scholarly journals Escape rate for cod (Gadus morhua) from the codend during buffer towing

2017 ◽  
Vol 75 (2) ◽  
pp. 805-813 ◽  
Author(s):  
Jesse Brinkhof ◽  
Bent Herrmann ◽  
Roger B Larsen ◽  
Manu Sistiaga
Keyword(s):  
Gadus Morhua ◽  
Disease Susceptibility ◽  
Barents Sea ◽  
Escape Rate ◽  
Commercial Fishing ◽  
Size Selectivity ◽  
Size Selection ◽  
Selection For ◽  
Significant Size ◽  
Growth And Reproduction

Abstract The high abundances of Northeast Arctic cod (Gadus morhua) in the Barents Sea have led to the development of a new fishing tactic called buffer towing. On factory trawlers, the trawl is deployed immediately after taking the catch onboard, a tactic used to ensure a continuous supply of fish is being processed. If the desired amount of fish is caught before the catch from the previous haul has been fully processed, the trawl is lifted off the seabed and towed at a given depth at low speed. This is called buffer towing. Cod that escape from the codend when the trawl is shallower than the initial fishing depth are exposed to an increased likelihood of barotrauma-related injuries, increased disease susceptibility, and predation, which could be lethal, or affect growth and reproduction capability. Therefore, this study quantified the escape rate and size selectivity during buffer towing of cod. A new analytical method was applied that allows using the same trawl configuration as applied during commercial fishing and avoids potential bias in the assessment of buffer towing size selection. Our results demonstrated a significant size selection for cod during buffer towing where cod measuring up to at least 42 cm in length were proven to escape. In particular, at least 60% of cod measuring 20 cm were estimated to escape during buffer towing. For cod measuring 30 and 40 cm, at least 53 and 45% were estimated to escape during buffer towing, respectively.

Comparison of a rigid grid to a square-mesh panel in size selection for commercial fishing in the Persian Gulf shrimp trawl fishery

2016 ◽  
Vol 32 (6) ◽  
pp. 1026-1031 ◽  
Author(s):  
M. Eighani ◽  
S. Y. Paighambari ◽  
S. Eayrs
Keyword(s):  
Persian Gulf ◽  
Commercial Fishing ◽  
Size Selection ◽  
Trawl Fishery ◽  
Shrimp Trawl ◽  
Selection For ◽  
The Persian Gulf

scholarly journals Potential for codends with shortened lastridge ropes to replace mandated selection devices in demersal trawl fisheries

2021 ◽  
Author(s):  
Manu Sistiaga ◽  
Jesse Brinkhof ◽  
Bent Herrmann ◽  
Roger B. Larsen ◽  
Eduardo Grimaldo ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Size Selectivity ◽  
The Barents Sea ◽  
Alternative Solutions ◽  
Trawl Fisheries

In many trawl fisheries, codend size selectivity is supplemented by adding selection devices to the gear. In the Barents Sea gadoid fishery, combining diamond mesh codends with sorting grids is compulsory. However, the use of grids increases the costs and complexity of the gear, causing discontent among fishermen and prompting researchers to seek alternative solutions. Lastridge ropes are ropes attached to the selvedges of the codend. In this study, we tested the effect of shortening the lastridge ropes of two diamond mesh codends with different mesh sizes on the size selectivity of cod (Gadus morhua), haddock (Melanogramus aeglefinnus), and redfish (Sebastes spp.). Shortening the lastridge ropes by 15% increased the mesh opening during the fishing process, which significantly improved the size-selective properties of the codends. Further, the L50 values were always higher for the codends in the short lastridge configuration. Therefore, codends with shortened lastridge ropes may be a simpler alternative to sorting grids in this fishery, and they may be applicable to many other fisheries in which additional selection devices are used.

scholarly journals Effect of a quality-improving cod end on size selectivity and catch patterns of cod in bottom trawl fishery

2019 ◽  
Vol 76 (11) ◽  
pp. 2110-2120 ◽  
Author(s):  
Jesse Brinkhof ◽  
Bent Herrmann ◽  
Roger B. Larsen ◽  
Tiago Veiga-Malta
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Relative Size ◽  
Bottom Trawl ◽  
Size Selectivity ◽  
Total Size ◽  
Trawl Fishery ◽  
The Barents Sea ◽  
Sea Bottom ◽  
Significant Difference

A new cod-end concept developed and tested exhibited significantly improved quality of caught cod (Gadus morhua) compared with that of the conventional cod end used in the Barents Sea bottom trawl fishery. However, the design of the new quality-improving cod end raised concerns about its size selectivity and the possibility that higher retention probability could negatively impact the catch pattern by increasing the proportion of undersized cod. Therefore, the goal of this study was to quantify and compare the size selectivity and catch pattern for cod when deploying, respectively, the conventional and new quality-improving cod end in the Barents Sea bottom trawl fishery. The new quality-improving cod end had significantly lower relative size selectivity than the conventional cod end, but no significant difference in the catch patterns was detected in the trawl. Further, estimation of the total size selectivity in the trawl revealed that the increased retention of small cod when using the quality-improving cod end was minor. Hence, despite the reduced selectivity, the quality-improving cod end can be used with low risk of retaining small cod.

scholarly journals Effect of a fish stock's demographic structure on offspring survival and sensitivity to climate

2017 ◽  
Vol 114 (6) ◽  
pp. 1347-1352 ◽  
Author(s):  
Leif Christian Stige ◽  
Natalia A. Yaragina ◽  
Øystein Langangen ◽  
Bjarte Bogstad ◽  
Nils Chr. Stenseth ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Condition Index ◽  
Wide Distribution ◽  
Commercial Fishing ◽  
Demographic Structure ◽  
Data Set ◽  
Spawning Period ◽  
Spawning Stock ◽  
Eggs And Larvae

Commercial fishing generally removes large and old individuals from fish stocks, reducing mean age and age diversity among spawners. It is feared that these demographic changes lead to lower and more variable recruitment to the stocks. A key proposed pathway is that juvenation and reduced size distribution causes reduced ranges in spawning period, spawning location, and egg buoyancy; this is proposed to lead to reduced spatial distribution of fish eggs and larvae, more homogeneous ambient environmental conditions within each year-class, and reduced buffering against negative environmental influences. However, few, if any, studies have confirmed a causal link from spawning stock demographic structure through egg and larval distribution to year class strength at recruitment. We here show that high mean age and size in the spawning stock of Barents Sea cod (Gadus morhua) is positively associated with high abundance and wide spatiotemporal distribution of cod eggs. We find, however, no support for the hypothesis that a wide egg distribution leads to higher recruitment or a weaker recruitment–temperature correlation. These results are based on statistical analyses of a spatially resolved data set on cod eggs covering a period (1959−1993) with large changes in biomass and demographic structure of spawners. The analyses also account for significant effects of spawning stock biomass and a liver condition index on egg abundance and distribution. Our results suggest that the buffering effect of a geographically wide distribution of eggs and larvae on fish recruitment may be insignificant compared with other impacts.

Understanding limits to cod and haddock separation using size selectivity in a multispecies trawl fishery: an application of FISHSELECT

2011 ◽  
Vol 68 (5) ◽  
pp. 927 ◽  
Author(s):  
Manu Sistiaga ◽  
Bent Herrmann ◽  
Kåre N. Nielsen ◽  
Roger B. Larsen
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Morphological Characteristics ◽  
Melanogrammus Aeglefinus ◽  
Size Selectivity ◽  
Sea Trial ◽  
Trawl Fishery ◽  
The Barents Sea ◽  
Morphological Differences

This investigation demonstrates how a multidisciplinary approach based on the FISHSELECT framework, sea trial data, underwater recordings, and laboratory investigations of netting can be applied to size selectivity studies and related management issues. We studied the morphological characteristics of Atlantic cod ( Gadus morhua ) and haddock ( Melanogrammus aeglefinus ) in the Barents Sea bottom trawl fishery. The differences between the L50 values (i.e., the size at which a fish has a 50% chance of being retained) that were recorded for the two species during sea trials can to a large extent be explained by the morphological differences between them. Because of these morphological differences, L50 is always larger for cod than for haddock with the grid and codend setup commonly used in the area. While catch separation of cod and haddock is a management objective in the Barents Sea, we demonstrate that the morphological differences between the species and the grid and codend setup in force today limit achievable differences in L50 to 5.5 cm. Furthermore, we show that for this fishery, the scope for increasing L50 differences between these species by changing the mesh shape configuration of the codend is minimal.

scholarly journals Prediction of square mesh panel and codend size selectivity of blue whiting based on fish morphology

2020 ◽  
Author(s):  
Elsa Cuende ◽  
Luis Arregi ◽  
Bent Herrmann ◽  
Manu Sistiaga ◽  
Xabier Aboitiz
Keyword(s):  
Morphological Characteristics ◽  
Mesh Size ◽  
Contact Angles ◽  
Size Selectivity ◽  
Blue Whiting ◽  
Size Selection ◽  
Fish Morphology ◽  
Selection For ◽  
Pass Through ◽  
Trawl Fisheries

Abstract Square mesh panels (SMPs) are selective devices used extensively to supplement codend size selectivity in trawl fisheries. Therefore, predictions of the effect of mesh size in both SMPs and codends on size selectivity are valuable. Here, we established a framework to predict the size selection of blue whiting through different SMPs and diamond mesh codends based on the morphological characteristics of this species. We hypothesized that size selection for an SMP is determined by different fish contact angles, whereas different mesh opening angles determine size selection for the codend. Based on these hypotheses, we first developed a model that enabled us to predict which sizes of blue whiting are able to pass through meshes of different sizes and shapes. We then tested whether the selectivity for blue whiting of the SMP, the codend, and the combination of both could be explained by the models. Finally, we predicted the size selectivity of multiple combinations of SMPs and diamond mesh codends. The method presented here can potentially be applied to make predictions for species other than blue whiting.

scholarly journals New approach for modelling size selectivity in shrimp trawl fisheries

2017 ◽  
Vol 75 (1) ◽  
pp. 351-360 ◽  
Author(s):  
Roger B Larsen ◽  
Bent Herrmann ◽  
Manu Sistiaga ◽  
Jesse Brinkhof ◽  
Ivan Tatone ◽  
...  
Keyword(s):  
Barents Sea ◽  
Cold Water ◽  
Small Fish ◽  
Size Selectivity ◽  
Size Selection ◽  
Trawl Fishery ◽  
Size Dependent ◽  
Shrimp Trawl ◽  
Pass Through ◽  
The Individual

Abstract In the deep sea trawl fishery targeting shrimp (Pandalus borealis) and other cold-water shrimp species, fishers often use a Nordmöre sorting grid ahead of a small mesh codend to avoid bycatch. However, small fish can pass through the grid and are subsequently retained in the codend. This makes shrimp size selection complex and the size-dependent curve for both the shrimp and the bycatch species often exhibits a bell-shaped signature. In this study we developed a new model and method to estimate size selection in this fishery, conducted fishing trials in the Northeast Barents Sea, and applied the new method to quantify the individual and combined size selection of the Nordmöre grid and codend for deep water shrimp and two bycatch species. The size selectivity for both bycatch species showed the expected bell-shaped signature with low retention probability of very small and larger fish. The Nordmöre grid had high passage probability for all sizes, although it decreased slightly for the largest shrimps. The smallest shrimps were released by the codend.

Apparel Research Network (ARN) Program Size Selection for ARNSCAN

2001 ◽  
Author(s):  
Carol Ring
Keyword(s):  
Research Network ◽  
Size Selection ◽  
Selection For

Optimal size selection for fuel cell and battery in a hybrid power system of the intercity locomotives

2021 ◽  
pp. 128498
Author(s):  
Guiju Zhang ◽  
Hao Li ◽  
Caiyuan Xiao ◽  
Kittisak Jermsittiparsert
Keyword(s):  
Fuel Cell ◽  
Power System ◽  
Optimal Size ◽  
Hybrid Power System ◽  
Size Selection ◽  
Hybrid Power ◽  
Selection For
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