摘要:

In an examination of 1352 whiting 0–5+ years old from Manx waters it was found that the digeneansHemiurus communisOdhner and Derogenes varicus Müller were restricted to the stomach.Stephenostomum pristisLooss,Podocotyle atomonRudolphi andLeci‐thaster gibbosusRudolphi were most commonly found in the anterior intestine and caeca of mature fish but were found more posteriorly along the intestine of young whiting. The metacercaria ofCryptocoty linguaCreplin were found predominantly in the skin above the lateral line. The fins contained fewer cysts than expected from the area available. Plerocercoids ofGrillotia erinaceusVan Beneden mainly infested the musculature of the pyloric stomach and those in the perivisceral cavity were concentrated in the extreme posterior corner. Unencapsulated forms of the nematodeContracaecum clavatumRudolphi were commonest in the anterior intestine and stomach. Encapsulated forms were most abundant in the liver. The acanthocephalanEchinorhynchus gadiRudolphi was usually found in the posterior intestine and its presence further restrictedContracaecumto the anterior intestine. In young whiting over two‐thirds of the copepodClavella uncinataMüller were attached to the operculum and posterior rim but in older whiting the majority were attached to the gill rakers. The first gill arch was the most heavily infested and the middle region of the gill arches contained most parasites. The frequency distributions of most of the helminths described more or less a negative binomial distribution. The frequency distribution ofContracaecumdid not conform to either a negative binomial or a Poisson distr

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1976.tb03924.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Studies were carried out to find appropriate techniques for securing a suitable karyotype from a population ofFundulus diaphanusin the Hudson River and to compare it with a published karyotype of a population of the same species from the New Haven, Connecticut area. A modification of the basic method of Denton&Howell proved to be a simple, effective and inexpensive approach for acquiring numerous and distinct chromosomal spreads for detailed karyotype analyses. The two karyotypes were identical in modal number, arm number and number of submetacentrics; however, they differed in numbers of acrocentrics and secondary constrictions. These differences may indicate incipient chromosomal evolution with the two distinct environments acting as selective agents. Preliminary work was carried out with banding techniques; the modified Denton&Howell method with banding appears to be an effective and promising direction for fish cytogenetics.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1976.tb03925.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

The anatomical adaptations to a benthic mode of life are reviewed and discussed. The functioning of the pectoral, pelvic and anal fins in moving sand from underneath the animal, during burrowing, are described. Jets of water directed downwards from the gill chambers, produce a fluid sand‐water mixture which facilitates the functioning of the pelvic fins, and the movement of the head into the sand. The direction of water movements associated with gill ventilation, which are propelled almost exclusively by the branchiostegal rays, are outlined. Inhalation is normally through the mouth, which is protected by papillae, from being blocked by sand. When the mouth is covered with sand, the water flow through it is reduced, and some inhalation occurs through the dorsal margin of the operculum, involving use of the supracliethru

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1976.tb03926.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

The leucocytes of plaice were examined and, at a morphological level, in addition to their response to the injection of carbon particles, they could be divided into four main types. Unlike previous reports, monocytes were seen. The neutrophil granules resembled the third granule type described in mammalian neutrophils. Monocytes and thrombocytes were the only cells to take up appreciable amounts of the carbon.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1976.tb03927.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

The leucocytes and related cells of the blood of plaice were examined morphologically and their various functions assessed using a number of procedures to identify phagocytosis histochemical reactions and antibody responses. Four morphologically different types of thrombocytes were identified in addition to lymphocytes, plasma cells, monocytes, macrophages and one type of granulocyte which histochemically resembled the mammalian neutrophil. The evolution and development of the cells was also investigated and the various stages described.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1976.tb03928.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

In the Glentui River, Canterbury, New Zealand,Galaxias vulgarisStokell spawned in late winter and early spring (from July to September), the onset of spawning being temperature‐dependent. No females matured in their first year, but 95 and 68 % of age 0+ males were mature in consecutive years. With the exception of one female, all fish aged 1 + and older spawned. In mature fish, overies reached nearly 23%, and testes 11%, of somatic weight. Maturity in males depended on size, whereas in females, age appeared to be the major factor affecting maturity. Recruitment eggs for next season's spawning were distinct from primary oocytes soon after the ripe eggs were shed. Egg numbers varied between 284 and 1911 per fish, and weight was the best indicator of fecundity. Sex ratios of whole samples were not significantly different from 1 : 1, but ratios of potential spawners revealed an excess of males, due mainly to the presence of age 0 + fish. Age0+ males probably play an important role in adverse conditions and act as a form of insurance by significantly increasing the proportion of ripe males, thereby ensuring that all eggs are fertilized. The nest, egg mass and behaviour during the spawning period are described. More than one female may lay eggs in each nest and it is probable that each egg mass receives sperm from more than one male. It is suggested that the presence of fewer and larger eggs inG. vulgaris, compared with the diadromous galaxiids, is the result of a more precise fertilization proces

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1976.tb03929.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Opercular bones of 261 pike from the River Stour and 117 from the River Frome were used for age and back‐calculated growth determinations. The annuli were laid down during late April and early May and most growth occurred between May and September. Pike growth in the two rivers was comparable with the fastest growth in other waters, though Frome pike grew slightly faster than Stour pike. Spawning occurred from the end of March into May. Elaboration of the ovaries commenced in September and was virtually completed by February, whereas the testes reached their maximum weight in October and maintained it until spawning. Immature pike had an annual cycle of condition reaching a maximum in May and a minimum during the winter. The gonad cycle affected the condition of mature females which had their minimum condition in mid‐summer. The fecundity of Stour pike is expressed by the formula: log10egg number =3.56 log10fish length (mm) – 5.40. Approximately 75% of all Stour pike were sexually mature by age II and these fish were, on average, larger than immature pike of the same age. The most numerous items in the diet of pike were small cyprinids, 30–80 mm fork length, although pike over 700 mm long ate larger fish. Few salmonids appeared in the diet of either Frome or Stour pike. The percentage of empty stomachs was highest in Stour samples taken during the summer, shorter digestion times and longer feeding periods in this period are suggested as reasons for the apparent

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1976.tb03930.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY