Diurnal Variation in the Feeding Intensity and Catchability of Silver Hake (Merluccius bilinearis)

1980 ◽  
Vol 37 (10) ◽  
pp. 1565-1572 ◽  
Author(s):  
Ray E. Bowman ◽  
Edgar W. Bowman
Keyword(s):  
Diurnal Variation ◽  
Feeding Intensity ◽  
Free Swimming ◽  
The Mean ◽  
Crangon Septemspinosa ◽  
A Chain ◽  
Silver Hake ◽  
Merluccius Bilinearis

Feeding intensity and catchability of silver hake (Merluccius bilinearis) during periods of daylight and darkness were examined. Silver hake feed at night from just after dark until predawn, but mostly between dusk and midnight. After ~15 h in the stomach, partly digested food passes into the intestine where it continues to be digested for another 9 h before being evacuated. A variety of free-swimming crustaceans (i.e. Crangon septemspinosa, Dichelopandalus leptocerus, and Monoculodes intermedius) make up the largest part of the diet. Silver hake are located on or immediately above the bottom during the day and off bottom at night. Pelagic trawls, off-bottom trawls, and bottom trawls with roller gear tend to pass over silver hake during the day, while bottom trawls with chain-disc sweeps and cable sweeps catch large quantities. A high opening trawl combined with a chain-disc sweep would substantially increase the mean yield per tow by a vessel operating on a 24-h basis.Key words: silver hake, Merluccius bilinearis; feeding, food, diurnal variation, catchability, availability

scholarly journals Diurnal variability of the atmospheric boundary layer height over a tropical station in the Indian monsoon region

2017 ◽  
Vol 17 (1) ◽  
pp. 531-549 ◽  
Author(s):  
Sanjay Kumar Mehta ◽  
Madineni Venkat Ratnam ◽  
Sukumarapillai V. Sunilkumar ◽  
Daggumati Narayana Rao ◽  
Boddapaty V. Krishna Murthy
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Diurnal Variation ◽  
Indian Monsoon ◽  
Winter Season ◽  
Monsoon Region ◽  
Diurnal Variability ◽  
The Mean ◽  
Indian Monsoon Region ◽  
Tropical Station

Abstract. The diurnal variation of atmospheric boundary layer (ABL) height is studied using high-resolution radiosonde observations available at 3 h intervals for 3 days continuously from 34 intensive campaigns conducted during the period December 2010–March 2014 over a tropical station Gadanki (13.5° N, 79.2° E; 375 m), in the Indian monsoon region. The heights of the ABL during the different stages of its diurnal evolution, namely, the convective boundary layer (CBL), the stable boundary layer (SBL), and the residual layer (RL) are obtained to study the diurnal variabilities. A clear diurnal variation is observed in 9 campaigns out of the 34 campaigns. In 7 campaigns the SBL did not form in the entire day and in the remaining 18 campaigns the SBL formed intermittently. The SBL forms for 33–55 % of the time during nighttime and 9 and 25 % during the evening and morning hours, respectively. The mean SBL height is within 0.3 km above the surface which increases slightly just after midnight (02:00 IST) and remains almost constant until the morning. The mean CBL height is within 3.0 km above the surface, which generally increases from morning to evening. The mean RL height is within 2 km above the surface which generally decreases slowly as the night progresses. The diurnal variation of the ABL height over the Indian region is stronger during the pre-monsoon and weaker during winter season. The CBL is higher during the summer monsoon and lower during the winter season while the RL is higher during the winter season and lower during the summer season. During all the seasons, the ABL height peaks during the afternoon (∼ 14:00 IST) and remains elevated until evening (∼ 17:00 IST). The ABL suddenly collapses at 20:00 IST and increases slightly in the night. Interestingly, it is found that the low level clouds have an effect on the ABL height variability, but the deep convective clouds do not. The lifting condensation level (LCL) is generally found to occur below the ABL for the majority of the database and they are randomly related.

Storage Life of Refrozen Silver Hake (Merluccius bilinearis) Processed as Fillets am Minced Flesh from Thawed, Stored, Round-Frozen Fish

1977 ◽  
Vol 34 (12) ◽  
pp. 2369-2373 ◽  
Author(s):  
Doris Fraser Hiltz ◽  
D. H. North ◽  
Barbara Smith Lall ◽  
R. A. Keith
Keyword(s):  
Key Words ◽  
Frozen Storage ◽  
Storage Life ◽  
Freeze Thaw ◽  
Acceptable Quality ◽  
Frozen Fish ◽  
Silver Hake ◽  
Merluccius Bilinearis ◽  
Protein Extractability

Refrozen silver hake (Merluccius bilinearis), processed as fillets and minced flesh after thawing of stored round fish that had been frozen within 14 h of capture, underwent rapid deterioration during storage at −18 °C compared with once-frozen control materials from the same lot of fish. The estimated maximum storage life of silver hake refrozen as fillets after 3 and 6 mo storage of the round fish at −25 °C was reduced to about 4.5 and 1 mo, respectively, from 10 mo for once-frozen control fillets. Quality of the refrozen materials immediately after thawing and refreezing was similar to that of the round-frozen fish, except after 6 mo, where some initial deterioration occurred, particularly in minced flesh. Minced flesh was more unstable in frozen storage than fillets. In all once- and twice-frozen materials, formation of dimethylamine occurred concomitantly with decrease in protein extractability. Round-frozen fish underwent no loss in protein extractability during 6 mo storage at −25 °C, but some lipid hydrolysis occurred. These results suggest that the freeze–thaw–refreeze process as applied to silver hake will yield a final product of acceptable quality provided that storage of the round fish does not exceed 3–4 mo and that the refrozen materials are marketed within a month after processing. Key words: silver hake, Merluccius bilinearis, refrozen storage, dimethylamine, minced flesh

Seasonal and Geographic Variation in the Species Composition and Size of Prey Consumed by Grey Seals (Halichoerus grypus) on the Scotian Shelf

1993 ◽  
Vol 50 (8) ◽  
pp. 1768-1778 ◽  
Author(s):  
W. D. Bowen ◽  
J. W. Lawson ◽  
B. Beck
Keyword(s):  
Atlantic Cod ◽  
Halichoerus Grypus ◽  
Scotian Shelf ◽  
Sand Lance ◽  
Atlantic Mackerel ◽  
Relative Contribution ◽  
Wet Weight ◽  
The Mean ◽  
Silver Hake ◽  
Commercial Size

The grey seal (Halichoerus grypus) population on the Scotian Shelf has grown significantly over the past 20 yr, thus increasing the potential for competitive interactions between grey seals and fisheries. The relative contribution (percent wet weight) and size of prey eaten were estimated from otoliths and squid beaks recovered from 143 stomachs that contained food of the 528 collected from 1988 to 1990. Although 22 taxa were found, only four species (Atlantic herring, silver hake, Atlantic cod, and squid) accounted for 80% of the estimated weight of food eaten. The mean length of prey eaten ranged from 19 to 35 cm for six species. Only 17% of the cod and none of the pollock and squid eaten were of the length taken in commercial fisheries. However, about 80% of the silver hake and herring eaten were of commercial size. Offshore at Sable Island, northern sand lance, silver hake, and squid (in order of importance) accounted for 86.1% of the wet weight ingested by seals during summer; sand lance and cod accounted for 96.1% of prey eaten in winter. At inshore locations, herring, cod, and pollock made up 90% of the diet in summer; Atlantic mackerel, cod, squid, and herring made up 83% of the diet in winter.

scholarly journals Study of the thermal regime of a reservoir on the Qinghai-Tibetan Plateau, China

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243198
Author(s):  
Yanjing Yang ◽  
Yun Deng ◽  
Youcai Tuo ◽  
Jia Li ◽  
Tianfu He ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Diurnal Variation ◽  
Water Temperature ◽  
Water Column ◽  
Temperature Structure ◽  
Observation Data ◽  
The Mean ◽  
Low Altitude ◽  
Mean Variance ◽  
Whole Water

The Qinghai-Tibetan Plateau region has unique meteorological characteristics, with low air temperature, low air pressure, low humidity, little precipitation, and strong diurnal variation. A two-dimensional hydrodynamic CE-QUAL-W2 model was configured for the Pangduo Reservoir to better understand the thermal structure and diurnal variation inside the reservoir under the local climate and hydrological conditions on the Qinghai-Tibetan Plateau. Observation data were used to verify the model, and the results showed that the average error of the 6 profile measured monthly from August to December 2016 was 0.1°C, and the root-mean-square error (RMSE) was 0.173°C. The water temperature from August 2016 to September 2017 was simulated by inputting measured data as model inputs. The results revealed that the reservoir of the Qinghai-Tibetan Plateau was a typical dimictic reservoir and the water mixed vertically at the end of March and the end of October. During the heating period, thermal stratification occurred, with strong diurnal variation in the epilimnion. The mean variance of the diurnal water temperature was 0.10 within a 5 m water depth but 0.04 in the whole water column. The mixing mode of inflow changed from undercurrent, horizontal-invaded flow and surface layer flow in one day. In winter, the diurnal variation was weak due to the thermal protection of the ice cover, while the mean variance of diurnal water temperature was 0.00 within both 5 m and the whole water column. Compared to reservoirs in areas with low altitude but the same latitude, significant differences occurred between the temperature structure of the low-altitude reservoir and the Pangduo Reservoir (P<0.01). The Pangduo Reservoir presented a shorter stratification period and weaker stratification stability, and the annual average SI value was 26.4 kg/m2, which was only 7.5% that of the low-altitude reservoir. The seasonal changes in the net heat flux received by the surface layers determined the seasonal cycle of stratification and mixing in reservoirs. This study provided a scientific understanding of the thermal changes in stratified reservoirs under the special geographical and meteorological conditions on the Qinghai-Tibetan Plateau. Moreover, this model can serve as a reference for adaptive management of similar dimictic reservoirs in cold and high-altitude areas.

scholarly journals Diurnal Corrected QT Interval and QT Dispersion Variation in Non-Alcoholic Cirrhotic Patients and Healthy Control: A Case-Control Study, Iran

2020 ◽  
Vol In Press (In Press) ◽  
Author(s):  
Taghi Amiriani ◽  
Vahid Khori ◽  
Ali Davarian ◽  
Niloofar Rajabli ◽  
Mahsa Niknam ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Diurnal Variation ◽  
Healthy Subjects ◽  
Alcoholic Cirrhosis ◽  
Qt Dispersion ◽  
Qtc Interval ◽  
Healthy Controls ◽  
Cirrhotic Patients ◽  
The Mean

Background: Cirrhosis could lead to a long corrected QT (QTc) interval in a subgroup of patients, but there are spare data on its diurnal variation. Objectives: The present study aimed to determine the diurnal variation of QTc interval and its relationship to heart rate and blood pressure variation during 24-hour Holter-monitoring in non-alcoholic cirrhosis in comparison with the healthy controls. Methods: The study population comprised 15 patients with non-alcoholic cirrhosis and 15 healthy subjects, undergoing 24-hour electrocardiogram (ECG), heart rate, and blood pressure monitoring. The mean QT interval, mean QTc, maximum and minimum QT, QT dispersion (QT disp), heart rate, and mean arterial blood pressure were measured for each person for 24 hours. Liver stiffness measurement (LSM) was performed by FibroScan® 502 machine (EchoSense, Paris, France, 5 MHz). The results were demonstrated as percentages and mean ± SD. P value ≤ 0.05 was considered significant. Results: Mean QTc was significantly higher in cirrhosis (438 ms) than healthy controls (401.7 ms) (P = 0.03). The mean heart rate was significantly different in cirrhotic patients (79.6 ± 2.9/bpm) compared to healthy controls (72.47 ± 2.0/bpm) (P = 0.05). Conclusions: In this study, QTc was prolonged and increased with the severity of cirrhosis, and its diurnal variation in cirrhosis was different from healthy subjects.

scholarly journals A zero percent plastic ingestion rate by silver hake (Merluccius bilinearis) from the south coast of Newfoundland, Canada

2018 ◽  
Vol 131 ◽  
pp. 267-275 ◽  
Author(s):  
France Liboiron ◽  
Justine Ammendolia ◽  
Jacquelyn Saturno ◽  
Jessica Melvin ◽  
Alex Zahara ◽  
...  
Keyword(s):  
Ingestion Rate ◽  
South Coast ◽  
The South ◽  
Silver Hake ◽  
Merluccius Bilinearis

Contribution of the Torsional Modes to the Equilibrium Distribution of Vibrational States and to the Specific Heat of a Chain Molecule

1983 ◽  
Vol 38 (12) ◽  
pp. 1285-1292 ◽  
Author(s):  
J. A. Borges da Costa ◽  
C. Scherer ◽  
A. Holz ◽  
J. Naghizadeh
Keyword(s):  
Specific Heat ◽  
Equilibrium Distribution ◽  
Spatial Configuration ◽  
Low Frequency ◽  
Chain Molecule ◽  
Vibrational States ◽  
Polymer Molecules ◽  
The Mean ◽  
A Chain ◽  
Increasing Temperature

Abstract The torsional modes of a chain molecule were studied recently under the assumption that it has a well defined spatial configuration at any time. Here we show how the averages over the possible configurations, for a distribution in thermal equilibrium, should be performed in the calculation of the thermodynamical properties. Our results show that the mean density of torsional states increases in the low frequency region with increasing temperature. The specific heat behaviour shows a considerable difference from the result obtained in the previous paper, where only the lowest energetic configuration was considered. The consequences of this result with respect to the configurational properties of polymer molecules near the θ temperature are discussed.

Behavioral inferences from regulatory observer data: catch rate variation in the Scotian Shelf silver hake (Merluccius bilinearis) fishery

1999 ◽  
Vol 56 (2) ◽  
pp. 288-296 ◽  
Author(s):  
D M Gillis
Keyword(s):  
Interference Competition ◽  
Temporal Trends ◽  
Catch Rate ◽  
Rate Variation ◽  
Scotian Shelf ◽  
Apparent Contradiction ◽  
Fishing Vessels ◽  
Catch Rates ◽  
Silver Hake ◽  
Merluccius Bilinearis

The detailed spatial and temporal data collected for the regulation of the silver hake (Merluccius bilinearis) fishery on the Scotian Shelf provide a unique opportunity to test hypotheses about variability in catch rates on the scale of individual trawls. I used these data to examine vessel interactions and long-term temporal trends in catchability. An index of course linearity, derived from observed positions, times, and speeds of fishing vessels, indicated that interference competition was present in the fishery. However, catch rate did not decline with local vessel density. This apparent contradiction is consistent with fleet dynamic theory and suggests that the direct examination of catch rates is a poor test for interference in the retrospective analysis of fisheries data. The study of extended periods of high, localized fishing activity revealed a cycle in catch rates with periods of about 6 days. Such periods may represent an interaction between tidal, diel, and (or) technological factors. Although more study is required to identify the cause of these cycles, their existence should be considered in the design of surveys and other population studies using catch and effort data.

I. On the solar-diurnal variation of the magnetic declination at Pekin

1860 ◽  
Vol 10 ◽  
pp. 360-374
Keyword(s):  
Diurnal Variation ◽  
First Year ◽  
Magnetic Observatory ◽  
Magnetic Element ◽  
Monthly Means ◽  
The North ◽  
The Hours ◽  
The Mean ◽  
The Times ◽  
North End

When the first year of hourly observations of the declination, January 1 to December 31st, 1841, was received at Woolwich from the Magnetic Observatory at Hobarton, and when means had been taken of the readings of the collimator-scale at the several hours in each month, and these monthly means had been collected into an­nual means, it was found that the mean daily motion of the declina­tion magnet at Hobarton presented, as one of its most conspicuous and well-marked features, a double progression in the twenty-four hours, moving twice from west to east, and twice from east to west; the phases of this diurnal variation were, that the north end of the magnet moved progressively from west to east in the hours of the forenoon, and from east to west in the hours of the afternoon ; and again from west to east during the early hours of the night, return­ing from east to west during the later hours of the night: the two easterly extremes were attained at nearly homonymous hours of the day and night, as were also the two westerly extremes; the ampli­tudes of the arcs traversed during the hours of the day were con­siderably greater than those traversed during the hours of the night. When, in like manner, the first year of hourly observations, July 1st, 1842, to June 30th, 1843, was received from the Toronto Ob­servatory, and the mean diurnal march of the declination magnet was examined, it was found to exhibit phenomena in striking corre­spondence with those at Hobarton. At Toronto also a double pro­gression presented itself, of which the easterly extremes were attained at nearly homonymous hours, as were also the westerly; whilst the hours of extreme elongation were nearly the same (solar) hours at the two stations, but with this distinction, that the hours at which the north end of the magnet reached its extreme easterly elongation at Hobarton were the same, or nearly the same, as those at which it reached its extreme westerly elongation at Toronto, and vice verâ Pursuing, therefore, the ordinary mode of designating the direction of the declination by the north end of the magnet in the southern as well as in the northern hemisphere, the diurnal motion of the magnet may be said to be in opposite directions at Hobarton and Toronto; but if (in correspondence with our mode of speaking in regard to another magnetic element, the Inclination) the south end of the magnet is employed to designate the direction of the motion in the southern hemisphere, and the north end in the northern hemisphere, the apparent contrariety disappears, and the directions, as well as the times of the turning hours, are approximately the same at both stations.

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