摘要:

Saddle‐shaped skin lesions commonly occurring in both wild and captive Bermudan reef silversides yielded a mixed infection of motile and non‐motile Gram‐negative cells ofAcinetobacter calcoaceticus, Aeromonas hydrophila, Pseudomonassp.,Vibrio parahaemolyticusand a myxobacterial‐like strain. Bacteria occurred as almost pure microcolonies and mixed clumps on proximal scale and fin ray surfaces, in intercellular epidermal spaces, on perimysium of fin erector muscle myomeres and on eroded dorsal fin rays and their intact membranes, but neither on healthy areas of the skin nor within muscle cells. Effects were epithelial destruction and liquefactive necrosis of myomeres, and raising and sloughing of Malpighian cells, scales and dermis. Host response was minimal, consisting of infiltration of a few lymphocytes and macrophages. The fish pathogenic dinoflagellateAmyloodinium ocellatumwas seen in one fish with a saddle lesion and caused muscle cell lysis, as evidenced by cloudy cell swelling. Antibiotic sensitivity tests showed increased drug resistance with mixed bacterial types compared to that of single pure isolates. This suggests that alternatives to chemotherapy for control of bacterial fish diseases is appropriate, because most are probably caused by mixed inf

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1988.tb05424.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The sediment‐feeding surgeonfishCtenochaetus striatuswas found to reduce the sizes of ingested carbonaceous particles. The mean sizes of particles in stomach samples of the surgeonfish were smaller than those from areas where the fish were observed feeding. The particle sizes in the rectal contents of the fish were smaller than those in the stomach samples. The sediment‐feeding activities of this and related surgeonfishes are likely to have a local impact on the particle‐size distributions of sediments in reef and lagoon habitats. The assimilation efficiencies of the fish were estimated by the ash‐ratio method to be 20% for total organic matter and 37% for n

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1988.tb05425.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Degree of silvering (colouration) is often used as an index of the degree of smoltification in salmonids. To judge the reliability of silvering as an indicator of migratory readiness, we examined the silvering of wild coho salmon,Oncorhynchus kisutch, smolts upon entry into the Carnation Creek, British Columbia, estuary. Silvering of migrants was greater in larger fish and increased over the course of the migratory period. Photoperiod appeared to account for most of the observed increase in silvering over time; increased silvering was not correlated with temperature or lunar phase. Overall, 50% of seaward migrants were completely silvered, 45% were in a transitional phase, and 5% still retained colouration characteristics of parr. Colouration thus appears to have limited utility as a reliable indicator of migratory readiness. Our findings suggest that estuarine residence is important for completion of parr‐smolt transformation and that acclimation of hatchery smolts in brackish water prior to sea water entry may enhance their surviva

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1988.tb05426.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Flow cytometry of nuclear DNA fluorescence in erythrocytes, coupled with gene dosage assessments derived from electrophoresis of proteins, reaffirmed that theMenidia clarkhubbsicomplex of unisexual atherinid fishes is diploid. Non‐recombinant hybrids betweenM. beryllinaandM. peninsulaerepresented 18% (108 specimens) of theMenidiacollected from three pools in the Copano Bay area and 9‐6% (42 specimens) of those from a pool on Galveston Island. Of those hybrids, 35 and 5%, respectively, were triploids. Zymograms indicated that the triploids either had two doses of genes fromM. beryllinaand one fromM. peninsulasor they had one from the former species and two from the latter. The hybrids seem to be maintained primarily, if not entirely, by ongoing hybridization and back‐crossing of F1hybrids to the parental species. Triploids apparently result from the combination of unreduced, diploid gametes from F1hybrids with haploid gametes from eitherM. beryllinaorM. penin

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1988.tb05427.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The presence of immunoglobulin–containing cells in the epidermis of rainbow trout was traced, using post–embedding immunocytochemical techniques, in resin–embedded fragments of skin. Light microscopy observations (for which the PAP method was used)revealed the presence of immunoglobulin–containing cells in the epidermis, although no accurate identification was possible. Electron microscopy observations (employing gold–labelling) showed that, in spite of the poor preservation thought unavoidable to protect the antigenicity of the immunoglobulins, the positive cells were either lymphocyte–like cells or mucous cells. Anti–Vibrio anguillariumantibody was detected in the epidermal mucous cells of rainbow trout juveniles vaccinated by immersion, using an immunoenzymatic sandwich technique, modified for resin–embedded tissue. The possibility of the existence of a local immune system is discussed, considering the involvement of t

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1988.tb05428.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Results of a study of plasma lipids levels and lipoprotein pattern modification during digestion in sea bass indicate that, after feeding, non‐esterified fatty acids are rapidly delivered in plasma, while triglycerides reach a maximum concentration only 24 h later. The time‐course change of the lipoprotein pattern shows a relationship between their concentration and the lipid class carr

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1988.tb05429.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The results of rearing salmon smolts, using warm water in winter time, are presented. Fishes weighing 25–50 g were released in spring time at the age of about 1 year, while smaller fishes were left to grow in ponds for release at age 2 years. As a result of warm‐water wintering of fingerlings, the yield to the fishery was at least doubled, while there was no decrease in fish size, nor in gamete quality. Three thousand to 5000 spawners entered the Narova River (Baltic Sea) per annum and the trend is to exceed these tot

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1988.tb05430.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Fish yields from Apo Island, Central Philippines were assessed based on detailed quantitative analyses of fish landings, with specific reference to seasonal changes in the size and nature of the yield in terms of familial composition and degree of reef association of contributing species. The total estimated annual yield is 24‐861 km−2year−1(±12.75, 95% C.I.)‐ Of the 39 families harvested, yields are dominated throughout the year by two, the Carangidae (40%) and the Acanthuridae (23.6%). The yield is likewise consistently dominated by two specific groups: reef‐associated, 39.1%, and reef planktivores, 23.1%. Reef species comprise only 17‐1%. Seasonal differences in yields were only detected in the Carangidae and the reef‐associated species group. Apo Island reefs appear to be highly productive. Possible reasons for this are discussed. The variety of methods used for estimating reef fish yields, however, make comparisons difficult. Standardized procedures are there

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1988.tb05431.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The species composition of the juvenile fish catch from part of the Sokoto–Rima floodplain was monitored over four seasons. In three of the years, 1981–1984, the flood pattern of the river was normal. During the 1984–1985 season the cycle was disrupted by completion of the Goronyo Dam, approximately 100 km upstream from the sampling area. The composition of the juvenile fish catch was markedly altered during this season and the diversity greatly reduced. Ways in which fish species could be affected by the change in flood regime are disc

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1988.tb05432.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Gill–netted samples of Arctic charr from Loch Rannoch, Scotland were bimodal when tested by univariate and multivariate morphometric analyses. The separation into two morphs corresponded very closely (95–98%) with fish classified subjectively in the field as benthic or pelagic, based largely on colour differences and ecological observations. The benthic charr had relatively longer heads, larger eyes and more powerful jaws than the pelagic charr. Unlike sympatric morphotypes described from Scandinavia and Greenland, neither Rannoch morph is dwar

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1988.tb05433.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY