摘要:

Six years' data from the River Coquet together with published information for other British rivers show that upstream migrant salmon and sea trout tend to be intercepted at counting fences and be caught on rod and line when river flows are somewhat higher than average and not when they are at their extreme values, though there is no particular river flow favoured all the year round. In years of highest river discharge the number of fish entering the River Coquet and the number of fish caught on rod and line are highest but the efficiency of angling is lowest.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1970.tb03250.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Perch PercafluviatilisL. newly introduced into waters were markedly vulnerable to traps for up to four or five days. Thereafter catches tended to be positively correlated with water temperature up to about 10.5°C and negatively correlated at higher temperatures. The catching power of traps is low; at a density of one per 354 m2 water surface, traps caught from 0.9 to 6.8 % and 0.3 to 1.4% of a perch and roachRutilus rutilus(L.) population per day. Perch did not become ‘trap‐shy’ and fin clipping did not affect their vulnerability. Applications of 0.1 to 0.5 ppm copper sulphate resulted in up to an 11‐fold increase in

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1970.tb03251.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

A population ofGyrodactylus unicopulaGlukhova, 1955, is described from the gill filaments of young plaice from a nursery ground on the north‐west coast of Scotland. The seasonal incidence of this parasite was followed by sampling the 1965 year class of plaice at intervals of from one to three months from April 1965 to April 1967. The level of intensity is usually low and shows no progressive increase, although the fish are shown to be capable of supporting much higher populations of the parasite, which suggests the existence of some mechanism controlling the level of intensity in the natural population.The distribution of G.unicopulaon the filamentous surface of the gills is shown in detail. χ2analyses indicated no significant association or antagonism between this parasite and two ciliates commonly found on the gills of the same population of plaice.Gyrodactyliasis, the disease caused by parasites of the genusGyrodactylus, is discussed with special reference to marine fish farmi

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1970.tb03252.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Infection of certain species of cyprinid fish with the plerocercoid larva of the cestodeLigula intestinalisis accompanied by a host tissue response.The tissue reaction is evident in roachRutilus rutilusas young as three months. An initial cellular infiltration is followed by the laying down of sheets of connective tissue. A case of calcification is described in a single infected ruddScardinius erythrophthalmus.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1970.tb03253.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Major pollutions resulted in the deaths of all fish in 8 km long stretches of two trout streams in central Scotland. Fish were collected, measured and weighed and the ages established by scale‐reading. The predominant species present wereSalmo trutta(L.) andThymallus thymallits(L.) with about five times as many trout as there were grayling in each stream. The Douglas Water, which was previously unpolluted, held five times as many fish as the River Gryfe which had a history of intermittent pollution. The trout and grayling of the River Gryfe grew faster than those from the Douglas Water and there were more of the larger sizes presen

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1970.tb03254.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Methallibure treatment inPoecilia reticulataresulted in an interruption of spermatogenesis. This inhibition occurred at the stage of transformation of secondary spermatogonia to primary spermatocytes. The possible endocrine nature of this inhibition is discussed and it is suggested that treatment with Methallibure might provide a suitable alternative to surgical hypophysectomy in the study of pituitary‐gonad relationships in teleost

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1970.tb03255.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

A description is given of the spawning of brook lampreysLampetra planedBloch and unusually small riverlampreys Lampetrafluviatilis L. in the same redd. No successful interspecific copulation was observed, although the possibility of accidental cross fertilization cannot be excluded.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1970.tb03256.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Two meristic characters were found to be significantly different in a species ofTaeniomembras(Pisces: Atherinidae) from two highly saline inland lakes in South Australia. It is suggested that the differences were induced by salinity differences between the lakes.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1970.tb03257.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Thirty‐one vital dyes were screened for marking bleak, roach and gudgeon by total body immersion in aqueous solutions of the dye. Only six dyes stained without killing, and of these Nile blue, neutral red and Bismarck brown were used successfully in the field. This approach to estimation of population size was abandoned because (1) the toxicity of the dyes varied at different times of year, (2) the numbers needed for release were impractically high and (3) fingerlings showed extremely high mortality on handlin

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1970.tb03258.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Three occurrences of thegoby Gobius (Macrogobius) cruentatusin the southwestern region of Ireland are recorded. This species had previously been recorded as far north as southern Biscay. The range of the species is discussed, a full description of the three Irish specimens, and details of its distinguishing features are given. A key to the British species of the genusGobiusis given. The discussion compares the occurrence of this species with the distribution of other Lusitanian fishes and invertebrates on the Irish coast.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1970.tb03259.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY