Environmental influences on the spatial distribution of European hake (Merluccius merluccius) and red mullet (Mullus barbatus) in the Mediterranean

2006 ◽  
Vol 22 (4) ◽  
pp. 678-685 ◽  
Author(s):  
Christos D. Maravelias ◽  
Efthymia V. Tsitsika ◽  
Costas Papaconstantinou
2021 ◽  
Vol 38 (1) ◽  
pp. 1-10
Author(s):  
Enis Darılmaz

In this study, aliphatic hydrocarbon levels were investigated in red mullet and european hake fish caught by trawler from Edremit Bay (Western Aegean, Turkey) in spring and autumn 2015. For this purpose, trawling was carried out from 3 different regions of the Edremit Bay in both seasons. As a result of the analyzes, total aliphatic hydrocarbon (TAH) levels in red mullet were found to be higher than that of european hake. TAH concentrations found for red mullet were in the range of 456-2090 ng/g, while it was found in the range of 61-746 ng/g for european hake. In general, TAH concentrations in red mullet were higher than that of european hake for both seasons. In addition, EOM amounts were found higher in red mullet like TAH. According to correlation, cluster and primary component analysis results, it was observed that the compounds affecting TAH levels in red mullet are C11 and C12 aliphatic hydrocarbon compounds, while european hake have C15, C17 and Pristane compounds. These results indicate that the source of aliphatic hydrocarbons in Edremit Bay fish is biogenic in european hake samples, although not exact, it may be petrogenic in red mullet samples.


2020 ◽  
Vol 83 (S1) ◽  
pp. 271 ◽  
Author(s):  
Pierluigi Carbonara ◽  
Walter Zupa ◽  
Aikaterini Anastasopoulou ◽  
Andrea Bellodi ◽  
Isabella Bitetto ◽  
...  

The uncertainty in age estimation by otolith reading may be at the root of the large variability in red mullet (Mullus barbatus) growth models in the Mediterranean. In the MEDITS survey, red mullet age data are produced following the same sampling protocol and otolith reading methodology. However, ageing is assigned using different interpretation schemes, including variations in theoretical birthdate and number of false rings considered, in addition to differences in the experience level of readers. The present work analysed the influence of these variations and the geographical location of sampling on red mullet ageing using a multivariate approach (principal component analysis). Reader experience was the most important parameter correlated with the variability. The number of rings considered false showed a significant effect on the variability in the first age groups but had less influence on the older ones. The effect of the theoretical birthdate was low in all age groups. Geographical location had a significant influence, with longitude showing greater effects than latitude. In light of these results, workshops, exchanges and the adoption of a common ageing protocol based on age validation studies are considered fundamental tools for improving precision in red mullet ageing.


2021 ◽  
Vol 38 (4) ◽  
pp. 515-521
Author(s):  
Habib Bal ◽  
Selim Esen

Otoliths are calcium carbonate (CaCO3) accumulations. Under the influence of different ecosystems morphological and chemical composition change. In this study, economically important two demersal fish species; European hake Merluccius merluccius (Linnaeus, 1758) and Stripet red mullet (Mullus surmuletus Linnaeus, 1758) was examined. Otoliths (Sagitta) belonging to these two species have been studied both chemically and morphologicall. Morphometric measurements of otoliths (length, mm; width, mm; area, mm2; perimeter, mm) in the sagittal of each species was made by the Leica M125 tri-ocular microscope. In the chemical analysis of otoliths, strontium (Sr), magnesium (Mg) and calcium (Ca) trace element amounts, the ratios of Sr and Mg trace elements to Ca element (Sr/Ca and Mg/Ca) were determined. For the micro-chemical analysis of otoliths ICP-MS was used. The highest magnesium (24.92±9.57 mmol/mol) and strontium (26.17±1.81 mmol/mol) element values were found in the otolith of red mullet. The difference between strontium (Sr) and magnesium (Mg) amounts for two fish species was found to be significant (P<0.05). In addition to it was found that the difference between them in the amount of calcium is significant (P<0.001). The shape indexes of otoliths are significantly different between the two fish species. Especially in terms of roundness (RD) and aspect ratio (AR) (P<0.001). The results of this study provide information about the habitats of two economic importance demersal fish species. Since such studies can give information about the habitat areas of fish species, they are important for tracking stocks, migration routes and sustainable fisheries.


2006 ◽  
Vol 51 (3) ◽  
Author(s):  
Adela Valero ◽  
María Mar López-Cuello ◽  
Rocío Benítez ◽  
Francisco Adroher

AbstractWe studied the parasitization by Anisakis spp. in European hake (Merluccius merluccius) of 40–52 cm from the Atlantic off north-west Africa and the Mediterranean off southern Spain. Infection parameters differed: The fish from the Atlantic showing a prevalence of 87.97% and a mean intensity of 4.69, while, in those from the Mediterranean, these were 41.27% and 1.73, respectively. In both samples the two-third larval stage types were isolated: Anisakis simplex sensu lato and Anisakis larvae type II, with prevalence of 85.71% and 30.83% in fish from the Atlantic and 41.27% and 1.59% for those from the Mediterranean, respectively. In both samples, the prevalence of larvae in viscera was clearly higher than in the muscle tissue. We also observed an increase in parasitization with increasing host length, those ≥ 46 cm having the highest prevalences (94.87% for those from the Atlantic and 58.33% for those from the Mediterranean; p<0.03).


2016 ◽  
Vol 67 (7) ◽  
pp. 1077 ◽  
Author(s):  
Sergio Vitale ◽  
Allen H. Andrews ◽  
Pietro Rizzo ◽  
Salvatore Gancitano ◽  
Fabio Fiorentino

The high variability of growth and longevity estimates for European hake (Merluccius merluccius) reflects the existence of two opposing hypotheses on growth rates that differ by a factor of 2: (1) a fast-growing hypothesis (FGH) with a maximum age near 15 years; and (2) a slow-growing hypothesis (SGH) with a maximum age near 30 years. A recently established regional radiocarbon (14C) reference led to a first-time application of bomb 14C dating in the Mediterranean Sea to three of the largest-sized and potentially oldest-catch female European hake. Because age reading of otoliths is very subjective and poorly defined, these fish were aged blind with bomb radiocarbon (14C) dating as an independent estimate of validated age. The validated ages were compared with the theoretical maximum ages from the most reliable FGH and SGH von Bertalanffy growth functions. Among the three bomb 14C ages, the most diagnostic length-at-age was an alignment with the bomb 14C rise period for two of the three fish, providing validated ages of 22 years (74.5-cm total length) and 25 years (88-cm total length). The results provide estimates of length-at-age that are in agreement with the SGH and cannot be accounted for by the FGH.


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