Newly hatched white sturgeon (Acipenser transmontanus) yolk-sac larvae are negatively phototactic, photokinetic and geotactic--seeking cover in the substrate during daylight hours. If cover is unavailable and the light intensity is low, they move into the water column and alternate periods of rapid, upward swimming with periods of quiescence during which they sink. In the dark they swim almost ...

1. Two common species of acorn barnacle, Chthamalus montagui and C. stellatus , with similar resource needs, occur together on rocky shores of NW Europe but differ in their adult distribution over two environmental gradients, wave exposure and vertical height on the shore. 2. A sampling programme was undertaken over 2 years to determine the causal mechanisms of this differential distribution. T...

Four new species of the genus Hatschekia Poche, 1902 (Copepoda: Siphonostomatoida: Hatschekiidae) are described based on female specimens collected from pufferfishes (Tetraodontiformes: Tetraodontidae) caught in coastal waters off the Ryukyu Islands, Japan: H. longiabdominalis sp. n. on Arothron hispidus (Linnaeus), H. geniculata sp. n. on A. hispidus (type host) and A. stellatus (Bloch et Schn...

Hypophysectomy was performed on sexually mature sterlets, Acipenser ruthenus L., in summer and autumn. The operation usually lasted about 45 sec, but never longer than 90 sec. After the parasphenoid was stripped, an ellipsoid hole was trepanated at the level of the eyes. The hypophysis was ablated by catching its rostral end with a pincer. As the result of the extirpation of the hypophysis the ...

The specific stimulatory effect of sturgeon Acipenser güldenstädti Br. gonadotropic hormone (GTH) on frog Rana temporaria L. oocyte maturation in vitro was investigated in relation to humic acid (HA) concentrations from 12.5 to 50 mg/l. HA was observed to bind to both the follicular membrane of the oocytes and the GTH molecule, reducing the oocytes' hormone sensitivity and maturation ability. I...

the aim of this study was to investigate on obtained caviar quantity status of sturgeon at fishing grounds of the southwestern caspian sea. data of catches by means of fixed gill nets in sturgeon fish fishing grounds and beach seine were used during 5 years survey (2005-2009). a total of 1361 female sturgeon was caught including: 788 acipenser persicus, 410 a. stellatus, 60 a. guldenstaedti, 70...

samples from five sturgeon species including persian sturgeon (acipenser persicus), russian sturgeon (a. gueldenstaedti), great sturgeon (huso huso),ship sturgeon (a. nudi-ventris) and stellate sturgeon (a. stellatus) were collected from the south caspian sea. dna was extracted from the fins, eggs and skeleton muscle of the five species. rapd markers were used for identifying different kinds of...

pomphorhynchus laevis is a common fish parasite in europe which   has been reported from acipenser stellatus, barbus capito, barbus lacerta, barbus mursa and onchorhynchus mykiss in iran. in a survey on the aquaculture potential of gamasiab river in hamedan province, endemic fish parasites were investigated in summer and autumn 2008. after recording biometric characteristics, common necropsy an...