摘要:

Growth rates of three commercial species of Lutjanidae were estimated from sections of vertebrae cross‐checked with scales. The von Bertalanffy growth constants forLutjanus malabaricuswereK=0.168,L∞=70.7 cm standard length (S.L.). ForPristipomoides multidensthese wereK= 0.219,L∞= 59.1cm, and forPristipomoides typus K=0.254,L∞= 51.5 cm. Length/weight was analysed in the formW= aLbwhereWwas fresh weight (g) andL= S.L. (cm). The constants were:L. malabaricus, a= 0.041,b= 2.842;P. multidens, a=0.032,b= 2.897;P. typus, a= 0.038,b= 2.822. The growth rates were considered low in comparison with demersal fish counterparts from tempera

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04233.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Three species of salmonids, rainbow trout,Salmo gairdneri, brown trout,S. trutta, and marble trout, S.marmoratus, have been studied for their karyotypes. In rainbow trout 316 metaphases were studied and recorded 2nof 60 with 44 meta‐ to submetacentric and 16 subtelo‐ to telo‐centric chromosomes, and the number of chromosome arms (NF) of 104. Observation on 243 metaphases of brown trout showed 2nof 80 with 20 meta‐ to submetacentric, 60 telocentric chromosomes and thenfof 100. While in 164 metaphases from the marble trout 2nwas of the order of 80 out of which 22 were meta to submetacentric and 58 telocentric chromosomes withn

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04234.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

This work presents the results of investigations of cytogenetic changes produced by pollutants of a water ecosystem (phenol, decamethrine, Malathion, Neguvon and crude oil). The changes have been measured by observing frequency of chromosomal aberrations in the tissues of gills and kidney of rainbow trout exposed to pollutants. The fish were exposed to two dose levels of the pollutants, the lowest being the legislative maximum permissible concentration in the waters of Yugoslavia, which were used as a dose‐response for the highest investigated concentrations. Exposure to the water polluted by chemical pollutants under investigation, raised the frequency of aberrations compared to the control

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04235.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

During 1980 to 1982, parasitological surveys were carried out at large impoundments in Venda and Lebowa, southern Africa, coinciding with fish harvesting programmes. Of the various fish species examined, onlyOreochromis mossambicuswas found to be infected byClinostomum tilapiaeprevalent in the gills, andEuclinostomum heterostomumprevalent in the muscles. Distribution records and infection statistics are presented for these two parasite species.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04236.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Two‐summer‐old Baltic salmon parr were brought to the laboratory and reared at 11 °C from February until early June under a simulated natural photoperiod and an accelerated photoperiod cycle in which the summer solstice was advanced by 2 months. The pattern of development of the ability to adapt to sea water was assessed by means of a periodic 24‐h challenge test with 25%o seawater. Both the increase in seawater adaptability and its decline occurred earlier under accelerated photoperiod. The synchronisation of the smolting cycle is discussed in relation to the environmental cues provided by photo

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04237.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Seaward migration of silver eels occurred at nights during autumn at decreasing water temperature. Maximum migration‐rate occurred mid‐October at medium and decreasing water discharge. Most eels descended in the first quarter of the lunar cycle, few eels descended at full moon. Most males and small females migrated earlier in the season than the larger females. The migration speed of silver eels in fresh water was independent of body len

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04238.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Studies of carp fry,Cyprinus carpio, showed that temperature elevation within the range of 18–26° C increases the mortality caused by lowering the pH of water. It was found that 26‐h acclimation in acidic water (mean pH 4.22) prolongs the survival of fish in water at pH 4.02–4.20. Carp fry obtained less oxygen in water at pH 4–0, as compared to pH 7–0. The differences–though insignificant–pointed to an adverse effect of acidification on the respira

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04239.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The diet of 1200 adultSarotherodon mossambicus[16–37 cm total length (t.l.)] in 12 man‐made Sri Lankan lakes, belonging to five different irrigational systems were studied over four climatic seasons using volumetric analysis. Food differed between seasons and reservoirs but overall, the diet consisted of 2, 2, 6 and 15 genera of diatoms, blue‐green algae, green algae and animal material respectively. However, none of the S.mossambicuspopulations maintained either a detritivorous, phytoplanktivorous or a zooplanktivorous habit through the year. Detritivory was most common during the rainy season while phytoplanktivory predominated in the dry season. Blue‐green algae were not an important constituent of the diet. Out of the 12 reservoir populations, five were predominantly detritivorous, six phytoplanktivorous and one zooplanktivorous. Detritus was completely absent in the ingested material in certain populations when they devoured animal or plant material, indicating the ability ofS. mossambicusto switch from deposit to suspension feeding. The mean relative intestinal length (m.r.i.l.) ofS. mossambicusranged between 5–1 and 15–2. The m.r.i.l. decreased significantly with increasing body length: m.r.i.l. = 14–1 –0.018 T.L. (r

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04240.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The hypothesis that the paired ovaries of turbot,Scophthalmus maximus, ovulate alternately was tested and rejected as a possible explanation for the double ovulatory cycles found in some captive turbot. It is suggested that these double cycles are caused by variation patterns in the hormone‐release cycles of individual female

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04241.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The distribution and accumulation of labelled N‐methyl‐N nitrosourea (MNU) has been described in the Amazon molly following intraperitoneal injection. Two hours after injection the label was present throughout the body, with enhanced deposition in the macrophages of the atrium of the heart, the kidney and the spleen; about half of the liver cells were labelled. The compound was taken up by the cells of the renal excretory tubules, and certain cells in the optic tectum and corpus cerebelli of the brain. By 6 h, the distribution picture had changed radically. There was little label remaining, except in a few macrophages in the heart and kidneys, and in the nuclei of the renal tubule cells. There was a slight decrease in the numbers of cells in the brain that were labelled, but the amount of material that the individual cells had accumulated had increased. By 48 h there was further loss and only brain cells were labelled. Our findings indicate preferential accumulation of MNU in undifferentiated, pluripotential cells of the optic tectum and corpus cerebe

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04242.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY