摘要:

A method designed to support thein vitromaintenance and proliferation of elasmobranch peripheral blood leucocytes (PBLs) has been developed. This method includes protocols for leucocyte isolation, the preparation of media, and culturing conditions. Leucocytes were isolated from whole blood using a Ficoll‐hypaque density gradient followed by nylon wool filtration. Recovered cells were washed and incubated at a density of 0.054 × 106cells per well of a microtitre plate using a novel medium designed for shark cells. Incubation was carried out at 17 and 37° C. These media represent a modification of RPMI1640or DMEM to account for isotonic and isoosmotic differences between mammalian and elasmobranch blood via the addition of trimethylamine‐N‐oxide, urea and sodium chloride to the RPMI

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1990.tb04318.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Sibling male Atlantic salmon parr that matured tended to be the larger fish in January, but their monthly specific growth rates between January and July did not differ from those of non‐maturing fish. Maturing fish had lower condition factors in March, but greater increases in condition factor during April, exceeding those of non‐maturing males by May. In maturing males, feeding rates between July and September, and specific growth rates in August and September, were lower than those of immature fish. Consequently, the mean size of immatures equalled or exceeded that of maturing males by October. Maturation rates were strongly correlated with increases in mean condition factor only during Ap

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1990.tb04319.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

A total of 149Anguilla japonicaelvers collected at 10 locations along the Japanese coast were aged according to otolith daily increments. The interrelationships among age, birth date, body size, pigmentation stage, sampling location and the timing of recruitment were examined in order to determine the recruitment mechanism of elvers to coastal waters.First catches of eels were earlier in the locations at lower latitudes. Age at recruitment was roughly constant, 218 ± 29 (mean ± s.d.) days old, disregarding the localities, but a weak positive correlation was obtained between age and sampling date or timing of recruitment. Body length at recruitment was also constant, 56.3 ± 2.3 mm s.l., and showed no significant correlation with either locality or recruitment timing. Estimated birth date ranged from April to November, the mean ± s.d. being 22 July 1982 ± 42 days, suggesting a peak season spawning in summer. Birth date was closely related with both the latitude of location and sampling time. Pigmentation developed more at lower latitude. Recruitment mechanism of the Japanese eel was summarized as follows: the earlier‐born individual recruits earlier at lower latitude and at younger age, but at a constant bod

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1990.tb04320.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The evacuation patterns of shrimp, crab and fish from the stomachs of black and yellow rockfish,Sebastes chrysomelas, were examined by feeding meals of known size and measuring the amount remaining after various post‐prandial intervals. Linear, square‐root, exponential, power exponential, logistic and Gompertz models (the latter two with unrestricted lower asymptotes, or with lower asymptotes restricted to 0% food remaining) were fitted to the wet weight, dry weight and volume of food remaining in the stomach as a function of post‐prandial time. Evacuation patterns ranged from steeply concave (fish wet weight, dry weight, volume, shrimp dry weight), to linear (shrimp wet weight, crab dry weight), to highly convex with lag phases of up to 30 h (crab wet weight, crab and shrimp volume). Friability, the ease with which a food item is fragmented in the stomach, may be an important factor in determining evacuation patterns. The evacuation of a crab meal by tagged, free‐ranging S.chrysomelasin the field was not significantly different from that of S.chrysomelasheld in the lab

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1990.tb04321.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The microhabitat of roach larvae (stages L1–L6) and 0+ juveniles was examined in a braided channel (Ilon) of the Upper Rhone River, France, from weekly samples (spring‐autumn 1985) using Point Abundance Sampling by electrofishing. During early development, microhabitat exploitation was characterized by two transitions: the first at larval step L3, when morphological and physiological attributes permit the active choice of microhabitat; the second at the end of the larval and start of the juvenile period. At larval step L3, and up to L5, roach were strongly associated with lentic waters of medium depth (0.5–1.0m) and with either macrophytes or ligneous debris. The L6 and 0+ juveniles were found more often than expected in shallower waters (<0.2m, 0.2–0.5 m) and were no longer associated with dense vegetation or ligneous debris. However, both larval (L3–L6) and 0+ juvenile roach preferred silty sand and/or silted gravel, and a lack of current. This shift, from moderately deep waters with vegetation and/or branches as larvae to open shallow waters as juveniles, demonstrates the young roach's perception and response to environmental change, with shallows exploited as a refuge from predation when protective structures become scarce or un

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1990.tb04322.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The sillaginid fishes of Visakhapatnam Coast, Bay of Bengal, are found to be hosts for 16 species of digeneans of which seven are adult digeneans belonging to families Opecoelidae, Zoogonidae and Hemiuridae and nine are larval digeneans representing families Bucephalidae, Heterophyidae, Cryptogonimidae, Acanthocolpidae, Hemiuridae and Didymozoidae. The digenean fauna of sillaginid fishes from shallow coastal waters (<10 m depth) and deeper offshore waters (30–50 m depth) are compared and results are discussed in the light of existing information on the migratory movements of different species of sillaginids and their occurrence in coastal or offshore waters. The usefulness of metacercariae of these fishes as ‘biological tags’ is consi

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1990.tb04323.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Preference of juvenile red‐breasted bream,Tilapia rendalli(Boulenger), for the macrophytesCeratophyllum demersumL.,Lagarosiphon ilicifolius(Oberm),Najas pectinata(Magnus) andValisneria aethiopica(Frenzl) was determined. Fish were offered a mixture of the four macrophytes in equal quantities to determine selection. Preference was shown forV. aethiopica, whilstC. demersumwas least selected. This preference order was checked by examination of stomach contents of fish from the same population in the wild and the differences are discusse

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1990.tb04324.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Seasonal microhabitat selection by sympatric young Atlantic salmon and brown trout was studied by diving. Both species, especially Atlantic salmon, showed seasonal variation with respect to surface and mean water velocities and depth. This variation is partly attributed to varying water flows and water temperatures. In winter the fish sought shelter in the substratum. A spatial variation in habitat use along the river due to different habitat availabilities was observed. Both species occupied habitats within the ranges of the microhabitat variables, rather than selecting narrow optima. It is hypothesized that the genetic basis allows a certain range to the behavioural response. Microhabitat segregation between the two species was pronounced, with brown trout inhabiting the more slow‐flowing and partly more shallow stream areas. Atlantic salmon tolerated a wider range of water velocities and depths. Habitat suitability curves were produced from both species. It is suggested that habitat suitability curves that are based on observations of fish occupancy of habitat at median or base flow may not be suitable in habitat simulation models, where available habitat is projected at substantially greater water flow

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1990.tb04325.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

This paper describes the application and evaluation of a stereological method for counting fish oocytes. The method has been applied to herring,Clupea harengusL., Dover sole,Solea soleaL., and mackerel,Scomber scombrusL., and compared with existing volumetric and/or automated particle counter methods. The stereological method has been shown to given similar results and to have a number of distinct advantages over the other methods.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1990.tb04326.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Various Aeromonas salmonicida antigen preparations were tested in an antigen‐induced blasto‐genesis assay on the kidney leucocytes of Atlantic salmon. The ECP antigens that had been particularized onto polystyrene beads were the most effective in control fish, and this was further enhanced in fish thymectomized 1 week prior to the assay. The use of this assay for screening potential vaccine antigens is discus

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1990.tb04327.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY