scholarly journals Otter trawls in Greece: Landing profiles and potential mιtiers

2010 ◽  
Vol 11 (1) ◽  
pp. 43 ◽  
Author(s):  
S. KATSANEVAKIS ◽  
C.D. MARAVELIAS ◽  
V. VASSILOPOULOU
Keyword(s):  
Expert Knowledge ◽  
Aegean Sea ◽  
Otter Trawl ◽  
Ionian Sea ◽  
Merluccius Merluccius ◽  
Step Procedure ◽  
Total Fish ◽  
Boops Boops ◽  
European Hake

A fleet of 326 bottom trawlers operate in Greek Seas and their landings represent approximately 30% of the total fish production in Greece. In this study, otter trawl landings data were analyzed in order to identify potential métiers. Landings data between 2002 and 2006 were used, collected from 42 ports in the Aegean and East Ionian Sea. A three-step procedure was applied to identify potential métiers: the first step involved a factorial analysis of the log-transformed landings profiles, the second step a classification of the factorial coordinates, and the third step a further aggregation of clusters based on expert knowledge. In all, six potential métiers were identified in the Aegean Sea, and five in the Ionian Sea. The most important target species were European hake (Merluccius merluccius), deepwater pink shrimp (Parapenaeus longirostris), red mullet (Mullus barbatus), caramote prawn (Melicertus kerathurus), picarel (Spicara smaris), cephalopods, bogue (Boops boops), anglers (Lophiusspp.), and Norway lobster (Nephrops norvegicus). Otter trawls in Greece use more or less the same gear with minor modification, and métier selection is basically reflected as a choice of geographical sub-area and hauling depth. The limitations of using landings profiles to identify métiers and the need for further verification are discussed.

scholarly journals Landings profiles and potential métiers in Greek set longliners

2009 ◽  
Vol 67 (4) ◽  
pp. 646-656 ◽  
Author(s):  
Stelios Katsanevakis ◽  
Christos D. Maravelias ◽  
Laurie T. Kell
Keyword(s):  
Aegean Sea ◽  
Sea Bream ◽  
Ionian Sea ◽  
Agglomerative Clustering ◽  
Small Vessels ◽  
Step Procedure ◽  
Diplodus Sargus ◽  
Hierarchical Agglomerative Clustering ◽  
Pagrus Pagrus

Abstract Katsanevakis, S., Maravelias, C. D., and Kell, L. T. 2010. Landings profiles and potential métiers in Greek set longliners. – ICES Journal of Marine Science, 67: 646–656. A very large number (>14 000) of generally small vessels operate as longliners in Greek seas. The aim of this study was to identify potential set longline métiers, based on a large sample of landings records from all over Greece. Landings data from set longliners between 2002 and 2006, collected from several ports in the Aegean and East Ionian Sea, were used. The landings profiles were grouped using a two-step procedure, the first involving factorial analysis of the log-transformed landing profiles, and the second a classification of the factorial coordinates (hierarchical agglomerative clustering). In all, 13 métiers were identified in the Aegean Sea and 7 in the Ionian Sea. The most important métiers identified were those targeting white sea bream (Diplodus sargus), hake (Merluccius merluccius), common sea bream (Pagrus pagrus), and common pandora (Pagellus erythrinus), and mixed métiers. Varying spatial (within the Aegean and Ionian Seas) and seasonal patterns were evident for the métiers identified, indicating that fisher motivation to engage in a specific métier varies both spatially and temporally.

Age, growth and reproduction of European hake (Merluccius merluccius (Linn., 1758)) in the Central Aegean Sea, Turkey

2015 ◽  
Vol 95 (4) ◽  
pp. 829-837 ◽  
Author(s):  
Ozan Soykan ◽  
Akin T. İlkyaz ◽  
Gülnur Metın ◽  
H. Tuncay Kinacigıl
Keyword(s):  
Gonadosomatic Index ◽  
Total Mortality ◽  
Aegean Sea ◽  
Age Composition ◽  
Merluccius Merluccius ◽  
Growth Coefficient ◽  
Mortality Ratio ◽  
Male Sex ◽  
European Hake ◽  
Growth And Reproduction

Specimens of European hake were collected by a traditional demersal trawl between July 2004 and June 2007 from İzmir Bay, Central Aegean Sea. A total of 2108 individuals were sampled during the study and the female: male sex ratio of the stock was 1:0.89. The length–weight relationship was W = 0.00341L3.24 (R2 = 0.994) for all individuals. A high gonadosomatic index was evident over most of the year but it was minimal from August to October. The estimated age composition was 1–5 years; the length and weight at infinity were calculated as L∞ = 54.53 cm and W∞ = 1455.77 g respectively. In addition, growth coefficient was found to be k = 0.315 y−1 and to = −0.223 y (R2 = 0.99). Total mortality ratio of the stock was calculated as Z = 1.539 y−1, while natural and fishing based mortality ratio were estimated as M = 0.579 y−1 and F = 0.959 y−1 respectively, with the exploitation ratio (E) of the stock estimated to be 0.624.

CLASSIFICATION OF HIGH-DIMENSIONAL MICROARRAY DATA WITH A TWO-STEP PROCEDURE VIA A WILCOXON CRITERION AND MULTILAYER PERCEPTRON

2011 ◽  
Vol 10 (01) ◽  
pp. 1-14
Author(s):  
VLADIMIR NIKULIN ◽  
TIAN-HSIANG HUANG ◽  
GEOFFREY J. MCLACHLAN
Keyword(s):  
Data Mining ◽  
Feature Selection ◽  
High Dimensional ◽  
Second Step ◽  
Support Vector ◽  
Step Procedure ◽  
Leave One Out ◽  
Natural Combination ◽  
Feature Selection Techniques

The method presented in this paper is novel as a natural combination of two mutually dependent steps. Feature selection is a key element (first step) in our classification system, which was employed during the 2010 International RSCTC data mining (bioinformatics) Challenge. The second step may be implemented using any suitable classifier such as linear regression, support vector machine or neural networks. We conducted leave-one-out (LOO) experiments with several feature selection techniques and classifiers. Based on the LOO evaluations, we decided to use feature selection with the separation type Wilcoxon-based criterion for all final submissions. The method presented in this paper was tested successfully during the RSCTC data mining Challenge, where we achieved the top score in the Basic track.

scholarly journals First Record ofAnisakis simplexThird-Stage Larvae (Nematoda, Anisakidae) in European HakeMerluccius merluccius lessepsianusin Egyptian Water

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yasmin Abou-Rahma ◽  
Rewaida Abdel-Gaber ◽  
Amira Kamal Ahmed
Keyword(s):  
Red Sea ◽  
Positive Relationship ◽  
First Record ◽  
Type I ◽  
Merluccius Merluccius ◽  
Molecular Analyses ◽  
Fish Samples ◽  
Third Stage ◽  
European Hake ◽  
Anisakid Larvae

The prevalence of infection and the identification of anisakid larvae in European hakeMerluccius merluccius lessepsianusfrom Hurghada City, Red Sea Governorate, Egypt, were investigated. Fish samples were collected during the period of February and November 2014. Twenty-two (36.66%) out of sixty examined fish specimens were found to be naturally infected withAnisakistype I larvae mostly found as encapsulated larvae in visceral organs. There was a positive relationship between host length/weight and prevalence of infection. Based on morphological, morphometric, and molecular analyses, these nematodes were identified as third-stage larvae ofAnisakis simplex. The present study was considered as the first report of anisakid larvae from European hake in the Egyptian water.

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