摘要:

Sexually mature male parr successfully mated with female anadromous Atlantic salmon,Salmo salar, in the absence of anadromous males. There was no significant difference between the proportion of eggs fertilized by mature male parr and anadromous males. One of the demographic consequences of our observations is that overfishing could eventually eliminate anadromy in male members of a population.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1987.tb05220.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The morphological characteristics of the peripheral leucocytes of the cichlidO. mossambicuswere studied using light microscopy. Cytochemical procedures and phagocytic studies were employed. Four main types of leucocytes could be recognized: lymphocytes, thrombocytes, monocytes and granulocytes. Two distinct types of granulocyte were identified. Monocytes and one type of granulocyte were found to be phagocytic.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1987.tb05221.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Four groups of yellow eels, three from three Po Delta brackish bays (Pila, Scardovari and Goro) and one from the French Atlantic coast, were marked by freeze‐branding and released at an open‐sea point 5 miles offshore. Of the 2137 eels released, 453 (21.2%) were recaptured over a 1‐month period. The percentage recaptured is not independent of either fish size (the larger eels being recaptured in greater quantity than the smaller ones which are supposed to be less catchable and more easily overlooked by fishermen) or fish origin (the recapture rate of the French stock was both the lowest, at 9.8%, and the most dispersed in time and space). The highest multiple catches were for eels from Pila and Scardovari and were made in the first days of the experiment. Of the recaptured eels, 75% were caught in the inland water closest (9 km) to the release point; only 8.6% were recaptured at the mouth of the two branches of the River Po. There is no evidence of a real homing tendency for yellow eels previously adapted to living in brackish water: the massive return to the nearest coast is probably only an avoidance reaction to the unfavourable open‐sea envi

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1987.tb05222.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Plasma and tissue metabolite levels were measured in the air‐breathingChanna maculataduring acute and prolonged exposure to normoxic and hypoxic water. Exposure of the fish to hypoxic water (water oxygen partial pressure,PwO2= 50 mmHg) for 1 h caused increases in plasma glucose and lactate, liver and brain lactate, liver a‐amino acid, heart and brain alanine and brain succinate levels. The metabolic changes in heart, brain and muscle could only be detected whenPwO2was 30 or 10 mmHg. Heart glycogen and liver lipid decreased during acute exposure. Prolonged exposure to hypoxic water (PwO2= 30 mmHg) for 3 days caused an increase in plasma glycerol and liver lactate dehydrogenase activity, and a depletion of glycogen store in all tissues investigated. However, metabolite levels which had been elevated during acute hypoxic exposure were observed to return to their normoxic values after prolonged exposure. It was concluded that anaerobic metabolism was triggered by acute exposure to hypoxic water. Prolonged exposure to hypoxic water induced a metabolic readjustment involving mobilisation of lipid and glycogen stores, which is probably a reflection of the high metabolic load of aerial respiration imposed on the fish during exposure to hypoxic wa

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1987.tb05223.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The antibody response to human gamma globulin (HGG) andAeromonas salmonicida(AS) in control and long‐term thymectomized rainbow trout was individually monitored in 120 fish. The fish responded poorly to HGG and no memory response was observed. There was no difference in response between control fish and fish which had been thymectomized for 5 months before immunization. However, 9‐month thymectomized fish had lower titres than controls. The response to AS was vigorous and significant memory was demonstrated after a second injection. There was no difference in response between control and thymectomized fish. The individual variation in response was not related to body size, antigen dose, sex or reproductive state. The results are discussed in terms of the thymus dependency or independency of antigens in fish, and the role and life span of T cell subsets, such as ‘helper’ and ‘;suppress

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1987.tb05224.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Anin vitroassay for estimating the proportion of phagocytic cells among peripheral leucocytes from rainbow trout by flow cytometry (FCM) and fluorescence microscopy was evaluated. Data from FCM were compared with fluorescence microscopic observations and good correlation (r= 0.87) was found. The influence of various culture conditions, such as serum type, duration of incubation and temperature, on thein vitrophagocytic assay was investigated. Cultures supplemented with brown trout serum and incubated for 18 h at 19° C were considered to give optimal conditions for phagocytosis. The proportion of phagocytic cells detected in the peripheral blood leucocyte preparation was 3.3 ± 1.5% with FCM and 5.5 ± 2.4% with fluorescence microscopy. The applicability of the method was demonstrated in a preliminary study with arsenic. In a concentration of 1 μg ml−1, arsenic increased the proportion of actively phagocytic cells, but, at a high concentration, 100 μg ml−1, it decreased the phagocytic activity. Electron microscopy was used for morphological classification of the peripheral leucocytes throughout t

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1987.tb05225.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Yearling brown trout,Salmo truttaL., were exposed to various concentrations of inorganic aluminium (0–3.7 μM1−1) over a pH range of 4.3–6.5 in a flow‐through bioassay apparatus using synthetic test media. Low pH, in the absence of aluminium, produced little effect on growth or survival except at the lowest pH tested (4.3). At pH less than 5.5, concentrations of total aluminium in excess of 1 μM 1−1(27μg 1−1) were found to retard growth. The effects of a given aluminium concentration were markedly reduced at pH above 5.5.The change in aluminium toxicity with pH must be related to changes in aluminium chemistry. When growth rates are correlated with the different aluminium species, calculated using thermodynamic equilibrium constants given in the literature, it appears that the Al(OH)2 +species is the most toxic, with a small contribution also coming from polym

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1987.tb05226.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Absorption of14C from the marine algaEnteromorphaby an herbivorous marine fish, the luderick,Girella tricuspidata, was used to demonstrate the capability of this species to utilize an herbivorous diet. Absorption of14C from protoplasts and cell walls clearly demonstrated a capability of the luderick to utilize cell walls. Two patterns of absorption of algal fractions were seen, but in all cases isotope absorption by the fish was highest from protoplasts over a 16‐h digestion period. The first pattern, demonstrated by the absorptive tissues of the gut, showed greater absorption of the radioactive label from cell walls over 5 days than over 16 h. The second, occurring in the anterior regions of the gut and in the liver and spleen, showed greater absorption of14C from cell walls over 16 h than over 5 days. It is suggested that the marker found in this second group of tissues derives from absorption in the pyloric caeca, the only absorptive region showing significant absorption of carbon label from cell walls over 16 h. Absorption of14C from cell walls is greater over 5 days than over 16

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1987.tb05227.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Two herbivorous fishes of the genus Kyphosus (family Kyphosidae) possess unique digestive tracts among fishes, with well‐developed caecal pouches and a complex gut‐resident microflora. The presence of high concentrations of volatile fatty acids in the gut confirms fermentative digestion in fishes for the first t

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1987.tb05228.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The North Atlantic wolffish,Anarhichas lupus, has a broad, relatively short gastro‐intestinal tract (0.55–1.05 of body length). The stomach‐like region has a high pH, suggesting a functionally stomachless condition. The ‘stomach’ is rarely parasitized by helminths. The gut pH tends to rise along its length as does the concentration of the ion Mg2+, while osmolarity and the ions Na+, Cl−and K+tend to decrease and Ca2+stays practically the same. The intestinal wall is deeply folded, particularly in the anterior region. The intestine commonly harbours several helminth species. The gall bladder and urinary bladder tend to be voluminous and both are commonly parasitized by digeneans.A. lupushas been recorded as harbouring over 30 species of parasitic helminth of which 10 are commonly found, often in large numbers. There is little overlap of parasite sites and there appear to be several empty niches. The parasites tend to fall into three categories, those stenoxenic to this genus of fish, those stenoxenic to other groups and accidental inA. lupus, and those forms which ar

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1987.tb05229.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY