22 research outputs found

    Evaluaci├│n preliminar de los desembarques y descartes de la pesquer├şa de arrastre de fondo de Turqu├şa en el mar Egeo nororiental (Mediterr├íneo oriental)

    Get PDF
    This short-term study on commercial discards was carried out in fishing grounds around G├Âk├žeada Island in the northeastern Aegean Sea, a geographic area where fisheries information is rather limited. A total of 28 bottom trawls were performed between 70 and 410 m depth from December 2009 to February 2010. All the samples were collected on board a commercial trawler under commercial fishing conditions. A total of 3143 kg of biomass was caught in 28 valid hauls. Landings accounted for about 67% of the total catch while the remaining 33% was discarded. Fish species comprised 85% of the total catch and their composition could be divided into four main groups related to depth: shallow shelf (70 to 88 m), deep shelf (155 to 180 m), shelf break (196 to 276 m), and upper slope (307 to 410 m). Fish dominated the abundance and biomass of both landings and discards in all bathymetric strata. Echinoderms also accounted for a large proportion of the discards. Mean total catches varied between 78.4 kg/h on the shallow shelf and 38.1 kg/h on the shelf break with no differences in the landing biomass between groups, but with slightly higher discards over the shallow shelf. Taking into account the preliminary nature of the findings, based on a short-term analysis, the minimum mesh size and minimum landing size currently applied in the Turkish bottom trawl fishery are not sufficient to reduce discards and to protect juveniles of commercially important species in the northeastern Aegean Sea.Este estudio a corto plazo sobre los descartes de la flota comercial de arrastre se llev├│ a cabo en las zonas de pesca alrededor de la isla G├Âk├žeada en el noreste del mar Egeo, una zona geogr├ífica en la que la informaci├│n sobre las pesquer├şas es bastante limitada. Se realizaron un total de 28 pescas de arrastre de fondo entre 70 y 410 m de profundidad de diciembre 2009 a febrero de 2010. Todas las muestras se recogieron a bordo de un embarcaci├│n de pesca de arrastre siguiendo las mismas condiciones de pesca comercial. Se capturaron un total de 3143 kg de biomasa en 28 lances v├ílidos. Los desembarques comerciales representaron alrededor del 67% de la captura total, mientras que el resto (33%) se descart├│. El 85% de la captura total estuvo compuesta por especies de peces. La composici├│n espec├şfica se pudo separar en cuatro grupos principales relacionados con la profundidad : la plataforma poco profunda (70 a 88 m), la plataforma profunda (155-180 m), el borde inferior de la plataforma (196 a 276 m) y el talud superior (307-410 m). Los peces dominaron la abundancia y biomasa tanto de los desembarques comerciales como de los descartes en todos los estratos batim├ętricos. Adem├ís los equinodermos tambi├ęn fueron un grupo importante de los descartes. La media de las capturas totales vari├│ entre 78.4 kg/h en la plataforma poco profunda y 38.1 kg/h en el borde de la plataforma, sin diferencias en la biomasa desembarcada entre los dos grupos, pero siendo los descartes ligeramente superiores en la plataforma poco profunda. Teniendo en cuenta el car├ícter preliminar de los resultados, obtenidos sobre la base de un an├ílisis a corto plazo, el tama├▒o m├şnimo de malla de la red y la talla m├şnima de las especies comerciales aplicada hoy en d├şa en la pesquer├şa de arrastre de fondo de Turqu├şa no son suficientes para reducir los descartes y proteger a los juveniles de las especies de importancia comercial en el Mar Egeo nororiental

    Evaluation of physical and physiological parameters of the elite underwater rugby players

    Get PDF
    Underwater rugby (UWR) is a developing sport which is organised under umbrella of Conf├ęd├ęration Mondiale des Activit├ęs Subaquatiques. Although this sports has over than 50 years history, very few studies have so far been published in the sports literature.┬á This research reveals physical and physiological profiles of UWR players in Turkey. Eleven male athletes participated to this study. Their body weight, height, body fat proportion, skinfold thicknesses, length and girth measurements, strength, flexibility, respiratory functions, anaerobic capacities, aerobic capacities were measured. In pool tests, 50 m crawl style, 50 m apnea, 8x25m apnea and 400 m crawl style with UWR equipments were done. Body mass index, body fat proportion, skinfold thickness of the underwater rugby players were higher compared to swimming and water polo literature. A positive correlation was found both between the 50 m apnea times and body fat proportions of the players and also among the 400 m crawl style with ABC equipments and body fat proportions and body weights of the players. A significant positive correlation was detected among skinfold thickness and the 50 m crawl style times with UWR equipments, 50 m apnea times, 8x25 m apnea times and 400 m crawl style times. Pulmonary volumes and capacities of the athletes were found higher than those of the water polo players and swimmers. This increase in the work of breathing muscles might be caused by hyperventilation of the underwater players before and after breathholding and blowing out the water in the snorkel after diving. In conclusion, more comparative data from UWR players is strongly warranted to define the physical and physiological features of UWR players

    A case study on catch characteristics of European hake gillnet fishery in the southern Sea of Marmara, Turkey

    No full text
    The focus of the present study was to provide information on European hake gillnet fishery in the southern Sea of Marmara (Turkey) based on samples collected during in high fishery season between April and May 2013 with experimental gillnets of different mesh sizes. European hake gillnets of three mesh sizes 28, 30, and 32 mm (nominal bar length) were set at between the 50 and 70 m depth water to test the effects of mesh size on the species composition, size of fish, catch rates, catch composition, bycatch and discard ratios and CPUE estimates. Cluster analysis was used to examine the stability of the results. Multi-dimensional scaling (MDS) was also applied to assess catch species aggregation patterns in the catch. The results showed that, 1062 specimens (182.79 kg) belonging to 8 species were caught and Merluccius merluccius and Solea solea were two dominant species of the catches with all studied mesh sizes with the percentage of 76.57, 19.54% in biomass and 48.96, 39.36% in number of specimens, respectively. The size frequency distribution of M. merluccius and S. solea are determined with the length range of 23.5 to 41.0 cm TL (mean 31.9 +/- 0.14 cm) and 18.5 to 35.5 cm TL (mean 22.2 +/- 0.09), respectively. The highest CPUE estimates by number and biomass of European hake was determined in 30 mm mesh size as 0.093 n.m(-1) and 25.153 g.m(-1), respectively. The similarity levels found by cluster analyses indicated that 32 mm mesh size is different from 28 and 30 mm mesh size with 85.67 and 85.55% respectively, for number of specimens and biomass based on standardized data. Since the present study reported here is the first concerning European hake gillnet fisheries and these findings will help to improve the management and conservation of this fishery

    Selectivity parameters of European hake gillnets for target and by-catch species with a perspective on small-scale fisheries management in the Sea of Marmara, Turkey

    No full text
    This study aims to describe the selectivity features of European hake gillnet for Merluccius merluccius (European hake, target species) and Solea solea (common sole, by-catch species) in the southern Sea of Marmara in terms of small-scale fisheries. For this purpose, the size selectivity of gillnets for European hake and the common sole was studied in the Sea of Marmara. Experimental fishing operations were carried out by using gillnets with a mesh size of 28, 30 and 32 mm. A total of 523 specimens of European hake and 418 specimens of common sole were caught. Total lengths ranging from 23.5 to 41 cm were recorded for European hake and from 18.5 to 35.5 cm for the common sole. The experimental data estimated by applying the SELECT method showed that the bi-modal and log normal models gave the best fit for European hake and the common sole selectivity, respectively. Estimated modal lengths were found to be 30.61; 32.80; 34.99 cm for European hake and 19.94; 21.37; 22.79 cm for common sole for each mesh size studied. The present study is the first report on the selectivity of these species using the SELECT method for European hake gillnets in Turkey. The results obtained from the present study show 30 mm mesh size which is used currently by fishermen is highly selective and very suitable for sustainable fisheries both European hake and common sole. These findings will help to improve the management and conservation of small-scale fishery, especially, in this region. (C) 2019 Elsevier B.V. All rights reserved

    The effect of mesh size and cod end material on the mortality and yield of the rose shrimp, Parapenaeus longirostris (Lucas, 1846) (Decapoda, Penaeidae) in the Turkish beam trawl fishery

    No full text
    Mortality and yield parameters of the rose shrimp, Parapenaeus longirostris were compared with length frequency data collected from the beam trawl fishery in the Sea of Marmara. Von Bertalanffy parameters were estimated as L infinity=16.28 cm and K=0.490 year(-1). The rates of total (Z), natural (M), and fishing (F) mortalitiy were calculated as 2.83, 0.97, and 1.86 for a 32 mm PE (polyethylene) cod end. The Z and F rates for two other cod ends, 32 mm PA (polyamide) and 36 mm PA, were, respectively, 2.13 and 1.16, versus 1.57 and 0.60. A study on the relative yield per recruit shows that maximum yield can be obtained at an exploitation rate (E) of 0.53, 0.52, and 0.45, respectively, for 32 PE, 32 PA, and 36 PA cod ends, whereas the current E values are 0.65, 0.54, and 0.38. Consequently, 32 mm PE and PA cod ends cause overfishing pressure on the stock of P. longirostris

    Selectivity of PE and PA material codends for rose shrimp (Parapenaus longirostris) in Turkish twin rigged beam trawl fishery

    No full text
    WOS: 000240431400009This study investigated the differences in the selective properties of 32 turn nominal polyethylene (PE) and 32, 36, 40 and 56 mm, nominal polyamide (PA) codends in beam trawl fisheries targeting rose shrimp, Parapenaeus longirostris, in the Sea of Marmara, Turkey. Data were collected in spring 2005 onboard a commercial trawler, on commercial fishing grounds. Selectivity data were collected using the covered codend method in two twin beam trawls in every haul. Using this method, four selection curves could be obtained in one haul. Selectivity parameters were calculated by fitting a logistic function using maximum likelihood. The L-50 values of 32, 36 and 40 mm PA codends were found to be 9.1, 10.2 and 12.6 cm, respectively. Due to retention of only a few specimens, realistic selectivity parameters could not be calculated for the 56 mm PA codend. Mean L-50 decreased with a change in mesh material from PA to PE. The lowest L-50 (8.0 cm) was found for the 32 mm PE material codend. This study has shown that for rose shrimp the 32 mm PA diamond mesh codend is not appropriate for the first maturity size (FMS) of 10 cm for rose shrimp in the Turkish twin rigged beam trawl fishery. In addition, the PE netting material provides a significantly lower L-50 value than the PA netting material. (c) 2006 Elsevier B.V. All rights reserved

    The effect of mesh size and cod end material on the mortality and yield of the rose shrimp, Parapenaeus longirostris (Lucas, 1846) (Decapoda, Penaeidae) in the Turkish beam trawl fishery

    No full text
    WOS: 000243470400007Mortality and yield parameters of the rose shrimp, Parapenaeus longirostris were compared with length frequency data collected from the beam trawl fishery in the Sea of Marmara. Von Bertalanffy parameters were estimated as L infinity=16.28 cm and K=0.490 year(-1). The rates of total (Z), natural (M), and fishing (F) mortalitiy were calculated as 2.83, 0.97, and 1.86 for a 32 mm PE (polyethylene) cod end. The Z and F rates for two other cod ends, 32 mm PA (polyamide) and 36 mm PA, were, respectively, 2.13 and 1.16, versus 1.57 and 0.60. A study on the relative yield per recruit shows that maximum yield can be obtained at an exploitation rate (E) of 0.53, 0.52, and 0.45, respectively, for 32 PE, 32 PA, and 36 PA cod ends, whereas the current E values are 0.65, 0.54, and 0.38. Consequently, 32 mm PE and PA cod ends cause overfishing pressure on the stock of P. longirostris

    Length-based estimates of growth parameters, mortality rates, and recruitment of Astacus leptodactylus (Eschscholtz, 1823) (Decapoda, Astacidae) in unexploited inland waters of the northern Marmara region, European Turkey)

    No full text
    WOS: 000248819500002The growth parameters, mortality rates, and recruitment pattern of Astacus leptodactylus from an unexploited area in inland waters of the northern Marmara region were investigated based on length-frequency data using FISAT software. Specimens were collected during eight scientific samplings carried out between March 2005 and May 2006. The seasonalized Von Bertalanffy growth function was fitted to the length frequency data (n = 2434) with the following parameters: L-infinity = 80.8 mm, K = 0.405 year(-1), C = 1, and WP = 0.90. The study of functional regressions permits us to conclude that the growth of this population is allometric. Natural mortality (M) was estimated at 0.578 year(-1)and total mortality at 0.589 year(-1). The longevity of the crayfish was calculated as t (max) = 7.4 year. The recruitment pattern shows that there is peak recruitment in May and June. We also estimated the potential instantaneous fishing mortality coefficient at F = 1.53-1.63 year(-1), the instantaneous total mortality coefficient at Z = 2.11-2.21 year(-1), and the exploitation rate E = 0.72-0.73, all through the length-converted catch curve procedure using the length-frequency data of the fyke-nets of 32 mm polyamide (PA) mesh size (stretched mesh)
    corecore