scholarly journals Comparing size selectivity and exploitation pattern of diamond-mesh codends for Southern velvet shrimp (Metapenaeopsis palmensis) in shrimp trawl fishery of the South China Sea

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12436
Author(s):  
Bingzhong Yang ◽  
Bent Herrmann ◽  
Lei Yan ◽  
Jie Li ◽  
Teng Wang
Keyword(s):  
South China Sea ◽  
South China ◽  
Mesh Size ◽  
The South China Sea ◽  
Size Selectivity ◽  
The South ◽  
Shrimp Species ◽  
China Sea ◽  
Trawl Fishery ◽  
Shrimp Trawl

In this study, size selectivity and exploitation pattern of six diamond-mesh codends with different mesh sizes, ranging from 25 to 54 mm, for Southern velvet shrimp (Metapenaeopsis palmensis) were tested and compared in a shrimp trawl fishery of the South China Sea (SCS). We used a codend with a mesh size of 25 mm (D25) as a starting point, which is the minimum mesh size (MMS) currently regulated in the studied area. Four different fishing population scenarios were applied to quantify and compare how mesh sizes of codends used would impact the size selectivity and exploitation pattern for the target shrimp species. The results demonstrated that the D25 codend was not proper for protecting juvenile shrimp at the studied area. By applying this legal codend, L50 (50% retention length) of the target shrimp species was below its minimum conservation reference size (MCRS, 7.0 cm total length), the retention probability of shrimp with a length of MCRS was above 95% CI [91–99] and more than 43% of undersized shrimp was retained. To mitigate the bycatch issue of undersized shrimp, increasing the mesh size in the diamond mesh codend is a simple and effective option. However, the loss of catch efficiency for marketable shrimp is a major concern while increasing the mesh size. A good compromise between releasing undersized shrimp and maintaining the legal individuals is manifested by using the codend with 35 mm mesh size (D35). Our study will be beneficial for the management of shrimp trawl fisheries in the SCS.

A multi-year investigation of the Temoridae (Copepoda, Calanoida) assemblage succession within the interplay waters of the northern South China Sea

Crustaceana ◽  
2020 ◽  
Vol 93 (3-5) ◽  
pp. 519-540
Author(s):  
Li-Chun Tseng ◽  
Yan-Guo Wang ◽  
Guang-Shan Lian ◽  
Jiang-Shiou Hwang
Keyword(s):  
South China Sea ◽  
South China ◽  
Northern South China Sea ◽  
Seasonal Succession ◽  
Mesh Size ◽  
Abundant Species ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
The Kuroshio

Abstract The South China Sea is the largest marginal sea in the world. The northern South China Sea has a complex hydrographic system affected by interplay waters of the Kuroshio Branch Current and the South China Sea waters. To understand the changes in the community structure of the planktonic calanoid copepod family Temoridae in relation to the interplay waters, we collected zooplankton samples in the northern South China Sea from surface waters (0 to 2 m) from November 2001 to January 2007 during 24 research cruises using a standard North Pacific zooplankton net (with a mesh size of 200 μm, a length of 1.8 m, and a mouth diameter of 0.45 m). Among a total of 253 samples, 5 species belonging to 3 genera of Temoridae were identified: Eurytemora pacifica Sato, 1913, Temora discaudata Giesbrecht, 1889, Temora stylifera (Dana, 1849), Temora turbinata (Dana, 1849), and Temoropia mayumbaensis Scott T., 1894. The 3 most abundant species were: T. turbinata (relative abundance, RA: 53.28%; mean density ± standard deviation, MD: 29.33 ± 89.53 ind. m−3), T. stylifera (RA: 36.02%, MD: 19.83 ± 145.22 ind. m−3), and T. discaudata (RA: 7.70%, MD: 4.24 ± 11.82 ind. m−3). The 3 most frequently occurring species were: T. turbinata (occurrence ratio, OR: 52.17%), T. discaudata (OR: 35.18%), and T. stylifera (OR: 9.88%). A noteworthy discovery in our samples was E. pacifica, a marine and brackish water species, collected from 3 stations located near the Kuroshio Branch Current in April 2003. This is the only month when this species was recorded during the investigation period. Variations of dominant species of Temoridae show a clear pattern of seasonal succession. The total abundance was significantly higher in the third quarter (September-November, 116.98 ± 314.49 ind. m−3) than in the fourth quarter (December-February, 24.26 ± 47.72 ind. m−3) (, one-way ANOVA). In general, the present results demonstrate that the assemblages of the Temoridae are very much structured by the water masses of the Kuroshio Current and the South China Sea.

A new mud shrimp species of Calastacus (Crustacea: Decapoda: Thalassinidea) from the South China Sea

Zootaxa ◽  
2009 ◽  
Vol 2088 (1) ◽  
pp. 24-30 ◽  
Author(s):  
TOMOYUKI KOMAI ◽  
FENG-JIAU LIN ◽  
TIN-YAM CHAN
Keyword(s):  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
Ventral Margin ◽  
Single Specimen ◽  
The South ◽  
The West ◽  
Shrimp Species ◽  
China Sea ◽  
Mud Shrimp

A new mud shrimp species of the deepwater calocaridid genus Calastacus Faxon, 1893, C. inflatus, is described on the basis of a single specimen from the South China Sea off the Pratas Islands. It is unique in the genus in having a faint cervical groove on the carapace, lacking spiniform projection at the dorsolateral distal angle of the second segment of the antennal peduncle, the possession of only one spine on the ventral margin of the merus of the cheliped, and the unarmed suture on the uropodal exopod. With the addition of the present new species, two species of the genus are now known from the West Pacific.

scholarly journals Effects of six codend meshes on the size selection of juvenile white croaker (Pennahia argentata) in demersal trawl fishery of the South China Sea

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0253723
Author(s):  
Bingzhong Yang ◽  
Bent Herrmann ◽  
Lei Yan ◽  
Jie Li ◽  
Teng Wang
Keyword(s):  
South China Sea ◽  
South China ◽  
Mesh Size ◽  
The South China Sea ◽  
Size Selectivity ◽  
White Croaker ◽  
Trawl Fishery ◽  
Minimum Landing Size ◽  
Pennahia Argentata ◽  
Selection Of

White croaker (Pennahia argentata) is a commercially important but overexploited species that is often caught in trawl fishery of the South China Sea (SCS). The codend size selectivity for this species in the local commercial trawl fishery is of concern when considering the established minimum landing size (MLS). This study investigated the size selectivity of white croaker for six different diamond-mesh codends with mesh size from 25 to 54 mm. We paid special attention to two codends, made with meshes of 25 and 40 mm in size, which are currently used according to the regulations established in the SCS. The results demonstrated that the legal codends do not perform satisfactorily in the fishing grounds where juvenile white croaker is relatively abundant. This is because at a length similar to the minimum landing size of the species (MLS = 15.0 cm), all white croaker were retained, and the estimated discard ratio was >97% in both cases of legal codends. Our study showed that by increasing the mesh size, the size selection of tested codends could be improved for white croaker, and the retention rates for juvenile fish would decrease. However, none codend was proved efficient to release undersized white croaker suggesting that other gear design changes may be necessary.

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