scholarly journals Mesh sticking probability in fishing gear selectivity: Methodology and case study on Norway lobster (Nephrops norvegicus) and mantis shrimp (Squilla mantis) in the Mediterranean Sea creel fishery

2019 ◽  
Vol 20 (3) ◽  
pp. 487 ◽  
Author(s):  
JURE BRČIĆ ◽  
BENT HERRMANN ◽  
MARINA MAŠANOVIĆ ◽  
SVJETLANA KRSTULOVIĆ ŠIFNER ◽  
MATEJA BARANOVIĆ ◽  
...  
Keyword(s):  
Carapace Length ◽  
Estimation Procedure ◽  
Sticking Probability ◽  
Fishing Gear ◽  
Nephrops Norvegicus ◽  
Mantis Shrimp ◽  
Size Dependent ◽  
A Value ◽  
Norway Lobster ◽  
Escape Probabilities

Fish or crustaceans stuck in the fishing gear meshes can lead to operational problems in some fisheries and thereby affect theeconomic gain. However, mesh sticking probability has never been formally quantified as a part of the estimation of fishing gearsize selectivity. Therefore, this study developed a size selection model and estimation procedure that, besides the size dependentretention and escape probabilities, includes the size dependent mesh sticking probability. The new method was applied to quantify the size dependent retention, sticking and escape probabilities for mantis shrimp (Squilla mantis) and Norway lobster (Nephrops norvegicus) in creels with 41 mm square mesh netting. The mesh sticking probability was found to display a bell-shaped curvature with a maximum value for a specific carapace length and decreasing probabilities for both smaller and bigger individuals. For mantis shrimp the maximum sticking probability was found for 32.5 mm carapace length with a value at 13.5%, while 63.1% and 23.4% of that size were respectively retained inside the creels and escaped. For Norway lobster the maximum sticking probabilitywas 2% and occurred for 34.0 mm carapace length. The method and estimation procedure presented in this study might be applicable for quantifying mesh sticking probability as an integral part of future fishing gear size selectivity studies on other speciesand fisheries.

Epizoic foraminifera on Nephrops norvegicus

1977 ◽  
Vol 57 (3) ◽  
pp. 877-878 ◽  
Author(s):  
A. S. D. Farmer
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Carapace Length ◽  
Mature Male ◽  
Nephrops Norvegicus ◽  
Anatomical Studies ◽  
Norway Lobster ◽  
Prepared Material ◽  
Inner Surface ◽  
Scanning Electron

During studies in 1972 on the setation and development of the secondary sexual characters of the Norway lobster, Nephrops norvegicus (L., 1758), Foraminifera were observed attached to the pleopods of a mature male (carapace length 2.47 cm). On subsequent examination of the prepared material with a scanning electron microscope it was found that the Foraminifera were attached to one of the first pair of pleopods. Three individuals were observed, all of which were attached to the same pleopod on the inner surface near the tip. No further specimens of Foraminifera were encountered during detailed anatomical studies of more than 30 specimens of N. norvegicus.

scholarly journals Ovary resorption in the Norway lobster (Nephrops norvegicus) and its possible causes with special reference to sperm storage

2020 ◽  
Vol 74 (1) ◽  
Author(s):  
Carola Becker ◽  
Jaimie T. A. Dick ◽  
E. Mánus Cunningham ◽  
Mathieu Lundy ◽  
Ewen Bell ◽  
...  
Keyword(s):  
North Sea ◽  
Demographic Data ◽  
Irish Sea ◽  
Natural Phenomenon ◽  
Nephrops Norvegicus ◽  
North East ◽  
The North ◽  
Norway Lobster ◽  
The North Sea ◽  
Reproductive Cycles

Abstract The Norway lobster, Nephrops norvegicus, is an important fisheries species in the North-East Atlantic area. In some circumstances, mature females of Nephrops norvegicus can resorb their ovary rather than completing spawning, but the implications of this phenomenon to reproductive biology and fisheries sustainability are not known. To understand after effects of ovary resorption, we studied long-term demographic data sets (1994–2017) collected from the western Irish Sea and the North Sea. Our considerations focused on potential correlations among the frequency of resorption, female insemination, and body size of resorbing females. Resorption was continuously rare in the western Irish Sea (less than 1%); whereas much higher rates with considerable year-to-year variation were observed in the North Sea (mean 9%). Resorption started in autumn after the spawning season (summer) had passed. The frequency stayed high throughout winter and declined again in spring. As sperm limitation can occur in male-biased fisheries, we expected a lack of insemination could be responsible for resorption, but affected females were indeed inseminated. Resorbing females were significantly larger than other sexually mature females in the North Sea, but the opposite trend was observed in the western Irish Sea. It is therefore possible that other, environmental factors or seasonal shifts, may trigger females to resorb their ovaries instead of spawning. Resorption may as well represent a natural phenomenon allowing flexibility in the periodicity of growth and reproduction. In this sense, observations of annual versus biennial reproductive cycles in different regions may be closely linked to the phenomenon of ovary resorption.

scholarly journals Construction of Gill Net 2 and 3 Inches in The Village Kampung Nelayan of Regency Tanjung Jabung Barat

2019 ◽  
Vol 10 (1) ◽  
pp. 15-23
Author(s):  
Nelwida Nelwida ◽  
Lisna Lisna ◽  
Ren Fitriadi
Keyword(s):  
Statistical Analysis ◽  
Survey Method ◽  
Fishing Gear ◽  
Environmental Friendliness ◽  
Gill Nets ◽  
A Value ◽  
Gill Net ◽  
Dimension Analysis ◽  
The Village ◽  
Descriptive Statistical Analysis

Gill nets is the most dominant fishing gear used by fishermen in Kampung Nelayan Village. Gill nets 2 and 3 inches are widely used by traditional fishermen and modern fishermen because this tool is very practical to catch fish also friendly to the environment. This study aims to determine the construction and friendliness of fishing gear gill nets 2 and 3 inches which include the length of the net, the width of the net, shortening, buoyancy and sinking power. This research was carried out in the Village of Kampung Nelayan, Tungkal Ilir Subdistrict, Tanjung Jabung Barat District in February 2018. The method used in this research was survey method. The data obtained were analyzed using net dimension analysis and descriptive statistical analysis. Based on the results of research on the construction of 2 and 3 inches gill nets consisting of nylon monofilament made from transparent colors. The knot used by the English knot. Top rope, float, and float buoy made from polyethylene (PE) rope and ballast rope made from polypropylene (PP). The sinker made from tin and gill net 3 inch weight based on bracelet-shaped wire.Net shortening value of 2 inch is 51.75% and has a buoyancy of 3.05 kgf and a sinking power of 9.97 kgf. As well as the value of gill shortening 3 inch 50.62% and the buoyancy generated 6.22 kgf and the sinking power of 365.4 kgf. The value of environmental friendliness of 2 and 3 inch nets has a value of 31.25 and 30.75 and is classified as environmentally friendly fishing gear.

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