The purpose of this study was to develop a novel method for the external attachment of ultrasonic transmitters on hard fin‐spines fish (Sparidae). Acanthopagrus latus, one of the main stocking Sparidae fishes in the northern South China Sea, was employed to conduct the 40‐day tank experiment by using dummy ultrasonic transmitters. The experiment consisted of 3 treatment groups, i.e., drilling on dorsal fin‐spine (DD) group, drilling on anal fin‐spine (DA) group, and control (C) group, with each group having 3 replicates and 30 fish per replicate. The feasibilities of DD and DA for the external attachment of ultrasonic transmitters were tested and evaluated using parameters: the specific growth rate, survival rate, and tag retention rate of each group. And the tagging procedures for the external attachment of hard fin‐spines fish were also proposed. The results showed that there were no significant differences in the specific growth rate of fish between groups. Both the survival rates of DD group (96.67%) and DA group (94.44%) were less (but not significant) than C group (97.78%), while the tag retention rate of DA group (100%) was higher (but not significant) than DD group (98.89%). These results demonstrate that drilling on dorsal or anal fin‐spines is feasible as an external attachment method of ultrasonic transmitters on Sparidae fishes. In addition, considering the friction between the tagged transmitters and rocks at the bottom of natural waters, which possibly affect the fish behaviors such as swimming, feeding, etc., or lead to tag loss, so drilling on the dorsal fin‐spine is preferred for rocky‐bottom Sparidae fishes like A. latus as small as 14 cm body length.

The threadfin Eleutheronema are the important fishery resources in Indo-Pacific regions and classified as the endangered species with considerable conservation values. Their genetic diversity and population structure remain essentially unknown but are critical for the proper management and sustainable harvests of such important fisheries. Here, the mitochondrial DNA sequences of CO1 and 16s rRNA were determined from 75 individuals of Eleutheronema tetradactylum and 89 individuals of Eleutheronema rhadinum collected from different locations of South China Sea and Thailand coastal waters. Genetic diversity analysis revealed that both E. tetradactylum (Haplotype diversity, H = 0.105–0.211; Nucleotide diversity, π = 0.00017–0.00043) and E. rhadinum (H = 0.074–0.663, π = 0.00013–0.01088) had low diversity. Population structure analysis demonstrated the shallow genetic differentiation among the South China Sea populations. The limited communication between China and Thailand populations caused the high genetic differentiation in all groups due to the low dispersal ability. Reconstruction of CO1 phylogenetic relationships and demographic studies across Indo-West-Pacific regions provided strong evidence for a shared common origin or ancestor of E. tetradactylum and E. rhadinum. Eleutheronema rhadinum were further subdivided into two distinct genetic lineages, with Clade A dominantly distributing in Thailand and Malaysia and Clade B distributing in China coastal waters. Phenotypic divergence, characterized mainly by the depth of caudal peduncle and length of caudal peduncle, was also observed for all populations, which was possibly associated with specific local adaptations to environmental changes. Our study suggested a strong need for the development of proper fishery management strategies and conservation actions for the imperiled Eleutheronema species.

The ocean has considerable potential to function as a carbon sink, absorbing anthropogenic CO2 and buffering the effects of climate change. How the culture of shellfish can be used to increase the ocean carbon sink warrants evaluation. We analyze the production and carbon sink capacity of six important mariculture shellfish species (oyster, ark clam, mussel, scallop, clam, and razor clam) in nine coastal provinces of China from 1981–2020 using quality assessment and logarithmic mean Divisia index (LMDI) decomposition methods. Over this time period both cultured shellfish production and its contribution to the carbon sink generally increase, averaging approximately 600,000 t annually over the last four decades. Both the annual production and carbon sink capacity of China’s mariculture shellfish industry vary geographically. The total annual tonnage (scale) of cultured shellfish, and to a lesser extent, coastal shellfish species composition (structure) influence carbon sink capacity, and affect China’s plans to achieve “dual carbon goals.” Combining historical analysis and the LMDI method, we propose a scheme that optimally and more sustainably manages China’s culture of shellfish.