摘要:

The skin of rainbow trout was examined at the ultrastructural and cytochemical level after a 3–h exposure to an elevation of the water temperature, from 15 to 22° C. Within 3 h, the thickness of the epidermis had significantly (P<0·05) decreased when compared to control fish. After 24 h it was restored, and from day 4 onwards even increased above control levels. The thickening of the epidermis was associated with appearance of many mitotic cells, not observed in control fish. Within 24 h many apoptotic epidermal cells were found, indicating enhanced ageing of the cells. Filament cells from the outer epidermal layers synthesized vesicles with peroxidasc activity within 3 h after temperature elevation. This enzyme was found also in apoptotic as well as in necrotic filament cells. Mucous cells became elongated and their mucosomes displayed peroxidase activity. Occasionally electrondense, probably serous, mucosomes appeared. In the epidermis rodlet cells were found. Both epideimis and dermis, became invaded by many lymphocytes and macrophages. The latter contained vesicles with peroxidase activity. Pigment–containing cytoplasmic extensions of melanocytes penetrated the epidermis while iridocytes disappeared from the dermis. The synthetic activity of dermal fibroblasts was stimulated. These results show that a moderate temperature elevation has pronounced and prolonged effects on the skin of the exposed fish. The effects are to a high extent comparable with those of stressors such as heavy metals, acid water or wou

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1994.tb01265.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Alburnus alburnus, Leuciscus cephalusandVimba vimbaefferent duct systems of the male gonads consist of testicular main ducts and spermatic ducts. These have similar histological, fine structural and (enzyme–) histochemical characteristics and function in (1) storage and (2) nutrition of spermatozoa, (3) synthesis of steroid glucuronides, (4) secretion of proteins and enzymes (5) formation of an ionic gradient in the seminal fluid and (6) they have auto– and heterophagocytotic activities. Therefore testicular main ducts and spermatic ducts are important in the formation of the seminal fl

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1994.tb01266.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Salmon eggs were incubated at 5, 8 or 11° C from fertilization to hatching. At Gorodilov stages 25, 27, 29, 31 and 33 transverse sections of whole embryos (at somite level 10–15) were prepared for histochemistry and electron microscopy. At every stage up to hatching, cross–sectional areas of the embryos were not different between temperatures, and from stage 27 onwards there was also no difference in the ratio of white to red muscle. However, there were more muscle fibres but of smaller average diameter in both the red and white muscle for the colder temperature embryos. At hatching there were also more nuclei (per cross–section) in the colder embryos but more nuclei per muscle fibre in the warmer embryos. In all cases the 8° C embryos were intermediate between 5 and 11° C embryos in their muscle parameters. Fast and slow muscle fibres could only be distinguished in the embryos by alkali–stable ATPase reactions. Succinic dehydrogenase activity was low in embryonic fish. No differences between the temperature groups were detected in the histochemical reactions for either ATPase or succinic dehydrogenase

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1994.tb01267.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Ultrasonography is a fast, accurate, and non–invasive method to determine the sex of cod (Gadus morhua). In this study it was used on 788 farmed cod ranging in age from 1 to 6 yr. Accuracy of sex determination was over 95% for fish subjected to Ultrasonography from October to Apri

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1994.tb01268.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

To test whether seawater–acclimatization of hatchery–reared anadromous and freshwater resident brown trout before release increased the survival of adults, smolts were retained 0, 2, 4 and 8 weeks in sea water before release. Total recapture rate increased for smolts retained 4 and 8 weeks in sea water before release relative to the controls. This trend was more pronounced for Freshwater resident than for anadromous stocks, Offspring of anadromous fish stayed longer at sea than offspring of freshwater resident fish. Recapture rates in fresh water were higher for brown trout released in the river than in the fjord in the R, Drammen area, but not in the R. Imsa. In both cases, most fish were recaptured in the sea. Moving into the R. Imsa (relative to other rivers) appeared higher for fish released at the mouth of the river (93%) than in the fjord (47%). Judged from the recapture rates, sea survival appeared to be the same whether released in the fjord or at the mouth of the ri

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1994.tb01269.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The gonadosomatic index (GSI) of pre–pubertal male rainbow trout, which had been injected biweekly with partially purified salmon gonadotropin (sG–G100, 50 μ mUg kg−1body weight), increased from 0.05 to 1.85 over 21 weeks from injection, while control GSI remained below 0.05. Plasma testosterone (T) increased from 2 to 11.34 ng ml−1by week 21 in injected fish, while control level remained below 1.5 ng ml−1. In injected fish plasma 11–ketotestosterone (KT) and 17,20–dihydroxyprogesterone (17α20βP) levels increased from 20.2 to 41.9 and 8.9 to 219.7 ng ml−1respectively. Plasma T, 11–KT, and 17α20βP were all correlated with the GSI (P<0–001) in injected fish. The most advanced stage of germ cells present in the control fish were spermatogonia. However, in injected fish spermatozoa were present by week 21. Eggs fertilized at this time with spermatozoa from injected fish achieved a 78% fertilization rate, whereas the testicular homogenate was incap

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1994.tb01270.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Ovarian maturation inNotothenia coriicepsis known to include a period during which yolk deposition begins to take place. This ‘adolescent’ phase was thought originally to last for about 1 year. The results from a 2–year study at Signy Island indicate that this adolescent phase lasts for about 4 years. There is also some evidence to indicate that not all sexually mature fish spawn each season. Two reproductive strategies are considered, one where adverse conditions are accompanied by a failure to spawn and an alternative where fecundity is controlled by the number of small oocytes which

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1994.tb01271.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

On the Atlantic Moroccan coast, two species of pleuronectiform fish coexist, wedge sole (Citharus linguatula) a temperate species, and spotted flounder (Dicohgoglossa cuneata) a tropical one. These two species are the definitive host forBothriocephalus andresiandAcanthocephaloïdes propinquus, respectively. A negative binomial fits the dispersion ofB. andresiin the population ofC. linguatula. The fish become parasitized between their first and third year, while still immature, with the highest abundances in the third year. After the fish become ichthyopagous, the level of infection drops drastically. We postulate that copepods are the sole source of infection. The presence ofB. andresiin both Atlantic and Mediterranean populations ofC. linguatulashows that the parasite follows the host during its migration along the Mediterranean coasts.The prevalence ofA. propinquusremains above 50% as a consequence of the large numbers of amphipods included in the diet ofD. cuneata, regardless of the age of the fish or the season. The amphipods,Phtisica marinaandPariambus typicusare an important food and represent potential intermediate hosts forA. propinquus. The population dynamicsof A. propinquuson the Atlantic Moroccan coasts are similar to those observed in parasite populations ofGobius nigerin the Gulf of Lion (French Mediterranean). The observation ofB. andresiandA. propinquusin both Moroccan Atlantic and Mediterranean fishes highlights the problem of the evolution of these parasite populations during the colonization of the Mediterranean by the hosts

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1994.tb01272.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Growth of captive juvenile Pacific halibut was linearly related to energy consumption (J g−1day−1) at 4°C by the following equation: growth (% body weight (b.w.) day−1)=0–007 (consumption J g−1day−1)– 0.192;r2=0.81. Weight gain was independent of size for fish between 9 and 7000 g when growth was expressed as a function of consumption in J g−1day−1. Maintenance ration determined in feeding–growth experiments averaged 27.4 J g−1day−1at 4–0°C. Small halibut ate significantly more food than large fish. Single meals following 2 day fasts averaged 4.1% b.w. for halibut under 100 g, 1.72% b.w. for 1.2 kg fish and 1.1% B.W. for 6.8 kg fish. Both large and small size categories of halibut tended to evacuate their meal in about 3 days even though small fish ate relatively larger meals. Minimum estimates for daily ration to achieve growth rates observed in the Gulf of Alaska were approximately 0.5 to 2.4% b.w. day−1depending on fish size and whether northern shrimp or y

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1994.tb01273.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The standard oxygen consumption rate and the activities of muscle citrate synthase, creatine phosphokinase and lactate dehydrogenase in the tropical fishOreochromis niloticusacclimated to either 20.5 ± 0.3° C or 26.5 ± 0 ± 5 ± C for at least 3 months were investigated. The standard oxygen consumption rate of individual fish from the two acclimation temperatures was determined at 20, 25 and 30 ± C. At all experimental temperatures, the standard oxygen consumption rate of fish acclimated to 20.5 ± 0.3° C was significantly higher than that of fish kept at 26.5 ± 0.5 ± C. In both groups smaller individuals had a higher oxygen consumption rate than large ones.Analyses of the activity levels of citrate synthase (CS), creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) in both red and white muscles isolated from fish kept under the two temperature regimes were performed at 26 ± C. The activity of CS in both red and white muscles isolated from the 20.5 ± 0.3° C acclimated fish was significantly higher than that of muscles isolated from the 26.5 ± 0.5 ± C acclimation group. Similarly, the CPK activity in white muscles isolated from fish acclimated to 20.5 ± 0.3 ± C was higher than that of muscles obtained from the 26.5 ± 0.5 ± C acclimation group. However, the CPK activity in red muscles isolated from the two fish groups was not significantly different. The opposite results were obtained for LDH activity. For example, the LDH activity of white muscles isolated from fish acclimated to 26.5 ± 0.5 ± C was significantly higher than that of the same muscles but from the 20.5 ± 0.3 ± C acclimated fish. No differences were observed in the LDH activity of red muscles isolated fr

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1994.tb01274.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY