scholarly journals Distribution of the Mediterranean hake populations (Merluccius merluccius smiridus Rafinesque, 1810) (Ostheichthyes: Gadiformes) based on six years monitoring by trawl-surveys: some implications for management

2002 ◽  
Vol 66 (S2) ◽  
pp. 21 ◽  
Author(s):  
Lidia Orsi Relini ◽  
Costas Papaconstantinou ◽  
Stjepan Jukic-Peladic ◽  
Arnauld Souplet ◽  
Luis Gil de Sola ◽  
...  

On the basis of trawl survey data collected during the MEDITS project (1994-1999), the distribution of Mediterranean hake populations was described in coastal areas corresponding to about three quarters of both the latitudinal and longitudinal extensions of the Mediterranean Sea, and in the 0-800 m range. Abundance and biomass indices (in terms of number and kg per km2) are presented in 15 geographical sectors and 40 subareas from the Alborán Sea to the Aegean Sea. A statistical analysis by generalized linear modelling performed on such indices per main national blocks (Greece, France, Italy and Spain), and considering the effects of the six years of sampling and the depth, showed that biomass increased from west to east, while for all areas the most significant depth effect appeared between 100 and 200 m, corresponding to the depth range that hosts most of the summer nursery areas. The overall size-frequency distributions in shelf and slope waters, average sizes and total mortality coefficient Z per sector showed that the bulk of the MEDITS samples consisted of young individuals and, with only a few exceptions (western Sardinia, central Aegean), a generalized condition of growth overfishing was apparent. However, no negative trend was found, either in biomass or in average size of fishes, during the six years of the present study. Recruitment patterns were studied by distinguishing the youngest fish as Gaussian groups (modal length from 6 to 9 cm total length) in length-frequency distributions of each subarea and main stratum (shelf and slope). Considering the timing of MEDITS surveys (May-July), this approach emphasised the nurseries in the northern part of the western Mediterranean (Gulf of Lions, Ligurian Sea, northern Tyrrhenian Sea) and in the northern central Mediterranean, where recruitment occurs mainly during spring. On the other hand, few recruits were found in part of the central and particularly in the eastern Mediterranean, where recruitment occurs mainly in summer. MEDITS recruitment patterns therefore gave support to distinctions among Mediterranean hake populations, previously suggested on the basis of vertebral counts and other morpho-physiological, albeit fragmentary, data. In particular the central Mediterranean hake populations do not seem to be homogeneous, with an Adriatic unit very close to the northwestern one. The MEDITS experience therefore suggests that future management measures could take into account both general and regional patterns, the latter concerning mainly the younger fraction of the populations.

Zootaxa ◽  
2012 ◽  
Vol 3263 (1) ◽  
pp. 1 ◽  
Author(s):  
PETER NICK PSOMADAKIS ◽  
STEFANO GIUSTINO ◽  
MARINO VACCHI

In this paper we update the Mediterranean fish inventory, analyse the biogeographic features of this fauna and provideexhaustive biodiversity data for the Ligurian and Tyrrhenian seas. According to the data available in 2010, the Mediterraneanfish diversity can be summarized as follows: 602 (including sub-species) bony fish species (Osteichthyes), 79 cartilaginous fishspecies (Chondrichthyes) and 3 cyclostomes (Agnatha); making a total of 684 species belonging to 173 families (147Osteichthyes, 24 Chondrichthyes, 2 Agnatha). Most species 403 (58.9%) have an Atlantic origin, 128 (18.7%) species arecosmopolitan, 90 (13.2%) species are Indo-Pacific, and 63 (9.2%) are endemic to the Mediterranean. In the Ligurian Sea,northern Tyrrhenian and southern Tyrrhenian Sea, the richness can be estimated at 454, 426 and 447 species, respectively. Themost speciose families for the Mediterranean as a whole, but also for the three intra-mediterranean areas studied are theGobiidae, Sparidae, Labridae and Blenniidae; whereas Carangidae is a numerically important family mainly at theMediterranean level. The percentage of endemic fishes within the intra-mediterranean areas studied gradually decrease acrosslatitude from the Ligurian Sea (9.4%) to the northern (8.7%) and southern (8.0%) Tyrrhenian Sea. The updated fish inventorycontains 81 Lessepsian and 48 Atlantic immigrant species, which represent 11.8% and 7.0% of the whole Mediterranean fishcommunity, respectively. The Ligurian Sea (3.1%) houses a higher amount of immigrants with respect to the northern (1.6%)and southern (2.7%) Tyrrhenian sectors.Field observations made during this study indicate that both the Ligurian and Tyrrhenian seas are presently subjected toincreasing colonization events by thermophilic species spreading from the southern Mediterranean and to a lesser degree by the arrival of exotic species either of Atlantic or Indo-Pacific origin.


Author(s):  
Alexandre Gannier ◽  
Justine Epinat

A total of 17,651 km of sailboat survey effort obtained with very good sighting conditions was pooled over the period 1995 to 2007 to provide an insight into Cuvier's beaked whales' (Ziphius cavirostris) distribution in the western and central Mediterranean Sea. Although only six confirmed sightings were obtained under such conditions, complementary sightings made a total of eleven confirmed records. Their distribution showed that only slope habitat, and its close proximity, was favourable to the species. In contrast to regions pointed out in the recent literature, such as the Alboran, Ligurian and Ionian Seas, it appeared that the Tyrrhenian Sea was likely to be an important area for Cuvier's beaked whales in the Mediterranean. Sighting rates of 0.1–0.25 sighting/100 km and sighting rates for individuals of 0.2–0.5 individual/100 km were obtained in favourable regions. When compared to sighting rates obtained on Risso's dolphins Grampus griseus during the same surveys, the Cuvier's beaked whale appeared to be quite a frequent species in its favoured habitats. The present study contributes a better knowledge of this poorly-known species, in the context of increasing and threatening anthropogenic noises.


2014 ◽  
Vol 15 (3) ◽  
pp. 545 ◽  
Author(s):  
A. MARCHINI ◽  
J. C. SORBE ◽  
F. TORELLI ◽  
A. LODOLA ◽  
A. OCCHIPINTI-AMBROGI

An anthurid isopod new to the Mediterranean Sea has recently been observed in samples from three localities of the Italian coast: the Lagoon of Venice (North Adriatic Sea), La Spezia (Ligurian Sea) and Olbia (Sardinia, Tyrrhenian Sea). The specimens collected showed strong affinity to a species originally described from the NW Pacific Ocean: Paranthura japonica Richardson, 1909. The comparison with specimens collected from the Bay of Arcachon (Atlantic coast of France), where P. japonica had been recently reported as non-indigenous, confirmed the identity of the species. This paper reports the most relevant morphological details of the Italian specimens, data on the current distribution of the species and a discussion on the pathways responsible for its introduction. The available data suggest that the presence of this Pacific isopod in several regions of coastal Europe might be due to a series of aquaculture-mediated introduction events that occurred during the last decades of the 1900s. Since then, established populations of P. japonica, probably misidentified, remained unnoticed for a long time.


Author(s):  
FRANCESCO L. LEONETTI ◽  
GIANNI GIGLIO ◽  
AGOSTINO LEONE ◽  
FABRIZIO COPPOLA ◽  
CHIARA ROMANO ◽  
...  

In this contribution the checklist of chondrichthyans of Calabria (Central Mediterranean, southern Italy) is reported. Data presented is derived from twenty years of opportunistic and active surveys from 2000 to 2020. A total of 55 species of chondrichthyans is present in Calabrian seas: 33 sharks, 20 rays, and 2 chimaeras. These species represent approximately 62% of the total reported for the Mediterranean. Approximately 71% of Calabrian species have been reported in the Tyrrhenian Sea, 49% in the Ionian Sea, and 33% in the Strait of Messina. According to IUCN criteria, new records of Endangered and Critically Endangered species (i.e., Carcahrodon carcharias [Linnaeus, 1758], Lamna nasus [Bonnaterre, 1788], Cetorhinus maximus [Gunnerus, 1765], Mobula mobular [Bonnaterre, 1788], Sphyrna zygaena [Linnaeus, 1758]) are reported, together with the first record of Raya brachyura Lafont, 1873 for the Ionian coasts and probably third confirmed record of the rare chimaera Hydrolagus mirabilis (Collett, 1904) for the Mediterranean.


2013 ◽  
Vol 14 (1) ◽  
pp. 162 ◽  
Author(s):  
A. ARIAS ◽  
A. GIANGRANDE ◽  
M.C. GAMBI ◽  
N. ANADON

First observations on the reproductive biology of the alien polychaete Branchiomma bairdi (McIntosh, 1885) (Sabellidae) in the Mediterranean Sea are provided as well as additional Mediterranean records of the species which can help to understand its introduction and spreading. Re-examination of the specimens from Miseno harbour (Tyrrhenian Sea, Italy) revealed the presence of B. bairdi in the central-Mediterranean since September 2004. The histological study of individuals collected in Malta revealed that the species is a simultaneous hermaphrodite, developing male and female gametes in the same body segments; embryos are brooded inside the parent tube. However, there is evidence also for asexual reproduction. The species shows a different reproductive pattern from the previously reported population from the eastern-Pacific; this demonstrates its great plasticity and adaptability. Branchiomma bairdi has an invasive behaviour, colonizing large areas in relatively short-time, and reaching relatively high densities (c.a. 50 individuals/m2). Its expansion throughout several Mediterranean localities is largely a consequence of the high capacity of this species to colonize extremely different habitats and substrates, to the occurrence of sexual and asexual reproductive strategies, and the combination of both. Further, B. bairdi appears to be particularly abundant in confined and anthropogenic degraded areas. Finally, our findings strongly suggest that the pathway of introduction in the Mediterranean, previously hypothesized as the Suez Canal (Lessepsian migration), is most likely via the Gibraltar Strait.


2009 ◽  
Vol 10 (1) ◽  
pp. 73 ◽  
Author(s):  
T. ROMEO ◽  
L. CASTRIOTA ◽  
P. CONSOLI ◽  
M. FALAUTANO ◽  
G. FLORIO ◽  
...  

This study provides information on bathymetric and longitudinal distribution heterogeneity of the rockfish Helicolenus dactylopterus in the southern Tyrrhenian Sea. Data were drawn from experimental bottom trawl (1996-2002) plus bottom trap (2001-02) surveys. The frequency of occurrence and mean relative density (N/km2) and biomass (kg/km2) indexes were calculated for two survey seasons (spring and autumn), four geographic sectors and three depth strata. MANOVA was used to test fish abundance among years, sectors and strata. Analysis of the length-frequency distributions was carried out by two-way (gears and depths) ANOVA, post hoc multiple comparisons for testing differences among depths and Student’s t test for testing differences between gears. Length-weight relationship was also estimated and the allometric coefficient was tested with the Student’s t test. The results showed a significant positive bathymetric gradient of sizes both for trawl and trap surveys; at same depths, fish caught by traps were significantly longer than those caught by trawl. In spring surveys, significant differences were found among strata for both abundance indexes; in autumn surveys, significant differences between depth strata were found only for density indices. The distribution and abundance patterns of H. dactylopterus along the southern Tyrrhenian Sea was homogeneous among sectors. Length-weight relationship showed a significant positive allometric growth.


Author(s):  
ROBERTO SIMONINI ◽  
SARA RIGHI ◽  
FEDERICA ZANETTI ◽  
SERGIO FAI ◽  
DANIELA PREVEDELLI

The fireworm Hermodice carunculata (Annelida) is emerging as a native invader and a neonative species in the Central Mediterranean basins. Its ongoing areal expansion has probably been triggered and pursued by the climate alterations which are affecting the Mediterranean environments and biota. However, increased H. carunculata abundance and distribution may be miscalculated and underestimated due to the lack of effective tools for collection and monitoring. Indeed, fireworms spend most of the daytime in crevices and holes, making it impossible to obtain reliable data in underwater surveys.In this study, traps were developed to provide suitable shelter and food to fireworms, and their effectiveness and specificity were assessed by testing different immersion times, environmental conditions and types of bait. Pierced plastic baskets adapted for fireworm capture proved to be extremely easy to set up, reproducible, cheap, and highly specific. The devices were used in 11 sites located along the Ionian Apulian coast (Italy). They resulted suitable and effective: more than 90% of the traps baited with raw fish succeeded in capturing H. carunculata specimens, with an average of 8-9 fireworms captured per trap. The traps were deployed in a depth range of 1.5-9 m with immersion times of up to 4 h, and even large sized fireworms (> 32 cm in length) were caught. These attracting devices could be successful in different forthcoming challenges, allowing the collection of a great number of fireworms to investigate their impact on rocky bottom communities, distribution and potential for bioprospecting. Besides, the cheapness and ease of use of the traps also make them suitable for Citizen Science studies and sampling campaigns aiming at characterizing the expanding populations. Future applications will be critical to improve deployment success and test user friendliness.


2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Sonia Baklouti ◽  
Abdelkarim Derbali ◽  
Khalifa Dhieb ◽  
Wassim Kammoun ◽  
Othman Jarboui

The Mediterranean green crabCarcinus aestuariiwas recorded in Tunisian waters several years ago. However, since its record in the Gulf of Gabes, no studies have been carried out about the spread of this crab. Because there is a lack of nutritional information concerning this species, this study aimed to characterize the chemical composition of hepatopancreas and gonads ofCarcinus aestuariiin view of potential health implication for consumers and to determine the seasonal nutritional quality of females and males taken separately for various size groups. In this study, a total of 1399 individuals were collected along the Sfax coast. The nutritional value of various edible parts ofCarcinus aestuariiwas evaluated, and gender differences in terms of edible yield and proximate composition, protein, mineral, lipid, and water content, were compared for season, age, and sex. The biochemical compositions were strongly influenced by sex, age, and seasons. The highest protein and lipid contents were detected in gonads and hepatopancreas of females. Autumn was the season with the highest protein content and lowest fat content. Therefore, people with particular diets constrains should consume the ovaries of females in autumn and it should moderate in winter. The hepatopancreas and gonads from Tunisian waters can be a good source of proteins and mineral.


Author(s):  
Lidia Orsi Relini ◽  
Daniela Massi

The presence of Stoloteuthis leucoptera in the Mediterranean is recorded on the basis of three specimens, including an adult male, caught by IKMT and by commercial otter-trawl in the Ligurian Sea. The hypothesis of a recent immigration is discussed.The list of Mediterranean cephalopods (Mangold Wirz, 1963; Torchio, 1968; Bello, 1986; Mangold & Boletzsky, 1987) includes the Sepiolidae of the subfamily Heteroteuthinae, whose members are supposed to be pelagic throughout their life cycle. Mangold Wirz (1963) recognizes in the Mediterranean fauna the unique species Heteroteuthis dispar, the other authors include H. atlantis Voss, which Voss himself (1955) reported at Messina. To this group may now be added Stoloteuthis leucoptera (Verrill, 1878) a species until now recorded in limited Atlantic areas. Verrill (1881) wrote “This species is an exceedingly beautiful one, when living, owing to the elegance and brilliancy of its colours and the gracefulness of its movements. In swimming it moves its fins in a manner analogous to the motion of the wings of a butterfly.”


Ocean Science ◽  
2011 ◽  
Vol 7 (4) ◽  
pp. 503-519 ◽  
Author(s):  
R. Sorgente ◽  
A. Olita ◽  
P. Oddo ◽  
L. Fazioli ◽  
A. Ribotti

Abstract. The spatial and temporal variability of eddy and mean kinetic energy of the Central Mediterranean region has been investigated, from January 2008 to December 2010, by mean of a numerical simulation mainly to quantify the mesoscale dynamics and their relationships with physical forcing. In order to understand the energy redistribution processes, the baroclinic energy conversion has been analysed, suggesting hypotheses about the drivers of the mesoscale activity in this area. The ocean model used is based on the Princeton Ocean Model implemented at 1/32° horizontal resolution. Surface momentum and buoyancy fluxes are interactively computed by mean of standard bulk formulae using predicted model Sea Surface Temperature and atmospheric variables provided by the European Centre for Medium Range Weather Forecast operational analyses. At its lateral boundaries the model is one-way nested within the Mediterranean Forecasting System operational products. The model domain has been subdivided in four sub-regions: Sardinia channel and southern Tyrrhenian Sea, Sicily channel, eastern Tunisian shelf and Libyan Sea. Temporal evolution of eddy and mean kinetic energy has been analysed, on each of the four sub-regions, showing different behaviours. On annual scales and within the first 5 m depth, the eddy kinetic energy represents approximately the 60 % of the total kinetic energy over the whole domain, confirming the strong mesoscale nature of the surface current flows in this area. The analyses show that the model well reproduces the path and the temporal behaviour of the main known sub-basin circulation features. New mesoscale structures have been also identified, from numerical results and direct observations, for the first time as the Pantelleria Vortex and the Medina Gyre. The classical kinetic energy decomposition (eddy and mean) allowed to depict and to quantify the permanent and fluctuating parts of the circulation in the region, and to differentiate the four sub-regions as function of relative and absolute strength of the mesoscale activity. Furthermore the Baroclinic Energy Conversion term shows that in the Sardinia Channel the mesoscale activity, due to baroclinic instabilities, is significantly larger than in the other sub-regions, while a negative sign of the energy conversion, meaning a transfer of energy from the Eddy Kinetic Energy to the Eddy Available Potential Energy, has been recorded only for the surface layers of the Sicily Channel during summer.


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