bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental control of teleost reproductive cycles: a brief review
Authors: de Vlaming Victor L.
Published: January 2006

Reports concerned with the environmental regulation of teleost reproductive cycles are critically reviewed. Photoperiod and temperature have been the most frequently studied environmental factors with respect to control of sexual cycling. Photoperiod may exert the dominant regulatory role in the salmonid family, but few species have been examined so no conclusive statement is presently possible. Both photoperiod and temperature may be important controlling factors in the cyprinid family, but inadequate controls prohibit meaningful interpretation. Temperature may be extremely important in regulating reproductive cycles in the cyprinodontiform fishes. Although the data are inconclusive, it appears that changes in daylength play some role in reproductive cycling in the gasterosteids. Photoperiod and temperature seem to interact in regulating the sexual cycles in the 2 periform species investigated.

It is concluded that short term laboratory studies may lead to erroneous statements concerning the importance of exogenous factors in controlling annual reproductive cycles. Although photoperiod has been credited as the dominant environmental regulatory factor in many previous investigations, photoperiodism seems to be temperature sensitive in a majority of the teleost species studied. Responsiveness to exogenous factors appears to depend on the gonadal condition of the beginning controls (effects vary with season). Considerable variation is seen in the reproductive timing mechanisms among the teleosts and few generalizations can be made with regard to phylogenetic, geographic or ecological relationships of the fishes studied.
Fish haematology‐A bibliography
Authors: Hawkins Rosemary I. , Mawdesley‐Thomas LionelE.
Published: January 2006

Over 900 references have been documented concerning Fish Haematology. This bibliography, it is hoped, will be of assistance to research workers particularly in their preliminary library search.
Revised food consumption estimate of a bluegill sunfish population in Wyland Lake, Indiana, U.S.A.
Authors: Gerking Shelby D.
Published: January 2006

The estimate of food consumption by the bluegill sunfish (Lepomis macrochirus) population of Wyland Lake, Indiana, was examined with reference to recent research on the length of the growing season and the effect of body weight, ration and activity on growth efficiency. Growth efficiency was measured in the laboratory in terms of protein, comparing nitrogen assimilated with nitrogen accumulated over a period of about 30 days.

The revised consumption of protein was 134.9kg (or 1407kg live weight of aquatic organisms, 444 kg/ha) during a growing season of 111 days compared with the original estimate of 127.3 kg calculated for an assumed growing season of 150 days, a difference of only 6%. The correspondence between the two estimates was coincidental. The original estimate was made at a time when the growing season had not been measured and the effect of ration and body size on growth efficiency was not precisely known. Corrections for these factors plus that for activity compensated for one another, closely approaching, by chance, the original value.
Biochemical genetics of the Atlantic salmon Salmo salar L.
Authors: Wilkins Noël P.
Published: January 2006

In recent years, blood group and protein polymorphisms in Atlantic salmon have been investigated extensively with a view, primarily, to their use in identifying individuals of different spawning populations present in high seas fisheries. Erythrocyte antigens, haemoglobins, serum proteins and various tissue enzymes—mainly esterases and de‐hydrogenases—have been studied by electrophoretic and immunological techniques. These studies are reviewed here for the first time.

Many of the protein systems exhibit multiple components and this fact, together with cytological evidence, indicates the occurrence of tetraploidy in the course of Salmonid evolution. The significance of a tetraploid origin in the evolution and ecological adaptation of Salmonids is discussed briefly.

Some protein systems studied exhibit phylogenetic variation, and analyses of phenotype ratios and allele frequencies indicate that the populations of different river systems are genetically distinct. Allele frequencies have not yet been shown to be stable from generation to generation however, and some of the factors likely to affect allele frequencies are discussed.

Different spawning populations can not be identified in high seas fisheries using these protein characters, although it may be possible to identify the continent of origin (N. America or Europe) of some individuals. Indeed, it has been proposed independently by two groups that North American and European populations of Atlantic salmon be assigned to different sub‐species viz. S. s. americanus and S. s. europaeus respectively. The contradictory evidence on which these taxa are proposed is discussed, together with the evidence for other population groups proposed in the European part of the salmon's range. The possible role and future direction of studies on the biochemical genetics of salmon are outlined.
The biology of the West African shad Ethmalosa fimbriata (Bowdich) in the Lagos Lagoon, Nigeria
Authors: Facade S. O. , Olaniyan C. I. O.
Published: January 2006

The biology of the population of Ethmalosa fimbriata occurring in the Lagos lagoon was investigated. Three size groups, 35–69 mm (Yoyo), 70–169 mm (Efolo) and 170 mm and above (Agbodo) occur in the lagoon and the spatial distribution of these size groups and the length frequency distribution of the species is given. The relationship between length, weight, age and growth is discussed and the food and feeding intra‐relationship of the size groups is shown. Information on the fecundity and possible spawning periods is discussed.
Some differences in the parasitic fauna of three samples of plaice (Pleuronectesplatessa L.) from the southern North Sea
Authors: Wickins J. F. , Macfarlane I. S.
Published: January 2006

