摘要:

During September and October, 1975, bottom‐dwelling fish from the Bering Sea were examined for diseases. The three most commonly observed diseases and their frequency of occurrence were epidermal papillomas of rock sole (Lepidopsetta bilineataAyres), 1‐0%; lymphocystis of yellowfln sole (Limanda asperaPallas), 2‐1 %; and epidermal tumours of the pseudobranch of adult Pacific cod (Gadus macrocephalusTilesius), 7‐4%. Both the appearance and the histological characteristics of epidermal papillomas on rock sole resembled those found on several species of flatfish in Puget Sound. The frequency of tumour‐bearing rock sole ranged from 0‐23%, with the highest occurrence at sampling stations around the periphery of the Bering Sea in water depths of 20‐30 fathoms (36‐54 m). The virus‐caused lymphocystis lesions were usually on the ‘blind’ side fins and skin surfaces of yellowfin sole, the largest lesions being found on the operculum, and the most common site of infection was the pectoral fin. The frequency of lymphocystis was 0‐15 %, with a gradual increase of prevalence from the northern to southern sampling stations. The Pacific cod tumours were always bilateral, and contained remnants of normal‐appearing pseudobranchial tissue on the surface or deep inside the tumours. Portions of some tumours were necrotic and liquefied. Tumour‐bearing cod were most commonly found in the south and south‐eastern Bering Sea and the frequency of af

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1978.tb04172.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The virucidal properties of iodophor, chlorine (sodium hypochlorite), formalin, thimerosal (organic mercurial compound), malachite green, and acriflavine were tested on infectious pancreatic necrosis virus (IPNV). Iodine and chlorine showed good activity, but efficacy depended on the concentration of virus, the presence of organic matter (calf serum), and waterpH. Water hardness (0‐300 mg 1−1as CaCO3) did not affect virucidal activity. In a 5 min exposure, 4 mg 1−1available iodine inactivated 103.9TCID50m1−1IPNV but 16 mg 1−1iodine were needed for inactivation of 106.3TCID50m1−1. The addition of 0‐5% calf serum significantly reduced the iodine concentration and the virucidal activity. In comparison, 4 mg 1−1chlorine were needed to inactivate 1046TCID50m1−1IPNV in 5 min. However, the addition of 0‐07 % serum greatly reduced the chlorine concentration and extended the virucidal contact time to 30 min or more. IPNV at 106.3TCID60m1−1was not inactivated by exposures for 60 min to 0‐2% formalin, 10 min to 0‐2% thimerosal, 60 min to 5 mg 1−1malachite green, or 20 min to 500 mg 1−1acriflavine. However, acriflavine at 0‐5 mg 1−1in cell culture media prevented the development of cytopathology caused by IPNV and may be usefu

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1978.tb04173.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The stomach contents of 1003 brown trout, 1551 bullheads and 800 minnows taken from the reservoir basin and below the dam, before and after impoundment of the river Tees, were examined. Their composition reflected observations by other workers on river and reservoir benthos, except for the increase in numbers ofHydraandNaisbelow the dam, and Mollusca, Hirudinea and oligochaetes in the reservoir.Trout below the dam ate more Ephemeroptera nymphs and Chironomidae larvae but fewer terrestrial casualties after river regulation, whereas bullheads ate more Mollusca but fewer Plecoptera nymphs. In both species Baetidae nymphs increased in numerical importance relative to Ecdyonuridae. Trout, but not bullheads, took zooplankton discharged from the reservoir.Before impoundment, trout within the reservoir basin ate chiefly benthic organisms and terrestrial casualties. Inundated terrestrial material, mainly earthworms, formed the bulk of their food for at least three years after impoundment, whilst from the second year onwards Chironomidae and, in some years,Gammarusbecame increasingly important. Zooplankton was taken by all sizes of reservoir trout.Bullheads within the reservoir basin ate chiefly river benthos before impoundment, with Ephemeroptera and Plecoptera nymphs predominant in older fish, and aquatic Diptera and Coleoptera also important in the fry. After impoundment, Chironomidae andGammaruswere the main items taken by older bullheads, and Chironomidae and micro‐crustacea by the fry. Among all sizes of minnow, Chironomidae, micro‐crustacea and detritus increased in numerical importance after impoundm

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1978.tb04174.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Rainbow trout trained to operate a demand feeder showed a marked preference for a diet flavoured with a synthetic mixture of chemicals over the unfavoured diet. The gustatory feeding stimulant activity resided in the amino acid fraction and was stereospeciflc for the L‐forms. Certain mixtures of L‐amino acids were stimulatory, while the individual components of the mixtures were inactive or repell

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1978.tb04175.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

In brackish water the variety of marine and freshwater parasite species is considerably reduced. The distribution in brackish water of most marine endoparasites is restricted by the salinity tolerance of their hosts, most of the parasite species are more tolerant than their hosts. The influence of salinity and temperature on nine species has been examined; first stage larvae ofContracaecum aduncumdevelop in 0‐32‰ salinity;Cryptocotyle linguaproved to be infective at salinities down to 4‰. The greatest resistance was found inAnisakislarvae from herringClupea harengus, which survived for more than half a year. Parasites in the fish intestines appear to be unaffected by changing water salinities, as the osmolarity in the intestines stays nearly constant. Marine ectoparasites (Acanthochondria depressa, Lepeophtheirus pectoralis) survive about three times longer than freshwater species (Piscicola geometra, Argulus foliaceus) when salinity is 16‰. High temperature increases the effects of adverse salinities on parasites. There is evidence that none of these ecto‐parasitic species can develop within the range of 7‐2

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1978.tb04176.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

An electrofishing survey of Lough Erne spawning streams indicates a continued decline in the populations of juvenile salmonids. This is particularly the case with salmon stocks, which are now seriously depleted or absent from the sampled areas. This finding complies with the recorded decline in the adult salmon escapement to the Erne system. Stocking operations of both salmon and trout appear to have been successful in boosting recruitment only on a localised basis.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1978.tb04177.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The annual cycles in female Three‐spined sticklebacks from an upland (275 m) and a lowland (25 m) population were compared. The average length and weight of the lowland females were greater, but in both populations growth was checked in winter and again in the breeding season. Both populations also showed a winter decline in condition followed by a sharp increase in spring associated with the maturation of the ovaries. The hepato‐somatic index of the females also increased during the spring, but the dry matter content of the liver declined during the spring and early summer. Lowland females had larger livers than the upland fish. In both populations average gonadosomatic index increased steadily throughout the winter, then abruptly in spring. The lowland population bred from May to early August, but the upland population bred only in May.The energy content of the carcases of females was lowest in winter and again during the breeding season whereas the ash content showed maxima at these two periods. Lipid and glycogen analyses of the carcase, liver and ovaries also suggested that winter and the breeding season were periods of depletion from the carcase and liver, but not from the ovaries.The observations indicate that the ovaries are to some extent insulated from fluctuations in resource availability. This supports experimental studies which indicate that egg production in the female stickleback can be subsidised by depletion from the carcase and liver when necess

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1978.tb04178.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The growth of 0‐group roach in a chalk‐fed river is traced over six seasons and the growth compared to that in a nearby gravel pit. The growth rate, the daily weight increase and the condition of the fish are all highest during the summer, falling to a minimum over the winter period and rising again in the spring. Considerable yearly variation in the growth of roach in the river was observed and correlated with water temperatures above 14° C. It is suggested that water temperature, acting through the food supply, is the dominant factor governing growth. The hot summer of 1976 appears to have resulted in excellent growth of roach in both habi

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1978.tb04179.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The effects of the anaesthetic quinaldine on oxygen consumption in an intertidal teleostBlennius pholis(L.) were investigated. Oxygen consumption generally decreases with increasing quinaldine concentration in environmental water. However, at low concentrations, oxygen consumption of smaller specimens is slightly increased. Generally, smaller specimens have their oxygen consumption affected less by a given quinaldine concentration than do larger specimens, as the former appear to be at less depressed stages of anaesthesia. This is thought to be due to smallerB. pholisbecoming saturated with quinaldine more rapidly but simultaneously being afforded more rapid removal, because of their greater relative gill area per unit body volume. The reduction of oxygen consumption at high concentrations of quinaldine is great.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1978.tb04180.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The biology of a Scottish population of the burrowing gobyLesueurigobius friesiiwas studied from February 1975 until October 1976. The fish lives at depths of 10–130 m on muddy grounds and attains a length of at least 94 mm and an age of 11 years, females generally living longer than males. Most growth takes place in the first three years of life after which it proceeds very slowly. Marked differences in year‐class strength were found. Both sexes mature in their third year and the breeding season lasts from late May until August. Each female can spawn at least twice during this period and the eggs are laid on the roof and sides of the U‐shaped burrows which the fish dig in the mud. Fecundity is length dependent and varies between approximately 3–11 000. The fish feeds predominantly on polychaetes, although small Crustacea and molluscs also feature commonly in its diet. No marked diurnal variation in the feeding pattern was noticed, although the amount of food in the stomachs was lowest in the early hours of the

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1978.tb04181.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY