Reproductive biology of the white spotted rabbit fish, Siganus sutor, in culture conditions

Growth of gonads and spawning time in white spotted rabbit fish, Siganus sutor, in culture conditions were surveyed. Around 800 juveniles weighing 50-80g were captured from wild and stocked at a density of a15 ind/m ^(3) in concrete tanks during years 2004-2005 located in the Persian Gulf &Oman Sea Ecology Research Center. The fishes were cultured for about 12 and 24 mounts to obtain 1 year and 2 year old specimens. Culture was continued till the year 2007. Using 574 records, the length-weight relationship was determined as W=0.0155(FL). Results revealed that Siganus sutor has alometric growth. Monthly changes in GSI showed the lowest GSI values at stage I and V. We observed that GSI values of females and males peaked in April and May. The total fecundity of Siganus sutorranged from 170,000 to 1,300,000 oocytes in specimens of 22-35cm, F.L. 215-800 g B.W. and ovary weight of 15-117g. The average (cSE) total fecundity was 737931.03 ±77503.41 oocytes per female. The relative fecundity ranged from 458.47 oocytes to 2303.80 oocytes per g B.W. with an average (cSE) of 1606.31 ±131.89 oocytes per g B.W. Results showed the best time for S. sutoe to culture is month of May According to the results, one year old males are mature and produce sperm whereas females are ready to reproduce at age 2

The growth of faunal aquatics on artificial reefs in Bandar Lengeh Area, Persian Gulf

The growth of organisms on seven different artificial reef structures was surveyed from 2004-2006 in Hormuzgan offshore waters (Bandar Lengeh area). The organisms consisted of 12 groups the main of which included Barnacle (Megabalanus tintinnabulum), Sponges with five families and Tunicates. The highest density was observed in 2005, amounting to some 409.224g wet weight on each structure. However, a decrease was observed afterwards in the total mass of aquatics living on the structures. Some organisms such as crabs, polychaets, bivalves and fish larvae showed an increasing in size in the first year. Bivalves showed a decreasing trend in density but otherwise an increasing trend in size over time. Artificial shape of the reefs was not effective on the total density of the organisms living on the structures. Total density of live organisms on different parts of the artificial reefs (surface, middle and bottom) was not statistically significant (P>0.05). Numbers of crabs on mixed artificial reefs were higher than the other artificial reefs. This was also the same for barnacles

Investigation on feeding of sardines and major tuna fishes in west of Oman Sea (Jask area)

Feeding habits of three dominant species of tuna fishes (Thunnus tonggol, Thunnus albacares, Euthynnus affinis) and dominant species of sardine (Sardinella sindensis) were investigated from December 2006 to November 2007 in the western waters of Oman Sea. Seasonally samples of three species of these tuna and monthly samples of sardine were collected. Feeding studies on 101 longtail tuna (T.tonggol) indicated that the bony fishes were main food of this species (98.3%) and followed by random foods included cephalopods (1.7%) and crustaceans (1.7%). Among the bony fishes, anchovy (66 %) and sardines (25.9 %) were most important than the other fishes. FI and CV for this species were calculated 26.4 and 21.8 respectively. Stomach content analysis of 85 specimens of E.affinis demonstrated that bony fishes were only food for this species (100%). Sardines (49.3%) and anchovy (11.9%) were foremost food items for E.affinis. Moreover FI and CV were calculated 64.7 and 15.3 correspondingly. The stomach of 120 yellowfin tuna (T.albacares) were analyze. Results showed that bony fishes,cephalopods and crustaceans were formed food items of this species .Yellowfin tuna were preferable fed on bony fishes (87.7%) specially sardines(41.2%),flying fish(13.9%)and M.cordyla(10.4%) and followed by cephalopoda (43.8%) specifically Loligo sp.(84.5%) and crustaceans(11.2%) . FI and CV were calculated 38.3 and 25.8.Study on 320 stomachs were determined that zooplankton and phytoplankton formed food of S.sindensis. Zooplankton (crustacean and molluscs) were main food (90%) and phytoplankton (Bacillariophyceae and Dynophyceae) were least food items (10%). Copepoda (crustaceans) with 58% were preferable food and bivalves and after that bivalves (molluscs) with 14%, Bacillariophyceae (8%) and Cyanophyceae (2%) CV and FI were 30.3 and 29.4 respectively

Study on feasibility of live Cobia (Rachycentron canadum) capturing in northern waters of Persian gulf & Oman Sea (Hormozgan province) and rearing them to subadult stage in concrete tanks

In order to obtain live individuals of cobia (Rachycentrun canadum) , coastal waters of Jask, Sirik, Kolahi , Bandar Abbas, Bandar-e Lengeh ,Bandar-e Bostaneh and Abu moosa ,Hormoz and Qeshm Islands have been surveyed from March 2008 to January 2010 in Northern waters of Persian Gulf (Hormozgan province). All in all 60 alive fishes obtained from fishing boats and transferred to Aquaculture Department of Persian Gulf and Oman Sea Ecological Research Institute (PGOSERI), but 50 of them died and only 10 fish survived. They divided in two groups and cultured in separated concrete tanks. Fished were fed with trush fish twice a day at a feeding rate of 4-5 percent of body weight. Culturing period last about 6 months. All the fishes gradually died through the culturing period. Average of specific growth rate in group 1 and 2 were about 0/49 and 0/77 respectively. The weight gain for group 1 (WG) was %75 for 75 days of culturing time and % 142 for 190 days of culturing time while for group 2 it was %31 for 54 days of culturing time and % 75 for 190 days . Average weight of fishes belong to group 1 reached from 950(g) to 2150 (g) during 6 months, while group 2 reached from 872(g) to 1271/5 (g) in 3 months. Feed conversion rate (FCR) for group 1 and 2 were respectively about 6.9 and 6.8. With regard to cost of trash fish (about 2000 Rials per kilogram trash fish) the per unit feed cost of cobia production were 13613 and 13730 Iranian Rials per kilogram, respectively for group 1 and group 2. Results revealed that obtaining live individuals of cobia is very difficult and also cobia didn’t grow well in concrete tanks but if we have better cooperation of local fishermen and also provide some Equipment such as cages in order to rear cobia in the sea , it is possible to achieve more success and obtaining better results

A survey of some biological aspects of cobia (Rachycentron canadum)

Biology aspects of cobia (Rachycentron canadum) were investigated from October 2005 to December 2006 in Northern waters of Persian Gulf (Hormozgan province).The reproduction cycle, sexual maturity, sex ratio, Fecundity, Lm50, feeding, length frequency, growth parameters and mortality of cobia were studied from total of 509 specimens ranged from 19 to 159 fork length. Gonadosomatic index peaked during spring and summer with main peak in June. Spontaneous spawning occurs around the year with peak in June. The overall female to male ratio was significantly 1 : 1.49 (P<0.05). Batch fecundity were estimated 1684954±118990 in 15 females. Relationship between total length and fecundity were calculated F=1.3717TL 2.9567 (r^2= 0.82). Feeding studies indicated that the bony fishes were main food of cobia (76%) and followed by crustaceans (25%) and mollusks (11%). Rays were least food items (22%). Maximum and Minimum GaSI were observed in March (33%) and August (0.07%) respectively. Females reached 50% sexual maturity at 81.25 cm TL. The total length -weight relationship was W=0.0042L3.1162 (r^2=0.9852). Thetotal length-fork length relationship was TL= 1.1561FL-2.533 (r^2= 0.9933). Growth parameters K, L, and t_0 were calculated by von bertalanfy growth equation: 0.11 (year1), 168.65 cm, 3.49 and -0.97 respectively. The instantons rate of total mortality (z), natural mortality (M) and fishing mortality estimated by catch curve analysis were 0.30, 0.25, 0.14 (year1). Exploitation rate and Tmax were 0.36 and 28 year respectively

A survey on Movement and estimation of growth rate in banana shrimp (Penaeus merguiensis) released to the Persian Gulf and Oman sea waters (Hormuzgan province)

Banana shrimp (Penaeus merguiensis) is important shrimp species for stock enhancement in recent year in Hormozgan Tiab region. These crustacean spent post larve to juvenile cycle in mangrove creeks. Thus majore creek in this investigation are Tiab, Kolahi, Koleghan and Khamir (Laft). Maximum concentration of post larvaes in creek of Tiab, Kolahi and Koleghan are occur at April and in creek of Khamir is at May. Concentration of crustacean zoea and copepods that are diet of shrimp post larvaes, increase at this moment. Juveniles of Banana shrimp stay at those creek until June. At this time, juveniles reach to 14.6 mm (CL) and 2.9 g (TW). So optimum date to release is June for about 2.9 g of individuals. After June, concentration of juveniles decrease in creeks but increase in coastal waters. This variation in juvenile’s concentrations has negative correlation with temperature and salinity of water in creek. Amount of 187 fish stomachs (from 22 species) in the creeks were reviewed, about 56 (29.9%) of those stomachs were full or semi full conditions. Amount of 12 fish stomachs (6.4%) contain of shrimp as diet. The most important of these fish was Mangrove red snapper (Lutjanus argentimaculatus). About of 104789 juveniles of Banana shrimp (1.4g TW) in 2007 and 51401 juveniles (1.3g TW) in 2008 were tagged and released from 23 June to 16 July each year. Most of the shrimp (tagged and not tagged) released in Tiab creek. For recapture of tagged shrimp used 386 trawl survey and about 49.3 Km2 swepted by wooden boats. During the catch season (October to early November) about 10% of wooden boats and some shrimp processing companies were search daily for tagged shrimp, but no tagged shrimp were found

