A novel machine learning approach to predict the export price of seafood products based on competitive information: The case of the export of Vietnamese shrimp to the US market.

Predicting the export price of shrimp is important for Vietnam's fisheries. It not only promotes product quality but also helps policy makers determine strategies to develop the national shrimp industry. Competition in global markets is considered to be an important factor, one that significantly influences price. In this study, we predicted trends in the export price of Vietnamese shrimp based on competitive information from six leading exporters (China, India, Indonesia, Thailand, Ecuador, and Chile) who, alongside Vietnam, also export shrimp to the US. The prediction was based on a dataset collected from the US Department of Agriculture (USDA), the Food and Agriculture Organization of the United Nations (FAO), and the World Trade Organization (WTO) (May-1995 to May-2019) that included price, required farming certificates, and disease outbreak data. A super learner technique, which combined 10 single algorithms, was used to make predictions in selected base periods (3, 6, 9, and 12 months). It was found that the super learner obtained results in all base periods that were more accurate and stable than any candidate algorithms. The impacts of variables in the predictive model were interpreted by a SHapley Additive exPlanations (SHAP) analysis to determine their influence on the price of Vietnamese exports. The price of Indian, Thai, and Chinese exports highlighted the advantages of being a World Trade Organization member and the disadvantages of the prevalence of shrimp disease in Vietnam, which has had a significant impact on the Vietnamese shrimp export price.

Clown knifefish (Chitala ornata) oxygen uptake and its partitioning in present and future temperature environments.

It has been argued that tropical ectotherms are more vulnerable to the projected temperature increases than their temperate relatives, because they already live closer to their upper temperature limit. Here we examine the effects of a temperature increase in environmental temperature to 6°C above the present day median temperature (27°C) in the freshwater air-breathing fish Chitala ornata, on aspects of its respiratory physiology in both normoxia and in hypoxia. We found no evidence of respiratory impairment with elevated temperature. The standard metabolic rate (SMR) and routine metabolic rate (RMR) in the two temperatures in normoxia and hypoxia increased with Q10 values between 2.3 and 2.9, while the specific dynamic action (SDA) and its coefficient increased from 7.8 to 14.7% in 27°C and 33°C, respectively. In addition, Chitala ornata exhibited significantly improved growth at the elevated temperature in both hypoxic and normoxic water. While projected temperature increases may negatively impact other essential aspects in this animal's environment, we see no evidence of a negative impact on this species itself.

Sodium fluoride induces hypercalcemia resulting from the upregulation of both osteoblastic and osteoclastic activities in goldfish, Carassius auratus.

The influence of sodium fluoride (NaF) on calcium metabolism was examined in goldfish (fresh water teleost). At 2days after administration of NaF (500ng/g body weight; 5µg/g body weight) (around 10(-5) to 10(-4)M in goldfish), we indicated that plasma calcium levels upregulated in both doses of NaF-treated goldfish. To examine the mechanism of hypercalcemia by NaF treatments, therefore, direct effects of NaF on osteoblasts and osteoclasts in goldfish were investigated by an original assay system using teleost scale which has osteoblasts, osteoclasts and bone matrix. Alkaline phosphatase activity in the scales increased with the treatment of NaF (10(-6) and 10(-5)M) during 6h of incubation. Also, tartrate-resistant acid phosphatase activity increased after exposure to NaF (10(-5)M) at the 6h of incubation. To investigate the osteoclastic activation, the mRNA expression of osteoclastogenesis related factors were examined. The receptor activator of the nuclear factor-κB ligand (RANKL) which is known as a factor for osteoclastogenesis, increased in the NaF-treated scales after 6h of incubation. The ratio of RANKL/osteoprotegerin (osteoclastogenesis inhibitory factor) significantly increased after 6h of incubation. Resulting from the increase of RANKL mRNA level, the expression of transcription-regulating factors was significantly increased. Furthermore, the expression of functional genes, cathepsin K and matrix metalloproteinase-9 mRNA, was significantly increased. In our knowledge, this is the first report concerning the effects of NaF on osteoblasts and osteoclasts in teleosts. We concluded that NaF influences calcium metabolism via osteoclastic activation in goldfish.

Potential uses of gut weed Enteromorpha spp. as a feed for herbivorous fish.

Three separate experiments were performed to assess the potential use of gut weeds Enteromorpha spp. as a food source for herbivorous fish. The fresh or dried gut weeds were used as a direct feed to replace commercial feed in an alternative approach for feeding spotted seat (Scatophagus argus), red tilapia (Oreochromis sp.), and giant gourami (Osphronemus goramy) juveniles for 60 days, 45 days, and 56 days, respectively. Four feeding regimes were applied to triplicate tanks and fish was fed daily either commercial feed or gut weed: (1) single commercial feed everyday as a control treatment, (2) single gut weed daily and 2 alternative feeding regimes where (3) 1 day commercial feed and 1 consecutive day gut weed or and (4) 2 consecutive days gut weed. The results indicated that survival of experimental fish was not affected by the feeding treatments. Growth performance of the S. argus fed single gut weed was not significantly different from the control group (P>0.05). Growth rates of Oreochromis sp. and O. goramy in the alternative feeding treatments were comparable to the control treatment. Application of the combined feeding regimes, feed conversion ratio could be reduced from 26.1 to 57.8%. These results indicated that fresh and dried gut weed can be used as a feed to substitute commercial feed for herbivorous fish. Moreover, using gut weeds as a feed could improve water quality in the rearing tanks.