This paper presents an update on the global sturgeon and caviar production until 2017, attempting to continue previous efforts on summarizing the global trends in these markets. For the current update, an expanded data base was derived from questionnaires sent to 86 regional contacts in 46 countries, mostly farmers or scientists, and personal interviews. A total of 2,329 commercial sturgeon farms were recorded by 2017 globally, which represented an increase by 7% compared to 2016.Of these farms 54% were located in China, followed by Russia (24%), the Middle East (8%), the Far East (7%) and Europe (6%). Among the rearing technologies flow-through (FT) systems (36%) were most common, followed by recirculation aquaculture systems (RAS) (21%), cages (18%), mix FT/RAS (11%), and ponds (6%). In total the aquaculture sturgeon biomass production peaked at about 129,608 t in the year 2015, with a decline to 119,979 t in 2016, and to 102,327 t in 2017. China contributed about 79,638 t to the overall production in 2017, followed by Russia (6,800 t), Armenia (6,000 t), Iran (2,514 t), and 52 other countries with less than 1,000 t each.This production exceeded the fishery harvest during the 1970-1980s by more than four times. Of the 25 species of Acipenseridae, 13 pure species and four hybrids were farmed for meat with Acipenser baerii dominating production in 2016 with a share of 39.5%, followed by the two hybrids, Huso dauricus × Acipenser schrenckii and A. baerii × A. schrenckii (35.6%), as well as A. schrenckii (10.2%). Global caviar production increased during the last years and the production for the year 2017 amounted to approximately 364 t. China contributed more than 100 t to the overall production in 2017, followed by Russia (49 t), Italy (43 t), France (37 t) and diverse other countries. The species composition in caviar production in 2016 was dominated by A. baerii (31% of the total volume), followed by Acipenser gueldenstaedtii (20%), the hybrid H. dauricus × A. schrenckii (13%), and Acipenser transmontanus (12%), while other species jointly contributed 24% to the overall yield. The trends of sturgeon meat and caviar productions of the last 5 years and the forecasts for the future suggest a short-term scenario in which the demand remains lower than the supply. In order to absorb the growing production, the market will have to be expanded by targeting new market segments. K E Y W O R D Saquaculture, markets, production data, sturgeon

Being the largest extant amphibian in the world, the IUCN Critically Endangered Chinese giant salamander Andrias davidianus is a charismatic species with great international public interest. While threats such as commercial overexploitation and habitat degradation have been extensively documented to affect natural populations of A. davidianus, still no information is available about the species sensitivity to climate change. Here, we develop an ensemble of species distribution models (SDMs) for A. davidianus and projected its habitat suitability under present‐day and future climate change scenarios. We based our SDMs on bioclimatic and topographic predictors, and recent (2012–2018) field‐collected occurrence data across the whole distribution range of the species. The ensemble SDMs exhibited good predictive capacity and suggested that slope, maximum temperature of warmest month, precipitation of driest month, and isothermality are the most influential predictors in determining distribution patterns in this species. The projections of our models point to a pronounced impact of climate changes over A. davidianus, with more than two‐thirds of its suitable range expected to be lost in all scenarios of future climates tested. In concert with the numerous other threats that are affecting this species, climate change poses a serious hindrance to the long‐term survival of A. davidianus. We emphasise the urgent need of undertaking strict measures to manage this species and safeguard the few remaining available suitable habitats. We suggest that adaptive management strategies including designation of new reserves should be considered to mitigate the impacts of climate change on A. davidianus.

Chinese sturgeon (Acipenser sinensis) is an endemic fish species of China listed as a critically endangered (CR) species on the IUCN Red List (since 2010). There was a recent outbreak of a novel disease characterized by haemorrhagic ascites and intestinal and renal haemorrhaging in cultured Chinese sturgeon, which clearly posed a serious threat to this species. Two kinds of pathogenic bacteria were isolated from moribund diseased Chinese sturgeon. Two isolates, AHth-1 and AVth-2, were selected as representative strains and were identified as Aeromonas hydrophila andAeromonas veronii based on their morphology, biochemical characteristics, and a phylogenetic analysis derived from 16S rRNA, gyrB, and rpoD gene sequencing.Experimental infection tests showed that both identified isolates were pathogenic to juvenile Dabry's sturgeon (A. dabryanus) via intraperitoneal injection. Histopathology of Dabry's sturgeon infected with A. hydrophila or A. veronii revealed liver hyperaemia, hepatic, and splenic necrosis, and enteritis. Antimicrobial susceptibility tests showed that both bacterial strains were equally sensitive to fluoroquinolones antibiotics, and to third-and fourth-generation cephalosporins. These results provide a scientific reference for the diagnosis, prevention, and treatment of haemorrhagic septicaemia caused by A. hydrophila or A. veronii in cultured sturgeon. K E Y W O R D SAcipenser sinensis, Aeromonas hydrophila, Aeromonas veronii, haemorrhagic septicaemia

Captive breeding has been explored in Chinese sturgeon (Acipenser sinensis) for species protection. However, gonad development from stage II to IV of cultured female broodstocks is a handicap. This study aimed to explore the physiological and metabolic changes during the ovary development from stage II to IV of female Chinese sturgeon and the related energy regulatory mechanism, which may be helpful to address the developmental obstacle. The results showed that the oocyte volume increased and the muscle lipid content decreased with the ovary development. Ovarian RNA levels of most genes related to lipid and amino acid metabolism were higher in stage II and III than in stage IV. Serum contents of differential metabolites in arginine, cysteine, methionine, purine, tyrosine, lysine, valine, leucine and isoleucine metabolism pathways peaked at stage III, while the contents of sarcosine, alanine and histidine, as well as most oxylipins derived from fatty acids peaked at stage IV. These results indicated the more active amino acids, lipid metabolism, and energy dynamics of fish body in response to the high energy input of ovary developing from stage II to III, and the importance of alanine, histidine, taurine, folate and oxylipins for fish with ovary at stage IV.