Epidemiological study on some environmental and management parameters affecting on WSD occurrence in Fenneropenaeus indicus and Penaeus vannamei

For the first time white spot disease (WSD) was reported in shrimp farms of khoozestan province, in southwest of IRAN in 2002. Then in 2005 the neighbor province, boushehr, was contaminated. In 2008 WSD outbreak reported in sistan-bloochestan province in southeast of Iran. In 2015 all of southern shrimp farms of country except Hormozgan, the middle southern province, which has remained free of WSD, are being contaminated. White Spot disease suspended shrimp culture in thousands hectares of shrimp farms. Considering that white spot disease has not been observed in Hormozgan province yet, the question is; to what extent environmental and management factors participated in preventing WSD outbreak or cause WSD outbreak. In this study (20102012), the effects of environmental factors and management, stressors that decrease immune system function of shrimp are discussed. In addition, the role of pathogen as the main factor of outbreak is discussed. The goal of this study is to define environmental parameters and management practices associates with outbreak of white spot disease in affected provinces and discover reasons of being Hormozgan province free of this disease. In this study the role of the local environmental factors and management practice stressors in susceptibility to WSD was determine. Both the effects of environmental factors in water of ponds including total ammonia, nitrogen, dissolved oxygen, pH, salinity, transparency, and temperature and management issues related to biosecurity are studied. There were overlaps on physical and chemical parameter values obtained in clear areas with contaminated areas .Results of the data analysis suggest that lack of association with WSD incidence was 7 times greater than WSD incidence despite of disease outbreak in sistan-bloochestan province, so other sources of white spot disease virus incidence was suspected in affected areas. Histopathological examinations and polymerase chain reaction (PCR) tests during project performance did not reveal white spot disease virus evidences in post larvae examined from khoozestan province stocked in farms but disease outbreak was happened in that farms , so we suspected to management practice include feed , pond preparation and carrier of disease. Recorded values of temperature and salinity in some months during inspection in Hormozgan province specified stressful condition that may lead to WSD outbreak, however the disease did not appear. Therefore the hypothesis that the water physical and chemical conditions are reasons to prevent disease outbreak in Hormozgan province is being rejected. The policy of Hormozgan’s fishery authorities, to replaced Fenneropenaeus indicus with specific pathogen free Litopenaeus vannamei, that is more resistant to some of diseases, before incidence of WSD in farms and to before being endemic in the Hormozgan province, made an advantage compare to affected southern provinces that introduced Litopenaeus vannamei after WSD prevalence to their farms. However it does not guarantee to maintain current trend of being Hormozgan province farms free of white spot disease. Therefore establishing the principals of biosecurity are strongly emphasized. Strategies taken by the proficient authorities in preparation of SPF shrimp broodstock can be the most important factor in preventing WSD. Regarding biosecurity principals purchased feed must be free of shrimp head powder. Construction the new shrimp farms should be as far as it could be away from contaminated areas

A kinematics-based model for the settling of gravity-driven arbitrary-shaped particles on a surface.

A discrete model is proposed for settling of an arbitrary-shaped particle onto a flat surface under the gravitational field. In this method, the particle dynamics is calculated such that (a) the particle does not create an overlap with the wall and (b) reaches a realistic equilibrium state, which are not guaranteed in the conventional discrete element methods that add a repulsive force (torque) based on the amount of overlap between the particle and the wall. Instead, upon the detection of collision, the particle's kinematics is modified depending on the type of contact, i.e., point, line, and surface types, by assuming the contact point/line as the instantaneous center/line of rotation for calculating the rigid body dynamics. Two different stability conditions are implemented by comparing the location of the projection of the center of mass on the wall along gravity direction against the contact points to identify the equilibrium (stable) state on the wall for particles with multiple contact points. A variety of simulations are presented, including smooth surface particles (ellipsoids), regular particles with sharp edges (cylinders and pyramids) and irregular-shaped particles, to show that the method can provide the analytically-known equilibrium state