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Zhu G.,Shanghai Ocean University | Xu L.,Shanghai Ocean University | Dai X.,Shanghai Ocean University | Liu W.,Hainan Provincial Fisheries Research Institute
Zoologia | Year: 2011

Age and growth parameters were estimated for the yellowfin tuna Thunnus albacares (Bonnaterre, 1788). Atotal of 443 individuals were sampled from China longline fisheries in the eastern and central Pacific Ocean from February to November 2006. The von Bertalanffy growth parameters were estimated at L_ = 175.9 cm fork length, k = 0.52 year-1, and t0 = 0.19 year. The total mortality rate (Z) was estimated to be from 1.19 to 1.93 year-1, the fishing mortality (F) and the natural mortality (M) were calculated to be 0.91 year-1 and 0.65 year-1, respectively. The rate of exploitation (U) was estimated to be 0.46. This study provides estimates of growth and mortality rate for yellowfin tuna in the eastern and central Pacific Ocean, which may be used as biological input parameters in future stock assessments for the oceanic region. However, age analysis with other techniques, additional validation of the size composition and stock structure are also needed. © 2011 Sociedade Brasileira de Zoologia. All rights reserved. Source

Qu M.,Xiamen University | Ding S.,Xiamen University | Xu X.,Jimei University | Shen M.,Hainan Provincial Fisheries Research Institute | And 2 more authors.
Aquaculture | Year: 2012

Histological studies were used to describe the ontogenetic development of the digestive tract and accessory glands in coral trout, Plectropomus leopardus, from the time of hatching to 54. days after hatching (DAH). According to the structural changes in the digestive system, four significant stages were established: the endotrophic stage (Stage I), the endo-exotrophic stage (Stage II) and the exotrophic stage (subdivided into Stages III and IV). The first stage spanned from hatching to the onset of exotrophic feeding at 2. DAH. During this stage, the digestive system started to differentiate into the buccopharynx, the oesophagus, the incipient stomach, the midgut, the hindgut and the rectum. During Stage II (2-3DAH), the coral trout larvae mouth opening reached a 0.24 ± 0.05. mm gape size, much smaller than most teleosts. Therefore, first-feeding coral trout must feed on small prey like protozoa or small size rotifers (Brachionus rotundiformis). Stage III (3-19. DAH) started after the depletion of the yolk sac. During this stage, goblet cells, taste buds and pharyngeal teeth appeared. The pharyngeal teeth may be a sign that the larvae can feed on some live prey with a hard outer cover, such as copepods. Eosinophilic supranuclear vacuoles and lipid vacuoles were found in the hindgut and midgut, respectively, indicating the beginning of protein and lipid absorption. The last stage (after 19. DAH) started when the gastric glands and pyloric caeca were formed. Gastric glands were only observed in the cardiac and fundic stomach and not in the pyloric region. The appearance of gastric glands and pyloric caeca could be regarded as the sign for coral trout to start weaning. The ultrastructure of the liver in the 54-DAH coral trout larvae proved that the liver was crucial for lipid storage and metabolism. This study suggested a relatively rapid development of the digestive system in coral trout and provided a theoretical basis for the nutritional requirements and digestive capacity of coral trout. © 2012 Elsevier B.V. Source

Tong Y.,Shanghai Ocean University | Tong Y.,Hainan Provincial Fisheries Research Institute | Chen X.,Shanghai Ocean University | Chen X.,Key Laboratory of Sustainable Exploitation of Oceanic Fisheries | And 4 more authors.
Chinese Journal of Oceanology and Limnology | Year: 2013

In the Indian Ocean, bigeye tuna supports one of the most important fisheries in the world. This fishery mainly consists of two components: longline and purse seine fisheries. Evidence of overfishing and stock depletion of bigeye tuna calls for an evaluation of alternative management strategies. Using an age-structured operating model, parameterized with the results derived in a recent stock assessment, we evaluated the effectiveness of applying constant fishing mortality (CF) and quasi-constant fishing mortality (QCF) strategies to reduce fishing effort of purse seining with fish aggregating devices (FADs) at different rates. Three different levels of productivity accounted for the uncertainty in our understanding of stock productivity. The study shows that the results of CF and QCF are similar. Average SSB and catch during simulation years would be higher if fishing mortality of FAD-associated purse seining was reduced rapidly. The banning or rapid reduction of purse seining with FAD resulted in a mean catch, and catch in the last simulation year, higher than that of the base case in which no change was made to the purse seine fishery. This could be caused by growth overfishing by purse seine fisheries with FADs according to the per-recruit analysis. These differences would be more obvious when stock productivity was low. Transferring efforts of FAD-associated purse seining to longline fisheries is also not feasible. Our study suggests that changes are necessary to improve the performance of the current management strategy. © 2013 Chinese Society for Oceanology and Limnology, Science Press and Springer-Verlag Berlin Heidelberg. Source

Tong Y.,Shanghai Ocean University | Tong Y.,Hainan Provincial Fisheries Research Institute | Xinjun C.,Shanghai Ocean University | Xinjun C.,The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources | And 2 more authors.
Scientia Marina | Year: 2013

Bigeye tuna (Thunnus obesus) support a large commercial fishery in the Indian Ocean. However, explicit management strategies and harvest control rules are yet to be developed for the management of this fishery. We used a stochastic age-structured production model as an operating model to evaluate several potential management strategies under different assumptions of stock productivity. Five management strategies-constant fishing mortality, constant catch, quasi-constant catch, constant escapement, and status-dependent strategies-were evaluated and compared using the performance indicators including average catch, average spawning stock biomass, variation in catch, average fishing mortality and lowest biomass during the time period considered in the simulation. This study shows that (1) for the constant catch strategy, an annual catch of 90000 t would result in a low risk of stock being overfished while obtaining a stable catch; (2) for the constant fishing mortality strategy fishing mortality of 0.3 per year could yield a higher catch, but might have a high probability (64%) of stock dropping below the spawning stock biomass (SSB) that could achieve maximum sustainable yield (SSBmsy); and (3) for the quasi-constant catch strategy an annual catch of 110000 t was sustainable if the current SSB was higher than SSBmsy. Constant escapement and status-dependent strategies were robust with respect to different levels of virgin recruitment and steepness. This study suggests that it is important to incorporate uncertainties associated with key life history, fisheries and management processes in evaluating management strategies. Source

Ye S.,Zhejiang University | Ye S.,Dalian Ocean University | Wu L.,Zhejiang University | Wu L.,Henan Agricultural University | And 4 more authors.
Fish and Shellfish Immunology | Year: 2013

Ubiquitin-conjugating enzymes (UBE2s or E2s) are characterized by the presence of a highly conserved ubiquitin-conjugating (UBC) domain, which predominantly determines the type of ubiquitin chains and directly controls the cellular fate of the substrate. In this study, an E2 homolog was identified and functionally characterized in abalone, which we named ab-UBE2D. The full-length cDNA consists of 1005bp with an ORF encoding a protein of 147 amino acids. The deduced amino acid sequence shows ab-UBE2D shares conserved UBC domain with other E2 proteins and belongs to class I E2 enzyme family, which are further confirmed by phylogenetic tree analysis. Real-time PCR and western blot analyses showed that ab-UBE2D was ubiquitously expressed in abalone and the expression level of ab-UBE2d was significantly induced by LPS and Poly (I:C). Immunofluorescence microscopy staining demonstrated that native ab-UBE2D was mainly distributed in the cytoplast. Ubiquitination assay showed that ab-UBE2D had ubiquitin conjugating activity to form the enzyme-(Ub)n conjugates. Taken together, these results strongly suggest that ab-UBE2D is an E2 homolog and it may be involved in the immune response of abalone, Haliotis diversicolor supertexta. •We identified and functionally characterized an E2 homolog in abalone named as ab-UBE2D.•Ab-UBE2D shares a conserved UBC domain with other E2 proteins and belongs to class I E2 enzyme family.•Ab-UBE2D is ubiquitously expressed in abalone and its expression level is significantly induced by LPS and Poly (I:C).•Native ab-UBE2D distributes in cytoplast.•Ab-UBE2D has ubiquitin conjugating activity to form the enzyme-(Ub)n conjugates. © 2013 Elsevier Ltd. Source

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