bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of parvalbumin isotypes in adult snook and their potential applications as species‐specific biomarkers
Authors: Ross C. , Tilghman R. W. , Hartmann J. X. , Mari F.
Published: April 2005

The highly stable Ca2+ binding protein, parvalbumin, is prevalent in fish white muscle tissue. The properties of this protein make it a promising antigen for use as a specific biomarker for fish identification. Parvalbumin was purified from white muscle of an adult common snook Centropomus undecimalis using ammonium sulfate precipitation, size‐exclusion chromatography (SEC) and anion‐exchange HPLC. Parvalbumins were characterized by the presence of an 11‐kDa band following gradient‐SDS gel electrophoresis and by their immunoreactivity against mouse anti‐parvalbumin antibodies. Anion‐exchange chromatography of the parvalbumin fraction separated from the SEC column yielded nine fractions. Subsequent analysis of these fractions by isoelectric focusing gel electrophoresis led to a total of seven parvalbumin isotypes, which may lend themselves as biomarkers in fish identification. The presence of these seven parvalbumin isotypes was confirmed independently by reversed‐phase HPLC. A dilution endpoint immunoassay was developed for C. undecimalis parvalbumin using a monoclonal antibody directed against its highly conserved calcium binding site. The utility of parvalbumin isotype distribution and specific monoclonal antibodies against fish parvalbumin in species identification is discussed.
Effects of light level and growth history on attack distances of visually foraging juvenile salmon in experimental tanks
Authors: Nicieza A. G. , Metcalfe N. B.
Published: April 2005

The effects of light level, developmental pathway, and previous growth history on the foraging attack distances of juvenile Atlantic salmon Salmo salar were examined in circular rearing tanks. Former manipulation of growth rates had no significant influence on distances moved to intercept food items despite the fact that it caused substantial differences in post‐treatment growth. Attack distances of fish that were entering a state of overwinter dormancy (lower modal group; LMG) were shorter than those of actively feeding (and growing) fish (upper modal group; UMG). These differences were explained generally by differences in body size between the two groups, suggesting that actual effort per attack was unassociated with growth requirements. Significant differences between growing and non‐growing fish in attack distances could contribute to the variation in growth rates through their effect on feeding rates, but were unlikely to have affected energetic costs. This may be due to the fact that attack distances were consistently short throughout the study period as is also evident from the pattern of change between night and daytime. Whereas in the first experiment (daylight v. twilight) fish moved further to reach food during the day, in the second (daylight v. overcast night) nocturnal attack distances matched (LMG fish) or exceeded (UMG fish) diurnal attack distances. Thus diurnal attack distances were probably minimized in the second experiment. These results are interpreted within a framework of overwintering strategies.
Comparison of response distance to prey via the lateral line in the ruffe and yellow perch
Authors: Janssen J.
Published: April 2005

The ruffe Gymnocephalus cernuus and the yellow perch Perca flavescens (both Percidae), have very different cephalic lateral line systems. The ruffe, which is nocturnal and frequents turbid water, has a cephalic lateral line with very wide canals, large neuromasts, and membranes covering the canal openings. This anatomy is convergent with that of many deep‐sea fishes. The yellow perch has a lateral line composed of neuromasts enclosed in narrow canals freely open to the water. This anatomy is typical of active, diurnal, shallow‐water fishes. Laboratory experiments in the dark using infra‐red video equipment revealed that the ruffe detects Daphnia magna (Crustacea: Daphnidae) and the mayfly Hexagenia limbata (Insecta: Ephemeridae) at a greater distance than the yellow perch and that it also swims faster whilst searching for prey. The swimming of the ruffe consists of a thrust by the pectoral and caudal fins, followed by a glide, the prey being detected during the glide. It is suggested that the membranes over the openings in the ruffe's lateral line function to eliminate self‐generated laminar flow ‘noise’ from reaching the neuromasts.
Food consumption of vendace Coregonus albula larvae in Lake Lentua, Finland
Authors: Sutela T. , Huusko A.
Published: April 2005

The daily ration of vendace larvae (mean TL 10·1–12·8 mm) was assessed after a time‐intensive field survey in Lake Lentua. Ten larvae were sampled every 2 h throughout the 10‐day sampling period and their alimentary tract contents analysed. The gut was cut into four quarters of equal length and each quarter was analysed separately. This procedure enabled the assessment of the proportions of different zooplankton taxa in the diet based on the least degraded first‐quarter contents and to reconstruct the entire gut contents. Secondly, the gut passage time of ingested zooplankton was evaluated by comparing the degradation rate of zooplankton in the guts of experimentally fasted larvae to the degradation of zooplankton in the gradient from pharynx to anus among the larvae sampled from the lake. Finally, food consumption was calculated as zooplankton individuals and carbon biomass based on the two variables, gut passage time of constantly feeding larvae and reconstructed gut contents. The daily ration of vendace larvae varied between 14 and 450 zooplankters in the monitored period.
Physiological stress effects of continuous‐ and pulsed‐DC electroshock on juvenile bull trout
Authors: Barton B. A. , Dwyer W. P.
Published: April 2005

