bluuebunny/crossref_metadata_2025 huggingface dataset:
Occurrence of aneuploidy in radiation gynogenesis of carp, Cyprinus carpio L.
Authors: Gervai J. , Mariaan T. , Krasnai Z. , Nagy A. , Csánuyi V.
Published: January 2006

DNA content and chromosome numbers were studied in gynogenetic and normal carp embryos. Gynogenetic embryos showed the haploid chromosome number; the occurrence of spontaneous diploidization was rare. Early cold shock treatment of the gynogenetic zygotes resulted in the retention of the second polar body producing a much higher proportion of normally developing viable larvae. The appearance of large numbers of aneuploid embryos in the cold‐treated gynogenetic group is explained by the loss or breakdown of chromosomes that are caused in their turn by the absorbtion of the second polar body through the cold treatment.
Structure of the gills of Barbus sophor (Ham), a cyprinid with tertiary lamellae
Authors: Hughes G. M. , Mittal A. K.
Published: January 2006

A study of the structure of the gills using light and transmission electron microscopy showed that though the basic organisation of the filaments and secondary lamellae is very similar to that of other bony fishes, there was also a number of unusual features. Most of the blood channels of the secondary lamellae remain embedded in the tissue of the primary lamellae. The secondary lamellar surface is increased by the presence of irregular expansions which may be referred to as tertiary lamellae. The presence of an unusual structure on one side of many secondary lamellae was observed; this structure might possibly be due to the presence of a parasite. The possible functional significance of these observations is discussed and indicates the need for morphometric and experimental investigation of the respiration of this species.
Seasonal anatomical variations in the testes of European pike, Esox lucius L.
Authors: Hoffmann R. , Wondrak P. , Groth W.
Published: January 2006

The seasonal development of the testes in European pike was examined using wild fish and biopsies from pike housed in tanks. The size of the tubules and the different cell types were measured and their histological appearance described. Four stages of development can be distinguished during the annual cycle. They are: (I) the stage of rest from June to August; (II) the stage of development from September to November with intensive spermatogenesis; (III) the stage of maturity from December to March/April with spermatogenesis completed; and (IV) the post‐spawning stage from March to May.
A specimen of Lutjanus argentiventris (Peters) lacking pelvic fins
Authors: Alvarez‐León R.
Published: January 2006

This is the first report of a specimen of the family Lutjanidae, L. argentiventris (Peters), in which the pelvic fins are abnormally absent.
The tolerance of grass carp, Ctenopharyngodon idella Val., to aquatic herbicides
Authors: Tooby T. E. , Lucey J. , Stott B.
Published: January 2006

Because grass carp may feed selectively on water plants, additional conventional methods may be necessary for effective control of aquatic vegetation. For economic reasons aquatic herbicides are most likely to be used in conjunction with grass carp within an integrated aquatic weed control programme. The acutely lethal toxicities of ten herbicides to grass carp were measured. A preliminary evaluation of the risk to these fish showed that, when used at the recommended rate, the maximum herbicide concentration likely to be found in water should cause little harm to the fish, although attention should be given to the possible inhibition of feeding.
The consequences of marine gravel extraction on the spawning of herring, Clupea harengus Linné
Authors: de Groot S. J.
Published: January 2006

The rapid increase of the mining for marine gravels in the North Sea offers a serious threat to the marine environment and especially for the herring populations of the southern North Sea and Channel. The paper reviews the literature dealing with the herring and its spawning ground, behaviour, abiological characteristics—type of substrate, depth, salinity, temperature and current velocity. A hypothesis is made that sound may play an important role in guiding the herring to its spawning site.
The food of larval blue whiting, Micromesistius poutassou (Risso), in the Rockall area
Authors: Conway D. V. P.
Published: January 2006

Larval blue whiting of 3–42 mm total length, taken in 1967 and 1968 in the Rockall Bank area, were found to have fed almost exclusively on various stages of small crustaceans; the eggs, nauplii and copepodites of copepods, along with fewer numbers of larval euphausiids and Evadne nordmanni, formed the major proportion of the diet. The guts of the larger larvae contained a greater number of, and larger organisms, than those of the smaller larvae. Feeding incidence was generally lower at night. There was a general increase in the weight of the gut contents as the daylight hours progressed followed by a decrease during the night. Diurnal variation in the percentage composition of the food was also demonstrated. Comparisons of the diet in the two years showed that more food was consumed by almost all sizes of larvae in 1968.

It has previously been suggested that blue whiting larvae may find better feeding conditions on Rockall Bank than off the Bank. However the present study suggests that larvae, particularly of 8 mm and longer, took more food when off the Bank. A brief comparison is made of the gut contents of the larvae of blue whiting and of the other eight most abundant species.
Histological differences in the lateral musculature of O‐group roach, Rutilus rutilus (L.) from different habitats
Authors: Broughton N. M. , Goldspink G. , Jones N. V.
Published: January 2006

The composition of the lateral muscles of first‐year roach was studied using histological techniques. It was found that all samples had significantly higher levels of red muscles in the hindermost regions, and these levels rose as the fish became larger. Fish from a running water habitat contained significantly more red muscle than fish of the same age from still water, and it is suggested that this results from muscle development during natural‘training’to water flow.
Feeding behaviour of underyearling hybrids of the grass carp, Ctenopharyngodon idella♀ and the bighead, Hypophthalmicthys nobilis♂ on selected species of aquatic plants
Authors: Cassani J. R.
Published: January 2006

Underyearling hybrids of the cross Ctenopharyngodon idella♀ (grass carp) and Hypophthalmichthys nobilis♂ (bighead), averaging 104.8 mm total length were stocked for two weeks in cement tanks holding 605 1 of water with various combinations of submersed or floating aquatic plants. The submersed species most preferred were Ceratophyllum demersum, Chara sp. and Najas guadalupensis. Hydrilla verticillata, Hygrophila polysperma, Myriophyllum pinnatum and Utricularia foliosa were fed on from a minor to moderate extent. No feeding damage was observed on Egeria densa and Potamogeton illinoensis. Azolla caroliniana, Lemna sp. and Wolffia columbiana were readily consumed while Salvinia rotundifolia was not preferred when in combination with these floating plant species. Feeding damage to the submersed roots of Eichhornia crassipes and Pistia stratiotes was minor during a 30 day period. Hybrid fingerlings readily fed on mosquito larvae and small leeches when offered to them in an aquarium on one occasion.
The early stages of development in Carcharhinus plumbeus
Authors: Baranes A. , Wendling J.
Published: January 2006

Six embryos of the sandbar shark, Carcharhinus plumbeus, were found in a gravid female caught at Ras Muhammad, southern tip of Sinai peninsula, in October 1975. Their external morphology, internal organs, and the structure of the egg case and the uterus are described. Embryos were estimated to be two months old and all were in a stage of development between the end of the external‐gill phase and before the beginning of the pseudoplacenta formation. The foetomaternal interrelation is based on oxygen supply from the maternal uterus mucosa and some mucus is produced by tubular glands also in the uterus mucosa. The compartments formation and the septum generation are described. An embryonic‐membrane‐storage chamber has been found for each embryo and we assume that this structure is common, at least, to all the genus Carcharhinus.
The effect of feeding androgenic hormones on the proteolytic activity of the alimentary canal of carp Cyprinus carpio L.
Authors: Lone K. P. , Matty A. J.
Published: January 2006

The effect of feeding testosterone, 11‐ketotestosterone and adrenosterone for 60 days on the proteolytic activity of the alimentary canal of carp is reported. The proteolytic activity of the gut increased in all the experimental groups compared with the controls. One month after the cessation of the drug feeding, the proteolytic activity dropped to less than the control values. A de novo synthesis of the enzymes is suspected.
Some aspects of the reproductive biology of perch Perca fluviatilis L. A histological description of the reproductive cycle
Authors: Treasurer J. W. , Holliday F. G. T.
Published: January 2006

Histological changes in the perch ovary during development are described and related to changes in gonad weight and to a macroscopic scale of maturity stages after Kesteven (1960). A single organ formed by the fusion of two primordial ovaries, a central internal oviduct, and an extremely thick chorion surrounding oocytes are characteristic features of the perch ovary. Resting oocytes can be differentiated from developing oocytes which are larger and possess a granulosa layer which permits formation of the chorion and yolk acquisition. In the maturing ovary, oocyte diameter increases rapidly and the chorion, which possesses four layers, the tunica propria, two middle zones forming a fine network, and the zona radiata, also expands. The spent ovary is disorganized with follicles and tunica wall contracted, and a number of residual oocytes may be apparent. There was no evidence of pre‐ovulatory degeneration although autolysis of a small number of residual oocytes was observed. The gonadosomatic index was highest for males in September and at a maximum in females immediately prior to spawning. After spawning the index fell rapidly with lowest values recorded in June and July. Variations in the gonadosomatic index are related to developmental stages in females.
Validity of fin‐ray ageing for brown trout
Authors: Shirvell C. S.
Published: January 2006

Ageing of brown trout from their fin rays is a valid method. Fin‐ray ages agreed with length‐frequency ages 84% of the time during the year, but agreement was only 66% during annulus formation (October‐December) compared with 94% during the rest of the year The seasonal record of the annulus at the edge of the ray only weakly validated the technique, but this was caused by difficulty in distingushing the winter growth band when it was outermost on the ray. The first annulus was usually not apparent in older fish; this could cause systematic underageing. Ageing from fin rays should be assessed prior to use in each situation.
Effect of ascorbic acid deficiency on the uptake of iodine by thyroid and non‐thyroid tissues of an air‐breathing freshwater fish Channa punctatus Bloch
Authors: Agrawal N. K. , Mahajan C. L.
Published: January 2006

Using 131I as tracer, iodine uptake by various thyroid and non‐thyroid tissues has been reported in Channa punctatus in which vitamin C deficiency was experimentally induced by feeding vitamin C deficient diet to a level when morphological deficiency syndromes appeared. This was compared with a parallel control, fed a complete diet. The study showed a highly significant decrease in iodine uptake by thyroid tissues in vitamin C deficient fish as compared to the controls. However, the blood and other non‐thyroid tissues recorded a significant increase in absorption and distribution of iodine. These findings suggested hypofunctioning of thyroid gland due to a prolonged deficiency of vitamin C.
Post‐stocking movements and recapture of hatchery‐reared trout released into flowing waters—a review
Authors: Cresswell R. C.
Published: January 2006

The success of stocking with hatchery‐reared trout has been the subject of varied investigations for the past half‐century. Percentage returns are summarised, and literature on the post‐stocking movements of hatchery‐reared trout is reviewed. Factors affecting the poststocking movements are considered, special attention being paid to studies on industrial rivers. Highest returns are obtained from stockings, with trout of a size suitable for angling, made during or shortly before the angling season. The majority of stocked brown trout, Salmo trutta tend to remain close to the area of stocking, but brook trout, Salvelinus fontinalis and rainbow trout, Salmo gairdneri show greater movement, usually in a down‐stream direction. Greater dispersion of all species occurs if they have overwintered prior to capture or have been stocked in‘cold water’or in small upstream stretches of river.
Haematological changes in fish following aerial spraying with endosulfan insecticide for testse fly control in Botswana
Authors: Matthiessen P.
Published: January 2006

Endosulfan, an insecticide highly toxic to fish, is currently applied from the air for tsetse fly control in the Okavango Delta, Botswana. Although dosages are very ow (6–12 g a.i. ha−1), they cause some fish mortality and affects the behaviour of survivors. In order to determine how quickly fish recover from sublethal poisoning, four haematological characteristics (erythrocyte count, leucocyte count, haemoglobin concentration and plasma protein concentration) were monitored in several species during and after six sequential applications of endosulfan (July–October 1978). In all cases, blood cel counts were significantly elevated during spraying (by up to a factor of four), while plasma protein levels were often disturbed. Total haemogobin (Hb) did not change, but the mean weight of Hb per erythrocyte declined significantly in Tilapia spp. from 59 to 39 pg. Im most instances these quantities began returning to normal before spraying ceased and reached prespray levels within six months.
The respiratory mechanisms of the dusky flathead, Platycephalus fuscus (Platycephalidae, Scorpaeniformes)
Authors: Douglas W. A. , Lanzing W. J. R.
Published: January 2006

The respiratory mechanisms of a shallow‐water, marine and estuarine flathead, Platycephalus fuscus C. & V. are described. Morphological and behavioural adaptations enabling respiration while the fish is buried in fine, unconsolidated sediments are investigated and related to the ecology of the species.
Haematological effects of prolonged sublethal hypoxia on channel catfish*Ictalurus punctatus (Rafinesque)
Authors: Scott A. L. , Rogers W. A.
Published: January 2006

Sub‐adult channel catfish, Ictalurus punctatus, were exposed to sublethal hypoxia for 24, 48 or 72 h. Haematological parameters were used to assess the physiological state of the catfish subjected to prolonged, sublethal hypoxia. Haemoglobin, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentreation, plasma lactic acid and plasma glucose deviated significantly from control values in channel catfish exposed to hypoxia for 24, 48 or 72 h. Haematocrit, total plasma protein, total erythrocyte counts, total leukocyte counts mean corpuscular volume and differential leukocyte counts were not sensitive indicators to the catfish's physiological status. After five days, of reacclimation to oxygen levels saturation, channel catfish continued to exhibit haematological responses to prolonged hypoxia.
The effect of growth inhibiting factors on the total lipid content of the zebrafish, Brachydanio rerio (Hamilton‐Buchanan)
Authors: Roales R. R.
Published: January 2006

The effects of growth inhibiting factors on the total lipid content of zebrafish was studied. Crowded zebrafish were subjected to extraction of the aquarium water using activated charcoal. Control fish were crowded, but were not subjected to extraction. This resulted in a gain in mean wet weight of 10.9% for the crowded, extracted fish (experimentals) as compared to the controls. In order to determine the effects of crowding on the total lipid content of the crowded fish, lipid analyses were conducted at the conclusion of the growth studies. These studies indicate that the fish in the extracted system had a greater lipid content than those in the‐non‐extracted system (15.4% v. 10.4% mean lipid). It is proposed that growth inhibiting factors libeerated from the crowded fish may affect the thyroid gland, causing lipid mobilization from the tissues resulting in resulting in lowered total lipid in these animals. Extraction of the aquarium water with activated charcoal removes the growth inhibiting factor, possibly decreasing thyroid function with a resulting higher total lipid content.
The utilization of grass carp, Ctenopharyngodon idella Val., for hydrilla control in Lake Baldwin, Florida*
Authors: Shireman J. V. , Maceina M. J.
Published: January 2006

Grass carp, Ctenopharyngodon idella, >300 mm t.l. were stocked in Lake Baldwin, Florida during 1978 (24 fish ha−1) to evaluate their effectiveness for hydrilla control. Hydrilla, Hydrilla verticillata, was nearly eradicated from Lake Baldwin 2 years after stocking. Control was effective with 130 kg grass carp ha−1 of hydrilla and control was definite when biomass exceeded 185 kg ha−1 of hydrilla. Grass carp growth was rapid during the first two years as fish reached 9.17 kg by June 1980. Grass carp >6 kg consumed 25–28% of their body weight of hydrilla per day. The use of grass carp for vegetation management is discussed.
The effects of powdered carp pituitary on ovarian development, ovarian ascorbic acid and ovulation in Carassius carassius L. exposed to various photoperiod and temperature regimes
Authors: Seymour E. A.
Published: January 2006

The effects of temperature, photoperiod and powdered carp pituitary on ovarian development (measured by change in diameter of intraovarian eggs and gonadosomatic index), ovulation and ovarian ascorbic acid have been studied in crucian carp in winter. Short photoperiods stimulated ovarian development but long photoperiods were inhibitory. Photoperiod seemed to exert this effect by altering the release of pituitary gonadotropin. Temperature affected ovarian development independently of photoperiod. High temperatures were stimulatory and overcame the negative effect of a long photoperiod. The results suggested that temperature acts at the level of the gonad rather than the pituitary. On the basis of these findings a hypothesis is suggested to explain gonadal cycles in cyprinids and similarities to previous findings in other fish groups are discussed.

Levels of ovarian ascorbic acid varied according to treatments. Ovulation was associated with a decreased level. The results suggested that this vitamin aids biosynthesis of sex steroids in a similar fashion to that observed in higher animals. The results also demonstrated that measurement of gonadal ascorbic acid can provide a useful indication of physiological events at the level of the gonad.
Aspects of the biology of grey mullet, Mugil cephalus L., adult populations of a coastal lagoon in Sri Lanka
Authors: Silva E. I. L. , De Silva S. S.
Published: January 2006

The biology of grey mullet, Mugil cephalus L., adult populations in a coastal lagoon in Sri Lanka is presented. The percentage of grey mullet catches increased with increasing salinity. The larger fish were found in the deeper areas and the relationship of total length to depth was L= 8.4602e0.0058D where L= total length and D= depth (cm). The overall female to male ratio was 0.95 : 1.0 and seasonal variation in the sex ratio is considered to be caused by the differential timing in the spawning migrations of the two sexes. Males mature at 34.0 cm and females at 31.5 cm. The main spawning season was between January and May and it is hypothesized that the breeding season is geared to utilize the favourable time period, for growth of fry, in the lagoon. Grey mullet sheds its eggs in batches. Fecundity varied from 0.45 to 4.2 million in fish ranging in length from 32 to 56 cm and in weight from 0.7 to 2.2 kg. Fecundity was significantly correlated to body length and weight and gonad weight.
Visual contrast thresholds in the cod Gadus morhua L.
Authors: Anthony P. D.
Published: January 2006

The contrast discrimination of Gadus morhua L. was studied by means of a cardiac conditioning technique. Fish were trained to respond to a projected pattern of spots and the contrast of pattern and background then reduced until the minimum contrast required to elicit a response was established. This was repeated at seven different background light levels to cover the range of light conditions naturally encountered by the cod. The minimum detectable contrast decreased with increasing light level to a minimum of around 2.0%. The contrast threshold curve showed a discontinuity at a light level of approximately 8.0 × 10‐6 W sr‐1 m‐2. This was thought to be linked to the change from photopic to scotopic vision. Significant differences were found in cod taken from two different locations. Overall, cod contrast detection compared very favourably with figures available for other species including man. Using the obtained contrast discrimination figures some estimates were made of the cod sighting distance of hypothetical targets under natural conditions.
The attachment of dace, Leuciscus leuciscus L., eggs to the spawning substratum and the influence of changes in water current on their survival
Authors: Mills C. A.
Published: January 2006

Dace lay adhesive eggs in fast‐flowing water which they attach to the gravel substratum. Artificial spates, similar in magnitude to those occurring naturally during the incubation period in early spring, produced transient peaks in egg drift. Even a severe spate caused the loss of only 2.4% of the estimated egg population. Dace eggs are negatively bouyant and, at a current speed of 50 cm S‐1 and a depth of 26 cm, only 2.4% of dace eggs introduced at the surface failed to attach to a gravel substratum within 6 m of the point of release.
Mathematical models of gastric emptying and the estimation of daily rates of food consumption for fish
Authors: Jobling M.
Published: January 2006

The literature relating to gastric evacuation in fishes is reviewed and, where appropriate, the data is re‐analysed and fitted to mathematical models of gastric emptying. A volume dependent model of emptying is suggested as being most appropriate and data for most species are adequately described by an equation of the form dV/dT= ‐cV0.5. The gastric emptying equations are then incorporated into models for the estimation of daily food consumption of fishes and the accuracy of the predictions tested.
Trophic biology of herbivorous reef fishes: alimentary pH and digestive capabilities
Authors: Lobel P. S.
Published: January 2006

Certain herbivorous fishes are well known for morphological specializations enabling trituration; such as scarids with a pharyngeal mill and mullets with a gizzard‐like stomach. However, utilization of plant foods by fishes is limited by these animal's digestive capabilities, most notably the apparent lack of cellulose digesting enzymes. Fishes possessing a grinding mechanism are able to break open plant cells for digestion. But how fishes without grinding mechanisms make plant cell contents accessible to digestion is unknown. These fishes include many acanthurid and pomacentrid species which are among the most abundant on reefs.

Another mechanism for rupturing plant cell walls has been recently proposed, namely lysis by gastric acidity. This study surveyed stomach and intestinal pH for 17 herbivorous species at Fanning Atoll, Central Pacific and two species from St Croix, Caribbean with additional data for seven selected carnivorous species. The herbivorous fishes included acanthurids (surgeonfishes), mugilids (mullets), pomacanthids (angelfishes), pomacentrids (damselfishes) and a scarid (parrotfish). The effect of different pH concentrations and trituration was examined experimentally for eight common Pacific marine algae including two reds, two blue‐greens, two greens, one brown, and the algal mat complex from inside damselfish territories.

