34 research outputs found

    Preliminary biological data on Pomadasys incisus (Osteichthyes: Haemulidae) in the Aegean Sea, Greece

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    The present paper gives, for the first time, some biological data concerning Pomadasys incisus in theArgolikos Gulf (C. Aegean Sea). The bastard grunt (Pomadasys incisus) is a thermophilic species welladapted in the above area, but the status of fishery suggests an overexploitation. The sex ratio was infavour of males. The length frequency distribution did not differ between the sexes. Growth in weight wasestimated by means of the length-weight relationship. Reproduction seemed to take place in summer. Certainmorphometric characters appeared to be useful while comparing populations among the differentpopulations in the Mediterranean

    Studies on the allometric growth of the caramote prawn Melicertus kerathurus (Decapoda, Penaeidae) in Western Greece (E. Mediterranean)

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    The relative growth of eleven body parts (carapace length, height, width, abdominal length, height and width, rostral length and telson length) of males and females of the caramote prawn Melicertus kerathurus was studied in samples from the Amvrakikos Gulf (Western Greece, E. Mediterranean). In addition to this, the relative growth of the length and the maximum width – and consequently the surface - of the appendix masculina of males was also studied. In general, both sexes showed similar patterns of relative growth. However, the females’ body appendages were significantly greater than those of the males. A negative allometry of escaping appendages (telson), abdomen (related to the metabolic processes, rapid locomotion and reproduction), rostrum, appendix masculina (related to mating and sperm transfer) and carapace height and width was found in both sexes. The biometric studies in this species in the central and western Mediterranean are in agreement with those from the eastern part of the basin, suggesting that all the populations throughout the Mediterranean could be considered as uniform

    First Occurrence Of The Tilapia Oreochromis Niloticus Niloticus (Linnaeus, 1758) In Lesina Lagoon (Eastern Italian Coast)

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    Individuals of the tilapia species Oreochromis niloticus niloticus(Linnaeus, 1758) were caught in Lesina Lagoon during experimental sampling for the shrimp Penaeus kerathurus using fyke net traps from December 1999 to September 2000. The species O. niloticusis not native in Italian coastal waters, although attempts of tilapia culture in land-based aquaculture farms were occasionally carried out in the past. The number of individuals captured in the samples suggests a colonization of the area of Lesina lagoon. The highest catches were observed during July. In July, the individuals caught represented the 22.3±4.1 % of the total catch weight. Such colonization of a marine environment byO. niloticusniloticus is the first case reported for Italy. The occurrence of the species in Lesina lagoon is attributed to fish which escaped from fish farms in the area and entered the lagoon through the numerous streams and irrigation-drainage channels that outflow along the south coastline

    Technical measures without enforcement tools: is there any sense? A methodological approach for the estimation of passive net length in small scale fisheries

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    Passive nets are currently among the most important fishing gears largely used along the Mediterranean coasts by the small scale fisheries sector. The fishing effort exerted by this sector is strongly correlated with net dimensions. Therefore, the use of passive nets is worldwide managed by defining net length and net drop. The EC Reg. 1967/2006 reports that the length of bottom-set and drifting nets may be also defined considering their weight or volume; however, no practical suggestions for fisheries inspectors are yet available. Consequently,  even if such technical measures are reasonable from a theoretical viewpoint, they are hardly suitable as a management tool, due to the difficulties in harbour control. The overall objective of this paper is to provide a quick methodological approach for the gross estimation of passive net length (by net type) on the basis of net volume. The final goal is to support fisheries managers with suitable advice for enforcement and control purposes. The results obtained are important for the management of the fishing effort exerted by small scale fisheries. The methodology developed in this study should be considered as a first attempt to tackle the tangled problem of net length estimation that can be easily applied in other fisheries and areas in order to improve the precision of the models developed herein

    Characterization of Color Production in XallaÂŽs Palace Complex, Teotihuacan

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    A multi-analytical approach was used to characterize color remains from Xalla, a Teotihuacan palace complex (project Teotihuacan, Elite and Government. Excavations in Xalla led by Linda R. Manzanilla). Color samples were obtained from polished lithic instruments and pigment ores. Those samples were analyzed combining microscopic and spectroscopic techniques. Our results coincide with previous studies in Teotihuacan, with the chromatic palette displaying a predominance of iron oxides such as hematite, yellow ochre and natural earths, as well as malachite, celadonite and glauconite. We have enlarged the corpus of raw materials with the characterization of jarosite and bone white and mica as aggregate. The identification of raw materials crossed with functional analysis of polished lithic artefacts suggests a production and application process for the pigmenting materials that were divided in four phases, from the crushing of the raw material to the application and finishing of the painted surfaces

    A study of oil pollution effects on the ecology of a coastal lake ecosystem

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    This study aims to examine ecological affinities in Lake Koumoundourou in Central Greece. The main finding of the study is that, although the lake is heavily polluted by crude oil, the water circulation, which is assisted by wind, is such that bioaccumulation of pollutants is avoided. The oil film on the surface of the lake is forced to outflow into Elefsis Bay and the concentration of heavy metals in the water column and sediment is lower than from other areas without oil pollution. The zoobenthos is rich in large-sized, pollution-resistant Nereis spp. and 64 phytoplankton species exist in the lake. The lake also supports mullets (Mugil spp.) and eels (Anguilla anguilla)

    Studies on Migratory Movements of the Prawn Penaeus kerathurus (Forskal, 1775) at Amvrakikos Gulf, Western Greece

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    Abstract. The prawn Penaeus kerathurus completes its life cycle in Amvrakikos Gulf. The reasons for not entering the open sea depend on the status of biotic and abiotic factors of the gulf. The migratory movements of the species in the gulf are described by a simple square model, in each corner of which, the wintering, spawning, nursery, and recruitment area exist. The wintering area is located below the 25m isobath and wintering period lasts from late December to late March. Spermatophores on females are observed throughout the year but the highest percentages between April and August. The spawning season begins late in spring and continues through the summer. The spawning area is located below the 10m isobath, mainly around 25m. The nursery area of Penaeus kerathurus is in shallow waters near river estuaries, and the temporal limits were determined to be between mid‐summer and mid‐autumn. Finally, the recruitment area is located near the nursery area, with recruitment taking place in autumn, while the major stock renewal is restricted to winter. Copyright © 1992, Wiley Blackwell. All rights reserve
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