Using distribution patterns of small fishes to assess small fish by-catch in tropical shrimp trawl fisheries

2013 ◽  
Vol 17 (3) ◽  
pp. 217-224 ◽  
Author(s):  
S. J. Foster ◽  
F. Arreguin-Sánchez
Keyword(s):  
Distribution Patterns ◽  
Small Fish ◽  
Shrimp Trawl ◽  
By Catch ◽  
Trawl Fisheries ◽  
Tropical Shrimp

scholarly journals Can vertical separation of species in trawls be utilized to reduce bycatch in shrimp fisheries?

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0249172
Author(s):  
Roger B. Larsen ◽  
Bent Herrmann ◽  
Jure Brčić ◽  
Manu Sistiaga ◽  
Kristine Cerbule ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Juvenile Fish ◽  
Melanogrammus Aeglefinus ◽  
Polar Cod ◽  
Small Fish ◽  
Vertical Separation ◽  
Shrimp Trawl ◽  
Pass Through ◽  
Trawl Fisheries ◽  
The Vertical Distribution

Several shrimp trawl fisheries use a Nordmöre sorting grid to avoid bycatch of fish. However, small fish can pass through the grid. Therefore, the retention of juvenile fish often remains an issue during shrimp trawling. We investigated the vertical distribution of deepwater shrimp (Pandalus borealis) and dominant bycatch species at the point where the Nordmöre grid section is installed. This was achieved using a separator frame which split the net vertically into three compartments of equal entry size. Our results showed that shrimp predominately follow the lower part of the trawl belly, whereas species such as redfish (Sebastes spp.), cod (Gadus morhua), polar cod (Boreogadus saida) and American plaice (Hippoglossoides platessoides) preferred the mid-section in the aft of the trawl. Haddock (Melanogrammus aeglefinus) primarily entered through the upper section of the trawl belly. Using these results, we predict that a vertical separation device installed forward of a 19 mm Nordmöre grid combined with a 35 mm codend would result in a significant reduction in bycatch with only minor loss of shrimp.

scholarly journals Effect of Cutting Ratio and Catch on Drag Characteristics and Fluttering Motions of Midwater Trawl Codend

2021 ◽  
Vol 9 (3) ◽  
pp. 256
Author(s):  
Wei Liu ◽  
Hao Tang ◽  
Xinxing You ◽  
Shuchuang Dong ◽  
Liuxiong Xu ◽  
...  
Keyword(s):  
Drag Force ◽  
Mesh Size ◽  
Current Speed ◽  
Midwater Trawl ◽  
Minimum Drag ◽  
Fish Catch ◽  
Spatial Geometry ◽  
By Catch ◽  
Trawl Fisheries ◽  
Crucial Part

The codend of a trawl net is the rearmost and crucial part of the net for selective fish catch and juvenile escape. To ensure efficient and sustainable midwater trawl fisheries, it is essential to better understand the drag characteristics and fluttering motions of a midwater trawl codend. These are generally affected by catch, cutting ratio, mesh size, and twine diameter. In this study, six nylon codend models with different cutting ratios (no cutting, 6:1, 5:1, 4:1, 7:2, and 3:1) were designed and tested in a professional flume tank under two conditions (empty codends and codends with catch) and five current speeds to obtain the drag force, spatial geometry, and movement trend. As the cutting ratio of empty codends decreased, the drag force decreased, and the drag coefficient increased. The unfolding degree of codend netting and the height of empty codends were found to be directly proportional to the current speed and inversely proportional to the cutting ratio. The positional amplitude of codend with cutting ratio 4:1 was the smallest for catch. The drag force of codends with catch increased as the current speed increased, and first decreased and then increased as the cutting ratio decreased. To ensure the best stability and minimum drag force of the codend, it is recommended to use the 4:1 cutting ratio codend.

scholarly journals Diversity, distribution and spatial structure of the cold-water coral fauna of the Azores (NE Atlantic)

2013 ◽  
Vol 10 (6) ◽  
pp. 4009-4036 ◽  
Author(s):  
A. Braga-Henriques ◽  
F. M. Porteiro ◽  
P. A. Ribeiro ◽  
V. de Matos ◽  
Í. Sampaio ◽  
...  
Keyword(s):  
Spatial Structure ◽  
Cold Water ◽  
Current Knowledge ◽  
Fish Habitat ◽  
Sustainable Use ◽  
Distribution Patterns ◽  
Taxonomic Diversity ◽  
Conservation Policies ◽  
Coral Fauna ◽  
By Catch

Abstract. Cold-water corals are widely considered as important structural components of benthic habitats, potentially enhancing local abundance in a variety of fish and invertebrate species. Yet, current knowledge of the taxonomic diversity and distribution patterns of these vulnerable, slow-growing organisms is scarce and fragmented, limiting the effectiveness of spatial management and conservation measures. We have conducted an exhaustive compilation of records of alcyonaceans, antipatharians, scleractinians and stylasterids available through present day to assess the diversity, distribution and spatial structure of coral assemblages in the Azores exclusive economic zone (EEZ). The resulting database comprises 2501 entries concerning historical oceanographic expeditions and other published sources, as well as unpublished data from bottom longline by-catch. Our taxonomic inventory appears to be fairly complete for the explored habitats, accounting for 164 species (79 alcyonaceans, 58 scleractinians, 18 antipatharians and 9 stylasterids), nine of which were documented for the first time. The Azores EEZ harbours a mixed coral fauna with several zoogeographic origins, showing the closest affinity with the Lusitanian–Mediterranean region. Very few apparent endemics were found (14%), and only in part supported by consistent sampling. Coral diversity is particularly high between 300 and 900 m depths, in areas recognized as traditional fishing grounds or exploitable fish habitat within the 100-mile limit of the EEZ. The composition of coral assemblages shows significant geographical structure among longitudinal sections of the study area at comparable depths (100–1500 m). There is no evidence of a possible role of the Mid-Atlantic Ridge or latitudinal effects underlying this pattern, which suggests that it may instead reflect assemblage variability among features. Stronger changes in species composition were found along the bathymetric gradient. Notwithstanding the mix of partially overlapping steno- and eurybathic species that characterize the vertical distribution of corals, there is a distinct transition from shallow (100–600 m) to intermediate (600–1000 m) depths. The analysis presented here constitutes a valuable contribution for efficient conservation policies of coral-associated vulnerable marine ecosystems and their sustainable use as fishing areas.

scholarly journals SEPARATE STOCKS OF RED SNAPPER EXPLOITATION AND MANAGEMENT IN THE INDONESIAN SECTOR OF THE ARAFURA SEA

2017 ◽  
Vol 15 (1) ◽  
pp. 81
Author(s):  
Badrudin Badrudin ◽  
Aisyah Aisyah
Keyword(s):  
Genetic Similarity ◽  
Red Snapper ◽  
Industrial Scale ◽  
Research Activities ◽  
Shrimp Trawl ◽  
Long Line ◽  
Arafura Sea ◽  
Trawl Fisheries

Red snapper resources in the Arafura Sea have been effectively exploited by the industrial scale of bottom long line, fish trawl and shrimp trawl fisheries. Research activities carried out by the ACIAR-RCCF revealed that there were genetic similarity of the three red snapper species between the Australian and lndonesian sectors of the Arafura Sea"

scholarly journals Distribution Pattern of Seahorse species (Genus: Hippocampus) in Tamilnadu and Kerala Coasts of India

2013 ◽  
Vol 5 (1) ◽  
pp. 20-24 ◽  
Author(s):  
Aaron Premnath LIPTON ◽  
Muthusamy THANGARAJ
Keyword(s):  
Dominant Species ◽  
Body Shape ◽  
Tail Length ◽  
Gulf Of Mannar ◽  
Meristic Characters ◽  
Trunk Length ◽  
Snout Length ◽  
Shrimp Trawl ◽  
Palk Bay ◽  
By Catch

The survey along the Tamilnadu and Kerala coats of India reveled that six species of seahors (Hippocampus fuscus, H. kelloggi, H. kuda, H. histrix H. mohnikei and H. trimaculatus) were distributed with different density. Out of the six species, H. fuscus, H. kuda and H. trimaculatus, were the commonly available species in all the observed areas. In Palk Bay, H. kuda was the dominant species constituting 49.10% of the total seahorses encountered. Hippocampus trimaculatus was the second dominant species which accounting 39.28%. The Gulf of Mannar region also most abounded with H. kuda (68.98%) followed by H. trimaculatus (20.80%), H. fuscus (9.80%), H. kelloggi (2.23%) and H. histrix (0.37%). In Kerala coast, H. trimaculatus was the dominant species (79.68%) followed by H. kuda (9.89%), H. kelloggi (8.33%) and H. fuscus (2.08%). To infer the variation of six seahorse species the morphometric and meristic characters were analysed. The important morphometric and meristic characters are trunk rings, tail rings, pectoral and dorsal fin rays, trunk length, tail length, coronet height, head length, snout length, snout depth and head depth. Variation in overall body shape, relative snout length, coronet height, number of tail ring was sufficient to separate the specimens to Hippocampus fuscus, H. kelloggi, H. kuda, H. histrix H. mohnikei and H.trimaculatus. The species density and diversity depends on the habitat and biogeography of those areas. Majority of seahorse fishing in Tamilnadu was by shrimp trawl, by-catch and very few target catch by divers also seen in some villages of Palk Bay and Gulf of Mannar region. The shrimp trawl by-catch only bringing more H. trimaculatus than the other species in Kerala coasts.

scholarly journals Aspects of the biology of the Atlantic Midshipman, Porichthys porosissimus (Teleostei, Batrachoididae): an important by-catch species of shrimp trawling off southern Brazil

2000 ◽  
Vol 48 (2) ◽  
pp. 131-140 ◽  
Author(s):  
Marcelo Vianna ◽  
Acácio R. G. Tomas ◽  
José R. Verani
Keyword(s):  
Growth Parameters ◽  
Northern Coast ◽  
Pink Shrimp ◽  
Stock Management ◽  
Spawning Period ◽  
Management Measures ◽  
Shrimp Trawl ◽  
Trawl Fishing ◽  
By Catch ◽  
The Impact

Trawl fishing for pink shrimp (Farfantepenaeus brasiliensis and F. paulensis) catches large quantities of by-catch fish, discarded due to their having no commercial va)ue. As these species have rarely been studied, the impact of fisheries on these populations is not known. This contribution studies the biology of a species of no commercial value, the Atlantic midshipman Porichthys porosissimus. The last haul /Tom a commercial trawler, operating on the northern coast of São Paulo State and the southern coast of Rio de Janeiro State, was preserved (/Tom being discarded) and identified at the species leveI. It was observed that this fishery affects the juvenile population which is intluenced by the seasonal variation of the water masses. Growth parameters were estimated: L∞ = 37.0 cm, K = 0.285 year-1. Instantaneous mortality coefficients were estimated: 2=2.14, M=0.63, F= 1.51, S= 11.8 and E=0.71. Considering the intensive activity of the shrimp trawl tleet operating in this area, the deleterious action of trawling is considered as of high impact. The stock management measures applied for pink shrimp are without effect regarding P. porosissimus. which has its spawning period before the closed season and its recruitment peak after it. The results show overfishing and the need to apply measures to reduce trawling action, such as adequate policies, introduction of selectivity devices and the creation of exclusion zones for trawl fishing.

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