scholarly journals Diamondvs.square mesh codend in a multi-species trawl fishery of the western Mediterranean: effects on catch composition, yield, size selectivity and discards

2006 ◽  
Vol 19 (4) ◽  
pp. 329-338 ◽  
Author(s):  
Francesc Ordines ◽  
Enric Massutí ◽  
Beatriz Guijarro ◽  
Ramon Mas
Keyword(s):  
Western Mediterranean ◽  
Size Selectivity ◽  
Trawl Fishery ◽  
Catch Composition

scholarly journals Selectivity of diamond- and square-mesh codends in the deepwater crustacean trawl fishery off the Balearic Islands (western Mediterranean)

2006 ◽  
Vol 63 (1) ◽  
pp. 52-67 ◽  
Author(s):  
Beatriz Guijarro ◽  
Enric Massutí
Keyword(s):  
Economic Loss ◽  
Western Mediterranean ◽  
Balearic Islands ◽  
Size Selectivity ◽  
Trawl Fishery ◽  
Commercial Species ◽  
The One ◽  
Catch Composition ◽  
The Impact ◽  
Upper Slope

Abstract An analysis of 38 bottom trawl hauls at depths of 251–737 m off the Balearic Islands (western Mediterranean) during autumn 2002 and spring 2003 was used to compare the species and size selectivity of 40-mm diamond- and square-mesh codends under commercial conditions. There was no difference in the catch composition or the yield that could be attributable to mesh shape, although the percentage of total and commercial species discarded with a diamond mesh was higher than with a square mesh. At least in the short term, the escapement ratio and the economic loss with the diamond mesh were lower than with square mesh, but economic efficiency was no different between them. For all the main species compared, except one flatfish, size selectivity parameters were lower for the diamond-than for the square-mesh codend. Selectivity values for the one flatfish species were similar. From the results it is concluded that, within the context of precautionary management, introduction of a 40-mm square mesh in the codend could be an appropriate and plausible measure to improve the state of the resources exploited by the deepwater crustacean trawl fishery of the upper slope off the Balearic Islands, and to reduce the impact of the fishery on the ecosystem.

Assessment of the deep water trawl fishery off the Balearic Islands (western Mediterranean): from single to multi-species approach

Hydrobiologia ◽  
2011 ◽  
Vol 670 (1) ◽  
pp. 67-85 ◽  
Author(s):  
Beatriz Guijarro ◽  
George Tserpes ◽  
Joan Moranta ◽  
Enric Massutí
Keyword(s):  
Deep Water ◽  
Western Mediterranean ◽  
Balearic Islands ◽  
Trawl Fishery

scholarly journals Prediction of delayed mortality using vitality scores and reflexes, as well as catch, processing, and post-release conditions: evidence from discarded flatfish in the Western Baltic trawl fishery

2018 ◽  
Vol 76 (1) ◽  
pp. 330-341 ◽  
Author(s):  
S B M Kraak ◽  
A Velasco ◽  
U Fröse ◽  
U Krumme
Keyword(s):  
Scientific Evidence ◽  
Handling Time ◽  
Fishing Ground ◽  
High Survival ◽  
Trawl Fishery ◽  
Fishing Vessels ◽  
Reflex Action ◽  
Delayed Mortality ◽  
Catch Composition ◽  
The Eu

Abstract The EU discard ban and its high-survival exemption exposed our lack of scientific evidence on discard survival in the fisheries. Discard survival is known to be highly variable and influenced by numerous factors, including conditions during the catch, on-board the fishing vessels, and post-discard. Therefore, obtaining unambiguous results in discard survival experiments is challenging. We conducted the first systematic year-round discard survival study of flatfish in the Western Baltic Sea on-board a commercial stern trawler under realistic fishing conditions (13 monthly hauls from May 2015 to May 2016) to test whether delayed mortality can be predicted by vitality scores and reflex action mortality predictor (RAMP) scores in combination with variable conditions during catch, processing, and post-release. The factors vessel type, gear, haul duration, fishing ground, depth, handling time, and processing procedures were kept constant as much as possible. On-board, live individual flatfish were tested for vitality and the presence of reflexes for RAMP, then “discarded” and kept in cages on the bottom of the seafloor for about a week after which the delayed mortality was determined. The proportions of “discarded” plaice, flounder, and dab that were dead after being kept in the cages ranged from 5% to 100%, 0% to 96%, and 33% to 100%, respectively. Higher mortalities occurred in summer-autumn when air and water temperatures were higher, catches smaller, and catches contained smaller proportions of roundfish. Relationships between RAMP scores and mortality probabilities varied substantially across the monthly trials. Indeed, in addition to RAMP or vitality scores and individual reflexes, the factors air and water temperature and catch weight and catch composition were significant in logistic GLMs explaining delayed mortality. Cross-validations indicated that delayed mortality could be predicted by these models with a reasonable accuracy. Nevertheless, the presence of possible confounding effects calls for caution in inferring causality and extrapolating the conclusions on predictability.

scholarly journals Catch pattern and size selectivity for a gear designed to prevent fish injuries during the capture process in a North-East Atlantic demersal trawl fishery

2020 ◽  
Vol 40 ◽  
pp. 101525
Author(s):  
Bent Herrmann ◽  
Manu Sistiaga ◽  
Roger B. Larsen ◽  
Jesse Brinkhof ◽  
Svein Helge Gjøsund ◽  
...  
Keyword(s):  
Size Selectivity ◽  
East Atlantic ◽  
Capture Process ◽  
Trawl Fishery ◽  
North East

The by-catch of sharks in the western Mediterranean (Balearic Islands) trawl fishery

2003 ◽  
Vol 61 (1-3) ◽  
pp. 7-18 ◽  
Author(s):  
A Carbonell ◽  
F Alemany ◽  
P Merella ◽  
A Quetglas ◽  
E Román
Keyword(s):  
Western Mediterranean ◽  
Balearic Islands ◽  
Trawl Fishery ◽  
By Catch

scholarly journals CATCH RATE AND CATCH COMPOSITION OF FISH TRAWL BASED IN SIBOLGA, NORTH SUMATERA

2017 ◽  
Vol 17 (2) ◽  
pp. 63
Author(s):  
Agustinus Anung Widodo ◽  
Mahiswara Mahiswara
Keyword(s):  
Indian Ocean ◽  
Fishing Ground ◽  
Fuel Price ◽  
Fishing Trip ◽  
Trawl Fishery ◽  
The Indian Ocean ◽  
Catch Composition ◽  
Operation Results ◽  
Engine Power ◽  
Design And Construction

To obtain data and information of fish trawl fishery performance operated in the Indian Ocean, a research was carried out through observation on board by observers as well as port sampling inSibolga Fishing Port by enumerators in September 2007, with the aimed to study the performance fish trawl fishery. These include fleet structure, trawl net design and construction, catch, fishing trip, fishing ground, and fishing operation. Results of research showed that there were 71 registered fish trawlers in Sibolga Fishing Port and only 25 boats active due to increasing of fuel price. The fleet structure of fish trawler consist of boat with size 31-114 GT which can be classified into 3 categories i.e. small(<60 GT), medium (60-150 GT), and large fish trawler (>150 GT). Design and construction of fish trawl net indicated that fish trawl net operates in the Indian Ocean was high opening trawl with head and ground rope of 27.8-41.5 m and 29,7-45.8 m, respectively. Fishing trip generally 10-12 days with effective days 7-9 days per trip and the number of net setting was 5-6 times each day. The fishing grounds of fish trawl based in Sibolga were the coastal waters area with maximum depth of 91 m. At least 40 species of fishes and shrimps identified during research and dominant fish species was ponyfish (Leiognathus spp.) threadfin bream (Nemipterus spp.), tall fin goatfish (Upeneus spp.), seacatfish (Arius sp.) as well as yellow striped goatfish (Upeneus vitattus). The average of catch of fish trawler fleet in the year of 2007 was 249.3 kg/haul and that number seems smaller than average of catch/haul previous years. This situation indicates that decreasing of catch per haul of fish trawlers based in Sibolga continues occurring and in other hand price of fuel raises significantly so that big fish trawlers size 150 GT with engine power more than 600 HP are not able to continue their fishing operation.

scholarly journals Bycatch reduction in the deep-water shrimp (Pandalus borealis) trawl fishery by increasing codend mesh openness

2021 ◽  
Author(s):  
Nadine Jacques ◽  
Hermann Pettersen ◽  
Kristine Cerbule ◽  
Bent Herrmann ◽  
Ólafur A. Ingólfsson ◽  
...  
Keyword(s):  
Deep Water ◽  
Barents Sea ◽  
Juvenile Fish ◽  
Size Selectivity ◽  
Pandalus Borealis ◽  
Trawl Fishery ◽  
Bycatch Reduction ◽  
Drag Forces ◽  
The Barents Sea ◽  
Trawl Fisheries

In most trawl fisheries, drag forces tend to close the meshes in large areas of diamond mesh codends, negatively affecting their selective potential. In the Barents Sea deep-water shrimp (Pandalus borealis) trawl fishery, selectivity is based on a sorting grid followed by a diamond mesh codend. However, the retention of juvenile fish as well as undersized shrimp is still a problem. In this study, we estimated the effect of applying different codend modifications, each aimed at affecting codend mesh openness and thereby selectivity. Changing from a 4-panel to a 2-panel construction of the codend did not affect size selectivity. Shortening the lastridge ropes of a 4-panel codend by 20% resulted in minor reductions for juvenile fish bycatch, but a 45% reduction of undersized shrimp was observed. Target-size catches of shrimp were nearly unaffected. When the codend mesh circumference was reduced while simultaneously shortening the lastridge ropes, the effect on catch efficiency for shrimp or juvenile fish bycatch was marginal compared to a 4-panel codend design with shortened lastridge ropes.

scholarly journals Biology and population dynamics of by-catch fish species of the bottom trawl fishery in the western Mediterranean

2014 ◽  
Vol 15 (3) ◽  
pp. 613 ◽  
Author(s):  
F. ORDINES ◽  
M.T. FARRIOLS ◽  
J. LLEONART ◽  
B. GUIJARRO ◽  
A. QUETGLAS ◽  
...  
Keyword(s):  
Population Analysis ◽  
Conservation Status ◽  
Fishing Effort ◽  
Western Mediterranean ◽  
Distribution Range ◽  
Bottom Trawl ◽  
Trawl Fishery ◽  
Virtual Population ◽  
Trawl Fishing ◽  
By Catch

The teleosts Chelidonichthys cuculus, Trigloporus lastoviza, Serranus cabrilla and Trachinus draco, are important by-catch species, in terms of landed biomass and commercial value, from the continental shelf bottom trawl fishery off the Balearic Islands (western Mediterranean). The main biological parameters of these species were calculated from monthly biological samplings, and were used along with three years pseudo-cohorts (2008-2010) obtained from monitoring on-board of the bottom trawl fleet, to assess their exploitation level through Virtual Population Analysis (VPA) and Yield per Recruit (Y/R) analysis. Time series of fishery independent indicators based on MEDITS surveys data such as the evolution of the abundance and biomass, the distribution range, and the Conservation Status of Fish b (CSFb), were also analyzed. All four species analyzed showed growth overfishing. The reductions of the fishing effort required to reach the Y/RF0,1 reference point were lower, 66-73% depending on the species, to those reported for the target species M. merluccius (87%), but higher than that reported for M. surmuletus (53%), in the study area in the period 2000-2010. The abundance and biomass, and the distribution range did not show any trend for the period 2001-2011, whereas the CSFb showed signs of recovery that may be due to the displacement of the trawl fishing effort from the shelf to the slope during the last decade. Our results underline the necessary incorporation of monitoring and assessment of by-catch species to the management of fisheries as their populations can show a more pronounced overexploitation than target ones.

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