No description available.

Neutral microsatellite markers were used to analyse genetic variation in three demersal finfish species, whiting (<i>Merlangius merlangus</i>) haddock (<i>Melanogrammus aeglefinus</i>) and anglerfish (<i>Lophius piscatorius</i>) in the north east Atlantic.  For each species samples were collected from the North Sea and west of the British Isles while geographically distant samples were also collected from Icelandic waters.  In the case of the anglerfish study samples were also taken from the Bay of Biscay and the Mediterranean Sea. Whiting appears to show the highest level of structuring in the north east Atlantic with samples from Icelandic waters being significantly divergent from samples on the continental shelf.  Just one of the continental shelf haddock samples, the Irish Sea, showed evidence of divergence from the Icelandic samples.  This general lack of divergence between Icelandic and continental shelf haddock is most likely reflective of a combination of relatively recent isolation and large effective population sizes (N_e).  Apart from a few significant results (P&lt;0.05) continental shelf haddock and whiting conspecific populations tended to show little divergence.  This would also appear to be due primarily to large effective population sizes and a relatively recent isolation.  <i>L. piscatorius </i>showed a total absence of genetic differentiation between all the Atlantic samples which is consistent with the long distance movements associated with this species.  There was however strong evidence of divergence between the Atlantic and Mediterranean anglerfish samples. Comparing the results of the molecular studies presented here with non molecular approaches to determining population structure highlights the importance of combining information from several approaches if a sustainable management plan is to be put in place for commercial species.

Yellow perch, Perca flavescens (Mitchill), were collected for food habit determination from a transect in Indiana waters of Lake Michigan near Michigan City, Indiana between June and October in 1971 and June and September in 1972.The most important food items utilized on a mean annual basis were: unidentifiable organic material (UOM), alewife eggs, Pontoporeia affinis, fish (primarily alewife), insects (primarily chironomid larvae and pupae), and Eurycercus lamellatus. E. lamellatus, alewife eggs and UOM dominated 1971 stomach contents with P. affinis more important than E. lamellatus in 1972.Monthly stomach contents revealed heavy consumption of alewife eggs when available during the alewife spawning period, but these were replaced by P. affinis and fish (alewife) especially after July in both years.Differences between sexes of yellow perch captured by day and by night were minor and inconsistent.Differences between selected size groups (100-175, 176-225, 226-275 mm) manifested themselves in greater use of larger food items such as P. affinis and fish with larger length groups and as the summer progressed. The mean volumes of alewife eggs consumed, the most important food of yellow perch in this study, decreased significantly within each month both years as length of the yellow perch increased. In the large length groups, greater use of larger food items was made, but only fishes as a food item showed a signigicant difference between the two larger length groups.

Aspects of the resting respiration rate, specific dynamic action (SDA) and components of the total energy budget of 55 - 80g common carp were studied in the laboratory. The resting respiratory rate was monitored in computer operated metabolic chambers under different photoperiods. Common carp showed a crepuscular respiratory rhythm with peaks at dawn and dusk during a 12L : 12D photoperiod, with a mean oxygen consumption of 152 mg/kg/h. When acclimated to longer or shorter photoperiods respiration was also cyclic but with a lower mean respiratory rate. In continuous light or darkness respiratory rhythm was suppressed with no significant peakings. In carp fed with three diets containing 20,35 and 50% protein at a ration level of 0.40 to 1.00% body weight per day, SDA coefficient varied from 8.99 to 15.94% and was dependent on dietary protein but not on ration levels. SDA magnitude and post-feeding peak oxygen consumption varied significantly with both dietary protein content and total daily ration level. SDA duration was only related to ration size. The pattern of food energy allocation between the major components of the energy budget varied with dietary protein content and ration levels. The energy lost as heat of metabolism was found to increase with dietary protein level and total ration. Energy lost as faeces 'F' varied from 19 - 24% of 'C' and did not appear to be related to either protein content or ration levels. Nitrogenous excretion increased with an increase of dietary protein but decreased with an increase of ration level in the diet. Regression equations were developed from the data to allow prediction of respiratory energy loss 'R', faecal energy loss 'F' and energy lost through excretion 'U' from the food ingested V. Complete energy budget models compiled from experiments conducted over a 17 days period and using different diets did not successfully predict the actual growth. The energy budget balance was between 66.04% and 81.96%. Observed growth was less than predicted growth in every trial and it is suggested that this difference might have been due to short-term cyclic growth regulation and other minor experimental features. The data presented form the basis for the first reported study of total energy budgets in Cyprinus carpio.

This research study is divided into 4 major sections. Section A deals with the world-wide distribution of the haematoprotozoan parasites of marine fishes. These are tentatively divided into 3 major groups: the Haemogregarines, the Trypanosomes and the Trypanoplasms and one group of ill defined and controversal organisms including Haemohormidium sp. and Dactylosoma sp. The results of extensive surveys of the coastal waters of France, Scotland and Wales with added examples from the Mediterranean Sea substantiate the zoogeographical distribution of these parasites. Two species of haematoprotozoan parasites Haemogregarina simondi and Trypanosoma soleae are re-described, earlier accounts dating from the beginning of the century being considered incomplete. A new species of haemogregarine is described from the farmed turbot (Scophthalmus maximus) as Haemogregarina sachai n. sp. and an unidentified species of Haemohormidium found occasionally in turbot and Dover sole (Solea soles) is also described. In addition Haemogregarina sp. were encountered in certain wild marine fish from the Atlantic coast of France e. g. Zeus faber, Sebastes sp., Trisopterus luscus, Pagellus bogaraveo and Raja sp. and from the coastal waters of Malta e. g. Peristedion cataphractum and Oblade melanura. However, they were not found in sufficient numbers to allow a definite description. The value of surveys of wild fish populations is discussed in the light of zoogeographical distribution, the apparent periodicity of these parasites and a seasonal variation of parasitism. Section B attempts to summarize the knowledge of the mode of transmission of marine haematoprotozoan parasites by piscicolid leeches as intermediate hosts and vectors. The developmental stages of a trypanosome, probably Trypanosoma murmanensis from the Atlantic cod Gadus morhua are described in the marine leech Calliobdella nodulifera. Stages of a haemogregaririe were observed in the same leech. The development of the turbot haemogregarine Haemogregarina sachai n. sp. in artificially infected leeches is also described up to the 20th day post infection. Transmission of this haemogregarine to apparently uninfected turbot via this leech was not successful. Various stages of development of Haemogregarina simondi are described in its apparently natural vector, the marine leech Hemibdella soleae, and transmission with infected leeches to apparently healthy hatchery reared soles was achieved. Thus it was shown for the first time that marine leeches can serve also as vectors for haemogregarines. Stages of this haemogregarine are also described in the blood-sucking ectoparasitic copepod Lernaeocera sp. parasitizing the haemogregarine infected soles. These results are discussed in relation to the feeding behaviour and migration patterns of the fish hosts, the periodicity of the parasites and possible other vectors or other ways of acquiring an infection with these haematoprotozoan parasites. In Section C the pathogenicity of the haematoprotozoan parasites of marine fishes is summarized from previous accounts among wild fish populations and compared with the situation in aquaculture. The pathogenicity of the two haemogregarines, Haemogregarina simondi and Haemogregarina sachai n. sp., accidentally introduced into several fish farming establishments connected with the effluent cooling waters of a nuclear power station is described with special reference to the possible source of the infection. The results of therapy trials and control programs are discussed in the light of the periodic reappearance of the parasites, the possibility of carrier fish existing, the immune status of the host and the possible role of an intermediate host or vector in maintaining the infection. Possible means of controlling the pathogenicity of marine haemogregarines and perhaps other haematoprotozoan parasites when they occur in farmed marine fishes are also discussed. In Section D are described for the first time, the ultrastructural characteristics of various stages of the haematoprotozoan parasites of marine fishes in fish hosts and vectors. The electronmicroscopical studies are limited to Haemogregarina sachai n. sp. and Haemogregarina simondi, for which the ultrastructure of schizonts from the spleen and blood, intracellular merozoites and free gametocytes were contrasted. In addition stages of H. simondi were demonstrated in Hemibdella soleae and Lernaeocera sp. The fine structure of the various organelles encountered was compared with that of related organisms from other cold-and warm-blooded vertebrates. In conclusion attention is drawn to the need for more investigations in this field of host-parasite relationship of marine haematoprotozoan parasites and their vectors and their pathogenic-action as seen in a confined and artificial environment such as the marine aquaculture.

Larval Anisakis simplex, Pseudoterranova decipiens, Contracaecum osculatum and larvae and adults of Hysterothylacium aduncum were recovered from specimens of cod, haddock, blue whiting and bull rout; however, only A.simplex were retrieved from long rough dab. The epidemiology of infection by these four nematode species was examined both in whole fish, and in individual host tissues and organs. Frequency distributions of nematodes were found to be generally overdispersed in fish. Preliminary investigations revealed no strong evidence to suggest that competi tive interactions occurred between ascaridoid nematodes wi thin fish. Stomach lesions in gadoids were associated with single (partially penetrated) and mul tiple (throughout stomach wall) worm infections of larval A.simplex; such lesions were discrete and raised in appearance. Lesions associated with 1-3 larval P.decipiens in an open cavity within the stomach of angler fish were diffuse and not significantly raised. Histological examination of each form of ulcer revealed general similarities in pathology, with infil tration of inflamatory cells being the initial response to the nematode\s. Changes in the cephalic morphology of A.simplex, P.decip1ens, C.osculatum and H.aduncu were examined at different life cycle stages under scanning electron microscopy. Due to their small size, newly hatched third stage larvae of P .decip1ens were cultured in a bacterial mat prior to fixation for S.E.M., and the external ultrastructure of these larvae is described. The most prominent external feature at this stage is the cephalic boring tooth. Aspects of the internal ultrastructure of A. simplex, P.decipiens, C.osculatum and H.aduncu were examined using transmission electron microscopy. Newly hatched third stage larvae of P.decipiens show little differentiation of internal organs. The ultrastructure of sensory amphids in H.aduncum and A. simplex is cons i stent wi th that of a chemoreceptor, that of the single papilla in P.decipiens a mechanoreceptor. The ultrastructure of the digestive tract, excretory gland and body wall of marine ascaridoids were also examined.

No description available.

Typescript. / Bibliography: leaves 166-171. / Microfiche. / xiv, 171 leaves, bound ill. 29 cm

Thesis (M.S.)--Auburn University, 2007. / Abstract. Includes bibliographic references (ℓ. 105-123)

Thesis (M.S.)--Oregon State College, 1952. / Typescript. Includes bibliographical references (leaves 120-121). Also available online.