ALBERT

Description: This study was carried out on 16 Sturgeon spawner(6 ship and 10 persian sturgeon) which were operated in shahid Dr. beheshti Rearing and Propagation Complex during 2001, 2002 and 2003. surgery performed on 16 spawners (6 ship sturgeon and 10 persian sturgeon). operation fulfilled in 3 ways: 1- without anesthesia 2- anesthesia by injection of Chanazin 2%(4 to 10 mg for per kilogram of fish body weight) 3- anesthesia by replacing fish in clove powder solution. In the surgery operation without anesthesia, the fish maintained by three persons and the eggs removed. In the case of applying anesthesia, 2% Chanazin, with commercial name Rompun(20 mg/ml), 4- 10 mg for per kilogram of body weight injected, but the rate of clove Powder application was 150 200 mg/l.surgery carried out by Kosarva method(making slight cut on Ventral area stitching). The cut length was 6-8 cm. The cut site stitched by Kapron unabsorbable thread and single knot with 6 to 7 mm distance.The mean weight of female spawners of ship(Acipenser nudiventris) was 35.3 ± 8.3 kg(n=6) which 3.9 ± 0.89 kg caviar, removed on average(11% of total body weight). The mean weight of female spawners in Persian sturgeon(Acipenser persicus) was 23.6 ± 3.2 kg(n=10) that the mean rate of caviar removed was 2.7 ± 0.62 kg(11.4% of total body weight). Investigation on reared spawner of ship(Acipenser nudiventris, n=16) and Persian sturgeon (Acipenser persicus,n=60) without surgical operation showed that the average body weight of spawners was 43.7 ± 8.8 kg and 28.9 ± 6.4 kg and the mean rate of caviar removal was6.4 ± 1.7 kg (15.7% of total body weight) and 4.4 ± 1.3 kg (15.4% of total body weight) respectively. During 2001, surgical operation performed on 8 spawners(5 ship and 3 persian sturgeon) which one Persian sturgeon and 2 ship after one day, one ship after 3 days and two ship after 32 days and 105 days and 2 persian sturgeon after 91 and 136 days were died. During 2002, totally five Persian sturgeon were operated which all of them died after 46,116,130,132 and 157 days. During 2003, 3 spawners(2 persian sturgeon and one ship) were operated which two Persian sturgeon died after 23 and 59 days and one ship spawnerdied after 72 days. This mortality can be due to not feeding of formulated food and even live food by the wild spawners after surgery. Also, other factors can be mentioned, such as existence of otter in the ponds with spawners are kept, breaking of swim bladder during egg sampling in catch stations & hatcheries small area for maintaining spawners after surgery and not tolerating of surgical operation by some spawners. It should be mentioned that surgery point has been fully improved in the spawners that survived more than 40 days after surgery. The results of the study indicated that removal of caviar from wild spawners is possible, but maintaining them in freshwater to remove caviar again, can be problematic. So, the surgery for caviar removal & removing of caviar for second time in following years should be carried out only on reared spawners.

Description: Iranian Fisheries Science Research Institute

Description: Published

Description: The osmoregulatory system was studied in wild adult and reared juvenile Persian sturgeon, Acipenser persicus. The mean osmolarity in blood serum of specimens from the Caspian Sea, estuary, the Kouraneski pools and the rearing tanks were 305.3±14.3, 308.7±25.8, 265.0±19.1 and 259.3±8.8 mosmol/L, respectively; the mean concentrations of Na+ were 151.2±6.3, 152.2±8.4, 142.5±5.9 and 131.4±4.1 meq/L whereas mean concentrations of K+ were 2.7±0.9, 3.6±0.9, 3.1±0.5 and 2.6±0.5meq/L, respectively. The concentrations for Mg++ ion in fish of the same four origins were 1.5±0.2; 1.5±0.3, 0.8±0.2 and 0.7±0.2 meq/L, and those of Ca++ were 2.31±0.51, 2.61±0.51, 1.85±0.58 and 1.46±0.43, respectively. The Pearson's correlation coefficient and regression equation indicated that Mg++(r =0.38) and Na+ (r=0.41) were effective ions for determination of blood serum osmotic pressure in A. persicus in brackish water and freshwater. This study also showed that blood serum osmotic pressure was independent of sex.

Description: Published

Description: The Persian Sturgeon, Acipenser persicus is the most important sturgeon species in the southern part of the Caspian Sea and it provides 51% of Iran's caviar production. We were used five different age groups of the larvae (7, 17, 22, 28 and 33 days after yolk absorption) in 3 replicates. The larvae were all transferred at the same time to 27 liter aquarium holding 15 liter of water at different salinities (0.5, 7 and 9 ppt) and were provided with continuous aeration. Analysis of data showed that during early stages of life, age is an important factor for development of osmoregulatory organs. However, in later stages, weight and length play a vital role in this regard. The present study reveals that during post hatch and active feeding, in favorable environmental and rearing condition A. persicus fingerlings could be released into rivers and estuaries in Guilan province at an age of 33-35 days after yolk sac absorption and when they attain weight of 1.8-2.4g and length of 6.2-7.5cm.

Description: Published

Description: Levels of two main steroid hormones in gonads, 17-B Stradiol (E2) and testosterone (T) were compared in males and females of Persian sturgeon at the start of autumnal migration to spawning rivers. Hormone levels were also studied for likely relationship with different stages of sexual maturity. The results showed that levels of T and E2 in females at the stage four of sexual maturity is significantly higher than the individuals with immature gonads (ovary in stages 2 and 3). We measured 11.81±2.86Ong/ml and 7±1.15ng/ml of T and E2 in mature females compared to 0.2±0.09ng/ml and 0.736±0.161ng/ml of T and E2 in immature females. Levels of the two hormones in males at different stages of sexual maturity showed that only testosterone was significantly different in mature and immature sturgeons (0.50±0.144 ng/ml and al 4.3 I 25±3.121ng/ml in mature and immature males, respectively) (P=0.04). In males and females with higher sexual maturity, differences between the two hormones were significant (T and E2 levels in females and males were 11.81±2.860ng/ml, 7±1.15ng/ml and 0.50±0.144ng/ml, 0.7023±0/212ng/ml, respectively). However, in immature fish of both sexes, only males showed significantly higher T levels (14.312513.121ng/ml in comparison with 0.2±0.09ng/ml). Disregarding the sexual maturity stages, we found significantly different levels of E2 in both sexes (4.779±1.827ng/ml in females and 0.709±0.121ng/ml in males) (P=0.00). Statistical analyses indicated no correlation between fish age and levels of steroid hormones of the fish (at 90% confidence level).

Description: Published

Description: Reciprocal crosses betvveen Beluga and Persian Sturgeon in four treatments and three replications were conducted and reproduction metrics including number of eggs per gram, percentage of fertilization, and survival rate were assessed. Also, we measured 32 morphomeiric and meristic attributes of brood stocks, hybrids and controls. To compare the growth rate of hybrids and controls, fingerlings were grown for 18 months in 2000 liter fiberglass tanks and fed by pellets. During rearing period, 17 samples were taken in 15-30 days interval and total weight and length of the specimens were measured. Average weight and length, standard deviation, analysis of variance, Duncan test and Heterosis were calculated. We found a significant difference (13〈0.003) between numbers of eggs of Beluga (controls) in comparison with hybrid (6Beluga x Persian sturgeon) and between Persian sturgeon's eggs with hybrids (Y Beluga x dPersian sturgeon). However, no significant differences were found (1)?0.001) between controls and treatments in terms of fertilization rate (in stage 4 and 35), number and mortality rate of larvae during active feeding and final stages. Hybrid and control fingerlings showed different growth performances. After an 18 months rearing period, the highest growth was found in Beluga (975±10 grams), with hybrid of female i al Beluga and male Persian sturgeon coming next (840±143 grams), hybrid of male Beluga with female Persian sturgeon being the third (681.152$1 grams). The slowest growth rate was seen in control Persian sturgeon with an average growth of 535.15±131 grams. Daily growth rate of hybrids produced from crossing of female Beluga with male Persian sturgeon was higher than control Beluga during second and third rearing period each taking six months. We observed significant differences (p〈0.05) in 31 morphometric and meristic parameters from a total of 32 attributes. The percentage of heterosis was variable, being -73.76 in early growth period and 0.79 at the final rearing stage with an average heterosis of -32.69. The hybrid produced from female Beluga and male Persian Sturgeon showed a very good o growth performance. However, with the inadequacy of female Beluga in the Caspian Sea and the priority of restocking Beluga, it is suggested that the hybrid production be conducted using male • Beluga and female Persian Sturgeon.

Description: Published

Description: Histological studies are of the most adequate way to determine the physiological condition of fish organs. The present research was carried out in order to conduct a qualitative evaluation of the growth and development of the reproductive system of three sturgeon species (Acipenser persicus, Acipenser gueldenstaedti, and Huso huso). In this evaluation two histological approaches, gonadectomy and biopsy, were employed. The studied sturgeons consisted of 58 one, two and six years old reared juveniles. Some 60% of the one-year-old Huso huso were of unknown sex, 20% were previtellogic females and 20% of the males were in the early stage of spermatogenesis. On the other hand 50% of the one-year-old Acipenser persicus were also of unknown sex, 30% premature females and 20% premature males. Some 30% of two-year-old Huso huso were of unknown sex, 40% premature females and 10% of the females were in stage I of sexual maturity and 10% were premature males. Among the six-year-old specimens, 60% of the Acipenser persicus were females in stage II of sexual maturity, 20% were males between stage II and III of sexual maturity and 20% were of unknown sex, while in the same age group 50% ofAcipenser gueldenstaedti were males in stage II of sexual maturity and 50% were females in stage II(semi lipid) of sexual maturity. The results of the study indicated that 28.75% were females were in stage II of the sexual maturity, 14.28% were female in stage II (lipid) of sexual maturity, 14.28% females in stage I of sexual maturity, 28.75% males between stage II and III of sexual maturity and 14.28% were males in stage IV of sexual maturity. The conducted study on the juvenile sturgeon confirmed that the growth process of the gonads occurred as it would have happened under natural circumstances. Occurrence of six-year-old Huso huso in stage IV of sexual maturity indicated that the rearing conditions in the fiberglass tanks and earthen ponds have been favorable and on the other hand no extra surplus energy has been used.

Description: Published

Description: Sturgeons are valuable species of the Caspian Sea and the Persian sturgeon Acipenser persicus is an endemic species of the south Caspian Sea. Possessing the highest breeding percentage in sturgeon hatcheries and catch numbers of this species is of particular importance in Iran regarding rehabilitation of stocks and fingerling release. The main aim of this study was to understand the histological structure of this valuable species and to make use of this information in other basic and applied research. The present study was conducted from 1998 through 2001 on a total of 34 A. persicus specimens (18 male and 16 female) with an average weight of 13.75 kg and an average length of 146.3 cm. Fishes under study were caught using gillnets and beach seine in the fishery zones 1 and 2. Biometric measurements of fish specimens were carried out on catch and primary gonadal staging was assessed by means of macroscopic examination. Tissue samples including gill (primary and secondary ray), male and female gonads (anterior, central and posterior), digestive tract (oesophagus, stomach and intestine), liver (different parts of the large and small lobules) and kidney (anterior, central and posterior) measuring a few millimeters in thickness and a few millimeters in width were prepared and fixed individually in buoin solution. Tissue samples were dehydrated in different dilutions of alcohol and chloroform solution until they were clear. They were then embedded in paraffin and sectioned at 5-7 µm using a Leitz microtome and stained following the hematoxylin and eosin (H & E) method. Distinct samples were photographed using a light microcopy in 10 microscopic fields. The microscopic examination of gills revealed the presence of chloride cells, secondary cartilage, erythrocytes, gill lamella, epitheleum, polar cells, respiratory cells and respiratory spines. Ovary in A. persicus was similar in structure with that of other sturgeons and a major part of it was comprised of stroma tissues. Follicles were the main structural and functional indices in ovary. The main distinguishing feature of the ovary in the early stage of growth is the presence of ovarian grooves in gonads. Grooves were observed in stage I of sexual maturity and oogonia were seen in the primary growth of protoplasmic ovary. They are attached densely to the dorsal part of the abdominal cavity and their development is slow. Oocyte cells are observed assembled in ovary sacs. In the II stage of maturity gonads are yellow to pink in color with distinct lateral folds. Fat tissue is the main energy source for oocytes. Duration of this stage is very long. Primary oocytes are single layered, follicle shaped and could be observed with naked eyes as white spots in an ovary section. The III stage of maturity is characterized with trophoplasmic growth of oocytes, reduction in fat reserves, increase in oocyte volume, appearance of pigments under cell membranes and growth of arc cilia on gelatinous part of follicles. Nucleus is located away from the center and surrounded by several nucleoli. The granulosa layer occurs at this stage. In the IV stage of maturity oocytes growth is increased and nucleus is seen migrating toward the animal pole. Tiny yolk granules are observed in the animal pole and larger yolk granules and fat droplets in the vegetative pole. Growth of external layers of oocyte continues while protoplasmic growth is completed at this stage. At this stage germinal vesicle reaches its final growth and oocyte is covered with follicle, jelly coat, zona radiata external, zona radiata internal, fatty layer and pigments. The stage V of maturity is characterized with intensive bleeding in ovaries, residues of non-ovulated oocytes, appearance of stage II oocytes and decomposition of residues of non-ovulated oocytes. In the stage VI of maturity oocytes resembling stage II of maturity are clearly observed. Ruptured follicles, pigment reserves and oocytes representing various maturity stages are also present. Testis in Persian sturgeon in the first stage of maturity includes spermatogony cells in its germinal parts. Male gonads are situated along notochord and attached to the dorsal diaphragm or primary area of kidney formation through short mesenchymes. In stage II of male gonad maturity, spermatogonia cells are situated in gonad channel walls in a single layer without wrinkles. Primary and secondary spermatocytes and sertoli cells are present. In stage III of male gonad maturity, spermatogony cells intensively divide and reproduce. Blood vessels are observed in the form of condensed blood cells. Development and formation of primary and secondary spermatocytes, meiotic divisions and presence of spermatids are characteristics of this stage. Stage IV is distinguished by an active cycle of spermatogenesis, further meiotic divisions and entrance of sperms into the sperm channels. In stage V intensive bleeding occurs in testis. Spermatozoids, sperm channels and numerous blood vessels are also observed in this stage. In stage IV of male gonad maturity large epithelial cells of follicle and emptied sperm channels are observed. Kidney in Persian sturgeon is comprised of three sections; anterior (pronepherose including malpighian bodies and nephritic segments) middle and posterior parts. Nephrons include malpighian bodies, glomerula, Buman capsule, renal tubes or urinary tubes, neck part, spiral section, middle part, distant spiral section and shows various patterns in microscopic histological studies. Liver tissue is composed of hepatocytes, biliary tubes, lymphatic vessels, liver capillaries or sinusoid, kupfer cells and liver cells. Liver cells are roughly circular and polygonal in structure with a single and distinct nucleus and single nucleolus. Endoplasmic reticulum and other essential cell organs are present in its cytoplasm and considerable fat and glycogen reserves are observed in cell cytoplasm. Therefore large numbers of theses vacuoles are observed in a stained liver cells. Pancreas in Persian sturgeon is comprised endocrine and exocrine parts. The exocrine part releases pancreatic excretions and the endocrine section (Langerhans islands) releases hormones. The digestive system is comprised of alimentary canal that includes the mouth, pharynx, esophagus and intestine with epithelial and muscular layers. The epithelial layer sustains epithelial coat, parenchyma, condensed layer, muscular epithelium, sub- epithelial layer, muscular layer including ring and longitudinal layer and serum membrane. The pharynx epithelium is stratified in anterior part and simple in posterior part. Epithelial cells of pharynx include mucus like matrix in cytoplasm. These cells lack muscular epithelium and a complex and condensed connecting tissue is present beneath the epithelium. Stomach has two independent sections of glandular structure for collecting food and commencement of chemical digestion and non-glandular structure with strong muscular layer specified to create stomach movement and mechanical digestion. Epithelial parts are simple or wrinkled in structure. Intestine stretches from the pyloric section of stomach to the anal part and includes duodenum, anterior and posterior intestine and rectum. Duodenum is a part of intestine where biliary canals, pancreas and pyloric ceaca enter. Intestinal epithelium is comprised of a single layer of stretched columnar cells that encompasses epithelial cells. Rectum is the last section of intestine and a sphincter separates it from posterior intestine. Anal is the terminal opening of the alimentary canal. Goblet shaped epithelium cells are observed in epithelial structure of rectum while simple tubular glands without large intestinal branched glands are present in Parin. Results obtained in this study along with characterizing microscopic structure of studied organs in Persian sturgeon facilitated implementation of other related specific researches.

Description: Iranian Fisheries Science Research Institute

Description: Published

Description: Histological studies are of the most adequate way to determine the physiological condition of fish organs. The present research was carried out in order to conduct a qualitative evaluation of the growth and development of the reproductive system of three sturgeon species (Acipenser persicus, Acipenser gueldenstaedti, and Huso huso). In this evaluation two histological approaches, gonadectomy and biopsy, were employed. The studied sturgeons consisted of 58 one, two and six years old reared juveniles. Some 60% of the one-year-old Huso huso were of unknown sex, 20% were previtellogic females and 20% of the males were in the early stage of spermatogenesis. On the other hand 50% of the one-year-old Acipenser persicus were also of unknown sex, 30% premature females and 20% premature males. Some 30% of two-year-old Huso huso were of unknown sex, 40% premature females and 10% of the females were in stage I of sexual maturity and 10% were premature males. Among the six-year-old specimens, 60% of the Acipenser persicus were females in stage II of sexual maturity, 20% were males between stage II and III of sexual maturity and 20% were of unknown sex, while in the same age group 50% ofAcipenser gueldenstaedti were males in stage II of sexual maturity and 50% were females in stage II (semi lipid) of sexual maturity. The results of the study indicated that 28.75% were females were in stage II of the sexual maturity, 14.28% were female in stage II (lipid) of sexual maturity, 14.28% females in stage I of sexual maturity, 28.75% males between stage II and III of sexual maturity and 14.28% were males in stage IV of sexual maturity. The conducted study on the juvenile sturgeon confirmed that the growth process of the gonads occurred as it would have happened under natural circumstances. Occurrence of six-year-old Huso huso in stage IV of sexual maturity indicated that the rearing conditions in the fiberglass tanks and earthen ponds have been favorable and on the other hand no extra surplus energy has been used.

Description: Levels of two main steroid hormones in gonads, 17-B Stradiol (E2) and testosterone (T) were compared in males and females of Persian sturgeon at the start of autumnal migration to spawning rivers. Hormone levels were also studied for likely relationship with different stages of sexual maturity. The results showed that levels of T and E2 in females at the stage four of sexual maturity is significantly higher than the individuals with immature gonads (ovary in stages 2 and 3). We measured 11.81±2.86Omg/ml and 7±1.15mg/ml of T and E2 in mature females compared to 0.2±0.09mg/ml and 0.736±0.161mg/ml of T and E2 in immature females. Levels of the two hormones in males at different stages of sexual maturity showed that only testosterone was significantly different in mature and immature sturgeons (0.50±0.144 mg/ml and al 4.3 I 25±3.121mg/ml in mature and immature males, respectively) (P=0.04). In males and females with higher sexual maturity, differences between the two hormones were significant (T and E2 levels in females and males were 11.81±2.860mg/ml, 7±1.15mg/ml and 0.50±0.144mg/ml, 0.7023±0/212ng/ml, respectively). However, in immature fish of both sexes, only males showed significantly higher T levels (14.312513.121mg/ml in comparison with 0.2±0.09mg/ml). Disregarding the sexual maturity stages, we found significantly different levels of E2 in both sexes (4.779±1.827mg/ml in females and 0.709±0.121mg/ml in males) (P=0.00). Statistical analyses indicated no correlation between fish age and levels of steroid hormones of the fish (at 90% confidence level).

Description: The Persian Sturgeon, Acipenser persicus is the most important sturgeon species in the southern part of the Caspian Sea and it provides 51% of Iran's caviar production. We were used five different age groups of the larvae (7, 17, 22, 28 and 33 days after yolk absorption) in 3 replicates. The larvae were all transferred at the same time to 27 liter aquarium holding 15 liter of water at different salinities (0.5, 7 and 9 ppt) and were provided with continuous aeration. Analysis of data showed that during early stages of life, age is an important factor for development of osmoregulatory organs. However, in later stages, weight and length play a vital role in this regard. The present study reveals that during post hatch and active feeding, in favorable environmental and rearing condition A. persicus fingerlings could be released into rivers and estuaries in Guilan province at an age of 33-35 days after yolk sac absorption and when they attain weight of 1.8-2.4g and length of 6.2-7.5cm.