Plaice (Pleuronectesplatessa L.) from three spawning areas in the southern North Sea were examined for six species of metazoan parasite. Differences of both incidence and level of infestation with particular parasite species were found in fish from the three areas. Neither the incidence nor the level of infestation was associated with the length of fish in the samples except in the case of the larger male fish from Flamborough, which tended to contain more larval nematodes (Anisakidae). All fish contained the intestinal nematode Cucullanus heterochrous, although fewer were found in fish from Flamborough. Southern Bight fish were more likely to contain Capillaria wickinsi than were fish from Flamborough or the German Bight. Flamborough fish were more likely to contain Anisakidae larvae than were fish from the other two areas. Fish from the three areas were similarly infested with Zoogonoides viviparus. Male fish from Flamborough were less likely to be infested with Lepeophtheirus pectoralis than male fish from the German Bight.
The scarcer freshwater fishes of the British Isles
Authors: Wheeler Alwyne , Maitland Peter S.
Published: January 2006

This, the first of two papers on the scarcer freshwater fishes of the British Isles, gives an account of the introduced species. Nineteen species are included. The natural distribution of these fishes, the history of their introduction, their success in acclimatization, and their present distribution in the British Isles are given. A brief discussion on the introduction of exotic fishes to aquatic ecosystems follows.
The spawning seasons of Caribbean reef fishes
Authors: Munro J. L. , Gaut V. C. , Thompson R. , Reeson P. H.
Published: January 2006

Observations are recorded on the time of spawning of 83 species of Caribbean reef fishes. Details of seasonal variations in the percentage of sexually active fishes are given for 35 species. The majority of species spawn mostly when water temperatures are minimal, in February, March and April. The expected biomass of reef fish eggs in the plankton is about twelve times greater in the above mentioned period than in the period from June to December. Normal recruitment to insular fisheries may be very greatly dependent upon the success of parent stocks spawning elsewhere in the Caribbean and the abundance of recruits to a particular area may be dependent upon the speed and direction of the prevailing currents which carry larvae and juveniles to the insular shelves.
Immune relations between mother and foetus in the viviparous poeciliid fish Xiphophorus hellerii Haeckel
Authors: Hogarth P. J.
Published: January 2006

Advanced embryos of the viviparous poeciliid fish Xiphophorus hellerii (swordtail) were removed from the site of gestation within the ovary and re‐implanted into the peritoneal cavities of unrelated immunologically competent adults of the same species. Most of those transplanted with intact fertilization membranes were normal in appearance, and many were clearly still alive. Those transplanted without a fertilization membrane were all dead, with lymphocyte infiltration and other evidence of rejection as allografts. The integrity of the membrane in late pregnancy was indicated by swelling of follicles in hypoosmotic liquid. It was concluded that the fertilization membrane is capable of protecting an antigenically foreign embryo in an immunologically hostile environment, and that it probably serves this function during normal pregnancy.
Lethal and ‘disturbing’ temperatures in some fish species from lakes with normal and artificially elevated temperature
Authors: Horoszewicz Lidia
Published: January 2006

The mean lethal temperatures and ‘disturbing’ temperatures of 14 species of freshwater fish have been determined in field tests carried out on lakes unheated and heated by power‐stations near Konin. The relationships between these parameters and the acclimation temperatures of fish in these lakes are analysed in relation to roach Rutilus rutilus (L.), rudd Scardinius erythrophthalmus (L.) and perch Perca fluviatilis (L.) and compared with the other published data for these species.
A comparison of the parasite fauna of young whiting, Odontogadus merlangus (L.) (Gadidae) from an inshore and an offshore location off the Isle of Man
Authors: Shotter R. A.
Published: January 2006

The occurrence of 12 helminth and 4 crustacean parasites on young whiting 0–2 years old from an inshore (Port Erin Bay) and an offshore (off Bradda Head) area of the Isle of Man were compared. No parasites were found on whiting 4.5–15 mm long and the intestinal digenean Lecithaster gibbosus Rudolphi together with the larvae of the copepod Caligus rapax M. Edwards were the first parasites to appear in whiting 15–42 mm long. This appears to be the only time during the life history of the whiting that C. rapax is of importance as a parasite. In whiting 6 months‐2 years old from off Bradda Head such helminths as the acanthocephalan Echinorhynchus gadi Muller and the digeneans Podocotyle atomon Muller and Cryptocotyle lingua Creplin (metacercariae) were found in significantly fewer fish than in an equivalent group from Port Erin Bay. The differences are correlated with the availability of intermediate hosts and the different food spectra of the two groups of fish and are used to support the theory that inshore and offshore whiting of these age groups form separate populations and that the offshore fish may be more important than the inshore fish in replenishing stocks of older whiting.
Ichthyophthirius multifiliis (Fouquet) in the mirror carp, Cyprinus carpio L.
Authors: Mines Ron S. , Spira Dan T.
Published: January 2006

Mirror carp were infected with Ichthyophthirius multifiliis (Fouquet) under standardized conditions. The size and number of parasites at selected sites on the body were recorded during the course of the infection. Initial exposure to 40 mature parasites resulted in a mild infection with 100% recovery after 18 days. Recovered fish did not appear to be carriers of the parasite. Exposure to 400 parasites resulted in 100% mortality between 22–25 days. The growth rate of the parasite was linear. Parasites were more numerous in the dorsal surface of the fish than in the lateral or ventral surface. The increase in parasite numbers during the disease was greater in the gills than in the skin.
Induced spawning of grey mullet Mugil cephalus L. with fractionated salmon pituitary extract
Authors: Shehadeh Ziad H. , Kuo Ching‐Ming , Milisen Kathy K.
Published: January 2006

The efficacy of fractionated salmon pituitary gonadotropin as a spawning agent in Mugil cephalus L. was tested. Natural spawning was induced in all females with a total dose of 11.9–20.9 μg/g body wt. Spawning dose varied inversely with initial mean egg diameters of recipient females. A ‘critical’ mean egg diameter of 650–700 μ was observed to precede the hormone dose that induced spawning. A ‘priming’ effect was observed following the initial injection and is discussed. The ‘latency period’ was determined to be 10–15 h; fecundity was estimated at 648 eggs/g body wt. Courtship, spawning and fertilization occurred naturally with uninjected males.
An analysis of five enzyme‐gene loci in four etheostomid species (Percidae: Pices) in an area of possible introgression
Authors: Martin F. Douglas , Richmond Rollin C.
Published: January 2006

The possibility of natural hybridization between two species of darters, Etheostoma spectabile and caeruleum was investigated using the technique of starch gel electrophoresis of skeletal muscle homogenates. Inter‐ and intraspecific genetic variability at five enzyme loci was found. Presumed morphological hybrids are most probably not genetic hybrids as judged by their enzyme genotypes. The analysis of enzyme variability supports a previously published phylogeny for the darters.
The apparent inability of cyprinid fish to produce skin‐sensitizing antibody
Authors: Harris J. E.
Published: January 2006

Both egg albumin and horse serum failed to induce systemic anaphylactic shock in cyprinid fish. The production of skin‐sensitizing antibody by these fish to either horse serum, egg albumin or antigenic extracts of the cestode, Caryophyllaeus laticeps or the acantho‐cephalan, Pomphorhynchus laevis, could not be demonstrated by homologous passive cutaneous anaphylaxis (PCA) or by heterologous PCA reaction in guinea‐pigs. It was considered therefore, that fish are unable to produce such antibody, at least in response to these antigens, and that it is unlikely that skin‐sensitizing antibody is involved in the rejection of C. laticeps by dace Leuciscus lueciscus (L.). The phylogenetic origins of skin‐sensitizing antibody are discussed.
A numerical integration method for fish population fecundity
Authors: Pitcher T. J. , Macdonald P. D. M.
Published: January 2006

The numbers of eggs laid by an age group of fishes is underestimated by a simple multiplication of fecundity at the mean length by the numbers of females when the conventional logarithmic relationship between fish length and egg numbers is employed. This paper sets out the conditions under which the error becomes significant and derives a method of calculating the correct integral.
The distinction between brown trout and sea trout by the strontium content of their scales
Authors: Bagenal T. B. , Mackereth F. J. H. , Heron J.
Published: January 2006

A method is described for distinguishing the scales of sea trout from brown trout by their strontium content. Scales of brown trout contain less than 200 μgSr/g and those of sea trout more than 300 μgSr/g.
Mercury concentrations in fish, plankton and water from three Western Atlantic estuaries
Authors: Cocoros Glenn , Cahn Phyllis H. , Siler William
Published: January 2006

Total mercury concentrations were determined in the clupeid, Brevoortia tyrannus, from three estuaries of the Western Atlantic, and in the plankton on which they feed, as well as in the water sampled from the same localities. Although there was some indication that the food chain is a likely source of mercury contamination in these fish, as seen by the very much higher levels found in viscera compared with the rest of the fish, there was no evidence of strong food chain intensification. Fish mercury levels (0.3 to 0.5 part/106 dry wt) were about twice that for plankton (0.1–0.2 part/106 dry wt), with higher levels in phyto‐than in zooplankton.
Observations on the age, growth, reproduction and food of the roach Rutilus rutilus (L.) in two rivers in southern England
Authors: Mann R. H. K.
Published: January 2006

Scales and opercular bones from 632 roach from the River Stour were used for age and back‐calculated growth determinations. The scales had clearer inner annuli but operculars clearer outer annuli in fish more than nine years old. The annuli were laid in late May or early June at the beginning of the growth period. Growth was minimal between November and April. Roach from both rivers grow faster than those in most other European waters. Female roach grow faster than males; River Frome roach faster than those from the Stour. Spawning occurred in May and elaboration of gonads between September and May. Immature roach have an annual cycle in condition with a maximum in June and a minimum in early Spring. The condition of mature females is affected by the gonad cycle. The fecundity of Stour roach is represented by the formula: log egg number=4.43 log length (mm)—1.69. Approximately half of the Stour males attained sexual maturity at age III and most of the rest by age IV. Half of the females were mature at age IV and the remainder by age V. Both brood success and growth rate varied from year to year but independently of one another. Most Stour roach ate aquatic insect larvae and molluscs but algae were more frequent in the diet of larger fish.
Error in haematocrit value produced by inadequate concentration of ethylenediamine tetra‐acetate
Authors: Blaxhall Peter C.
Published: January 2006

A rise in the haematocrit value of blood from rainbow trout Salmo gairdneri (Richardson) after collection into dipotassium ethylenediamine tetra‐acetate and storage is reported. Investigation using blood from brown trout Salmo trutta (L.) showed this effect can be due to a too low concentration of anticoagulant in the blood. The need for studying the effects of anticoagulants on the blood of other fish species is stressed.
Development of colour patterns in relation to behaviour in Tilapia mossambica (Peters)
Authors: Lanzing W. J. R. , Bower C. C.
Published: January 2006

The development of chromatophores and the formation of colour patterns in Tilapia mossambica are described. A number of colour patterns are associated with certain aspects of behaviour. Four different melanophore systems are involved in the colour pattern formation. There appear to be 14 patterns which, in various combinations, produce a series of colour patterns. Each of these may convey a different message to different species of Tilapia.
Microspectrophotometric and enzymatic analyses of fish plasma proteins electrophoretically separated in thin polyacrylamide gels
Authors: Balsano J. S. , Rasch E. M.
Published: January 2006

A system for horizontal, discontinuous electrophoresis in thin sheets of polyacrylamide gel was developed to permit rapid and direct comparison of multiple samples of fish plasmas for population studies. The resulting electropherograms are suitable either for screening for enzyme polymorphisms or for densitometric scanning after gels are stained for total proteins. Each gel sheet (110×90×0.8 mm) can be used for simultaneous separation of 10–15 different samples. Since total voltage and the running time required for successful resolution of fine protein bands are greatly reduced in this system, minimal heating occurs within the gel matrix during electrophoresis. Up to 120 different blood samples (8 gel sheets) can be processed in about 8 h. Gel sheets are routinely stained overnight in Coomassie Brilliant Blue (0.1%, v/v), rinsed several times and stored overnight in 7% acetic acid to complete destaining. Particular gel sectors are then transferred to distilled water and mounted on glass microslides for photography or for densitometric evaluation with a Leitz microspectrophotometer. These procedures have been used to identify characteristic differences in the electrophoretic mobilities of plasma enzymes and albumin fractions from several populations of poeciliid fishes. Observed differences in albumin mobilities (albumin phenotypes) were verified by mixing isoaliquots of test plasmas with plasma samples containing albumins of known mobility. Resultant patterns for albumin bands for such mixed plasmas were indistinguishable from those obtained with plasma samples from the F1 hybrid progeny of parents possessing albumins of characteristically different electrophoretic mobilities. Procedural details for gel casting, electrophoresis and sample evaluation are described.
Respiratory metabolism of Utah chub, Gila atraria (Girard) and speckled dace, Rhinichthys osculus (Girard)
Authors: Rajagopal Pokkavil K. , Kramer Robert H.
Published: January 2006

Measurements of active, standard and routine oxygen consumption were made for 207 Utah chub at 6°, 9°, 12°, 18° and 22° C; and 123 speckled dace at 4°, 8°, 12° and 18° C. These were expressed as mathematical functions of water temperature and size of the fish. The mean slopes of loge oxygen consumption (mg O2/h) and loge wet weight (g) were 0.771, 0.526, and 0.619 for active, standard, and routine rates respectively for Utah chub, and 0.943, 0.486, and 0.683 respectively for speckled dace.
Observations on the age, growth, reproduction and food of the dace, Leuciscus leuciscus (L.), in two rivers in southern England
Authors: Mann R. H. K.
Published: January 2006

Scales of 497 dace from the river Stour and 573 from the river Frome were used for age determinations. Annuli were laid down in late May to early June at the start of the growth period. Minimal growth occurred from November to April. Male dace grew minimally faster than females; Frome dace faster than those from the Stour. Growth rates in the two rivers were similar to those published for most other European waters. Variation in growth rates in different years was not great, but there were marked differences in recruitment success. Spawning occurred in the second half of March and elaboration of the gonads between September and March. Immature dace have an annual cycle in condition with a maximum in June and a minimum during the winter months. The condition of the mature females is affected by the gonad cycle. The fecundity of Stour dace is represented by the formula:

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and for Frome dace by:

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Most dace were mature by age IV, but there were more mature II and III group fish in the Frome population. Molluscs and Trichoptera larvae comprised the bulk of the winter diet of Stour dace, and Ephemeroptera nymphs, Simulium and chironomid larvae were the principal constituents during the summer.
A population study of Barbus barbus (L.) in the River Severn, England
Authors: Hunt P. C. , Jones J. W.
Published: January 2006

Five hundred and thirty one of a total of 3122 tagged Barbus barbus (L.) in the middle Severn were recaptured using electric fishing and angling. Ninety two barbel were recaught downstream of the site of tagging, 152 upstream and 287 did not move. Electric fishing was selective for home recaptures. The barbel population was divisible into mobile and static components; 86% remained within 5 km, the remainder wandering more widely up to a maximum of 34 km from their site of tagging. Movement seemed to be dependent on size of the fish.
Seasonal changes in the hypothalamo‐hypophyseal‐ovarian system in the catfish, Heteropneustes fossilis (Bloch)*
Authors: Viswanathan N. , Sundararaj Bangalore I.
Published: January 2006

The annual reproductive cycle of the catfish, H. fossilis (Bloch) is divided into the preparatory period (February‐April), the prespawning period (May‐June), the spawning period (July‐August) and the postspawning period (September‐January). During the early postspawning period (September‐November), the hypothalamo‐hypophyseal‐ovarian system shows a gradual regression. In January, the hypothalamic nuclei, the pars magnocellularis (PMC), the pars parvocellularis (PPC) of the nucleus preopticus (NPO), and the nucleus lateralis tuberis (NLT) show renewed activity, as shown by a significant increase in their nuclear diameters and an accumulation of neurosecretory material (NSM) in their cell bodies. The hypophysis and the ovary remain quiescent. During the preparatory period, all the hypothalamic neurons studied indicate decreased activity but simultaneously show an accumulation of NSM in their cell bodies. The number of granulated basophils in the proximal pars distalis (PPD) of the hypophysis remains low but ovarian weights increase, presumably due to the multiplication of oogonia. In the prespawning period, there is a marked accumulation of NSM in the cell bodies of the hypothalamic neurons and at the same time the number of granulated basophils in the PPD of the hypophysis dramatically increases with concomitant increase in vitellogenic activity in the ovary. During the spawning period, the hypothalamic neurons continue to store NSM in their cell bodies and simultaneously there is a tremendous increase in the number of granulated basophils in the PPD of the hypophysis and the ovary has a large proportion of yolky primary oocytes. Spawning is associated with a significant degranulation of the granulated basophils in the PPD of the hypophysis. The significance of the results is discussed in relation to the environmental and hormonal regulation of seasonal ovarian activity.
Effects of cortisol and human chorionic gonadotrophin (HCG) on ovulation in ayu Plecoglossus altivelis (Temminck & Schlegel) with special respect to water and ion balance*
Authors: Hirose Keiji , Ishida Rikizo
Published: January 2006

This study was undertaken to discern the effects of cortisol and human chorionic gonadotrophin (HCG) on ovulation in ayu, Plecoglossus altivelis (Temminck & Schlegel), with special reference to water and ion changes. Cortisol as well as HCG was very effective in inducing ovulation of ayu. The best response was obtained with 10 mg of cortisol. In combination of cortisol and HCG, the effective dosage of cortisol was less than when cortisol was used singly. In fish which received cortisol and/or HCG, both the gonadosomatic index (GSI) and the percentage increase in body weight were significantly greater when compared to the control. The increase in body weight appeared to be due to an ingestion of water in fish treated with hormone, as described in our previous report. At ovulation there was a high sodium content in the ovary of fish treated with hormone, whereas a low sodium content was seen in the muscle. It appears that the fish imbibes some water resulting in hydration of the oocytes with concurrent ion movement during maturation and ovulation. These results suggest that gonadotrophin and cortisol may exert their initial effect on the oocytes in a direct or indirect manner, possibly acting to affect the sodium transport system or to alter passive permeability of the egg membrane.
Parasites of fishes from Laurel Creek, Ontario
Authors: Molnar Kalman , Hanek George , Fernando C. H.
Published: January 2006

Two‐hundred and nine fish of 13 species from Laurel Creek, Ontario, were examined for parasites between May and October 1973. Eighty‐four species of parasites (22 of Protozoa, 24 of Monogenea, 17 of Digenea, 11 of Cestoda, 4 of Nematoda, 1 of Hirudinea, 1 of glochidia, and 4 of Crustacea) were collected and are listed and discussed.
Thermal response of juvenile Hawaiian mullet Mugil cephalus (L.) to acclimation time and fluctuating low temperatures*
Authors: Sylvester J. R.
Published: January 2006

Rates of acclimation and the response to fluctuating low temperatures of juvenile striped mullet Mugil cephalus (L.) have been described in terms of changes in heat resistance over a period of time. Fish changed from 25.5 to 27 or 29° C were acclimated within seven days. Acclimation to 23 or 15° C required a maximum of 11 days. Thermal responses to fluctuating low temperatures were lower than responses to constant temperature levels. Cyclic variations in heat resistance were present in all experimental and control tests.
Osmoregulation in juvenile Rhabdosargus holubi (Steindachner) (Teleostei: Sparidae)
Authors: Blaber Stephen J. M.
Published: January 2006

Juvenile Rhabdosargus holubi (Steindachner), one of the commonest teleosts in south east African estuaries, are strong osmoregulators, showing little change in their internal osmotic concentration over an extremely wide salinity range. In 35‰ seawater the internal osmotic concentration is held at 370 mosmol/1. At a salinity of 1‰ the internal osmotic concentration falls to 216 mosmol/1 and at a salinity of 65‰ rises to 381 mosmol/1. When exposed to a new salinity the internal osmotic concentration does not change until after 10 h; this may be of considerable importance to fish living in areas subject to short term changes of salinity.
Some aspects of the infrastructure of the ‘Stäbchendrüscnzellen’, a peculiar cell associated with the endothelium of the bulbus arteriosus and with other fish tissues*
Authors: Flood Mary T. , Nigrelli Ross F. , Gennaro Joseph F.
Published: January 2006

The fine structure of an unusual cell, the ‘Stäbchendriisenzellen’ (the so‐called foliaceous or rodlet cells of several authors), associated with the endothelium of the vascular system of marine and freshwater fishes was studied in the goldfish Carassius auratus (L.). The bulbus arteriosus was fixed with either a 6 % solution of buffered glutaraldehyde or with one part of a 3 % solution of lanthanum nitrate plus two parts of a 3 % solution of buffered glutaraldehyde and then post‐fixed in a 1.2% solution of osmium tetroxide. Electron micrographs of the vascular tissue show four cell forms which appear to be phases in the life cycle of the endothelium‐associated cell. Two of the phases are not encased and are characterized by their inclusions: in one cell these are crystalline, while in the second, they are amorphous and granular. In the other phases the cell is encased partially or completely within an apparently contractile fibrous wall surrounded by the plasmalemma. In the encased phases, the arrangement and condition of the cell organelles appears to have been changed, and in the fully‐encased phase mitochondrial activity seems to have decreased. This apparent change in the mitochondrial activity is accompanied by a thickening of the mitochondrial membrane from 48 to 109 Å. The micrographs seem to indicate that this cell in question behaves as a foreign body and, in some way, may be interacting with the epithelial tissue of the bulbus arteriosus.
Critical thermal maxima of three species of Hawaiian estuarine fish: a comparative study*
Authors: Sylvester J. R.
Published: January 2006

Crticial thermal maxima (CTM) of three species of Hawaiian estuarine fishes were determined in relation to acclimation temperature and time of day. The species studied were Mugil cephalus L., Chelon engeli (Bleeker) and Kuhlia sandvicensis (Steindachner). Critical thermal maxima of all three species were significantly affected by acclimation temperature and time. In relation to acclimation temperature, Mugil cephalus and Chelon engeli have similar critical thermal maxima with Kuhlia sandvicensis having a critical thermal maxima about 1° C below that of the other two species studied. Mugil cephalus and Chelon engeli showed an increasing critical thermal maxima toward midday which decreased therafter. Critical thermal maximum of Kuhlia sandvicensis increased throughout the day.
A report of suspected erythrodermatitis in carp in Great Britain
Authors: Bucke D. , McCcarthy D. , Hill B.
Published: January 2006

An epizootic in imported carp (Cyprinus carpio L.) was examined by bacteriological, viro‐logical and histological methods. The microbiological investigations did not reveal the aetiology of the disease, but the histological description of the lesions is similar to that for carp erythrodermatitis ‘CE’.
Some aspects of the biology of the plerocercoid of Gilquinia squali Fabricius 1794 (Cestoda: Trypanorhyncha)
Authors: MacKenzie K.
Published: January 2006

The eyes of more than 24 000 northern North Sea whiting were examined for infection with Gilquinia squali plerocercoids. Infection, which is apparently non‐seasonal, begins when the fish are aged 1 +, builds up to a peak at 2+ to 4+, and decreases thereafter. The intensity of infection ranged from 1–18 plerocercoids per fish. Evidence is presented of the development of immunity in whiting to G. squali, and observations on the parasite's eggs suggests that they are not randomly distributed but tend to aggregate. One or both of these features could give rise to the negative binomial type of frequency distribution observed. The frequency of left eye infection was consistently greater than that of right eye.
The effect of electric fishing on the subsequent capture of fish*
Authors: Cross D. G. , Stott B.
Published: January 2006

Experiments show that the first of a series of replicate electric fishings can cause a decrease in catchability so that the second and subsequent catches are made from what is, effectively, a reduced population. Depletion (DeLury) estimates can be thus seriously low. Species affected are roach Rutilus rutilus (L.), gudgeon Gobio gobio (L.), rudd Scardinius erythophthalmus (L.) and, from other published data, probably rainbow trout Salmo gairdneri Richardson and eels Anguilla anguilla (L.). Being caught does not, apparently, cause fish to become less catchable. The reason why an electric field causes a proportion of a population to become uncatchable is obscure but it may be that refractory behaviour is involved; the effect lasts for between 3 and 24 h. A method is given for adjusting DeLury estimates for decreased catchability.
Renicola metacercariae (Digenea: Renicolidae) in clupeoid fish: new host records
Authors: Mackenzie K.
Published: January 2006

Two distinct types of Renicola metacercariae were found in herring, Clupea harengus L., from Scottish waters, and one in anchovies, Engraulis encrasicholus (L.), from the central North Sea. Both constitute new host records. These parasites may prove to be of value as biological tags for herring and other clupeoid fish.
The transport of freshwater fish
Authors: Hattingh J. , Le Roux Fourie F. , van Vuren J. H. J.
Published: January 2006

A method is described for the transport of fish resulting in very few or no mortalities during or after this procedure. Commercial salt is added to the water to give a final conentration of 0–5 %, compressed air is bubbled through the water and the fish are kept in ‘salt water’ after transportation to decrease the incidence of skin infections.
An assessment of a tow net used to sample coarse fish fry in rivers
Authors: Brown D. J. A. , Langford T. E.
Published: January 2006

The design and use of a tow net for sampling coarse fish fry in rivers are described, and its performance over a year is discussed with regard to species selectivity and size selectivity. The extent to which it can be used to provide data on the comparative abundance of the fry and their mean lengths and associated variances are described.
Life history variations in populations of American shad, Alosa sapidissima (Wilson), spawning in tributaries of the St John River, New Brunswick
Authors: Carscadden James E. , Leggett William C.
Published: January 2006

Shad were sampled at four locations in the St John River area, New Brunswick; St John Harbour, Kennebecasis River, Washademoak Lake and Mactaquac Dam. The effect of the St John Harbour fishery on upstream spawning populations was minimal. Mactaquac Dam began operation in 1967 and since that time the populations of shad arriving at that facility have been in a state of flux. When shad populations from Kennebecasis River and Washademoak L. were compared, the Washademoak Lake population exhibited higher relative fecundity, lower mean age at maturity and possessed a lower proportion of repeat spawners. The combinations of reproductive characteristics occurring in the populations of the St John River were the same as those occurring over the Atlantic coast range of shad. The possible environmental factors influencing the variations in reproductive characteristics are discussed.
Salinity and oxygen tolerances of eggs and larvae of Hawaiian striped mullet, Mugil cephalus L.*
Authors: Sylvester J. R. , Nash C. E. , Emberson C. R.
Published: January 2006

Salinity and oxygen tolerances of eggs and larvae of Hawaiian striped mullet (Mugil cephalus L.) were studied. Optimal salinities for eggs incubated at 19.5‐20.5°C were 30–32‰. Maximum larval survival occurred within the salinity range of 26–28‰. Significant decreases in egg survival occurred with eggs incubated in mean oxygen concentrations below 5.0 p.p.m. and for larvae held in mean oxygen concentrations below 5.4 p.p.m. The results are discussed in terms of spawning sites and the effects of oxygen saturation values on fish eggs and larvae.
Ecological notes on the Haplochromis (Pisces: Cichlidae) species‐flock of Lake George, Uganda (East Africa)
Authors: Dunn I. G.
Published: January 2006

Lake George, a shallow equatorial lake, supports a Haplochromis species‐flock of 17 species. Of the five species that dominate the species‐flock, two feed mainly on benthic and mid‐water dipteran larvae, one is a piscivore, one exploits microcrustacea and another the abundant blue‐green phytoplankton population. There is little stenophagy in this group. There is a seasonal variation in the total gill‐net catch of the three dominant Haplochromis of the sandy shoal habitat, with high catches in ths wet season and low catches in the dry. Similar fluctuations are known to occur in the commercial catches of Sarotherodon niloticus. No seasonal changes were observed in the proportions of the individual species making up this community and the individuals breed all the year round.

A combination of ecologically unspeeialized species, resulting in an efficient exploitation and stability of the ecosystem may account for the observed high fish biomass and the high numbers of individuals. Taking into account the effect of the monotony of the environmental conditions, the physical continuty of the available habitat types and the relatively short time that the lake has been in existence, coupled with the apparent lack of rigid ecological requirements by the individual members of the Haplochromis group, it is suggested that this species‐flock may still be at an early stage in its evolutionary develoment.
A hermaphrodite specimen of Coregonus lavaretus (L.) (Salmoniformes, Salmonidae) from Loch Lomond, Scotland
Authors: Scott D. B. C.
Published: January 2006

A single hermaphrodite specimen of Coregonus lavaretus (L.) was caught mid‐January in Loch Lomond, Scotland.
Larval development of Bothriocephalus sp. (Cestoda: Pseudophyllidea) from carp (Cyprinm carpio L.) in Germany*
Authors: Körting Wolfgang
Published: January 2006

Life cycle experiments with the tapeworm Bothriocephalus sp. from carp were carried out using Cyclops abyssorum Sars as the intermediate host. The eggs expelled from gravid segments were embryonated but not fully developed. Hatching of the coracidia occurred by the third day. Procercoid development was completed after 8–10 days. Comparing the results and descriptions of previous authors, it is suggested that the cestode belongs to Bothriocephalus acheilognathi Yamaguti, 1934 according to the priority of name.
The effects of parasitism by the plerocercoid of Schistocephalus solidus Muller 1776 (Pseudophyllidea) on the respiration of the three‐spined stickleback Gasterosteus aculeatus L.
Authors: Meakins R. H. , Walkey M.
Published: January 2006

Rates of oxygen consumption by parasitized and unparasitized sticklebacks were recorded at three levels of activity in February and August. Negative correlations were demonstrated between specific respiratory rates and fish body weights. At routine and maximum activity, infected fish consumed more oxygen than uninfected fish. At minimum activity levels no significant differences in respiration rates were detected. Seasonal variation in respiration rates was attributed to acclimation. Difficulties of determining specific respiration rates for parasitized organisms are discussed and attempts are made to assess the physiological basis of the respiratory and behavioural characteristics of infected fish.
Differences in low pH tolerance among strains of brook trout (Salvelinus fontinalis)*
Authors: Robinson G. D. , Dunson W. A. , Wright J. E. , Mamolito G. E.
Published: January 2006

Survival time of brook trout (Salvelinus fontinalis Mitchill) at low pH was directly related to size, and inversely related to temperature. Between pH 2.50 and 3.25 an increase in pH by increments of 0.25 each led to a 2–3 fold increase in survival time. At higher pH's (3.25–3.75) elevations in pH by the same increments each produced a 3–5 fold increase. Brook trout tested at pH 3.35 and 3.50 showed maximum survival times in June‐August. Members of seven inbred lines of brook trout were tested for acid tolerance; the lines differed markedly providing strong evidence that acid tolerance is hereditary. Tests involving either intercrossed or backcrossed offspring of tolerant or intolerant parentals demonstrated intermediate survival in 12.5% of all experiments and heterosis in 66.7% of the tests. Differences in survival of inbred lines were the most marked at pH 3.25. Exposure for 1 week at pH 3.75 resulted in a 20–25% decrease in survival time of 18 fish tested at pH 2.50 and 3.00. Out of a total of 24 trout (17 g) tested at pH 3.75 two highly tolerant individuals were still alive after 6.1 weeks. Thus it is likely that a strain resistant to a pH below 4.1, the previously recorded lower limit, can be developed by selective breeding.
The distribution of some helminth and copepod parasites in tissues of whiting, Merlangius merlangus L., from Manx waters
Authors: Shotter R. A.
Published: January 2006

In an examination of 1352 whiting 0–5+ years old from Manx waters it was found that the digeneans Hemiurus communis Odhner and Derogenes varicus Müller were restricted to the stomach. Stephenostomum pristis Looss, Podocotyle atomon Rudolphi and Leci‐thaster gibbosus Rudolphi were most commonly found in the anterior intestine and caeca of mature fish but were found more posteriorly along the intestine of young whiting. The metacercaria of Cryptocoty lingua Creplin were found predominantly in the skin above the lateral line. The fins contained fewer cysts than expected from the area available. Plerocercoids of Grillotia erinaceus Van Beneden mainly infested the musculature of the pyloric stomach and those in the perivisceral cavity were concentrated in the extreme posterior corner. Unencapsulated forms of the nematode Contracaecum clavatum Rudolphi were commonest in the anterior intestine and stomach. Encapsulated forms were most abundant in the liver. The acanthocephalan Echinorhynchus gadi Rudolphi was usually found in the posterior intestine and its presence further restricted Contracaecum to the anterior intestine. In young whiting over two‐thirds of the copepod Clavella uncinata Müller were attached to the operculum and posterior rim but in older whiting the majority were attached to the gill rakers. The first gill arch was the most heavily infested and the middle region of the gill arches contained most parasites. The frequency distributions of most of the helminths described more or less a negative binomial distribution. The frequency distribution of Contracaecum did not conform to either a negative binomial or a Poisson distribution.
Breeding biology of a non‐diadromous galaxiid, Galaxias vulgaris Stokell, in a New Zealand river
Authors: Cadwallader P. L.
Published: January 2006

In the Glentui River, Canterbury, New Zealand, Galaxias vulgaris Stokell spawned in late winter and early spring (from July to September), the onset of spawning being temperature‐dependent. No females matured in their first year, but 95 and 68 % of age 0+ males were mature in consecutive years. With the exception of one female, all fish aged 1 + and older spawned. In mature fish, overies reached nearly 23%, and testes 11%, of somatic weight. Maturity in males depended on size, whereas in females, age appeared to be the major factor affecting maturity. Recruitment eggs for next season's spawning were distinct from primary oocytes soon after the ripe eggs were shed. Egg numbers varied between 284 and 1911 per fish, and weight was the best indicator of fecundity. Sex ratios of whole samples were not significantly different from 1 : 1, but ratios of potential spawners revealed an excess of males, due mainly to the presence of age 0 + fish. Age0+ males probably play an important role in adverse conditions and act as a form of insurance by significantly increasing the proportion of ripe males, thereby ensuring that all eggs are fertilized. The nest, egg mass and behaviour during the spawning period are described. More than one female may lay eggs in each nest and it is probable that each egg mass receives sperm from more than one male. It is suggested that the presence of fewer and larger eggs in G. vulgaris, compared with the diadromous galaxiids, is the result of a more precise fertilization process.
Variations in the energy content of freshwater fish
Authors: Meakins Robin H.
Published: January 2006

The calorific value of the three‐spined stickleback, Gasterosteus aculeatus, varied with its size, sex and the season. Fish of 16 mg dry weight had a value of 1950 cal/g while for fish of 313 mg the value was 470 cal/g. The califoric value of gravid females was 23% above that of males of comparable size. The califoric value of a tropical cichlid, Tilapia nilotica, with a dry weight of 11 g was 4300 cal/g, the calorific values of the tissues ranged from 2500 cal/g for bone to 5190 cal/g for muscle.
Ultrastructural changes in the hepatocytes of green sunfish, Lepomis cyanellus Rafinesque, exposed to solutions of sodium arsenate
Authors: Sorensen Elsie M. B.
Published: January 2006

The rate and level of arsenic accumulation in the liver of green sunfish is greater than that in the other organs examined. The level to which arsenic is concentrated is positively associated with the concentration of arsenic, in solution in the immediate environment of a fish, the duration of exposure to arsenic, and water temperature, Since it was found that accumulation causes histopathological changes, a study was made to examine the appearance of and rate of change in hepatocyte ultrastructure morphology following exposure to arsenic concentrations of 0, 30, or 60 ppm and after exposure times of one, two, or three weeks at 20°C. As arsenic concentration and exposure time increased, electron dense particles were observed, and the numbers of intranuclear and cytoplasmic electron dense particles and aberrant mitochondria increased. Also, lysosomes and smooth endoplasmic reticulum increased in number, while the number of myelin figures decreased.