean ◽  
Carcharodon Carcharias ◽  
Strait Of Sicily ◽  
Male Individual ◽  
Great White Shark ◽  
Central Mediterranean Sea ◽  
By Catch ◽  
Available Information

In November 2015 an immature male individual of great white shark, Carcharodon carcharias (Linnaeus 1758), was caught as by-catch by a bottom trawler in the Strait of Sicily, in the Central Mediterranean Sea. The shark, reaching 266 cm in length and weighing 290 Kg, was identified and measured by means of a video provided by fishers. This record is discussed considering the available information on the presence of the great white shark in the area and confirms the importance of the Strait of Sicily for the conservation of this vulnerable species.

scholarly journals Anglerfish discard estimates and patterns in Spanish Northeast Atlantic trawl fisheries

2008 ◽  
Vol 65 (7) ◽  
pp. 1350-1361 ◽  
Author(s):  
Paz Díaz ◽  
Juan Santos ◽  
Francisco Velasco ◽  
Alberto Serrano ◽  
Nélida Pérez
Keyword(s):  
Atlantic Ocean ◽  
Length Distribution ◽  
Bottom Trawl ◽  
Trawl Survey ◽  
Marine Science ◽  
Target Species ◽  
Northeast Atlantic ◽  
Northeast Atlantic Ocean ◽  
Trawl Fisheries ◽  
Trawl Surveys

Abstract Díaz, P., Santos, J., Velasco, F., Serrano, A., and Pérez, N. 2008. Anglerfish discard estimates and patterns in Spanish Northeast Atlantic trawl fisheries. – ICES Journal of Marine Science, 65: 1350–1361. Estimates of Spanish bottom trawl discards of anglerfish Lophius budegassa and Lophiuspiscatorius in the Northeast Atlantic Ocean are presented. Both species are commercially valuable in ICES Subareas VI and VII, and Divisions VIIIc and IXa. Information was obtained from observers on board during discard-monitoring programmes. Raising by effort, rather than by landings and target species, was used to determine the total annual discards by weight and number, the discard percentage, and the discard length distribution by stock throughout the dataseries. By weight and number, discards varied interannually, ranging from 4 to 600 t (∼28 000–7 000 000 fish) in northern stocks of anglerfish, and from 1 to 100 t (∼20 000–400 000 fish) in southern stocks. The discard percentage for both species and northern and southern stocks therefore ranged between 2 and 76% by number. Length distributions of the discarded anglerfish show that most were juveniles, although the pattern differed in years with high or with low rates of discarding. The number of juveniles caught apparently increased in most areas after 2000. Correlations between the quantities discarded and recruitment indices from French and Irish trawl surveys were found for northern stocks and with Spanish trawl survey indices for southern stocks.

scholarly journals Effect of Cutting Ratio and Catch on Drag Characteristics and Fluttering Motions of Midwater Trawl Codend

2021 ◽  
Vol 9 (3) ◽  
pp. 256
Author(s):  
Wei Liu ◽  
Hao Tang ◽  
Xinxing You ◽  
Shuchuang Dong ◽  
Liuxiong Xu ◽  
...  
Keyword(s):  
Drag Force ◽  
Mesh Size ◽  
Current Speed ◽  
Midwater Trawl ◽  
Minimum Drag ◽  
Fish Catch ◽  
Spatial Geometry ◽  
By Catch ◽  
Trawl Fisheries ◽  
Crucial Part

The codend of a trawl net is the rearmost and crucial part of the net for selective fish catch and juvenile escape. To ensure efficient and sustainable midwater trawl fisheries, it is essential to better understand the drag characteristics and fluttering motions of a midwater trawl codend. These are generally affected by catch, cutting ratio, mesh size, and twine diameter. In this study, six nylon codend models with different cutting ratios (no cutting, 6:1, 5:1, 4:1, 7:2, and 3:1) were designed and tested in a professional flume tank under two conditions (empty codends and codends with catch) and five current speeds to obtain the drag force, spatial geometry, and movement trend. As the cutting ratio of empty codends decreased, the drag force decreased, and the drag coefficient increased. The unfolding degree of codend netting and the height of empty codends were found to be directly proportional to the current speed and inversely proportional to the cutting ratio. The positional amplitude of codend with cutting ratio 4:1 was the smallest for catch. The drag force of codends with catch increased as the current speed increased, and first decreased and then increased as the cutting ratio decreased. To ensure the best stability and minimum drag force of the codend, it is recommended to use the 4:1 cutting ratio codend.

Sign in / Sign up

Export Citation Format

Share Document