Juvenile bull trout Salvelinus confluentus exposed to continuous‐ or pulsed‐DC electroshock exhibited rapid elevations in plasma cortisol and glucose, but plasma chloride did not change. In a 1‐h experiment using 240 V at 1·4 A of 60‐Hz pulsed DC (voltage gradient 0·81 V cm−1), which proved lethal, plasma cortisol and glucose rose significantly within 15 min of a 10‐s electroshock. Plasma cortisol reached a peak level of 156 ± 18 ng ml−1 at 45 min and then decreased, whereas plasma glucose reached its highest level of 179 ± 7·5mg dl−1 at 1 h. In a 24‐h experiment using lower dosages, plasma cortisol increased from 6·1‐16 ng ml−1 to peak levels of 155–161 ng ml−1 in 1 h in response to a 10‐s electroshock of continuous (130 V, 0·5 A, 1·45 V cm−1) or pulsed (120 V, 0·5 A, 60 Hz, 0·55 V cm−1) DC. Although plasma concentrations declined thereafter, levels remained above control values at 24 h. Plasma glucose was elevated from 60–65 to 120–134 mg dl−1 after 1h by both electroshock treatments and remained near or above those levels for the 24‐h duration. Plasma cortisol and glucose levels were much higher in electroshocked bull trout at 1 h compared with those in fish 1 h after receiving a 30‐s handling stressor (cortisol, 90 ± 12 ng ml−1; glucose, 82 ± 6·1 mg dl−1). The results indicate that both continuous and pulsed DC were more stressful to juvenile bull trout than handling and that recovery, at least for pulsed DC, may take longer than 24 h.
Temperature effects on spawning and egg development in Eurasian perch
Authors: Sandströ O. , Abrahamsson I. , Andersson J. , Vetemaa M.
Published: April 2005

Spawning, egg strand development and embryo survival was studied during 1995–1996 in perch Perca fluviatilis exposed to heated effluent from two coastal nuclear power plants on the Baltic. Spawning was earlier and more prolonged in the heated areas. Although the fertilization rate was high, most egg strands sampled in the heated areas did not develop to hatching. The egg strands disintegrated within a few days of spawning, and egg mortality was very high. All samples collected from reference areas developed up to hatching. Exposure to high temperatures during the final maturation of the gonad influenced the follicular mechanism producing the jelly membrane which constitutes the matrix of the egg strand. Effects were observed in fish in open effluent areas as well as in an enclosed research basin. These results suggest that there is a conflict between optimal reproduction and temperature preference in temperate area fish. Fish are attracted to cooling water effluent, at the expense of reduced reproductive performance.
Location‐dependent infection of fish parasites in Lake Constance
Authors: Balling T. E. , Pfeiffer W.
Published: April 2005

Perch Perca fluviatilis and roach Rutilus rutilus were caught at various locations around Lake Constance (Bodensee). Infection of perch and roach with the eyeflukes Diplostomum spathaceum and Tylodelphis clavata was greatest in the western location (Bottighofen). The varied occurrence of parasite species at different locations indicated that maximum interchange between fish populations was slight. Whitefish Coregonus lavaretus migrating up the River Rhine were less infected with both the tapeworm Proteocephalus exiguus and the copepod Ergasilus sieboldi than whitefish from the middle of the lake. Some of the parasites had already left their hosts. Newly established infections were not found in migrating whitefish.
Downstream movements of young‐of‐the‐year fishes in Catamaran Brook and the Little Southwest Miramichi River, New Brunswick
Authors: Johnston T. A.
Published: April 2005

Downstream movements of young‐of‐the‐year fish in Catamaran Brook and the Little Southwest Miramichi River, New Brunswick, Canada were monitored by drift sampling during June and July of 1994, 1995 and 1996. Atlantic salmon Salmo salar, white sucker Catostomus commersoni, Cyprinidae, and sea lamprey Petromyzon marinus, were the most commonly captured taxa. All taxa moved downstream almost exclusively at night. Movement was greatest near midnight then declined towards dawn. Drift abundances peaked in mid‐June for Atlantic salmon, late June for white sucker, and early July for Cyprinidae. Dates of peak movement were earlier in the Little Southwest Miramichi River than in Catamaran Brook for all taxa. Salmon fry captured in drift samplers were shorter than salmon fry captured by electrofishing near the sampling sites. Salmon fry captured in Catamaran Brook drift samplers were heavier at length than those captured in Little Southwest Miramichi River drift samplers. Results suggest that Catamaran Brook provides relatively better habitat for Atlantic salmon fry growth and relatively poorer habitat for larval white sucker growth than the Little Southwest Miramichi River.
Chaunax pictus Lowe 1846—first record of the family Chaunacidae in the Mediterranean Sea
Authors: Ragonese S. , Giusto G. B.
Published: April 2005

A medium‐sized coffinfish, 183 mm total length and 170 g body weight, Chaunax pictus Lowe 1846, a species previously unrecorded in the Mediterranean Sea, has been trawled recently on deep‐sea red shrimp grounds near the Sentinelle Bank (off the Algerian coast, central Mediterranean Sea).
Field observations of the spawning behaviour of European grayling
Authors: Darchambeau F. , Poncin P.
Published: April 2005

During observations of the River Ourthe, Belgium, 70 spawning attempts were recorded during the reproductive period of the European grayling. Thirty‐six per cent of the spawning attempts proceeded to completion, while interference by another male may explain some of the incomplete acts. Sneaking behaviour was observed and one spawning act included two males and one female.
Size‐assortative nest choice by the Japanese fluvial sculpin in the presence of male‐male competition
Authors: Natsumeda T.
Published: April 2005

