The effect of temperature on the duration of spawning markers—migratory-nucleus and hydrated oocytes and postovulatory follicles—in the multiple-batch spawner Japanese flounder (Paralichthys olivaceus)

The duration of spawning markers (e.g. signs of previous or imminent spawnings) is essential information for estimating spawning frequency of fish. In this study, the effect of temperature on the duration of spawning markers (i.e., oocytes at early migratory nucleus, late migratory nucleus, and hydrated stages, as well as new postovulatory follicles) of an indeterminate multiple-batch spawner, Japanese f lounder (Paralichthys olivaceus), was evaluated. Cannulation was performed to remove samples of oocytes, eggs, and postovulatory follicles in individual females at 2–4 hour intervals over 27–48 hours. The duration of spawning markers was successfully evaluated in 14 trials ranging between 9.2° and 22.6°C for six females (total length 484–730 mm). The durations of spawning markers decreased exponentially with temperature and were seen to decrease by a factor of 0.16, 0.36, 0.30, and 0.31 as temperature increased by 10°C for oocytes at early migratory nucleus, late migratory nucleus, and hydrated stages, and new postovulatory follicles, respectively. Thus, temperature should be considered when estimating spawning frequency from these spawning markers, especially for those fish that do not spawn synchronously in the population.

Effect of temperature on the oxygen consumption of Penaeus monodon postlarvae

The study aimed to determine the oxygen consumption of P. monodon postlarvae at different temperatures. Results suggest dependence of oxygen consumption on both weight of postlarvae and temperature. The relationships appear linear at the temperature range examined. Temperature dependence of oxygen consumption suggests that oxygen requirement (and metabolism) increases with temperature.

Effect of temperature on genomic and some biological indices during embryonic and larval development of Caspian trout Salmo trutta caspius Kessler, 1877

Since 1966 especially recent decade, Caspian trout (Salmo trutta caspius Kessler, 1877) considered as a strategic endemic species for Caspian Sea fisheries resources also coldwater aquaculture in Iran. Nowadays habitat condition effects on this subspecies during life stages, artificial breeding and incubation period noticed by research and execution sessions of fisheries in Iran. Incubation duration of Caspian trout from artificial fertilization followed by green egg and eyed egg, hatching and yolk sac absorption identified as most sensitive stages for fish and any pollution, stress and deviation by natural life conditions of embryo up to larvae could provide possible mortalities and observable or hidden alterations. Among all vital factors for Caspian trout welfare even in conservation plans and stocks rehabilitation programs or recent attempts for domestication of this fish for introduction to cold water aquaculture industry, water temperature as the most important physical factor which might conserve or induce stress to rearing environment condition is not considered yet. In hatcheries activities, the temperature for incubation and rearing Caspian trout eggs is determining by available water temperature and wide range of temperatures in governmental or private farms is using depend on the water resources availability. Also global climate change consideration and increase temperature trend accompany with group of physical and chemical factors provided by fish farm discharges and other source points entered to the migration pathway of Caspian trout in spawning season were not investigated before. Natural spawning migration pathway is upstream of Caspian tout south and south west rivers especially in Cheshmehkileh upstream in Tonekabon, Iran directed this research focus on the mentioned location. For simulation of natural spawning bed for Caspian trout, water supplied from the upstream of Daryasar branch as headwater of Cheshmehkileh River which provided REDD water condition for in vitro incubation. Green eggs treatments of wild and F1 cultured brooders both 3+ were incubated. Incubation implemented in dark, constant temperature (4, 8, 12 degree centigrade) and DO–pH–temperature digital monitoring in 3 recycling incubators ended to yolk sac absorption and entering larval stage. Hatching success, possible genome alterations by HSP70 gene expression and comet assay implemented as diagnostic tools in 3 life stages of eyed egg– Alevin and Larvae. Numbers and diameters of larvae white fiber muscles measured by histology experiment and Hematoxylin–eosine staining. Results stated significant effect of incubation temperature on hatching success, genome and white fiber muscles of wild and F1 samples. Hatching success measured as 31% and 38% for cultured and wild cold treatments, 79% and 91% for normal and 64% and 73% for warm cultured and wild treatments respectively. Considerable mortality occurred for cold treatment and 8 degree centigrade stated the best thermal condition in normal incubator according to hatching success in wild Caspian trout samples.

Acute effect of sumithion on certain blood parameters and mortality rate of fish, Heteropneustes fossilis (Bloch)

The acute toxic effect of the toxicant sumithion (50% E.C.) on mortality rate (after 24, 48, 72, and 96 h), total RBC count and haemoglobin content (after 48 and 72 h) on Heteropneustes fossilis was investigated at four concentrations (9.7, 10.7 and 11.1 ppm). The sumithion treated fishes showed lower RBC and Hb levels than the untreated ones. A gradual decrease in the total RBC counts and Hb contents was recorded with increasing concentration of toxicant after 72 h but the blood showed fluctuating values after 48 h of treatment.

Effect of salt on the level of histamine in preserved fish (Herring, Clupea harengus)

Histamine levels in batches of heavily salted (fish:salt ratio 4:1) herring (Clupea harengus) were monitored during ripening at 4°C and 25°C. The batches studied were prepared from both pre-spawning and post-spawning (spent) fish using new and used salt. Salt levels in the flesh, which reached 11 to 14% (wet weight basis) during the ripening period, were found to retard histamine formation. During normal spoilage of ice chilled fish, histamine levels had been reported to exceed 50mg/100g flesh as it approached the limit of edibility whilst, in the heavily salted fish, levels remained below 20mg/100g flesh throughout the ripening periods of 18 months for the 4°C batches and 3 months for the 25°C batches. This was the case when the samples were set up and the salt allowed penetrating the flesh at 4°C. When, however, the samples were set up and initially stored at ambient (10-15°C) temperature the histamine levels in the flesh rose above 20mg/100g before enough salt had penetrated to inhibit its generation. The gradual rise in levels which, nevertheless, occurred over the ripening periods followed significantly (5% level of significance) different trends, being greater in the batches prepared from pre-spawning than those from spent fish.

Effect of gibbing on protein hydrolysis during the ripening of salted herring at 4°C in polypropylene barrels

Effect of gibbing process on the protein hydrolysis in terms of free alpha amino nitrogen (FAN) content during the ripening of barrel salted herring at low temperature (4°C) was investigated. For this purpose North Sea herring (Clupea harengus) from north-east British coast was salted in polypropylene barrels and allowed to ripen at 4°C. This process of barrel salting was carried out for whole fish in one batch and gibbed fish in another batch. The investigation was performed by using new salt and used salt in separate barrels for each batch of experimental fish. Results of the present study show that protein hydrolysis was significantly higher in the ripened salt-herring produced from whole fish which was found to have more characteristic sensory properties than those produced from gibbed fish. Similar result (proteolysis) was obtained when the investigation was repeated for the spent herring although the spent herring fails to produce a ripened product with the desired characteristic sensory attributes, compared to those of pre-spawning herring.

Effect of salinity on food consumption and growth of juvenile Nile tilapia (Oreochromi niloticus L.)

The effect of salinity (0, lO and 20%o, water temperature 28 ± l oC) on food consumption and growth of juvenile Nile tilapia, Oreochromis niloticus L. (9.94 ± 0.15 g) were investigated by feeding group of 20 fish at 2% body weight day. Individual food consumption was measured using X-radiography. There were no significant differences in growth or white muscle protein concentrations among groups. During feed deprivation, weight loss was similar for fish held at O%o and 10 %o salinity, but after 7 days over 50% of the fish maintained at 20%o salinity developed lesions covering 5-25% of the body. No significant relationships were observed between individual specific growth rates and food consumption rates within the groups. The fish in all salinity groups showed a negative correlation between specific growth rate and food conversion ratio. The coefficient of variation for wet weight specific food consumption and the mean share of meal for each fish were used as a measure of social hierarchy strength. A negative correlation was observed between coefficient of variation in food consumption and mean share of meal. The social hierarchy structure was similar in all salinities; 25% of the fish were dominant (18.29% above an equal share of meal) and 30% were subordinate (16.19% below an equal share of meal) and the remainder 45% fish fed theoretical share of meal (MSM, 5.26%).

Effect of furanace on the development of larval stages of Penaeus monodon Fabricius

Zoea 2(Z SUB-2 ) Mysis 1 (M SUB-1 ) and Postlarva 1 (P SUB-1 ) of P. monodon artificially spawned in closed-system concrete hatchery tanks were bioassayed for their tolerance to the antibiotic furanace. The setup consisted of four 20-liter capacity plastic basins previously conditioned for 15 days with freshwater in full sunlight. During the experiment, each basin was filled with 5 liters of seawater to which was added filtered Chaetoceros and Brachionus to give densities of 5 . 0-7 . 5 x 10 SUP-4 cells/ml and 10-20 individuals/ml, respectively. The following are the properties of the water used throughout the experiments: salinity, 26-32%; pH, 7 . 3-8 . 4; temperature, 25-30 degree C; dissolved oxygen, 4 . 5-8 . 4 ppm; nitrite, 0 . 36-0 . 99 ppm; and ammonia, 0 . 10-0 . 30 ppm. To each basin were added 50 healthy larvae of specific stages of P. monodon. After an initial acclimation of one hour in the medium, preweighed amounts of the antibiotic were added and thoroughly dissolved. The concentrations tested were 1 . 0, 2 . 0 and 3 . 0 ppm. One basin always served as control. After 24 hours of exposure, the surviving population in each basin was counted. The survivors were then examined thoroughly under the microscope for unusual behavior and morphological defects brought about by the exposure. To minimize wide variations in the medium as a result of feeding and other manipulations, the systems were all prepared at 9:00 a.m. each time, and the feeds on two instances, one at 5:00 p.m. and another at 5:00 a.m. Fifteen trials conducted with Z SUB-2 showed survival ranges of 68% to 98% with a mean of 77 . 6% in the controls; 32% to 94% with a mean of 65 . 7% at 1 ppm, and 0% to 56% with a mean of 36 . 5% at 2 ppm. There were no survivors at 3 ppm. Interpolation from the survival-dose curve gave a 24-hr LC SUB-50 of approximately 1 . 6 ppm.

Effect of alum on the histological changes of silver barb (Barbodes gonionotus)

Studies were conducted to know the effects of alum on the histological changes of silver barb (Barbodes gonionotus) fry in the aquarium. The use of up to 0.5 g/L of alum for 120 hours as means of treatment of fish diseases is safe. At this level, no abnormal behavior and pathological alteration were observed in the organs of experimental fish. As the doses increased to 1.25 g/L and above (1.5 g/L), experimental fishes exhibited abnormal movement and with marked histopathological changes in the various organs. A dose of above 0.5 g/L should be strictly prohibited.

Effect of butachlor on spermatogenesis, testosterone amount and testes tissue Rutilus frisii kutum Kamenskii 1901

Morphological assessment of sexually mature Rutilus frisii kutum Kamenskii 1901 caught from the rivers (Shirud, Khoshkrud, Sepidrud and Chelavand Rivers) flowing in the southwest Caspian Sea region was conducted and sperm volume, total sperm count and sperm concentration of abnormal sperms were determined after exposing the spawners to 60% herbicide butachlor (machete). Spawners under study were maintained in tanks (1000 l) at the Shahid Ansari Teleost Fish Hatchery and exposed to two different concentrations (25% and 75% of its LC50 value) of butachlor. Results obtained indicate that exposure to high butachlor toxicity (75% of its LC50 value) decreased sperm volume to 0.61 ± 0.42 cc in 2-3 year old fishes and to 0.55 ± 0.42 cc in fishes above 3 years of age, while that in fish exposed to low butachlor toxicity (25% of its LC50 value) decreased to 1.55 ± 0.42 cc in 2-3 year old fishes and to 1.28 ± 0.42 cc in fishes above 3 years of age. The sperm volume under normal conditions in R. frisii kutum is 4.6 ± 0.42 cc in 2-3 year olds and 4.58 ± 0.42 cc in fishes above 3 years of age. The total sperm count in R. frisii kutum is 39.74 ± 2.5 billion spermatozoa/cc in 2-3 year olds and 42.99 ± 2.5 billion spermatozoa/cc in fishes above 3 years of age. When exposed to high butachlor toxicity, total sperm count dropped to 16.92 ± 2.5 billion spermatozoa/cc in 2-3 year olds and to 15.98 ± 2.5 billion spermatozoa/cc in fishes above 3 years of age. Similarly total sperm count in R. frisii kutum exposed to low butachlor toxicity was recorded as 23.6 ± 2.5 billion spermatozoa/cc in 2-3 year olds and 29.4 ± 2.5 billion spermatozoa/cc in fishes above 3 years of age. Under normal conditions, on the basis of morphology, spermatozoa showed only 10 ± 1.92% of abnormal sperms. The number of abnormal sperms increased by 28.6 ± 1.92% in fishes exposed to high butachlor toxicity, while that in fishes exposed to low butachlor toxicity increased by 19.7 ± 1.92% in 2-3 year olds and 16.6 ± 19.2% in fishes above 3 years of age. It is evident from the results obtained that increase in level of pollution caused a decrease in sperm volume but an increase in the percentage of abnormal sperms. Results obtained indicate that exposure to high butachlor toxicity (75% of its LC50 value) decreased testostron hormone to 0.31 ± 0.22 ng/ml in high butachlor toxicity, and to 0.45 ± 0.22 ng/ml in low butachlor toxicity (25% of its LC50 value). Testostron hormone dropped to 0.53 ± 0.22 ng/ml in 2-3 year olds and to 0.79 ± 0.22ng/ in fishes above 3 years of age. The testostron hormone under normal conditions in R. frisii kutum is 2.7 ± 0.22 ng/ml. It is evident from the results obtained that increase in level of pollution caused a decrease in testostron hormone

Effects of temperature on the biology of the northern shrimp, Pandalus borealis, in the Gulf of Maine

Length-frequency data collected from inshore and offshore locations in the Gulf of Maine in 1966-1968 indicated that ovigerous female northern shrimp (Pandalus borealis) first appeared offshore in August and September and migrated inshore in the fall and winter. Once eggs hatched, surviving females returned offshore. Juveniles and males migrated offshore during their first two years of life. Sex transition occurred in both inshore and oll'shore waters, but most males changed sex offshore during their third and fourth years. Most shrimp changed sex and matured as females for the first time in their fourth year. Smaller females and females exposed to colder bottom temperatures spawned first. The incidence of egg parasitism peaked in January and was higher for shrimp exposed to warmer bottom temperatures. Accelerated growth at higher temperatures appeared to result in earlier or more rapid sex transition. Males and non-ovigerous females were observed to make diurnal vertical migrations, but were not found in near- surface waters where the temperature exceeded 6°C. Ovigerous females fed more heavily on benthic molluscs in inshore waters in the winter, presumably because the egg masses they were carrying prevented them from migrating vertically at night. Northern shrimp were more abundant in the southwestern region of the Gulf of Maine where bottom temperatures remain low throughout the year. Bottom trawl catch rates were highest in Jeffreys Basin where bottom temperatures were lower than at any other sampling location. Catch rates throughout the study area were inversely related to bottom temperature and reached a maximum at 3°C. An increase of 40% in fecundity between 1973 and 1979 was associated with a decline of 2-3°C in April-July offshore bottom temperatures. Furthermore, a decrease in mean fecundity per 25 mm female between 1965 and 1970 was linearly related to reduced landings between 1969 and 1974. It is hypothesized that temperature-induced changes in fecundity and, possibly, in the extent of egg mortality due to parasitism, may provide a mechanism which could partially account for changes in the size of the Gulf of Maine northern shrimp population during the last thirty years. (PDF file contains 28 pages.)

Effect of salinity on growth and survival of Clarias gariepinus (Burchell, 1822): Clariidae fry

The effect of different salinity levels on the growth and survival of Clarais gariepinus fry was studied in indoor hatchery system for a period of three weeks. 1000 Clarias gariepinus fry of an average weight 0.37~c0.06g were stocked at 100 fry in five replicated 20 liters plastic bowls. Five salinity levels of 0.2, 0.4, 1.1, 2.1 and 4.2ppt were tested. The results indicated that significant difference P~.0.05 highest weight gain of 0.89~c0.05g was presented by fry in 0.2ppt medium. All fry raised in 4.2ppt died within 24 hours. No significant difference P~,0.05 in weight gain is presented in fry raised in 0.2ppt-2.1ppt. From this study, the weight gain decreases with increase in salinity. Also the survival rate decreases from 0.2ppt to 1.1ppt raised fry while the lowest significant difference P~.0.05 survivals were presented in fry raised in 2.1 and 4.2ppt. Based on these results and foregoing, salinity rate of 0.4ppt is favourable for growth and survival of C.gariepinus fry

The effects of temperature on growth and metabolism of flowing water cold-stenotherms [Translation from: Archiv fur Hydrobiologie 74(4) 479-495, 516-522, 1974]

A small stream in the French Alps was sampled at regular intervals to determine the size distribution of animals for growth studies. The temperature was also measured. The results obtained for Gammarus fossarum were compared with laboratory cultures and the laboratory animals were physiologically and chemically analysed. Chemical analysis was also carried out on field animals.