Search

• The majority of fresh elasmobranchs sold at Singapore's fishery ports are imported from Indonesia and Malaysia while a minority are caught locally. • The large volumes of Maculabatis gerrardi and M. macrura for local delicacy BBQ stingray is of concern. • The majority of shark species sold are small-bodied species utilised for their meat. • The high proportion of immature Carcharhinus sorrah and C. sealei and/or C. tjutjot is of concern. • Wedgefish snouts are used for a local delicacy however since they were added to CITES Appendix-II their supply into Singapore will be limited. The status of elasmobranchs in Southeast Asia has been highlighted as a serious concern, yet there are limited data to assess stocks and develop appropriate management plans. Surveys of elasmobranchs at two fishery ports in Singapore were conducted between 2017 and 2020. These fishery ports receive fresh, whole imports of seafood from the region as well as seafood caught in Singapore waters. Data were collected on 13,817 rays, 2,480 sharks, and 1,297 wedgefishes and giant guitarfishes over 102 surveys. The majority of elasmobranchs were imported from Indonesia or Malaysia, and only a few individuals (six sharks and 278 rays) were reportedly caught within Singapore waters. In Singapore, elasmobranchs are predominantly used for their meat, and wedgefish snouts are also commonly used in collagen soup. The data collected highlights potential conservation concerns, particularly surrounding the large volumes of Maculabatis gerrardi and Maculabatis macrura rays (categorized as Vulnerable and Not Assessed by the IUCN) that are imported, and the high proportions of immature individuals of Carcharhinus sorrah and Carcharhinus sealei sharks. During this study, a single Rhynchobatus cooki was discovered – the first reported sighting in over 20 years. [ABSTRACT FROM AUTHOR]

Infectious myonecrosis virus (IMNV) is a highly contagious shrimp virus that is epidemic in few countries. The risk of global transmission of IMNV is increasing due to the frequent transboundary trade of farmed shrimp. Here, we describe a case of IMNV infection in cultured Penaeus vannamei (P. vannamei) in Liaoning province of China. Abnormal deaths in cultured juvenile shrimp from a local farm started in July 2020. The diseased shrimp were tested to be strongly positive for IMNV by nested reverse transcription (RT) PCR and real-time RT-PCR assay. The genome of a novel IMNV variant (designated CN-20-1) was cloned from the diseased shrimp and shared 97%–98% sequence identity with the reference strains. Phylogenetic analysis showed that the novel variant was more closely related to strains isolated from Indonesia than from Brazil. The characteristic histopathological changes of IMNV infection, including myonecrosis of skeletal muscle fibers and appearance of lymphoid organ spheroids (LOS), were observed in the diseased shrimp tissues. IMNV infection in the diseased shrimp was also confirmed by electron microscopy and in situ hybridization (ISH). In the artificially challenge experiment, purified IMNV at an injected dose of 2.0 × 10^7 copies could cause 100% mortality of healthy shrimp within 9 days post-infection, and the infected shrimp exhibited typical clinical signs and histopathological changes of IMNV infection. Strong hybridization positive signals of the IMNV probe were detected in the tissues of artificially challenged shrimps in the ISH assay. The IMNV variant (CN-20-1) was suspected to have been introduced into the farm through the importation of IMNV-contaminated P. vannamei broodstock from Thailand in the investigation of the origin of IMNV. Subsequent active surveillance in 2020–2021 showed that the IMNV infections did not spread to adjacent areas but occurred only at the original site. However, as the risk of transboundary transmission of IMNV is high, continuous monitoring of IMNV and implementing strict measures to prevent its spread through trade are really urgent to control its threat to global shrimp farming. • IMNV infection in cultured Penaeus vannamei had been confirmed in two farms during April to July 2020 in north-east China. • The novel IMNV strain (CN-20-1) is more closely related to the stains isolated in Indonesia than Brazil in genome. • A specific IMNV RNA-probe was developed for in situ hybridization analysis as an additional test to confirm infection. • Surveillance results indicate that the IMNV infection occurred only within a controllable location till the end of 2021. [ABSTRACT FROM AUTHOR]