摘要:

Rates of food consumption are notoriously difficult to measure under field conditions and indirect methods must be used. Using data for cod collected from three different areas (North Sea, Faroes&Balsfjorden), food consumption was estimated from stomach fullness and rates of gastric evacuation. These estimates were then compared with estimates given by analysis of food‐growth relationships. Although estimates were of the same order of magnitude there were differences. These differences were suggested to be largely due to insufficient knowledge relating to feeding rhythms of wild fish and lack of data regarding the‘costs of reproduction’. Differences between the annual energy budgets of cod from the three stocks are disc

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02841.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The effect of excess vitamin D3on calcium metabolism in rainbow trout was investigated. Trout were reared for 24 weeks on diets containing 4000, 104 000 or 1 004 000 iu of supplemental vitamin D3kg‐1dry diet. No effect of excess vitamin D3was detected in the weight gain, feed efficiency or total mortalities of trout in the different groups. None of the fish showed any signs of hypercalcaemia and no significant difference was detected in the calcium, magnesium, phosphorus and sodium content of the trout vertebrae or total carcass. However, there was a significant increase in the calcium, magnesium and phosphorus content of the skin in trout reared on the highest supplemental level of vitamin D3(1 004 000 iu kg‐1diet). No overt signs of renal calcinosis were detected in any of the trout. This study indicates that trout are resistant to excess vitamin D3, and that excess vitamin D3does not appear to be related to the increased incidence of renal calcinosis in rainbow tr

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02842.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Differential copper uptake within brain, visceral, gill, somatic and residual tissue was examined in the two sympatric species of killifishesFundulus heteroclitusandF. majalis. Various salinities and copper concentrations were tested on both juvenile and adult stages to examine their effects on copper uptake. Salinity played a significant role in copper uptake in both species of killifishes. However, the effect of salinity was specific for each species and life history stage. Copper content of various tissues was directly related to the uptake pattern exhibited by whole adult fishes.Fundulus majalisbrain tissue andF. heteroclitusmuscle tissue were exceptions. Severe body lesions and subcutaneous haemorrhaging were observed after 2–3 day exposure to both 2 and 8 ppm coppe

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02843.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Convict cichlids,Cichlasoma nigrofasciatum, inbred for four and five generations exhibited moderate and severe morphological deformities. Deformed fishes were characterized by a more vertically sloping forehead, irregular jaw, hyoid, opercula and fin structure, reduced growth and irregular swimming behaviour. Inbred fish (F4, F5) did not differ from F1s in their age of maturation or the average size of their first broods. Brood survival was 18.7% in F5inbred fish, compared to 75.5% in F1s.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02844.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The monthly feeding activity and food habits of populations ofEthmalosa fimbriataoccurring in the sea and an estuary in Cape Coast, Ghana district were investigated during a 14‐month period. The juvenile fish, whose total length (T.L.) ranged from 5.3 to 14.7 cm, occur in the estuary and appeared to be more active feeders than the marine samples which measured 15.0–30.4 cm. The peak feeding activity in the marine population coincided with the onset of‘upwelling’ in the sea, which period is characterized by high salinities, decreasing temperatures and high zooplankton production. The species is primarily a plankton feeder. The stomachs of the marine samples contained mainly protozoa, crustacea, molluscan larvae and a considerable amount of detritus while the stomachs of the estuarine fish contained mainly phytoplankton, protozoa, sand grains and organic detritus. These observations have been discussed in relation to other reports on populations occurring along the West Africa

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02845.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The concentration of lead acetate which caused 50% mortality of bluegill in 96 h (96 h LC50) is approximately 400 ppm. Sublethal concentrations of 0.1, 1, 10, 100, 200 and 300 ppm lead acetate did not produce any effects on the locpmotor activity of the bluegill. The observation that lead can reach concentrations which are lethal without sublethal effects on locomotor activity at lower concentrations is unusual and in sharp contrast to studies with other metals (Ellgaardet al.. 1978).

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02846.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The structure and distribution of red and white muscles have been investigated in femaleAnguilla anguillaof varying sexual maturity. Red muscle volumes increased with sexual maturation from approximately 5% of total muscle volume in sexually immature eels to a maximum of 13.3% in sexually maturing animals. Volume increase was due to increasing fibre diameter rather than recruitment of new fibres. Intracellular volume fractions of lipid and mitochondria increased markedly in maturing fish. Artificially matured cels showed the largest increases in muscle lipid. The possible functional roles of red and white muscle during migration are discussed.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02847.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Plasma norepinephrine and epinephrine from cannulated trout were measured by high pressure liquid chromatography with electrochemical detection. The catecholamines were extracted with acid‐washed alumina using a microfilter assembly which permitted analysis of small volumes of plasma. Mean (± S.D.) values for plasma norepinephrine and epinephrine were 1.83 (0.97) pmol ml−1and 8.95 (4.94) pmol ml−1, respectively. These values are compared with catecholamine levels from other vertebrate s

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02848.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

In a spawning area survey in the Askö area, northern Baltic proper, undertaken in the beginning of summer 1978, 100 randomly established and sampled transects were studied by diving. Herring spawn was found at 45 of the transects. The eggs were usually found onPilayella littoralis, a filamentous brown algae, at the more exposed transects. Eggs were only found down to a depth of 11 m. In a neighbouring oil spill area spawn were found at only four out of 20 transects. Of eggs taken to the laboratory for hatching, 54% of those from the unaffected area hatched but only 25% of those from the oil spill area

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02849.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

A diseased American ell,Anguilla rostrata(Le Sueur), was captured during a survey of Little Mosquito Creek, Accomac County, Virginia, U.S.A. Two skin lesions were present. One was caused by the dermal encystment of a nematode,Eustrongylides tubifex; the other was of undetermined origin.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1982.tb02850.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY