摘要:

The digestive tracts of 138 marine, freshwater and farmed fish representing 42 species were assayed for cellulase activity using viscometry. Activity was exhibited by the majority of fish but the level of activity was variable within and between species and was not located in any particular region of the gut. The majority of omnivorous and piscivorous fish demonstrated nil or slight activity, whereas most‘invertivores’†exhibited moderate and high activity levels. This suggests that cellulase activity in fish is the direct result of the ingestion of invertebrates containing cellulase and/or a cellulolytic micro

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb03700.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Foregut emptying inBlennius pholisat 16–18°C is exponential (St=Soe‐Rt; R=0.006 whentis in min andsin mg dry weight). In consequence, the time for the foregut to empty completely varies in proportion to ln (meal size) in a chosen size of fish or to ln (body weight) in different sized fish fed to the same relative amount (% body weight). Appetite returns rapidly in comparison with other species (4–15 h for fish of 0.5−30 g) and, because of the tidal constraints imposed on this littoral fish, voluntarily ingested meals are large (14–9% body weight depending on fish size). Studies on digestion in small, stomachless fish are not adequately made using X‐radiography and must be supported by sequential gut samples

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb03701.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Unfertilised cod eggs showed a mean oxygen uptake rate at 5°C of 0.089 μl O2, dry wt.−1h−1; this gradually rose to 0.768 μl O2mg dry wt.−1h−1in eggs about to hatch. From hatching to complete yolk absorption larvae respired at 1.6 μl O2, mg dry wt.−1h−1. During starvation following yolk absorption, uptake fell significantly to 1.1 μl O2, mg dry−1h−1. Much of this decrease in oxygen consumption was shown to be caused by reduction in activity. Loss of weight during the embryo and larval phases could not easily be reconciled with total oxygen consumption; it is suggested that cod embryos and larvae may not rely solely upon endogenous energy reserve

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb03702.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

A three day experiment compared angling returns for rainbow trout,Salmo gairdneriRichardson, using fly, spinner and worm fishing methods. The catches of these methods were most similar on the first day: 3.36/h, 2.61/h and 3.75/h for spinner, fly and worm fishing, respectively. Catch rates on subsequent days declined, but less so for worm fishing. Overall, the worm fishing method returned the highest catch rate and estimates of catch rates for a year on a trout fishery also indicated that this method returned the highest catch rate.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb03703.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

A study of the epideictic behaviour patterns of maleXiphophorus helleriHeckel was made, and the social rank of individual fish in 12 groups of three was assessed over a ten‐day period. Straight‐line hierarchies were established in most groups. An anatomical study was made to locate the adrenocortical tissue, and the adrenocortical activity of each fish was assessed by measuring mean nuclear diameter of 25 adrenocortical cells. Although results were somewhat variable, the highest‐ranking fish in 7 out of 12 groups showed the least adrenocortical activity. The remaining two fish showed no significant difference from each other in adrenocortical activity, though their rank was in most cases clearly distinguishable on behavioural gr

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb03704.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The growth of charr (Salvelinus willughbii Günther) caught in Windermere from 1941–1952 has been studied. Scales were used for determination of age and back‐calculation of length for age. Autumn and spring spawners, males and females, and charr of normal and dwarf growth were treated separately. In fish of normal growth, the spring spawners were significantly smaller than the autumn spawners at ages 1 and 2 years, and significantly larger from age 4 years onwards. There was little difference in growth between males and females within the two spawning populations. Charr of lengths of less than 200 mm at age 4 years were considered to be dwarfs. Mean lengths at capture of male charr were: autumn spawners normal growth 272 mm, dwarf 218 mm; spring spawners normal growth 327 mm, dwarf 194 mm. The oldest recorded age was 8 y

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb03705.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Pink salmon transplanted to the north Atlantic coast from the Soviet Union reached a peak in 1973, both in the Soviet Union and in Finnmark. Pink salmon catch statistics were compiled in 1977 for the inshore coastal and fjord areas of Finnmark from the atlantic salmon fisheries conducted locally and outside the coastal limits of Finnmark. The survey indicated a total sea catch of 12 800 specimens or 18 450 kg in Finnmark in 1977. The pink salmon reached the coast in the western regions of Finnmark during the first half of July, after which the main migration continued eastwards along the coast. The migrations into the western fjords were few, with half the total inshore catch captured in the most eastern fjord, Varangerfjord.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb03706.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The ultrastructural details of Z‐discs from red, intermediate, and white axial muscle fibres from the sharksEtmopterus spinaxandGaleus melastomusare described. Red fibre Z‐discs contain the most amorphous matrix material, and are thicker (100–115 nm) than intermediate (85–88 nm) and white Z‐discs (75–80 nm). Four sets of oblique bars extend tangentially from each thin filament. In each set two bars are present, those of white fibres are close together (approximately 5 nm), while those of red fibres are separated by a distance of 15 nm. A model of shark Z‐disc structure is proposed. The denaturation (heat transition) temperatures of the muscle proteins were studied by differential scanning calorimetry (DSC). The heat transitions of collagen, actin, and myosin were identified; the actin heat transition temperature increased in the sequence red, intermediate, and white. The total protein pattern of red and white muscle were studied by SDS electrophoresis. A protein with a molecular weight of about 55000 may represent a Z

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb03707.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The differentiation of the myotomal muscle types in the propulsive musculature ofSalmo truttahas been investigated histochemically and ultrastructurally from late embryonic to free‐swimming fish at 5° months post fertilisation and related to observed changes in swimming behaviour. A histochemical and ultrastructural characterisation was also made of the major myotomal muscle fibre types in fingerling and yearlingS. trutta. Two distinct populations of muscle cell types can be recognised prior to hatching. The early development of the white fibre population is related to the short, burst‐type swimming activity at early stages. The later increase in the development of the red fibre population is directly related to the appearance of sustained swimming activity. The swimming performance of freeswimming alevins has been investigated and the results are discussed in comparison to adult

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb03708.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The pseudobranchs of bass,Dicentrarchus labrax L., and grey mullet,Liza ramada(Risso) (Mugil capito), were examined in the scanning electron microscope (S.E.M.). Both pseudobranchs appeared gill‐like in situ but the S.E.M. revealed their gross morphology to be different. The bass pseudobranch was a‘free’ pseudobranch, having separate lamellae along the filaments, with areas of fusion on the leading edges of some lamellae, whilst the mullet pseudobranch was ‘semi‐free’ since the secondary lamellae were fused over a large area and only free along their trailing (opercular) edge where the chloride cells were situated. The surface of the epithelial cells presented different patterns of microridges and microvilli depending on their position in the pseudobranch. Three types of cell opening were found at the cell surface, belonging to chloride cells, mucous cells, and possibly rodlet cells. The S.E.M. observations were correlated with those of transmission electron microscope (T.E.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb03709.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY