ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb05708.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The food and feeding of the whiting (Merlangius merlangus) of the inshore waters and sea lochs of the west of Scotland were studied from 1969–1973. Fish and Crustacea were the main food items and their occurrence in the stomachs was clearly related to the size of the whiting and also to their seasonal abundance. The diurnal changes in feeding were also investigated and the results indicated that the size of fish was again an important factor which could affect the interpretation of the seasonal dat

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb05709.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The stomach contents of 1015 charr, (Salvelinus willughbiiGünther)] from Windermere, of which 658 were feeding fish, were examined. The fish were caught over a period of several years and in every month of the year. The data were analysed by two methods, by a points system, which takes into account the abundance and volume of the food organisms, and by the frequency of occurrence of each organism. Charr of all sizes had fed mainly on planktonic Crustacea (particularly Cladocera); larval and pupal chironomids and Chaoborus were also important. From November to April most stomachs of charr netted on the spawning grounds contained charr eggs. The diet of charr is compared with that of seven other fish species in Windermere. There was almost no overlap between the food of charr, which was obtained in the pelagic region, and that of the seven other species, which was mostly bottom fauna, obtained from the littoral region. Thus by occupation of these two different niches the charr and the seven other fish in no way compete for food in Windermere. Some limited data from six other lakes in the English Lake District are presented, in these planktonic Crustacea are also found to be the main food

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb05710.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Using a continuous flow respirometer it was shown that youngTilapia rendallihad three distinct phases of oxygen consumption over the temperature range of 17–40° C. In the first phase (17–28° C) the metabolic energy demand followed the normal logarithmic increase with increasing temperature. Between 28 and 37° C the increased oxygen uptake was suppressed and showed a relatively small increase with increasing temperature. This feature was believed to be a significant energy saving function important to the growth of these fish which feed in the warm eulitoral margins of lakes during the day. The final phase shows a return to the original logarithmic increase in oxygen consumption. These results were related to, and compared with, actual changes in biomass at various temperatures and the theoretical and actual biomass changes were found to compare favo

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb05711.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Analyses of the incidence and intensity of infestation withGrillotia erinaceusplerocerci in 8228Melanogrammus aeglefinusindicate two distinct groups of haddock at Faroe, and three groups in the area to the north and west of Scotland. In the North Sea the following four groups were recognized: (1) in the Moray Firth and (2) to the north and east of Shetland where, in both groups, incidence of infestation was consistently high; (3) an intervening area where incidence was considerably lower up to three years of age, after which it increased to about the same level as in groups (1) and (2); and (4) in the central North Sea where incidence was consistently low. Changes in the pattern of infestation with host age and with host length within single age‐groups, when considered together with conventional tagging data, suggest that many 3+ and older haddock may migrate from Scottish inshore waters via the Shetland area to the north‐eastern North Sea. The results support other studies in suggesting a northward movement of haddock along the Scottish east co

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb05712.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Each of 16 mature female sockeye salmonOncorhynchus nerkafrom two river drainages were spawned with individual males, and the progeny from each pair were later challenged with virulent infectious haematopoietic necrosis (IHN) virus. At each of 4 monthly challenges, distinct differences were detected in the susceptibility of the fish to IHN from each family. Average percentage mortality was 98 or more in highly susceptible families, in families of intermediate susceptibility, 85 and in resistant families, 52. Furthermore, the mean time to death was only 9.8 days for fish from the susceptible families but 17.9 days for fish from the more resistant families. These results were similar at each monthly challenge. Challenging the fish at various virus‐dosage levels did not change total mortality, but high dosages hastened the onset of mortality. A genetic basis for resistance is proposed to explain these result

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb05713.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The activities of some glycolytic and associated enzymes have been determined in the muscles of trout and carp to investigate the possibility that the discrepancies previously reported between lactate accumulation and anoxic tolerance in these two fish result from underlying differences in glycolytic potential. Steady state concentrations of certain glycolytic intermediates were also determined in freeze‐clamped muscles from tankrested fish. The activities of hexokinase, phosphorylase and phosphofructokinase were approximately 2–3 times lower in carp than trout white muscles. Pyruvate kinase and lactate dehydrogenase activities were 5 times lower in carp white muscle. The lower, broader pH optima of lactate dehydrogenase and pyruvate kinase from carp compared to trout muscles is thought to be correlated with the greater anoxic tolerance of the carp. Glycolytic enzyme profiles were markedly different between the red and white muscles of the rainbow trout but broadly similar, with the exception of hexokinase activity, for the corresponding muscles of the carp. The results are discussed in relation to what is known about anaerobiosis in these two species and the comparative physiology of red and white muscles in f

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb05714.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

An electron microscopic description is presented of the mitochondria‐rich‘chloride‘cells of the gill epithelium in the cichlid fishTilapia aureakept in freshwater or adapted to seawater and injected with the pesticide p,p′DDT. The‘chloride‘cells may have a light or dark (electron dense) appearance. Dark‘chloride‘cells are more common in seawateradapted than in freshwaterT. aurea. Characteristic features of‘chloride‘cells include an abundance of mitochondria and an elaborate tubular reticulum, which communicates directly with the basal and lateral membranes of the cells. The apical portion of the‘chloride‘cells is often larger in seawater‐adapted than in freshwater fish. Differences in‘chloride‘cell ultrastructure, which can possibly be associated with a response to different salinities, arc described and discussed. No significant ultrastructural differences are detectable in response t

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb05715.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The acute toxicity of inorganic chloramines to brook trout alevin, fry, and juvenile life stages was determined in 96‐h tests. Toxicity was not constant between the life stages. Alevins were more tolerant than the fry group tested. Alevins showed a decreased tolerance with an increase of body weight. Two groups of juveniles were similar in tolerance to the heaviest alevin group. A relationship between life stage‐body weight of brook trout and 96‐h median tolerance limits is pres

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb05716.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

A reciprocal transplant of marked roach between two spatially separated (3.3 km) spawning grounds is described. The recapture rates on the‘home grounds‘were higher than those obtained elsewhere in the lake, which suggests that the roach exhibit a degree of fidelity to specific spawning grou

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb05717.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY