Studies of the Trematode Stephanostomum baccatum (Nicoll, 1907): I. The Distribution of the Metacercaria in Eastern Canadian Flounders

1954 ◽  
Vol 11 (6) ◽  
pp. 954-962 ◽  
Author(s):  
R. W. Wolfgang

Stephanostomum baccatum, an acanthocolpid trematode, encysts during its larval stage in eastern Canadian flounders, the most consistently and heavily infected species being the winter flounder, Pseudopleuronectes americanus (Walbaum). The infection is heaviest in Passamaquoddy Bay. Hosts are usually more heavily infected in inshore than in offshore waters. Infections are light in the Bras d'Or Lakes and the northern Gulf of St. Lawrence. Larger fish have heavier infections than smaller fish. S. baccatum infects both European and North American flounders; two of its hosts occur on both sides of the Atlantic: the witch, Glyptocephalus cynoglossus (L.), and the American plaice (European long rough dab), Hippoglossoides platessoides (Fabric.).

1987 ◽  
Vol 65 (3) ◽  
pp. 499-503 ◽  
Author(s):  
J. Stevenson Macdonald ◽  
Kenneth G. Waiwood

Feeding chronologies of three species of cohabiting benthic fish, winter flounder (Pseudopleuronectes americanus), ocean pout (Macrozoarces americanus), and American plaice (Hippoglossoides platessoides), are described. The volume of food eaten by each species at each of four collection times over 24 h was analysed using analysis of covariance (ANCOVA), with fish length as the covariate. Daily ration was estimated using a gastric evacuation model, incorporating mean stomach volumes at four subdaily intervals and independent evacuation rates for slower (bivalves) and faster digested prey (amphipods and polychaetes). Winter flounder, American plaice, and ocean pout were daylight feeders with American plaice feeding more heavily later in the day. Winter flounder had the highest consumption rate (1.77% body weight/day) followed by ocean pout (1.68%) and American plaice (1.28%). Estimates of daily and subdaily food consumption were compared with corresponding estimates based on prey-specific state of digestion indices. This study indicates that estimating total and individual prey consumption at subdaily intervals provides a useful tool in determining feeding chronology and draws attention to potential biases encountered when more traditional analyses are used.


1954 ◽  
Vol 11 (6) ◽  
pp. 963-987 ◽  
Author(s):  
R. W. Wolfgang

Stephanostomum baccatum, an acanthocolpid trematode, has the following host succession in eastern Canadian waters: Buccinum undatum and Neptunea decemcostatum (Gastropoda), primary intermediate hosts; the six common species of pleuronenctids, second intermediate hosts; Hemitripterus americanus and Hippoglossus hippoglossus, common definitive hosts. Infection of flatfish is by penetration of the integument of the host by an atypical Ophthalmoxiphidiocercous cercaria.The infection of the winter flounder, Pseudopleuronectes americanus, as investigated in Passamaquoddy Bay, N.B., shows the following characteristics:1. The infection in inshore waters is greater near open water than on shoal grounds.2. For any given location deeper water samples show a higher incidence of infection than shoal samples.3. Larger fish have heavier infections than small ones.4. The growth of the flounder is not impeded by heavy cyst infections.5. No marked seasonal variation of infection can be demonstrated. Control is impractical.


1977 ◽  
Vol 34 (11) ◽  
pp. 2142-2150 ◽  
Author(s):  
C. M. Campbell ◽  
D. R. Idler

Hypophysectomized winter flounder (Pseudopleuronectes americanus) did not undergo spontaneous oocyte maturation, but the glycoprotein fraction of extracts of American plaice (Hippoglossoides platessoides) pituitaries induced maturation and ovulation. The nonglycoprotein fractions, previously shown to contain a vitellogenic factor, were less efficient than the glycoprotein fractions in the induction of maturation and ovulation. The activity of the nonglycoprotein fraction was further reduced by rechromatography on Con-A Sepharose, suggesting that its action on oocyte maturation and ovulation was due to contamination by the glycoprotein gonadotropin. Key words: hypophysectomy, gonadotropin, oocyte, maturation, ovulation, vitellogenesis, flounder, plaice, Pseudopleuronectes, Hippoglossoides


1985 ◽  
Vol 63 (7) ◽  
pp. 1699-1705 ◽  
Author(s):  
J. S. Scott

Examination of monthly samples of winter flounder (Pseudopleuronectes americanus) from Passamaquoddy Bay revealed seven digenean parasites (Genolinea laticauda, Podocotyle atomon, Stenakron vetustum, Fellodistomum furcigerum, Derogenes varicus, Lecithaster gibbosus, and Steganoderma formosum) in the alimentary tract and two metacercariae (Stephanostomum baccatum and Cryptocotyle lingua) in the body surface tissues and gills. Prevalence of alimentary tract parasites ranged from 0.2 in S. formosum to 39.8 in P. atomon and intensity ranged from 1.5 for D. varicus to 7.0 for S. formosum (one fish). Monthly and seasonal levels of prevalence varied: high in spring and autumn and low in summer and winter for most species. Prevalence and length-frequency distributions of the parasites did not support differential migration by size group or diminishing feeding activity from spring to winter in winter flounder, as proposed in other studies.


2018 ◽  
Vol 96 (12) ◽  
pp. 1291-1298 ◽  
Author(s):  
M. Bélanger ◽  
F. Turcotte ◽  
R. Tremblay ◽  
Y. Lambert ◽  
M.K. Litvak ◽  
...  

Metamorphosis is a critical developmental stage that presents particular challenges in fish aquaculture. The sharp increase in mortality that accompanies this transformation has often been attributed to nutritional deficiencies. Providing live feed (the rotifer Brachionus plicatilis Müller, 1786 and the brine shrimp Artemia salina (Linnaeus, 1758)) during the larval stages is costly and labour intensive, which explains why much effort has been put on early weaning. However, previous observations in winter flounder (Pseudopleuronectes americanus (Walbaum, 1792)) indicate that juveniles weaned after settlement had better survival than those weaned at the larval stage. In this study, we tested whether late weaning (at settlement (W0) and groups maintained on co-feeding for 1 month (W1), two months (W2), or 3 months (W3) after settlement) could improve juvenile survival and lipid composition. Our results demonstrated that maintaining co-feeding beyond the larval stage was essential for after-settlement survival. Juveniles co-fed until 90 days after settlement were 32.5% heavier. Analyses of fatty acid trophic markers suggested that juveniles preferentially fed on enriched rotifers rather than inert food. No pigmentation or fin erosion problems were observed in any of the weaning treatments, which indicates good rearing conditions.


1982 ◽  
Vol 39 (5) ◽  
pp. 651-659 ◽  
Author(s):  
J. Stevenson Macdonald ◽  
Kenneth G. Waiwood ◽  
Roger H. Green

Stomachs of ocean pout (Macrozoarces americanus), Atlantic cod (Gadus morhua), winter flounder (Pseudopleuronectes americanus), and American plaice (Hippoglossoides platessoides) were removed and dissected 5, 12, 20, and 30 h after the fish had fed voluntarily to test the evacuation rates of three different prey species. Two evaluation procedures were used: a visual index of recognizabiiity, and a graphical analysis of percent of each prey recovered versus time since feeding. Three decay models were tested for goodness of fit to the evacuation data. The polychaete worms were the first to become unrecognizable, followed by amphipods. These species showed significantly different rates of evacuation when compared with the bivalves which were recognizable for the longest time. The exponential decay curve gave the best overall fit to the data. However, a linear model gave a good or better fit to the decay rate of the bivalve. The evacuation rates of different prey should be considered in estimating daily rations of fish in their environment.Key words: digestion, stomach content, food organism, Yoldia sapotilla, Tmetonyx cicada, Nephtys incisa


1976 ◽  
Vol 33 (1) ◽  
pp. 63-75 ◽  
Author(s):  
A. V. Tyler ◽  
R. S. Dunn

Six ration levels were established among 120 large, adult winter flounder (Pseudopleuronectes americanus) by setting different feeding frequencies, but with unlimited feeding at each meal. All fish were maintained at 7 C. With decrease in feeding frequency, fish ate less food per month but more food per meal — i.e. ration compensation was attempted. At the lowest frequency, two meals per month, fish did not compensate. At any one feeding frequency, fish ate progressively more per meal from the first to the fourth (final) month of the experiment.Maintenance ration was 7.9 gcal/g per day. Weight loss on starvation was equivalent to 2.14–2.35 gcal/g per day. Gross conversion efficiency ranged from 1 to 16%, and was positively correlated with ration. Net conversion efficiency averages 24.3% and was not related to ration.Positive correlations were found between mean calories consumed per day and condition, liver weight, percent fat in the liver, percent of fish with yolk-bearing ovaries, ovary weight, and percent of ovarian follicles with yolk. The decrease in proportion of yolked oocytes with decrease in ration was not due to increased follicular atresia, but to a decrease in number of oocytes starting vitellogenesis.Comparisons with flounders sampled directly from Passamaquoddy Bay, N.B. showed that the negative correlation between condition index and percentage of oocytes not in vitellogenesis was the same for Bay and laboratory fish, the range of response being greater in the laboratory fish. The existence of this relationship was interpreted as evidence that some flounders within the Bay were not getting all the food they could use. In the face of food scarcity, the winter flounder’s adaptive reproductive strategy seems to be to sacrifice egg production and maintain body weight, and so when a good year comes its body will be large and able to carry a larger ovary.


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