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Somatic Condition, Growth and Reproduction of Hake, Merluccius merluccius L., in the Portuguese Coast  [PDF]
Ana Maria Costa
Open Journal of Marine Science (OJMS) , 2013, DOI: 10.4236/ojms.2013.31002
Abstract:

Weight/length relationships, condition factor, gonadosomatic and hepatosomatic indices, conversion factor for gutted to total weight and spawning season of hake in the Portuguese Coast (36.92 to 42.22 degrees latitude N; 9.61 to 6.07 degrees longitude W) were investigated for the first time, aiming to fill the lack of information on the biology of hake of the Portuguese waters. Data were obtained from commercial samples collected between 2005 and 2010 and pooled by month. Sex ratio observed in fish below 40 cmwas close to 1:1; females were always dominant above50 cmlength. All the parameters were analysed by month and by sex and by combined sexes. The relationships obtained for combined sexes for the entire period concerning the growth in length and weight were: total length-total weight =0.0038L3.172, total length-gutted weight =0.0052L3.059. The relationship total weight-gutted weight was Wt = 15.8112 + 0.8480Wg and the conversion factor was of 1.1524. The growth rate is similar for both sexes but different when based on total weight or gutted weight. The analysis of the condition factor, gonadosomatic index, hepatosomatic index and the monthly distribution of the maturity stages seem to indicate that hake from thePortugueseCoasthas a long spawning season, with three spawning peaks in March, May and August but the start of the spawning season seems independent of the fish length.

 

Spatial variations of the Argentine hake (Merluccius hubbsi (Marini, 1933)) spawning shoals in the Patagonian area during a reproductive season
Macchi,Gustavo J; Pájaro,Marcelo; Dato,Claudia;
Revista de biología marina y oceanografía , 2007, DOI: 10.4067/S0718-19572007000300013
Abstract: displacements of argentine hake merluccius hubbsi shoals in the spawning area of patagonia before and during a reproductive season were analyzed. in particular, monthly changes in fish density, sex composition, size structure and spawning location were described for this stock. during october-november, hake shoals moved from deeper waters to the coast at about 44°s, where spawning took place in december. during january the main reproductive aggregations stayed near the coast (50 m depth) but displaced to the southern area (45°s); in february spawning activity diminished and spent females began to return to deeper waters. in general, this process was first completed by young spawners (35-45 cm tl), which have a breeding season shorter than the old females. we observed that males arrived at the spawning area first and remained there for a longer period than females. during the reproductive period skewed sex ratios in different sampling sites were observed. these differences in sex composition were attributable to: 1) local segregation produced by the reproductive behavior of hake, in which males form groups with a single female, and 2) migration of spent females to deeper waters, which causes male-biased samplings in coastal areas
Concentration of antioxidant compounds and lipid peroxidation in the liver and white muscle of hake (Merluccius merluccius L.) in the Adriatic sea
Ognjanovi? Branka I.,?or?evi? Nata?a Z.,Perendija Branka R.,Despotovi? Svetlana G.
Archives of Biological Sciences , 2008, DOI: 10.2298/abs0804601o
Abstract: Specimens of a marine freshwater fish - hake (Merluccius merluccius L.) - were collected at the localities of Platamuni and Valdanos (Montenegro, South Adriatic) in the spring of 2003. Our results showed higher concentrations of LPO, Vit C, and Vit E in the liver in comparison with white muscle. The concentration of LPOin both tissues was higher, while that of Vit E was lower at Valdanos compared to Platamuni. These differences in parameters of oxidative stress are partly due to differences in temperature and the concentrations of nitrites, nitrates, and detergents in the waters of Valdanos compared to Platamuni.
Biometric properties of the European hake, Merluccius merluccius (Osteichthyes: Merlucciidae), from the central Adriatic sea
?anti? M.,Ra?a Biljana,Paladin Antonela,?uri? Ana
Archives of Biological Sciences , 2011, DOI: 10.2298/abs1101259s
Abstract: The relationship between morphometric measurements (16) and meristic characters (6) was examined in 460 specimens of the European hake (225 females, 210 males and 25 immature ones) caught in the central Adriatic Sea. Morphological difference between males and females was not marked. Biometric analyses of the morphometric and meristic characteristics indicated a homogenous morphology stock of M. merluccius in the central Adriatic Sea. Changes in some morphometric characteristics obtained in conjunction with an increase in body length showed that smaller specimens have a longer head, anal and ventral fin than adult specimens. The negative correlation recorded for the maximum and minimum body depth indicated that the body becomes progressively elongated. The meristic characteristics of the European hake from different Mediterranean and NE Atlantic areas are mostly in agreement with the data in our study.
Effect of hook size and seasonality on the artisanal long-line fishery of southern hake (Merluccius australis Hutton, 1872) in Chile
Queirolo,Dante; Ahumada,Mauricio;
Revista de biología marina y oceanografía , 2009, DOI: 10.4067/S0718-19572009000300003
Abstract: the effect of hook size and seasonality on the artisanal long-line fishery of southern hake (merluccius australis) in chile was studied. we analyzed the effect of four hook sizes on the size-at-catch and catch rates of southern hake (merluccius australis) caught with mixed long-lines between seno de reloncaví and golfo de ancud (41o42's-42o48's). sixty fishing hauls were done in four periods (march, may, july, september); a total of 59,294 hooks were set and 14,358 specimens (26,165 kg) were caught. the analysis showed overlapping retention sizes for each hook size in the months studied, indicating no significant effects in either catch size composition or in catch rates between hooks of different size. nevertheless, significant differences were observed between periods in the catch rates, fluctuating between 31.75 and 16.17 individuals per 100 hooks from march to september. the above results suggest that it is necessary to analyze alternative fishing gear and management measures for the fishery.
Estimating codend size selectivity of bottom trawlnet in Chilean hake (Merluccius gayi gayi) fishery
Gálvez,Mauricio; Rebolledo,Hernán;
Investigaciones marinas , 2005, DOI: 10.4067/S0717-71782005000200003
Abstract: this paper examines codend size selectivity in the chilean hake (merluccius gayi gayi) industrial fishery by means of four mesh sizes opening in the codend (100, 110, 130 and 140 mm mesh openings) and using the cover codend method. the data was analyzed by haul, using the select model with both the logistic and richards selection curves. for each mesh size opening and sex the combined haul analysis was made with the fryer model, and with these results we determine the master curves, by sex. based on critical length and maturity length at 50% estimated for this specie we determined the optimum mesh size opening for the trawl fishery. the rate of escape of cmomon hake increased exponentially with the size of mesh opening. the logistic selection model was chosen based on the likelihood ratio test for all hauls analyzed. from the mean selection curves (incorporating haul variation) fitted to data for combined sexes, the total length of 50% retention (l50) were estimated to be 39.3, 39.7, 41.1 and 43.6 cm of total length for 100, 110, 130 and 140 mm of mesh size opening. the values of l50 for females were higher than those for males. we recommended 120 mm of mesh size opening in the codend in order to protect the spawning fraction of chilean hake stock and maximize the biomass of the cohorts
The effects of subsampling and between-haul variation on the size-selectivity estimation of Chilean hake (Merluccius gayi gayi)
Queirolo,Dante; Ahumada,Mauricio; Hurtado,Carlos F; Soriguer,Milagrosa C; Erzini,Karim;
Latin american journal of aquatic research , 2012,
Abstract: using the data collected in a size selectivity experiment on chilean hake (merluccius gayi gayi) carried out in 2000, the selectivity parameters for four codend mesh sizes (100, 110, 130, and 140 mm of mesh size opening) were estimated and modelled by the select model. these analyses included considerations of the sampling proportions of the catch in the codend and cover. furthermore, the analyses took into account between-haul variation. the l50 values were 30.8, 29.9, 30.0, and 41.2 cm of total length, respectively, values lower than the estimates obtained from previous studies. the contribution of explanatory variables to the selectivity model was also tested in order to determine the role of mesh size, catch size (in number), and towing speed. increases in catch size and in towing speed were accompanied by decreases in the l50 estimates. these results demonstrate how incorporation of subsampling effect and explanatory variables to model between-haul variation can improve selectivity estimates and management of a valuable resource.
Identification of the stages of ovarian maturation of the Argentine hake Merluccius hubbsi Marini, 1933 (Teleostei: Merlucciidae): advantages and disadvantages of the use of the macroscopic and microscopic scales
Honj, Renato M.;Vaz-dos-Santos, André M.;Rossi-Wongtschowsk, Carmen Lúcia D. B.;
Neotropical Ichthyology , 2006, DOI: 10.1590/S1679-62252006000300004
Abstract: the argentine hake merluccius hubbsi is a demersal-pelagic species on which few studies have been undertaken, despite its importance for the fisheries of the south-southeastern brazilian region, . the species is the most important commercial fishery resource in uruguay and argentina, where several studies have permitted the proper monitoring of the species. the ovarian maturation of the argentine hake is analysed in this study. a scale of maturation is presented in the light of the oocyte development and the use of macro and microscopic scales of ovarian maturation are compared. it was detected that the oocyte types and derived structures present in the ovaries are similar to those already described both for the species and for teleosts in general; group synchronous development and multiple spawning are typical. the identification of ovarian maturation based only on external morphological characteristics of the gonads presents many errors, mainly in the characterization of the stages of maturation, which makes imperative the parallel analysis of the oocyte development, undertaken through histological ovarian cross-sections.
Mortalidad natural de larvas de merluza común (Merluccius gayi gayi) frente a Chile centro-sur en relación a su distribución espacial y grado de agregación Natural mortality of chilean hake (Merluccius gayi gayi) larvae of central-south Chile in relation to their spatial distribution and patchiness  [cached]
Cristian Vargas,Guillermo Valenzuela,Sergio Nú?ez,Dagoberto Arcos
Investigaciones Marinas , 1996,
Abstract: Existe escasa información sobre la ecología y sobrevivencia de estados larvales de merluza común frente a las costas de la VIII Región, Chile. Debido a que la agregación puede ser un factor determinante en la depredación de larvas de peces, en el presente trabajo se estudia su influencia en la mortalidad natural instantánea de larvas de merluza común (Merluccius gayi gayi Guichenot, 1848), estimada a través del modelo mortalidad-agregación de McGurk (1986). Las muestras (red bongo 500μ) fueron obtenidas durante un crucero efectuado en la zona costera del centro-sur de Chile (36o22'S _ 37o10'S) durante septiembre de 1991. La tasa de mortalidad natural instantánea fluctuó entre 0,1 y 0,38 d-1 para larvas en un rango de tallas de 4 a 11 mm de longitud estándar. Los valores de mortalidad obtenidos a través del modelo de interacción mortalidad-agregación (McGurk, 1986), revelaron que la distribución espacial (agregación) podría influenciar considerablemente a la mortalidad, especialmente en larvas de mayor longitud (> 9 mm). At the present time limited information is available about ecology and survival of Chilean hake larvae off coast from VIII Region, Chile. Because spatial patchiness of larvae may be an important factor on the predation of fish larvae, its influence on the instantaneous natural mortality of larval Chilean hake (Merluccius gayi gayi Guichenot, 1848) was studied using the mortality-patchiness model (McGurk, 1986). Samples (bongo net 500μ) were taken during a survey carried out in the coastal zone off Central-South Chile (36o22'S _ 37o10'S) during september 1991. The natural mortality for larvae between 4 to 11 mm of standard length fluctuated between 0,1 and 0,38 d-1. The mortality values obtained using the mortality-patchiness model (McGurk, 1986), showed that the spatial distribution (patchiness) would influence the larval mortality, specially in the largest ones (> 9 mm).
Diet of Two Large Sympatric Teleosts, the Ling (Genypterus blacodes) and Hake (Merluccius australis)  [PDF]
Matthew R. Dunn,Amelia M. Connell,Jeff Forman,Darren W. Stevens,Peter L. Horn
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013647
Abstract: Ling and hake are tertiary consumers, and as a result both may have an important structuring role in marine communities. The diets of 2064 ling and 913 hake from Chatham Rise, New Zealand, were determined from examination of stomach contents. Ling was a benthic generalist, and hake a demersal piscivore. The diet of ling was characterised by benthic crustaceans, mainly Munida gracilis and Metanephrops challengeri, and demersal fishes, mainly Macrourids and scavenged offal from fishing vessels. The diet of hake was characterised by teleost fishes, mainly macrourids and merlucciids. Multivariate analyses using distance-based linear models found the most important predictors of diet variability were depth, fish length, and vessel type (whether the sample was collected from a commercial or research vessel) for ling, and fish length and vessel type for hake. There was no interspecific predation between ling and hake, and resource competition was largely restricted to macrourid prey, although the dominant macrourid species predated by ling and hake were different. Cluster analysis of average diet of intraspecific groups of ling and hake confirmed the persistent diet separation. Although size is a central factor in determining ecological processes, similar sized ling and hake had distinctly different foraging ecology, and therefore could influence the ecosystem in different ways, and be unequally affected by ecosystem fluctuations.
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