Nest choice by the Japanese fluvial sculpin Cottus pollux and its relationship to male reproductive success, was examined in a natural habitat, central Japan. The larger males tended to occupy the deeper nest cavities, suggesting size‐assortative nest choice by the species. Stepwise regression analysis showed that cavity area was correlated positively to male reproductive success. Nest choice experiments without a competitive male indicated an absence of size‐assortative nest choice, but larger males tended to choose a large nest when another male was present, suggesting that size‐assortative nest choice by the species is attributable to male‐male competition for large nests, such being related to a resource‐defence polygynous mating system.
Habitat‐related differences in the abundance of parasites from a coral reef fish: an indication of the movement patterns of Hemigymnus melapterus
Authors: Grutter A. S.
Published: April 2005

The prevalence and number of an undescribed Benedenia sp. on Hemigymnus melapterus were significantly greater on fish from the reef flat than from the slope at Heron Island, Great Barrier Reef. In contrast, the abundance of gnathiid isopods on the fish did not differ significantly between habitats. As monogeneans do not leave their hosts, the differences in parasite abundance between the habitats suggest that H. melapterus does not move between the reef flat and reef slope, habitats separated by only a few hundreds of metres. Benedenia may thus be a useful biological tag for following the small‐scale movement patterns of coral reef fish.
Comparison of growth rate and formation of otolith increments in age‐0 red snapper
Authors: Szedlmayer S. T.
Published: April 2005

For wild red snapper Lutjanus campechanus, mean otolith increment deposition rate after marking with oxytetracycline dihydrate (OTC) was daily (0.97 increments day−1) when growth rates were fast (0.63 mm fork length, LF day−1), but were not daily (0.82 increments day−1) when somatic growth was slow (0.2 mm LF day−1). For reared larvae (n=8), increment deposition rates were daily (0.99–1.03 increments day−1), and growth rates ranged from 0.6 to 0.9 mm LF day−1. Growth rate affected increment deposition rate as a threshold function, i.e. when growth rate was <0.3 mm LF day−1, deposition was less than daily, but above this level increment deposition did not exceed a daily rate. As growth rates increased increment widths increased. Examination of a sub‐sample (n=8) of the otoliths from the slowest growing wild fish by scanning electron microscopy did not increase increment counts. Because L. campechanus are late spring‐early summer spawners, young fish can expect maximum growth due to warm summer temperatures. Thus, daily ageing methods should be well suited to this species.
Alternative reproductive tactics and courtship in the common goby
Authors: Magnhagen C.
Published: April 2005

In the marine common goby Pomatoschistus microps, males either build nests and attract females to spawn or act as sneakers, forcing themselves into other males' nests during mating, to fertilize some of the eggs in the clutch. The reproductive tactics of small males were studied in the presence of surplus nest material and an excess of gravid females, while a larger, nestholding male spawned with a female. Of 24 small males, 13 only attempted to sneak, seven only courted females and/or spawned in their own nest, and four performed both behaviours. The small males who attracted females successfully were significantly larger than the ones who failed to do so. Females had been courting the small male more often when he subsequently spawned in his own nest, than when he did not get a female. The small males did not court the females very frequently, and their courtship rate did not depend on whether or not they attracted females. Instead, female courtship behaviour may be a cue for a male either to spawn as a nest holder or become a sneaker. The study pointed out the importance of female behaviour for male reproductive tactics, which could be more important in fish than is known currently.
Reproductive cycle and sexual maturity of the anglerfish Lophiomus setigerus in the East China Sea with a note on specialized spermatogenesis
Authors: Yoneda M. , Tokimura M. , Fujita H. , Takeshita N. , Takeshita K. , Matsuyama M. , Matsuura S.
Published: April 2005

The reproductive cycle and sexual maturity of the anglerfish Lophiomus setigerus were examined. Spermatids were released from the germinal cysts into the lumina of the seminal lobules, and both spermatids and spermatozoa were present in the lumina of the seminal lobules and sperm ducts. Spermatogenesis and vitellogenesis occurred throughout most of the year. The testes of males were full of spermatozoa throughout the year, with spawning from May to November. Males and females reached sexual maturity at a mean total length and age of 178 mm, 3.3 years and 303 mm, 6.1 years, respectively. There were clear seasonal cycles in the gonadosomatic index (IG) and hepatosomatic index (IH) in females. The mean IG of females increased rapidly with ovarian development while the mean IH decreased from the middle of vitellogenesis to final maturation. Mean values of IG and IH in males increased with testicular development.
Morphometric and allozyme variation in the African catfishes Clarias gariepinus and C. anguillaris
Authors: Rognon X. , Teugels G. G. , Guyomard R. , Galbusera P. , Andriamanga M. , Volckaert F. , Agnèse J. F.
Published: April 2005

This study investigated morphological characters and electrophoretic polymorphism at 25 protein loci in nine wild populations of the African clariid catfish Clarias gariepinus and seven wild populations of C. anguillaris. Two other clariid species, Clarias albopunctatus and Heterobranchus longifilis, were used as outgroups in the allozyme study. Morphometric and allozyme data are congruent for the Nilo‐Sudanian populations of C. gariepinus and C. anguillaris. Both approaches also distinguished two groups amongst the C. gariepinus populations, one containing Nilo‐Sudanian populations and the other including Lake Victoria and southern African populations. However, allozyme data suggest that C. gariepinus is not a monophyletic group and show that C. albopunctatus is more divergent from C. gariepinus and C. anguillaris than it is from H. longifilis, stressing the need for a revision of clariid systematics. The variation observed in C. gariepinus is discussed in terms of palaeogeographical events and its use in aquaculture.
Identification of Spanish barbel species using the RAPD technique
Authors: Callejas C. , Ochando M. D.
Published: April 2005

The RAPD‐PCR technique was employed to identify three endemic Spanish species of Barbus: Barbus bocagei, B. graellsii and B. sclateri, that present very similar morphologies. Using seven primers, six diagnostic bands were found in B. bocagei, 11 in B. graellsii and nine in B. sclateri. Cluster analysis of the genetic similarity values obtained from RAPD data indicated that the species B. bocagei and B. graellsii are more related to each other than to B. sclateri.
Drinking rate, uptake of bacteria and microalgae in turbot larvae
Authors: Reitan K. I. , Natvik C. M. , Vadstein O.
Published: April 2005

The drinking rate of turbot larvae increased from 14 to 120 nl larva‐1 h‐1 from day 2 to 11 after hatching, which gave a slightly increased specific drinking rate (calculated per biomass) from day 2 to 7 (0·8–1·9 nl μg carbon‐1 h‐1. The clearance rate of both algae and bacteria was 10–100 times higher than the drinking rate, which indicated that the larvae had an active uptake of both algae and bacteria. On day 2 and 4 after hatching highest clearance rate was observed for Tetraselmis sp. On day 6 about the same clearance rate was observed for bacteria, Isochrysis galbana and Tetraselmis sp. Until day 4 the turbot larvae had a higher ingestion rate of Tetraselmis sp. than of I. galbana, whereas on day 6 the rates were similar (28–41 ng carbon larvae‐1 h‐1). The assimilation efficiency was somewhat higher for I. galbana than for Tetraselmis sp., and on day 6 the assimilated algae constituted 1·5 and 0·9% of the larval biomass for I. galbana and Tetraselmis sp., respectively.
Erythropoiesis in Arctic charr is not stimulated by anaemia
Authors: Lecklin T. , Nikinmaa M.
Published: April 2005

Red blood cell number in circulation in Arctic charr Salvelinus alpinus increases in spring at a time when water temperature in the natural environment is increasing. Experimental anaemia was unable to stimulate erythropoiesis in charr acclimated to 8 or 14o C in any of the four seasons, in contrast to other fish species studied.
Electrophoretic identification and phylogenetic relationships of indigenous tilapiine species of Zimbabwe
Authors: Feresu‐Shonhiwa F. , Howard J. H.
Published: April 2005

In order to characterize Zimbabwean tilapias 34 populations of seven species, two in the genus Tilapia and five in Oreochromis, were analysed using horizontal starch gel electrophoresis. Twenty‐seven loci were polymorphic while five were monomorphic but had fixed allelic differences among some species and six were monomorphic for the same allele in all species. No fixed allelic differences were found between O. mossambicus and O.mortimeri, and only one locus distinguished O. andersonii from O. mossambicus and O. mortimeri. Pairwise comparisons of O. mossambicus or O. mortimeri populations of genetic distances frequently showed a greater degree of difference within the species than was evident in some O. mossambicusO. mortimeri pairs. This study failed to distinguish O. mortimeri as a distinct species from O. mossambicus. The Tilapia species formed distinct clusters from Oreochromis in both consensus eighbourjoining and distance Wagner topologies. Oreochromis ossambicus, O. mortimeri and O. andersonii clustered together consistently. Although some differences from the taxonomic arrangement of Trewavas are discussed, the principal relationships revealed in our analysis are consistent with most recent studies.
Factors affecting the outcome of territorial contests between hatchery and naturally reared coho salmon parr in the laboratory
Authors: Rhodes J. S. , Quinn T. P.
Published: April 2005

In aquarium experiments using coho salmon as a model species, prior residents dominated intruders of the same size but intruders with a 6% length advantage were equally matched against prior residents. Prior winning experience (distinct from individual recognition) also strongly influenced competitive success and overcame a prior residence effect. Coho salmon reared in a hatchery dominated size‐matched fish from the same parental population reared in a stream. Hatchery‐reared salmon also dominated naturally spawned salmon, even when the wild salmon were prior residents. Thus the combined effects of greater size and rearing experience of hatchery‐produced salmon were sufficient to overcome a wild salmon's advantage of prior residence. Efforts to rehabilitate salmonid populations must consider such behavioural interactions if displacement of wild fish is to be prevented.
Patterns of agonistic behaviour, shelter occupation and habitat preference in juvenile Lipophrys pholis, Coryphoblennius galerita and Gobius cobitis
Authors: Faria C. , Almada V. , do Carmo Nunes M.
Published: April 2005

The patterns of agonistic behaviour and substratum preferences were investigated in captive groups of juveniles of Lipophrys pholis (Blenniidae), Coryphoblennius galerita (Blenniidae) and Gobius cobitis (Gobiidae). In monospecific groups, size was an excellent predictor of the rank attained by each individual. In heterospecific groups, both C. galerita and L. pholis were dominant over G. cobitis of similar size, and C. galerita dominated L. pholis. Although G. cobitis showed higher rates of activity and of attacks per minute, and a higher ratio of attacks over threats, all these measures were depressed in the presence of either blenniid. In both blennies, in monospecific groups, the dominance rank of each fish was a good predictor of the time spent inside shelters. G. cobitis occupied preferentially the sandy substratum both in mono‐ and heterospecific groups. Both blennies, when in monospecific groups, occupied preferentially the rocky substratum, with C. galerita showing the highest level of selectivity. In nature, C. galerita also showed a marked preference for rocky substrata, while G. cobitis was especially abundant in mixed bottoms. L. pholis occupied an intermediate position. In the blenniids studied, competition for access to shelter may be one major functional consequence of agonistic behaviour in non‐reproductive contexts.
Life history of Maurolicus muelleri in fjordic and oceanic environments
Authors: Kristoffersen J. B. , Salvanes A. G. V.
Published: April 2005

Life history parameters are compared for populations of Maurolicus muelleri from Norwegian fjords and the Norwegian Sea in 1995 and 1996. The mortality rate was higher in the oceanic population (2·55 for males, 2·00 for females) than in the fjords (1·15 for males, 0·97 for females). Fish from the Norwegian Sea population occupied a depth with higher light levels, which may have contributed to the higher mortality through increased visibility to predators. Differences in growth, condition and gonad weight indicated different resource levels caused by different population densities. Recruitment was weak in many fjords in 1994, but not in the Norwegian Sea. It is suggested that wind‐generated advection may affect recruitment in fjords on the western coast of Norway.
Monogenic inheritance of trunk banding patterns in Barbus tetrazona
Authors: Frankle J. S.
Published: April 2005

The Sumatra barb Barbus tetrazona exhibits two trunk banding patterns: a four‐banded and a five‐banded pattern characteristic of B. t. tetrazona and B. t. partipentazona, respectively. Segregation patterns in the progenies from 11 different matings suggest monogenic inheritance of trunk banding in this species.
Rapid HPLC analysis of retinoids and dehydroretinoids stored in fish liver: comparison of two lake sturgeon populations
Authors: Doyon C. , Boileau S. , Fortin R. , Spear P. A.
Published: April 2005

All major retinoids (vitamin A) stored in the liver of lake sturgeon from two Québec lakes were analysed by high‐performance liquid chromatography (HPLC). Four HPLC peaks represented approximately 90% of all liver retinoids. Their relative proportion was remarkably consistent in the two sturgeon populations with dehydroretinyl palmitate/oleate accounting for the largest proportion (50–60%). Most retinoids demonstrated significant positive correlations with age, but only in the Lake Berthelot sturgeon. The concentrations of all major retinoids were significantly (P<0·0001) lower, as much as 40 times lower, in the Lake Saint‐Louis population. Possible explanations for the extremely low liver stores in the Lake Saint‐Louis sturgeon are discussed.
Fatty acid content of some freshwater fish of commercial importance from tropical lakes in the Ethiopian Rift Valley
Authors: Zenebe T. , Ahlgren G. , Boberg M.
Published: April 2005

Fifty samples of freshwater fish, representing eight tropical species, were collected from Ethiopian Rift Valley lakes in order to study the variation of lipids and fatty acids (FA) both within and between species. Most specimens (36 samples) were low in fat, ≥5% of dry weight (dw). Medium‐ (nine samples) and high‐fat fish (five samples) contained ≤6% and >10% dw, respectively. The extent of variation was more pronounced in the herbivore Oreochromis niloticus than in the omnivorous (e.g. Barbus sp.) or carnivorous–piscivorous (Clarias gariepinus) fishes. Twenty‐eight FA of various chain lengths and saturation levels were identified. Most FA were unsaturated and long‐chained. The major individual FA were palmitic acid (16:0), stearic acid (18 : 0), oleic acid (18 : 1ω9) and docosahexaenoic acid (DHA) (22 : 6ω3). The ω3/ω6 ratio varied considerably (1·1–7·6) and O. niloticus from Lake Haiq was found to be superior in lipid quality to all the tropical fish species considered in this study. The data show that tropical freshwater fish are comparable to temperate freshwater fish as sources of polyunsaturated FA.
Population structure of seabass in Portugal: evidence from allozymes
Authors: Castilho R. , McAndrew B. J.
Published: April 2005

Starch‐gel electrophoresis was used to assess the level and distribution of genetic variation in juvenile European seabass sampled from five different nursery grounds along the coast of Portugal between November 1992 and February 1994. Thirty‐eight loci were examined, of which six (AAT‐3*, ADA*, GPI‐1*, GPI‐2*, G3PDH‐2*, SOD*) were polymorphic at the 99% level and were used in population surveys. Low but statistically significant multilocus FST values suggest that population structuring exists along the Portuguese coast. There is some restriction in gene flow between the population at Faro and all other sites to the north.
Comparison of field‐based and indirect estimates of daily food consumption in larval perch and zander
Authors: Worischka S. , Mehner T.
Published: April 2005

Since bioenergetics models for 0+ fish have seldom been validated by field consumption estimates, field‐based and indirectly estimated daily food rations were compared in larval perch Perca fluviatilis and zander Stizostedion lucioperca. Field‐based estimates were calculated with linear and exponential evacuation rates based on gut fullness data during a 24‐h cycle, with hourly field samplings instead of the normally recommended 3‐h intervals. Indirect calculations used bioenergetics modelling with variable activity multipliers (A). Field‐based estimates of daily rations ranged between 0·21 and 0·27 g g−1 day−1 in perch (mean LT 13·1 mm) and 0·31–0·40 g g−1 day−1 in zander (mean LT 10·6 mm). The higher values were calculated by using the exponential model. Daily rations calculated by bioenergetics modelling with A= 1 were only slightly higher than direct estimates in both species. However, if A values >1 were used, calculated daily rations were substantially higher than direct estimates. Estimates of daily ration based only on every third value ranged between 41 and 72% compared with 1‐h intervals, mainly because of lower estimates of evacuation rate.
Food consumption and growth of two piscivorous fishes, the mandarin fish and the Chinese snakehead
Authors: Liu J. , Cui Y. , Liu J.
Published: April 2005

Rates of maximum food consumption and growth were determined for immature mandarin fishSiniperca chuatsi(47·2—540·2 g) and Chinese snakeheadChanna argus(45·0—546·2 g) at 10, 15, 20, 25, 30 and 35) C. The relationship between maximum rate of food consumption (Cmax), body weight (W) and temperature (T) was described by the multiple regression equations: InCmax=−4·880+0·597 InW+0·284T−0·0048T2for the mandarin fish, and InCmax=−6·718+ 0·522 InW+0·440T−0·0077T2for the Chinese snakehead. The optimum temperature for consumption was 29·6) C for the mandarin fish and 28·6) C for the Chinese snakehead. The relationship between growth rate (G), body weight and temperature was ln(G+0·25)=−0·439−0·500 lnW+0·270T−0·0046T2for the mandarin fish, and ln(G+0·25)=−6·150+ (0·175−0·026T) lnW+0·571T−0·0078T2for the Chinese snakehead. The weight exponent in the growth–weight relationship was −0·83 for the mandarin fish, but decreased with increasing temperature for the Chinese snakehead. The optimum temperature for growth was 29·3) C for the mandarin fish, but tended to decrease with increasing weight for the Chinese snakehead, being 30·3) C for a 45‐g fish, and 26·1°C for a 550‐g fish.
Susceptibility of carp, roach and goldfish to a Dermocystidium‐like organism
Authors: Athanassopoulou F.
Published: April 2005

A visceral form of a Dermocystidium‐like organism was found at 13% prevalence in a carp and in 7·4% in a roach population from Greece. Successful experimental transmission was recorded only in carp. Pathology of the parasite in experimental fish and naturally infected fish was similar. ©1998 The Fisheries Society of the British Isles
Low genetic variability in a widely distributed and abundant clupeid species, Sardinella aurita. New empirical results and interpretations
Authors: Chikhi L. , Bonhomme F. , Agnèse J.‐F.
Published: April 2005

Considering the wide geographic distribution and the catches of Sardinella aurita, the observed allozyme diversity (H=0·011) is strikingly small. Potential explanations for this low gene diversity, which include restrictions on effective population size owing to variance in reproductive success, demographic instability, historical bottlenecks in population size, selection, and technical artifacts are examined and quantified. This quantification, though rough, shows that no single factor can account for the lack of diversity. However, demographic instability of S. aurita, especially if this instability has persisted over evolutionary time scales, together with much greater than Poisson variance in individual reproductive success, could account reasonably for the results. Pleistocene reduction of population size seems also a necessary co‐factor. Technical artifacts, mostly scoring difficulties linked to liver autolysis, are considered also and analysed in different clupeid species.
Microsatellite DNA variation in wild populations and farmed strains of turbot from Ireland and Norway: a preliminary study
Authors: Coughlan J. P. , Imsland† A. K. , Galvin P. T. , Fitzgerald R. D. , Naevdal G. , Cross T. F.
Published: April 2005

Turbot Scophthalmus maximus is the focus of a rapidly expanding aquaculture industry, while at the same time wild catches appear to be in decline. As a preliminary investigation into the effects of hatchery rearing, genetic variation at three polymorphic microsatellite loci was assessed in two wild populations and two farmed strains of turbot, from Ireland and Norway. Although a considerable loss of rare alleles was observed in the Irish farmed strain, no statistically significant reductions were found in mean heterozygosity or allelic diversity in farmed strains compared to wild populations. Significant genetic heterogeneity was found between wild and farmed samples from each country but not between the two wild populations. Genetic differentiation between the farmed strains was presumed to be caused by drift in the hatcheries. The utility of these particular microsatellite loci in comparing these samples and the importance of molecular genetic testing of farmed strains is stressed.
An indirect estimate of bimodal gillnet selectivity of smelt
Authors: Kurkilahti M. , Appelberg M. , Bergstrand E. , Enderlein O.
Published: April 2005

This study showed that it is possible to model a bimodal gillnet selectivity curve without knowing how individual fish have been caught. A bimodal model based on a modified normal density distribution was fitted over the length ranger of smelt Osmerus eperlanus from 8·9 to 17·0 cm. The model had eight parameters, and the height of the second peak was allowed to change with fish length. The coefficient of determination (r2) was 0·915 and the residuals were distributed symmetrically against variable axis. Corrected relative length distribution did not differ statistically from the relative length distribution of the trawl catch. In earlier studies of other species, pooled relative efficiency of multimesh gillnets composed by a geometric series mesh‐size combination has been constant on the average. Because the model increased along fish length, the pooled relative efficiency was increasing also with fish length. Therefore, it is suggested that the gillnet catches of smelt always have to be corrected for gillnet selectivity.
Ring formation on otoliths and scales of Pagrus pagrus: a comparative study
Authors: Machias A. , Tsimenides N. , Kokokiris L. , Divanach P.
Published: April 2005

One annulus formed on the scales of farmed red porgy Pagrus pagrus each year during March and one opaque zone on the otoliths during June. Scales proved to be more sensitive than otoliths in recording the life history of the red porgy. A false annulus (ring of capture) was observed on the scales of the 0+ age group, but not on the otoliths. A gradual lengthening of the period of annulus formation was observed, from the younger to the older fish. The annulus formation in fish older than 2+ was less synchronized, due to the aquaculture conditions. Scales were more accurate than otoliths in annuli formation. A high percentage of missing or additional opaque zones were observed on otoliths of older fish. These irregularities were related to fish maturation and/or farming conditions. Farmed fish grew three times as fast as the wild fish.
Relationships between heart rate and metabolic rate of pike: integration of existing data
Authors: Armstrong J. D.
Published: April 2005

The percentage contribution of heart rate (fH) to change in oxygen consumption (V o2) was examined in relation to body weight and across the metabolic scope of pike. Also the consequences of variability around the regression relating V o2 and fH for estimating V o2 were considered. The percentage contribution of fH was calculated using two equations, one that ignored and one that included an estimate for oxygen consumed by the gills and absorbed across the skin (V o2s). Using both equations the percentage contribution of fH calculated using maximum and resting values for fH and V o2 decreased with weight of pike. The omission of V o2s, resulted in erroneously high estimates of the percentage contribution of fH for pike of any given weight. The omission of V o2s resulted in erroneously high estimates of the percentage contribution of fH over the region of the metabolic scope where fH is related linearly to V o2, whereas the equation that included V o2s resulted in the expected value of 100%. Assuming zero experimental error and under normoxic conditions, the 95% confidence limits for single estimates of V o2 from 30–60‐min readings of heart rate are ±39% at a heart rate of 30 beats min −1. Averaged over longer periods the error decreases, and used over several days to estimate meal size the error is of the order of 1%.
The occurrence of aerial respiration in Rhinelepis strigosa during progressive hypoxia
Authors: Takasusuki J. , Fernandes M. N. , Severi W.
Published: April 2005

Rhinelepis strigosa did not surface for air breathing in normoxic or moderate hypoxic water. This species initiated air breathing when the Pio2 in the water reached 22 ± 1 mmHg. Once begun, the air‐breathing frequency increased with decreasing Pio2. Aquatic oxygen consumption was 21·0 ± 1·9ml O2 kg−1h−1 in normoxic water, and was almost constant during progressive hypoxia until the Pio2 reached 23·9 mmHg, considered the critical oxygen tension (Pco2). Gill ventilation increased until close to the Pco2 (7·9‐fold) as a consequence of a greater increase in ventilatory volume than in breathing frequency. Gill oxygen extraction was 42 ± 5% and decreased with hypoxia, but under severe hypoxia returned to values characteristic of normoxic. The critical threshold for air breathing was coincident with the Pco2 during aquatic respiration. This suggests that the air‐breathing response is evoked by the aquatic oxygen tension at which the respiratory mechanisms fail to compensate for environmental hypoxia, and the gill O2 uptake becomes insufficient to meet O2 requirements.
Description of Careproctus guillemi n. sp. (Pisces: Scorpaeniformes) from Weddell Sea
Authors: Allanas J. Mat
Published: April 2005

Careproctus guillemi differs from the other Careproctus species in the following combination of characters: pectoral fin rays 22 (11 + 4+7); pectoral girdle with three round radials (1 + 0+ 1 + 1); mouth oblique and maxillary extending beyond posterior edge of eye. Relationships between C. guillemi and C. longipectoralis are provided. The endochondral pectoral girdle of C. longipectoralis is described for the first time.
Conventional karyotype, nucleolar organizer regions and genome size in five Mediterranean species of Syngnathidae (Pisces, Syngnathiformes)
Authors: Vitturi R. , Libertini A. , Campolmi M. , Calderazzo F. , Mazzola A.
Published: April 2005

Conventional karyotypes, NOR‐bearing chromosomes by means of silver impregnation and genome size were investigated in five Mediterranean species in three genera of the Syngnathidae. A karyotype of 48 subtelocentric‐acrocentric chromosomes was found in the seahorse Hippocampus hippocampus (FN=48) while a diploid value of 44 occurred in H. guttulatus (2 sm‐m+42 a; FN=46) and the pipefish Syngnathus abaster (44 a; FN=44) and S. typhle (44 a; FN=44). The pipefish Nerophis ophidion, possessing a diploid chromosomal set of 58 made up of 50 meta‐submetacentric and eight subteloacrocentric elements (FN=108) and a genome size three to four times larger than those known to date, differs cytogenetically from all other Syngnathids studied so far. A single pair of active NOR‐bearing chromosomes was found in both species of the genus Hippocampus while in Syngnathus and Nerophis species more than two silver positive chromosomes were found to be involved in nucleolus organization giving rise to NOR‐bearing chromosome polymorphism. The possible evolutionary routes of quantitative and qualitative changes in chromosome and DNA are discussed. The resulting phylogenetic scheme is shown to coincide with that constructed from morphological characters.
Effect of size‐selective mortality on growth of coastal cod illustrated by tagging data and an individual‐based growth and mortality model
Authors: Kristiansen T. S. , Svåsand T.
Published: April 2005

In a release experiment with cod in Norway, the apparent mean growth rates of 3+ cod, calculated by sampling the released cohorts at different ages, were very slow (<0·08 mm day−1). However, when individual growth rates of individual tagged cod of the same size range were measured, the mean growth rates were much faster (0·24 mm day−1). These observations were attributed to size‐selective fishing mortality and were illustrated by an individual based simulation model of a cohort of cod with variable individual growth rates. The effects on mean length at age of the surviving cohort of increasing fishing intensity were demonstrated. The model showed that size‐selective fishing with the observed individual growth variation, removed the fastest‐growing individuals at proportionally higher rates than the slower‐growing ones, leading to decreased apparent mean growth rate. The fishing pattern which gave the optimum yield, changed when individual variation was included, and when the apparent growth rate was used in the model the yield per recruit reduced dramatically. This study has shown that individual growth heterogeneity and size‐selective mortality are factors which should be considered in future fisheries management models.
Population genetic substructure in blue whiting based on allozyme data
Authors: Giæver M. , Stien J.
Published: April 2005

The genetic population structure of the pelagic gadoid blue whiting Micromesistius poutassou throughout its east Atlantic distribution range was explored using polymorphisms at the tissue enzyme loci IDHP‐2* and PGM‐1*. The study included 5025 individuals from 65 locations in the east Atlantic and the Mediterranean. Significant geographic heterogeneity in allele frequencies was demonstrated at both loci (IDHP‐2*: P=0·030, PGM‐1*: P=0·005). The degree of genetic differentiation (FST= 1·1%) in blue whiting appears to be at the same level as for the demersal gadoids cod and haddock. Several separate reproductive units were indicated at the fringes of the distribution range, i.e. in the Barents Sea, and in one Norwegian fjord (Romsdalsfjord).
Diploids v . triploids of Rutilus alburnoides: spatial segregation and morphological differences
Authors: Martins M. J. , Collares‐Pereira M. J. , Cowx G. , Coelho M. M.
Published: April 2005

Rutilus alburnoides complex is a common and widely distributed Iberian cyprinid, whose natural populations include mainly diploid and triploid forms. The Guadiana populations of R. alburnoides were studied to determine whether habitat segregation and morphological differences exist between these forms. The ploidy level of each specimen was determined by measuring erythrocyte DNA content using flow cytometry. Evidence of spatial segregation between diploid males and the two female forms was found. Diploid males were best represented in the River Degebe, which was shallow, with higher temperatures (especially during the spring and summer), and silt and sandy substrate. Diploid females were found in deeper water, on steeper gradients and coarse substrata, while triploid females preferred higher current velocity and a high proportion of instream cover, especially during the spring. The ecological differences may reduce competitive interactions, and should promote a stable coexistence of the different forms. Morphological distinction between fish of different ploidy levels was not established, but differences were found between the males and females. Discriminant analysis allowed, with a 10% error, the separation of both sexes through six morphological characteristics that could be recorded in the field.
Transgenesis changes body and head shape in Pacific salmon
Authors: Ostenfeld T. H. , McLean E. , Devlin R. H.
Published: April 2005

Insertion of a pOnMTGH1 gene construct into coho salmon altered centroid size significantly (P<0·05). The dorsal caudal peduncle and abdominal regions were also distinctly enhanced in transgenic fish when compared to controls. Shape change patterns of both whole body and syncranium were prominent.
Zinc binding to the gills of rainbow trout: the effect of long‐term exposure to sublethal zinc
Authors: Galvez F. , Webb N. , Hogstrand C. , Wood C. M.
Published: April 2005

The effects of sublethal waterborne Zn (2·28 μmol l−1) on Zn binding kinetics to the apical gill surface were studied in juvenile rainbow trout (Oncorhynchus mykiss). Two separate radiotracer techniques were employed to ascertain this information. First, in vitro binding kinetic experiments were performed at extremely elevated zinc concentrations (up to 20 mmol l−1) to measure relatively low‐affinity binding sites at the gill epithelium. There were no differences in Zn binding parameters (Km and Bmax) for fish sublethally exposed to Zn for 21 days and their simultaneous controls. Nevertheless, Ca did have an increased inhibitory effect on Zn binding in Zn‐exposed fish suggesting that the anionic groups on the gill epithelium of these fish had been altered in some manner. Additionally, in vivo Zn binding kinetics were investigated using environmentally relevant waterborne Zn concentrations (low μmol l−1 range) to isolate high‐affinity Zn binding sites (Ca transporters). No appreciable alterations in the Km and Bmax values for Zn binding were seen between the Zn‐exposed group and its simultaneous control following 15 days of exposure. Furthermore, no significant differences in CC morphometry were observed between treatments. Despite these lack of treatment effects, there were temporal alterations in Km, Bmax and CC fractional surface area in both groups. It is proposed that these fluctuations are controlled by hormonal factors (such as stanniocalcin), believed to play a role in Ca influx.
Comparison of phospholipid and fatty acid composition of wild and cultured striped bass eggs
Authors: Gallagher M. L. , Paramore L. , Alves D. , Rulifson R. A.
Published: April 2005

The dominant fatty acids in all neutral lipid fractions of non‐water hardened eggs from two wild and one cultured stock of striped bass Morone saxatilis were the monoenes, 18 : 1n9/n7>16 : 1n7>17 : 1. The dominant fatty acids in the phospholipid fraction of all eggs, regardless of origin, were 22 : 6n3>18 : 1n9/n7>20 : 5n3>16 : 1n7>16 : 0>18 : 0. Arachadonic acid (AA, 20 : 4n6) was significantly lower (2·0%) in cultured fish eggs compared to either wild stock (5·8–6·1%). Fatty acids from the liver and eggs of wild Shubenacadie fish were similar to one another with respect to both neutral and phospholipid fractions. However, the AA and eicosapentaenoic acid (EPA, 20 : 5n3) content of the phospholipid fraction varied according to the hypothesized migration behaviour of Shubenacadie fish. The total lipid content of wild fish eggs was significantly greater than that of cultured fish. The total phospholipid content of Shubenacadie eggs was significantly higher than either Roanoke or cultured fish eggs. Phosphotidylinositol (PI) was the dominant phospholipid found ins all egg samples from all origins as opposed to phosphotidylcholine, which is usually the dominant phospholipid. These data indicate that PI and AA may have important and as yet unidentified roles in fertilization and embryonic development in these fish.