Fishes, possessing morphological adaptations for trituration, ingested quantities of calcium carbonate material and did not contain gastric acidity low enough to lyse algal cell wells. However, fishes without grinding mechanisms but with defined stomachs have gastric pH values from 2.4 to 4.25 which can be as effective as trituration in releasing algal cell contents of certain algae. These results are considered in a review of previous studies of herbivory in fishes. The trophic relationship between fishes and algae of specified morphologies are predicted by extrapolation from the experimental results on algae vulnerable to acid lysis or trituration.
Gross and fine structure of the pseudo branch of the climbing perch, Anabas testudineus (Bloch)
Authors: Munshi J. S. D. , Hughes G. M.
Published: January 2006

The structure of the glandular pseudobranch of the air‐breathing fish Anabas testudineus is described on the basis of light and electron microscopy. It is shown that the pseudobranch has the same basic structure as a typical gill, although in this case it is not freely exposed to the water.

Individual secondary lamellae can be recognized in which well‐defined, but narrow, blood channels are present between typical pillar cells. The epithelial layer is mainly represented by enlarged mitochondria‐rich cells which constitute a large proportion of the whole organ. Mitochondria‐rich cells contain an abundant endoplasmic reticulum which is in close contact with the mitochondria and becomes concentrated near the vascular borders of the cell and opens directly into the basement lamina.

The presence of numerous pinocytotic vesicles in the enlarged pillar cell flanges may transfer material to the blood channels. The precise nature and role of any materials released in this way remains to be investigated.
Temperature tolerance and the final preferendum—rapid methods for the assessment of optimum growth temperatures
Authors: Jobling M.
Published: January 2006

The relationship between the temperature requirements of some fish species, using published data for growth optima, final preferences and lethal limits were examined. A good correlation was found and it is suggested that the data established gives a good estimate of the temperature promoting maximum growth. Determinations of final preferenda are easily conducted in the laboratory and could therefore be used to give rapid assessments of optimum growth temperatures of potential culture species. The practical application of such measurements is discussed.
The seasonal distribution of Echinorhynchus salmonis (Acanthocephala: Echinorhynchidae) among rainbow smelt, Osmerus mordax Mitchell, in Lake Michigan*
Authors: Amin O. M.
Published: January 2006

The seasonal distribution of Echinorhynchus salmonis Müller, 1784 among rainbow smelt, Osmerus mordax Mitchell, in Lake Michigan was studied. Echinorhynchus salmonis showed no pronounced seasonal periodicity in infection prevalence and intensity or development and maturation in rainbow smelt. Worms were predominantly overdispersed with the negative binomial distribution being the best descriptive model. It is suggested that the observed monthly distributions were primarily determined by climatic and other ecological conditions affecting the heterogeneity in the temporal and spatial distribution of infection sources, i.e. Pontoporeia affinis (Lindstrom) (Amphipoda) and alewife, Alosa pseudoharengus (Wilson), and in the feeding behaviour of rainbow smelt.
A note on the distribution of ectopic thyroid tissue in five species of poeciliid fishes
Authors: Woodhead A. D. , Bryant Paulette C.
Published: January 2006

The intraperitoneal injection of polycyclic aromatic hydrocarbons in young Amazon mollies induces proliferation of ectopic thyroid tissue in the spleen. We have surveyed untreated mollies, Poecilia formosa, and four closely related poeciliid fishes to see if ectopic thyroid tissue occurs normally in the spleen. If this were the case, it is possible that the tissue may have been stimulated to proliferate by the injected compounds. We found no instances of ectopic thyroid at any site in 50 untreated Amazon mollies examined nor in some 50 spleens dissected from other untreated fish. Splenic thyroid tissue was found in five guppies from 50 surveyed, but did not occur in other species.
Food intake and growth of hybrid carp (female grass carp, Ctenopharyngodon idella× male bighead, Aristichthys (Hypophthalmichthys) nobilis) fed on zooplankton and Chara
Authors: Kilambi R. V. , Zdinak A.
Published: January 2006

Hybrid carp were raised in 1651 indoor tanks. Two tanks were used in this study each stocked with five fish (average total length and weight = 235.7 mm; 116.1 g); one tank was provided with zooplankton and the other with zooplankton and Chara sp. The hybrids fed actively on zooplankton at an average daily rate of 39% and Chara at 2.6% by body weight. Growth was estimated as 0.36% (0.43 g) per day. The hybrids on the two food types showed no significant differences either in plankton consumption or growth rate.
The biology of Fries’ goby, Lesueurigobius friesii (Malm), in the Firth of Clyde, Scotland, and a comparison with other stocks
Authors: Nash R. D. M.
Published: January 2006

The general biology of a population of Lesueurigobius friesii in the Firth of Clyde, Scotland, was studied between October 1977 and December 1979. In this population the fish attained 95 mm and lived a maximum of nine years. The population growth characteristics from von Bertalanffy growth curves showed that the Clyde stock of L. friesii attained a greater maximum theoretical length (L∞) than stocks in the Lynn of Lorne or Biscay and had a lower growth coefficient (K). In all three stocks, the majority of the growth in length (A0.95) was achieved by the end of the fourth year of life. In general the sex ratio was 1: 1 throughout the season. Spawning occurred from May to August, approximately the same time as the Lynn of Lorne stock. Sexual maturity was first reached at a smaller size in males than females. The abundance of L. friesii in the Clyde fluctuated considerably with reduced numbers of fish caught just after spawning.
The effects of formalin and isopropyl alcohol on length and weight measurements of Sarotherodon mossambicus Trewavas
Authors: Billy Allen J.
Published: January 2006

Two groups of 30 Sarotherodon mossambicus were weighed and measured when alive, after 5 days in 10% formalin, and after 5, 10, 15, 20, 25, 30 and 65 days in 37.5% isopropyl alcohol. Fish from two size classes were preserved and all fish initially increased slightly in length and increased greatly in weight. The greatest increases in length and weight were noted after 5 days in formalin solution. After 65 days in isopropyl alcohol, the length of the preserved fish decreased to approach the live length while the weight of the fish stabilized at a higher than live weight value. This study is the first report of slight length increases or no shrinkage in preserved fish. Comments on the use of standard correction factors for lengthweight studies of preserved fish are provided.
Spawning period and growth of yellowfin bream, Acanthopagrus australis (Günther), in Moreton Bay, Australia
Authors: Pollock B. R.
Published: January 2006

Monthly changes in the gonosomatic index indicate that yellowfin bream, Acanthopagrus australis, in Moreton Bay have a short spawning season with a peak during the period July to August each year. The growth rate of A. australis was estimated from tag‐recapture data and by length‐frequency analysis. Modes representing age classes 0, I and II often appeared in length‐frequency distributions, however modes for older age classes were difficult to identify. The von Bertalanffy growth curve parameters calculated from release–recapture data are: L∞= 29.5 cm; K= 0.51; t0=– 0.32 years.
Food and growth relationships of the cod, Gadus morhua L., with special reference to Balsfjorden, north Norway
Authors: Jobling M.
Published: January 2006

Rates of food consumption are notoriously difficult to measure under field conditions and indirect methods must be used. Using data for cod collected from three different areas (North Sea, Faroes & Balsfjorden), food consumption was estimated from stomach fullness and rates of gastric evacuation. These estimates were then compared with estimates given by analysis of food‐growth relationships. Although estimates were of the same order of magnitude there were differences. These differences were suggested to be largely due to insufficient knowledge relating to feeding rhythms of wild fish and lack of data regarding the‘costs of reproduction’. Differences between the annual energy budgets of cod from the three stocks are discussed.
Plasma catecholamines in resting rainbow trout, Salmo gairdneri Richardson, by high pressure liquid chromatography*
Authors: Woodward J. J.
Published: January 2006

Plasma norepinephrine and epinephrine from cannulated trout were measured by high pressure liquid chromatography with electrochemical detection. The catecholamines were extracted with acid‐washed alumina using a microfilter assembly which permitted analysis of small volumes of plasma. Mean (± S.D.) values for plasma norepinephrine and epinephrine were 1.83 (0.97) pmol ml−1 and 8.95 (4.94) pmol ml−1, respectively. These values are compared with catecholamine levels from other vertebrate species.
Eustrongylides tubifex(Nitzsch) encystment in an American ellAnguilla rostrata(Le Sueur)
Authors: Bursey C. R.
Published: January 2006

A diseased American ell,Anguilla rostrata(Le Sueur), was captured during a survey of Little Mosquito Creek, Accomac County, Virginia, U.S.A. Two skin lesions were present. One was caused by the dermal encystment of a nematode,Eustrongylides tubifex; the other was of undetermined origin.
Juvenile salmonid production in a Lake Erie nursery stream
Authors: Gordon D. J. , MacCrimmon H. R.
Published: January 2006

Normandale Creek (2531m2) provides spawning and nursery grounds for lake‐run rainbow trout, Salmo gairdneri Richardson, brown trout, Salmo frutta L., and coho salmon, Oncorhynchus kisutch (Walbaum). Upstream movements are significantly correlated with peak stream discharge (P < 0.05). In 1973–1974, 59 adult salmonids constructed 86 nests of which 60% were disturbed by re‐use or sand deposition. From a calculated deposition of 90 400 ova, 483 juveniles, 6 cm in fork length (f.l.), were resident in the stream when estimates by electrofishing first became valid. Estimated within‐stream (i.e. all sections combined) monthly densities of wild juveniles >6 cm f.l. ranged from six to 22 fish (100 m2)−1, and biomass from 1.3 to 3.1 gm−2. The highest within‐section biomass was 8.3 gm−2 in November. Additions of hatchery‐reared rainbow trout temporarily increased monthly within‐stream juvenile density up to 23 fish (100 m2)−1, and biomass to 8.2 g m−2. Density and biomass were positively correlated (P < 0.05) with both instream and bank cover, and biomass negatively correlated (P < 0.05) with gradient. The importance of substratum and flow characteristics on juvenile density and biomass was strongly indicated although not statistically significant. Annual within‐section production of juveniles > 6 cm f.l. ranged from 4.79 to 5.93 g m−2 year−1 in Sections III and IV, respectively. Inclusion of calculated probable numbers of fish < 6 cm f.l. increased within‐section production from 5.93 to 18.65 g m−2 year−l in upstream Section IV.
Observations on the reproductive biology of the shad, Ethmalosa fimbriata (Bowdich), in the coastal waters of Cape Coast, Ghana
Authors: Blay J. , Eyeson K. N.
Published: January 2006

The gonads of Ethmalosa fimbriata have been classified according to five and four maturity stages in the male and female, respectively. The species appears to mature at 22.0 cm in Ghana waters. The fecundity and frequency distribution of oocytes have been determined. Monthly changes in the proportions of gonadal stages and gonadosomatic index indicate that the species spawns in the sea from October to March. The results have been compared with data on populations occurring in other West African countries.
Cell types and interactions in the spleen of the dogfish Scyliorhinus canicula L.: an electron microscopic study
Authors: Pulsford A. , Fänge R. , Morrow W. J. W.
Published: January 2006

The cell composition of the spleen of the dogfish, Scyliorhinus canicula L. was investigated by electron microscopy. It comprised areas of red and white blood cells. The red cells were observed in various stages of development and the spleen is probably the main erythropoietic organ, it is likely that thrombocytes are also produced in the spleen. The presence of plasma cells, and the appearance of rosette‐like contacts between lymphocytes and phagocytic cells, probably macrophages, indicated that immunological processes were taking place. Destruction of effete blood cells, primarily erythrocytes, was indicated by the presence of macrophages containing residues of ingested blood cells.
Evaluation of the radioimmunoassay (RIA) for detection of Ciguatoxin (CTX) in fish tissues
Authors: Kimura L. H. , Abad M. A. , Hokama Y.
Published: January 2006

The results of the radioimmunoassay (RIA) procedure for the direct determination of ciguatoxin (CTX) in fish tissues are presented. The RIA procedure detected CTX in 93% of fish tissues obtained from clinically documented ciguatera cases. The immunoglobulin nature of the reactive serum factor in sheep immunized with CTX was ascertained by DEAE‐cellulose chromatography and by the ability to distinguish toxic from nontoxic fish tissues. Furthermore, a longitudinal study with commercial Seriola dumerili proved the RIA procedure to be effective in protecting the consumer from ciguatera poisoning by eliminating the potentially hazardous fishes from the markets. It is suggested that the RIA procedure has potential use in surveying areas for fishery development and is of value in keeping potentially toxic large fish off the market.
The identification of the British grey mullets
Authors: Anderson M.
Published: January 2006

In the absence of a suitable key for the identification of adult British grey mullets, a simple key has been compounded from the relevant literature; the 1957 key of Perlmutter, Bograd and Pruginin was used for the identification of juvenile specimens. The correspondence between identifications of young and old fishes was checked by rearing fishes in the laboratory and by gel‐electrophoresis.
Plasma cortisol stress response in fingerling rainbow trout, Salmo gairdneri Richardson, to various transport conditions, anaesthesia, and cold shock
Authors: Barton B. A. , Peter R. E.
Published: January 2006

Plasma cortisol levels of fingerling rainbow trout were measured as an index of the stress resulting from various procedures used for transport of the fish for stocking. When transported under ‘normal’ conditions, which included water at the hatchery acclimation temperature (10–11°C), O2 saturation or supersaturation, and neutral pH, there was a marked increase in plasma cortisol levels within 0.5 h, which was maintained over the next 4 h of transport; there was a significant decrease in plasma cortisol by 8 h of transport. It was found that the plasma cortisol levels at 4 and 8 h were not appreciably altered by transport under partial O2 desaturation, O2 saturation, O2 supersaturation, or 0.5% NaCl, or by anaesthesia with tricaine methanesulfonate (MS 222) prior to capture and transport in MS 222‐free water or 0.5% NaCl. A 15 min exposure to an immobilizing dose of buffered or unbuffered MS 222, or 2‐phenoxyethanol, caused an increase in plasma cortisol of about 2 h duration, indicating that anaesthetics are themselves stressful. Exposure to chilled water (1° C) caused a large increase in plasma cortisol levels by 4 h after initiation of exposure; plasma cortisol had decreased at 1 day, and by 2 days a constant level was reached which was above the level in fingerling trout under ‘normal’ hatchery conditions. Trout acclimated to chilled water for 24 h and transported in chilled water had an increase in plasma cortisol during transport. Anaesthesia prior to transport or addition of salt did not reduce the stress of transport as judged by plasma cortisol levels. The results indicate that stress from capture and transport during stocking cannot be avoided using present methods.
The effect of pre‐fasting diet and water temperature on liver glycogen and liver weight in rainbow trout, Salmo gairdneri Richardson, during fasting
Authors: Hilton J. W.
Published: January 2006

The effect of feeding an isocaloric and isonitrogenous trout diet that contained different levels of digestible carbohydrate (cerelose) to rainbow trout at either 10 or 15° C on liver glycogen and liver weight was determined in two fasting studies of 12 and 41 days duration. Trout fed diets with increased levels of digestible carbohydrate (HC) had significantly higher liver‐body weight ratios (LW) and liver glycogen (LG) than trout reared on low digestible carbohydrate diets (HF). Both LW and LG declined in fasting trout previously fed HC diets but declined little in fasting trout previously fed HF diets. Trout reared at 10° C had higher LW and LG than trout reared at 15° C on either the HC or HF diets. During fasting, the trout reared on HC diets at 10° C required a longer period of time for the LG and LW to decline to the levels of trout reared on the low carbohydrate diets, than did trout reared on the HC diets at 15° C. The results indicate that both pre‐fasting diet and water temperature can affect liver glycogen utilization and liver weight in fasting trout. Prolonged elevation of LW and LG in fasting trout could jeopardize the survival rate of stocked trout, particularly at low water temperatures.
Development and function of the swimbladder‐inner ear‐lateral line system in the Atlantic menhaden, Brevoortia tyrannus (Latrobe)*
Authors: Hoss D. E. , Blaxter J. H. S.
Published: January 2006

The swimbladder‐acoustico‐lateralis system of the Atlantic menhaden, Brevoortia tyrannus, is described and compared with that of the Atlantic herring, Clupea harengus. The system develops in the larva at a much earlier stage than the herring, being functional by about 2 mm tl. The volume of the gas‐filled pro‐otic bullae is five times that of the herring, and the gas ducts to the swimbladder, instead of being short and separate, are three times the length and join to form a common duct well in front of the swimbladder. The menhaden swimbladder is baggy and totally compliant when subjected to pressure changes. There is no toughened anterior end as in the herring, but the swimbladder is steeply angled in the body cavity, causing gas to collect at the anterior end after a pressure increase, unless the fish is diving very steeply. The guanine content of the swimbladder is comparable with that of the herring and makes the wall very impervious to gas diffusion. When subjected to quick pressure increases and decreases, the pro‐otic membrane returns to its flat position with a time constant of 31‐44 s. Very large quick pressure changes of about 3 atm burst the pro‐otic membrane in adult fish but not in larvae.
Feeding habits of Scymnorhinus licha in Catalan waters
Authors: Matallanas J.
Published: January 2006

A study has been made of the diet of Scymnorhinus licha in Catalan coastal waters by means of the analysis of the stomach contents of 97 specimens caught at depths ranging from 300 to 600 metres during a 12 month survey. The annual coefficient of repletion is 80%. Bony fishes form the basic group in the diet for all seasons: they are followed by sharks, crustaceans and cephalopods, which are secondary. As the size of G. licha increases, there is an increase in the frequency of crustaceans and sharks in the stomach contents and a drop in the frequency of cephalopods. Bony fishes are slightly more frequent in the larger specimens. The males have a higher coefficient of repletion and a higher average of prey per stomach and show a greater preference for sharks and bony fishes.
An analysis of a specialized feeding mechanism of the spined loach, Cobitis taenia (L.), and a description of the related structures
Authors: Robotham P. W. J.
Published: January 2006

Aquarium observations and gut analyses of the spined loach, Cobitis taenia, suggested the use of a technique by which small items of food could be removed from an almost constant stream of substrate, taken in through the mouth and passed out through the gills. The small amount of indigestible substrate present in the gut contents indicated a very high efficiency level for the process. Photographic investigation revealed a two phased feeding cycle based on the respiratory pumps, consisting of an induction/separation phase and an expulsion/swallowing phase. A morphological study showed large concentrations of mucus secreting goblet cells on the roof of the anterior buccopharyngeal cavity. Other morphological adaptations were noted which resulted in a narrowing of the anterior buccal cavity and a widening of the posterior part along with an increase in the distance between the gill rakers. In the light of this information a method of separation based on differential densities of particles being trapped in a constant stream of mucus is postulated.
A new species of the deep‐sea fish genus Cyclothone Goode & Bean (Stomiatoidei, Gonostomatidae) from the tropical Atlantic
Authors: Badcock J.
Published: January 2006

A new gonostomatid species, Cyclothone parapallida, is described from the tropical Atlantic. Its affinities with C. pallida are shown by the shared characters especially the presence of an enlarged caniniform tooth in the premaxilla and a posterior, irregular series of minute teeth on the pterygoid, but it is distinguished from this species by its lower gill raker count [21‐22 (23) v. 23–24 (22–25) first arch], its more restricted meningeal pigment, its lack of internasal pigment and its transparent dorsal and anal fin rays. Furthermore, it attains a larger maximum size, has a different geographic distribution pattern and, when sympatric, lives deeper than C. pallida. A synopsis of characters useful in distinguishing Cyclothone spp. in the Atlantic is presented.
Histochemical fibre types in the lateral muscle of fishes in fresh, brackish and salt water
Authors: Carpenè E. , Veggetti A. , Mascarello F.
Published: January 2006

The histochemical pattern of red, pink and white muscle of fish living in fresh, brackish, and salt water is reported. The muscle fibres were stained routinely during the year for lactate dehydrogenase (LDH), menadione α‐glycerophosphate dehydrogenase (Mα—GPDH), succinic dehydrogenase (SDH), myosin adenosine triphosphatase (myosin ATPase), phosphorylase, lipids and glycogen. The pink and red muscles contain more glycogen and lipids and have a higher SDH activity, which is in accord with their aerobic metabolism and function in sustained swimming activity. The acid labile myosin ATPase activity characteristic of fast twitch fibres is present in the white fibres of most species, however in the white muscle of Gobius paganellus the enzyme activity is stable to both acid and alkali and, in addition, there is a scattered distribution of different fibre types in red and, especially, pink muscle. A study of seasonal variation patterns of myosin ATPase in white muscle of mugilidae over a period of two years has demonstrated, in late summer, the appearance of new small diameter fibres, with a high acid stable enzyme activity, that develop into the large diameter acid labile fibres.