The migration time of newly hatched Acipenser sinensis from the spawning area (river km 1675) to the Yangtze estuary (rkm 0) was ascertained in the years 1996-2007 (time range 192-243 days), and its relationship to water levels surveyed at 12 typical hydrological monitoring stations in the middle and lower reaches of Yangtze River was determined. Migration time showed a positive correlation (R = 0.621−0.738, P = 0.013−0.041) with the water levels surveyed during April at eight stations (from Jianli to Anqing, rkm 1356.2 to rkm 639.4). Stepwise regression analysis indicated that when the water level at a typical station, Luoshan (rkm 1244.2), increased by 1 m, migration time deferred 11.6 days. The high water level created expanded riparian habitat and thus may have prolonged juvenile residence time. This variable residence time due to variations in water flow caused by the Three Gorges Project needs to be addressed, and more investigation is required. RÉSUMÉEffets du niveau des hautes eaux sur la période de résidence en rivière des juvéniles d'esturgeon chinois Acipenser sinensis dans le fleuve Yangtsé La période de migration de Acipenser sinensis depuis la zone de frai (km 1675) à l'estuaire du Yang Tsé Kiang (km 0) a été observée dans les années 1996-2007 (intervalle de temps : 192-243 jours juliens), et sa relation avec les niveaux d'eau étudiée dans 12 stations de surveillance hydrologique dans les cours moyen et inférieur du fleuve Yangtze. La période de migration est corrélée positivement (R = 0,621 à 0,738, P = 0,013-0,041) avec les niveaux d'eau enregistrés en avril dans huit stations (à partir de Jianli à Anqing, rkm 1356,2 au km 639,4). L'analyse de régression montre que lorsque le niveau d'eau dans une station typique, Luoshan (km 1244,2), augmente de 1 m, le temps de migration est différé de 11,6 jours. Le niveau d'eau élevé crée un habitat rivulaire plus important et permet donc un allongement du temps de séjour des juvéniles. Ce temps de séjour variable influencé par les changements de débit causés par le projet des Trois Gorges doit être étu-dié, et une recherche plus approfondie est nécessaire.

Animal food sources provide human beings with minerals considerably in adequate quantities. Fish is an indispensable reliable source of nutrients, as aquaculture is a sector that is fast growing and which provides 50% of the world's fish production. However, fish production is hampered by the increasing costs of feeds due to the ever rising cost of fish meal, an integral component of fish feeds. Substituting fish meal with cheap, yet highly nutritious ingredients in fish feeds is therefore paramount. This study investigated the effects of substituting fish meal with adult cricket meal (ACM) and black soldier fly meal (BSFM) on minerals content of extruded fish feeds, where four levels of substitution (0, 25, 50 and 75%) were used. The effect of feed moisture content on minerals was also studied where 20 and 30% feed moisture levels were used. Leaching effects of the pellets were studied as well. The results showed a significant increase (P \ 0.05) in the levels of phosphorus and potassium as the level of fish meal substitution increased from 0 to 75%. On the other hand, iron and sodium levels reduced significantly (P \ 0.05) as the level of fish meal substitution increased. Magnesium content increased with increasing level of substitution with BSFM, but decreased with increasing level of substitution with ACM. Copper, zinc and manganese were not greatly influenced by levels of fish meal substitution. Diets that had zero substitution showed higher leaching effect for most minerals than diets that were substituted with 75% ACM or BSFM. This study found that both ACM and BSFM can be used to substitute fish meal in fish feeds and obtain adequate mineral profile and low leaching effect.

The digital economy may accelerate the upgrading of industrial structures and boost regional innovation output, effectively contributing to China’s green economic transformation. The impact of the digital economy on developing the urban green economy is analyzed using data from 280 cities across China from 2010–2019. Using a fixed-effects model and the Spatial Durbin model, the digital economy is found to have a significant impact on urban green economy development. This result is shown to be robust to various factors. There is significant regional variability in the impact of the digital economy on green economic growth, with the strongest impact in the northeast, followed by the central and western regions. Meanwhile, non-resource-based cities and policy pilot cities have a more pronounced role in promoting the digital economy. The intermediate transmission chain of industrial structural upgrading and regional innovation output fosters the growth of the urban green economy via the digital economy. Regional innovation production is responsible for 30.848% of this growth, with the intermediate effect of industrial structural upgrading contributing to 38.155%.