摘要:

The age, growth and reproduction ofLeuciscus pyrenaicus(Günther, 1868), an endemic cyprinid from the Iberian Peninsula, was studied from November 1987 to September 1989 in a small seasonal tributary of the Guadalquivir river basin. Maximum fork lengths observed were a 160 mm male with six scale annuli and a 171 mm female aged 7 +. Maximum ages observed were 7 + in males and 8 + in females. There were no significant differences in the annual growth increments between sexes. Seasonal growth period started in March and continued for 5 to 6 months. Mean lengths of 1 + specimens onwards diminished during summer and/or autumn. Males and females matured in their third and fourth year of life respectively. The overall sex ratio (272 males: 310 females) differed significantly from equality. Spawning began in May and ended in July.L. pyrenaicusis a multiple spawner that releases a minimum of two batches of eggs per female each year. Eggs in each batch were similar in both size (egg diameter) and number released. The relationship between fecundity (Fee) and fork length (mm) was represented by the formula: Fec=1.96 10−3L2.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb05977.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

To examine the effects of triploidy on rainbow trout myogenesisin vitro, mononuclear cells were liberated enzymatically from the lateralis muscles of diploid and triploid trout. The muscle of diploids yielded 1 × 106± 1 × 105(±s.e.m.) mononuclear cells g−1muscle compared to 0.7 × 106± 8 × 104cells g−1from triploids (P<0.01). The plating efficiencies of diploid and triploid mononuclear cells on Matrigel™ following 18 h of culture in Leibovitz's L‐15 + 10% foetal bovine serum were not significantly different, 35.0 ± 3.5% and 33.0 ± 2.9%, respectively. For most time points examined, the proportion of nuclei in multinucleated cells and the proportion of nuclei in myosin positive cells were not significantly different for diploid and triploid trout. Taken together, these data suggest that diploid and triploid myogenic cells will differentiate similarly when compared under identical,in

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb05978.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Gut residence times of first‐feeding walleye pollock larvae were measured at 6°C in continuous and discontinuous feeding regimes. Larvae fed tagged copepod prey evacuated their guts more quickly in continuous feeding as compared to the discontinuous feeding treatment. The mean gut residence time was estimated to be 5.0 h for larvae feeding continuously. Gut evacuation by larvae fed tagged prey and then isolated without food (discontinuous treatment) was slower and more variable, with an estimated gut residence time exceeding 8.0 h. Field and laboratory observations suggest that the larval fish gut may be modeled as an intermittent plug‐flow reactor (PFR) in response to diel feeding patterns. The cyclical nature of gut dynamics has implications for gut content analyses and the estimation of daily food rat

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb05979.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The effect of feeding and starvation on growth, gross body composition and fatty acid composition of body muscle and liver were investigated in juvenile African catfish (Clarias gariepinus). The relative composition of fatty acids was influenced by starvation. In both liver and muscle there were marked relative decreases of 14: 0, 16: 1n9 and 18: 1n9 fatty acids and relative increases of 20: 5n3 and 22: 6n3 when these were compared to the controls. Preference of utilization of fatty acids from liver and body muscle during starvation was highest for 14: 0>16: 1n9>18: 1n9 and conservation highest for 22: 6n3>20: 5n3. The changes of these fatty acids were smaller in muscle than in the liver.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb05980.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Brown trout (Salmo trutta) from anadromous River Lierelva, resident Lake Tunhovd, and resident Nordmarka stocks were exposed toGyrodactylus salaris‐infected salmon parr. The brown trout were fed pellets before the experiments, except for one group of the Nordmarka stock which was starved for 19 days before the experiments. The mean number of parasites declined directly and rapidly post infection for all groups of trout. There were no pronounced differences in resistance between the anadromous and the resident stocks.G. salarisinfections tended to persist longer on starved than on fed trout of the Nordmarka stock. The maximum parasite persistence on trout was 50 days, and as parasite numbers increased on some fish parasite reproduction must have occurred on those trout. However, the limited susceptibility and marked innate resistance of trout toG. salarisestablishment, development and reproduction, suggest parasite metapopulations will not survive on this species. Nevertheless, trout may still play a role in the dispersal ofG. salariswithin and between river

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb05981.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Infection levels by 17 species of ectoparasite on 491 yellowfin bream collected throughout 1990 from Moreton Bay, S.E. Queensland were compared to infections on 82 bream collected during the same period from a captive population in a large pond at Sea World, Gold Coast, Queensland. There was a significant increase in prevalence and/or intensity of monogeneansLamellodiscus acanthopagriandPolylabroides multispinosus, but a decrease in the monogeneanAnoplodiscus australisand the copepodsErgasilus australiensis, Lernanthropus atrox, Bomolochus stockiandAlella macrotracheluson captive fish. Twenty‐eight bream collected from the pond during autumn were placed in an experimental 1 m3cage within the pond for 4–6 weeks. Compared to the baseline data for the pond, the caged fish showed increased prevalences of the monogeneansLamellodiscus acanthopagri, L. squamosus, L. majorandHaliotrema spariensis, and increased intensities ofL. squamosus, Allomurraytrema robustumandP. multispinosus.The copepodCaligus epidemicusdropped off in preservative, but its abundance (average number per fish) was significantly higher on caged fish than on pond or wild fish. Increased infection levels byL. acanthopagriandA. robustumwere due in part to autoinfection. The large skin area promoted large populations ofC. epidemi

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb05982.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

We examined the effects of separation and freezing on fish leukocyte and erythrocyte morphology by light microscopy and on DNA content as measured by flow cytometry (FCM). Leukocytes and erythrocytes of largemouth bassMicropterus salmoideswere isolated by density gradient centrifugation of whole blood, and frozen in liquid nitrogen in a buffer containing DMSO as a cryopreservative. The coefficient of variation (CV) of the G0/G1peak of the cells was used to assess variation in nuclear DNA content within cell populations before and after separation and freezing treatments. In erythrocytes, the CV did not change significantly (P>0.05) when nuclei were isolated and stained without freezing or when erythrocytes were frozen prior to nuclear isolation and staining. In leukocytes, freezing and thawing prior to isolation and staining of nuclei significantly increased the CV (P0.05). Microscopy showed that the freezing protocol had little effect on erythrocyte morphology, but caused irregular swelling in leukocytes. Freezing intact leukocytes also significantly (p<0.05) altered the apparent distribution of cells among the phases of the cell cycle as measured by FCM. The distributions of leukocyte nuclei that were isolated and stained prior to freezing were not different to non‐frozen leukocytes. DNA measurements of nucleated blood cells are widely used in physiological, genetic and toxicological studies. Our results suggest that whole blood and erythrocytes for use in such studies can be frozen whole using a simple protocol, but leukocyte nuclei must be isolated and stained before freezing to avoid serious artifa

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb05983.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

During the early spring four groups of sub‐adultPleuronectes asperwere fasted for either 0, 2, 4 or 6 weeks at the beginning of a 12‐week experiment, then fed to satiation to examine their ability to compensate with faster growth after food deprivation. All fish increased their stored energy reserves markedly and at the end of the experiment all four groups had similar body energy content (J g−1), length gains and dry weight to wet weight ratios. The groups of yellowfin sole fed continuously or fasted for 2 weeks gained the most weight, 25 and 24% respectively. Fishes fasted either 4 or 6 weeks exhibited significantly lower weight gains of 16 and 15% respectively over the 12‐week experiment. Because of this disparity in weight gain the total body energy content of the continuously fed fish and those fasted for only 2 weeks increased by approximately 60vs46% or 35% for sole fasted for 4 or 6 weeks.The experiment showedP. asperhad a limited capacity for compensatory growth. When food was scarce yellowfin sole allocated energy preferentially to growth in length instead of weight. These findings may account for some of the interannual differences in mean length and weight at age for yellowfin sole from the Bering Sea where variations in extent and duration of ice cover and the boreal bottom water delimit the growing

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb05984.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Three species of tilapia (Oreochromis lidole, O. karongaeandO. niloticus) were fed on four planktonic algal diets in the laboratory. The algal concentrations were measured over a 24‐h period and the ingestion rates calculated. In monocultures of large algae (average filament length=477 μm)O. niloticushad the highest ingestion rate, but on small algae (particle size<8 μm)O. lidolewas the fastest, whileO. karongaeenhanced nanoplankton production. With algae of mixed sizes,O. niloticuswas able to remove small algae quicker than the other fish species. Thus, the presence of larger algae can influence the impact of a planktivorous species on nanoplankton.O. lidoleis likely to have the greatest impact on plankton communities heavily dominated by smaller al

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb05985.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Much less is known about the behaviour of female beaugregory damselfish than about males of the species. This study was initiated to determine behavioural patterns and interactions of female beaugregories on the back reef of Discovery Bay Marine Laboratory, North shore of Jamaica. Females fed, patrolled, and chased intruders in a significantly larger area and ate significantly more per 15‐min observation period than did males. Males spent significantly more time patrolling their territories and chased significantly more total intruders than did females. However, this difference in total chases comes from the fact that males chased the bluehead wrasse, an egg predator, significantly more often than did females while all other species of intruder were chased the same by both sexes. The distance that females travelled from their homesite to court was significantly positively correlated to female body length. This increased distance travelled may relate to mate assessment. Female beaugregory damselfish may be able to be more selective in their choice of mate with increased size and distance travelle

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb05986.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY