摘要:

The distribution ofTrachinus vipera, worldwide and around the British coast, is summarised. Field observations indicate that the fish occurs throughout the intertidal zone; is more active at low light intensities, and can survive the low tide period buried in the intertidal sand; can tolerate salinities as low as 19%0, for short periods; exhibits a tidal periodicity, is more active on the flood tide than the ebb tide; moves into deeper warmer water in winter, the extent.of the movement being temperature dependent. The critical temperature initiating this movement is probably 5deg; C. The fish is not available for capture in cold weather, because it may be hibernating, buried in the sand.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb02747.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Comparative tissue ascorbic acid levels in four species of major carpviz., Labeo rohila, L. calbasu, Cirrhina tnrigalaandCatla catla, were investigated. The ascorbic acid level was found to be the highest in the spleen in the four species studied (range 430–380 μg/g) followed by the anterior (adrenal) kidney, gonads, liver, renal kidney, brain and/or eye. Heart and blood had the lowest levels (range 26–18 μg/ml) amongst the tissues studied. Overall tissue ascorbic acid levels were the highest inL. rohitaand the lowest inC. mrigala. Investigation on seasonal variations in blood and kidney ascorbic acid levelsof Notopterus notopterusrevealed peak levels in spring (February‐April) and the lowest levels in the postspawning period (August‐S

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb02748.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The differential distributions of juveniles and adults of 25 species of teleost were investigated and compared from four habitat types in sub‐tropical Moreton Bay, Queensland. The aim of the study was to identify factors influencing the distribution of juveniles, particularly the species which enter estuaries. The following habitats were sampled: a shallow, sheltered tidal estuary (Caboolture); a shallow, exposed bay with muddy substrates (Deception Bay); an exposed area of sandy substrates and seagrass (Toorbol Point) and a sheltered oceanic site with sandy substrates and seagrass (Kooringal). Data on diet, spawning seasons and recruitment periods of fry are presented together with measurements of salinity, temperature and turbidity. Species entering estuaries recruited mainly in summer (rainy season). The possible preference of juveniles for calm water, the roles of food and predation pressure, the effects of salinity, temperature and turbidity are discussed in relation to the biology and distribution of the fish. Salinity and temperature were probably not important to most juvenile fish. The effects of calm water, suitable food and predators vary according to species. Although all juveniles studied preferred shallow water, in the case of those entering estuaries, turbidity was the single most important factor. Juveniles of the same species occurred in both the estuary and Deception Bay where abiotic and biotic factors other than turbidity were different. During summer, turbidity gradients extended from east to west in Moreton Bay with highest turbidities in Caboolture estuary and Deception Bay. In winter, turbidities throughout Moreton Bay were low and relatively uniform. At this time many of the ‘clear water’ species occurred in Deception Bay. The influence of high turbidity on fish may be linked to reduced predation pressure and perhaps food supply in shallow water. Turbidity gradients in summer may aid fry in locating estuarine nursery grounds. It is apparent however, that juveniles of many species are probably not attracted to estuariesper sebut to shallow turbid

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb02749.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Scales from 682 gudgeon from the River Frome and 504 from the River Stour were used for age determinations. Growth in length was confined to the period May to October, but some weight increase occurred during the winter because of gonad development. Growth rates in the two rivers were the same, and were higher than most of those reported from other European rivers. Wide fluctuations, up to 12‐fold, occurred in the year‐class strengths of Frome gudgeon, caused by variations in the survival of juvenile gudgeon in their first year of life. Density‐independent factors, particularly water temperature, were major influences. Female gudgeon grew marginally slower than the males, but they matured earlier and at a smaller size. They were fractional spawners but their total reproductive effort each season was high. Both sexes had low survival rates and their reproductive life spans were rarely more than three years. These life history traits support the premise that these gudgeon populations are r‐s

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb02750.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Channel catfish,Ictalurus punctatus, were injected intraperitoneally with a sublethal dose ofAerornonas hydrophilaand then stressed for 144 h by being maintained either in a dissolved oxygen concentration of 1·5 mg/1, 1·2 mg/1 total ammonia, and/or 6·5 mg/1 free CO2with a continuous inflow of water. A significant difference in percentage of mortality was noted between treatments (P<0·05). The trunk kidneys of surviving stressed fish had significantly higher total bacterial counts than non‐stressed controls.A. hydrophilawas isolated from 67% of the stressed fish and 9% of the control fish.Edwardsiella tarda, apparently endemic in the population, was isolated from 43% of the stressed fish and 7% of the control fish. Histopathological lesions were in the gills, liver, spleen, trunk kidney, and head kidney of stressed fish, but not control

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb02751.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Using a volume dependent model of evacuation, the effects of dietary energy level and source upon gastric emptying were examined. Diets containing small amounts of energy were evacuated from the stomach more rapidly than those with a higher energy content. When the data is examined with respect to the evacuation of energy from the stomach and is plotted as √Energy = ce−meTime; the rate of evacuation (me) is seen to be independent of energy level and the composition of the d

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb02752.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The presence of oocytes in the testes of several males indicates that the redbanded perchEllerkeldia huntiiexhibits protogynous hermaphroditism. All males appear to be secondary in origin; however the structure of the testes differ from most other protogynous serranids. In samples collected from the Poor Knights Is., New Zealand, males outnumbered females 2.7: 1 (n= 52). The numbers in each sex were equal until a length of 100–110 mm, after which the male proportion increased to 100%. The oldest female was aged 2+ years, whereas males were found as old as 5+ years. There were no colour differences associated with sex. The mean testes weight was only 7% of the mean ovary weight. Both sexes grew at the same rate. Observations during December indicated that although many individuals were solitary, some were paired. The larger individuals of pairs were males, the smaller females. Individuals foraged in the algal canopy on gammarid amphipods and mysid shrimps. The average range of movements was only 2·2

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb02753.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

First year roach from a Stillwater habitat were maintained in an’artificial stream for periods of up to 40 days and samples of the lateral musculature were subjected to histological examination. It was found that there was a highly significant increase in the percentage of red muscle present in the hindermost regions of the fish confined for 30 days or more in the stream. In subsequent exercise tests, it was shown that the FV50was higher for fish conditioned for 40 days, but it was considered unlikely that this increase in swimming ability was as a direct result of changes in muscle compositio

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb02754.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

A classical conditioning technique was employed with cod,Gadus morhuaL., to determine thresholds for the detection of the L‐forms of some α amino acids which are thought to be attractants or feeding stimulants for fish. The amino acids investigated, in order of effectiveness, were tyrosine, cysteine, phenylalanine, glycine and methionine with mean threshold response levels ranging from 2·5 × 10‐8M to 7·4 × 10‐8M. Histidine and lysine resulted in similar thresholds with a mean value of approximately 3 ± 10‐7M while taurine and leucine were least effective with mean threshold levels of 2·1 × 10‐6M and 2·1 × 10‐5M respectively. Comparison is made with electrophysiological and behavioural response data from other species. The effect of raising the background level of glycine on the threshold to glycine for cod is described. The results are discussed with reference to data on levels of dissolved free amino acids in shallow sea waters which may have a bearing on determining chemosensory threshold levels. To detect a specific amino acid against a background level of the same substance the difference in level for detection is proportionally greater for higher back

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb02755.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The lateral‐line system of the Ponto‐Caspian gobiidCaspiosoma caspium(Kessler, 1877) is described, with new data on the arrangement of sensory papillae over the head. The systematic status of related forms, especiallyAsra turcomanusIljin, 1941, is briefly discus

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1980.tb02756.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY