摘要:

The main types of body deformation found in sea bass,Dicentrarchus labrax(L), reared at the Centre Océanologique de Bretagne, from hatching to 100 days, are described and classified. Frequency of occurrence of each type of abnormality was followed in different batches of reared fishes. Results suggest that the majority of the abnormalities which appear in larval fish are lethal (from 0 to 40 days), while those which become apparent only in the post‐larval fish (after 40 days) do not interfere with surviv

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02830.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The concentrations of zinc, lead and cadmium in four species of fish from several lacustrine sites were determined. Cyprinids were found to have significantly higher levels of the three metals studied than perch,Perca fluviatilis. Whilst zinc thresholds may be species specific, levels of lead and cadmium vary both within species and sites. There is some evidence that lead and cadmium levels increase with age in roach,Rutilus rutilus. Additionally both cadmium and lead appear to accumulate in the heart, liver, kidney and brain as well as in the bone. Relatively high levels of lead and cadmium were recorded in the eyes of bream,Abrama bramis.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02831.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Cortisol was undetectable in rainbow trout plasma 24 h after the fish had been injected with betamethasone. This drug is known to suppress ACTH release and, consequently, cortisol production in teleosts. The blood glucose, chloride, sodium, potassium and total protein concentrations were not significantly affected by betamethasone. However, significantly increased blood packed cell volume values were found.Betamethasone‐injected fish when exposed to hypoxia or phenol had a pattern of blood component changes similar to those found in sham‐injected fish also exposed to the pollutants. These changes in turn were similar to those found in exposed but uninjected and unhandled fish. Suppression of rainbow trout plasma cortisol concentrations with betamethasone apparently has no effect on the fish's short‐term blood component responses to pollutants under the conditions used in these experiments, but does prevent a stressormediated increase in plasma cortisol concentra

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02832.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The structure of the integument of 26 wild and nine artificially matured femaleAnguilla anguilla, and 30 sexually immature eels maintained in controlled lighting, was investigated. Melanophore densities varied in a way unrelated to maturity while xanthophores were progressively lost from lower levels in the skin. Reflecting layers made up of the purines, guanine and hypoxanthine were associated with chromatophore layers. Purine concentrations (as a percentage of total skin dry weight) decreased with maturity but a reorganization of the reflecting elements occurred. Colour changes associated with maturation were due to the redistribution of purines. Spectral and angular reflectance measurements indicate that the integument has camouflage value and colour changes can be related to the change in habitat occurring with migration. The usefulness of colour as an index of sexual maturity is discussed.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02833.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Levels of androgens and oestradiol in dogfish,Scyliorhinus canicula, plasma, measured by radioimmunoassay, decrease markedly after ovariectomy (OVX). The magnitude and latency of these responses varies according to length of captivity preceding the operation and the time of year at which ovariectomy is performed. Androgens are cleared more rapidly than oestradiol from plasma following OVX, and levels of both steroids are reduced after laparotomy (LAP) in November but not in March. An extract of ventral lobes of the dogfish pituitary induces a significant increase in the circulating androgen levels in LAP fish but not in OVX fish, indicating that the ovary is the major site of androgen production in response to stimulation by dogfish gonadotrophin. Intramuscular injections of oestradiol benzoate (2.5 mg per fish) into LAP fish produce a significant reduction in the gonadotrophin content of the pituitary ventral lobe, measured in the quail testicular cell bioassay, when compared to LAP and unoperated controls. However, no significant changes in the gonadotrophin content of the ventral lobe were seen five days after OVX in June.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02834.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

A blood profile ofIctalurus punctatuswas determined from a total of 35 fish. The values obtained included plasma protein, haemoglobin, red cell counts and differential white cell counts.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02835.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Yearling coho salmon were fed either a commercial trout (TC) diet or a diet consisting of homogenized adult Pacific Ocean coho salmon (PS), supplemented with vitamins and minerals. The hepatosomatic index of the TC‐fed fish killed 12 h after the last feed or after 4 or 8 weeks of fasting were significantly larger (P0.05) than comparable PS‐fed groups.‘Light’ and‘dark’ hepatocyte cell types were evident in all groups although the dark cells were less numerous in the fasted fish. Hepatocytes of fasted fish contained markedly more endoplasmic reticulum than fed fish. Hepatocytic glycogen content of the TC‐fed fish was higher than in PS‐fed fish. Whereas in the TC‐fed group hepatic glycogen was still evident in fish fasted for 8 weeks, the hepatocytes of the fasted PS‐fed group contained little or no glycogen. The suitability of commercial fish diets for sal

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02836.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

A first report and description is given of the formation of‘mirror’ scales on dace,Leuciscus leuciscus(L.), Cyprinidae; a similar scale formation in carp,Cyprinus carpio, Cyprinidae is often associated with decreased growth rate, but this was not observed in the d

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02837.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The uptake of zinc by young O‐group plaice,Pleuronectes platessawas investigated at levels of high input from sea water and food (Artemianauplii). Zinc concentrations in the fish were strongly weight‐specific and accumulation effects were distinguished by regression analysis. Sea water was estimated to contribute>10% of the total input up to levels corresponding to high environmental concentrations (c.0.1 μg Zn ml−1) and food was the major source of zinc up to sea water concentrations ofc.0.6 μg Zn ml−1. A high degree of regulation obtained along the food pathway to the fish although, in the system studied, most of this regulation was effected by the food organism. Regulation of food input explained the lack of variation in zinc levels previously observed in wild po

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02838.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The intestinal role in osmoregulatory preadaptation of freshwater‐adapted (FW) yearling coho salmon during smoltification was examined. Measurements of intestinal net fluid absorption (JV) using anin vitrosac preparation showed that JVof FW parr was significantly less than that of either FW or seawater‐adapted (SW) smolts. From two to four weeks following the springtime thyroxin surge, JVincreases in FW coho to a level comparable with that observed for SW smolts. JVremained elevated in FW smolts throughout most of the summer and then decreased in the autumn. Two months after the thyroxin peak, intestinal wet weight per unit serosal surface area increases. Coho stunts resulting from premature transfer into sea water had significantly higher JVthan that seen in SW smolts. The elevated JVof stunts is only partially explicable on the basis of differences in body weight between stunts and smolts.Our observations indicate that an increase in intestinal fluid absorption is a preadaptive change associated with smoltification occurring in concert with alterations in renal and branchial osmoregulatory mechanisms. The timing of the increase in JVsuggests a phase relationship to the thyroxin surge. This temporal relationship may help to explain the efficacy of using changes in plasma thyroxin levels to predict hatchery‐fish release dates that may optimize eventual seawater sur

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02839.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY