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Studied were the quantities of volatile amines, total volatile bases nitrogen (TVB-N) and trimethylamine nitrogen (TMA-N) in stored sardines ( Sardina pilchardus) and herring ( Clupea harengus) over a 24-h period after defrosting. At the beginning of the experiment analyses showed TVB-N quantities in the flesh of both species to be higher than the FAO-recommended limit. TMA-N concentrations exceeded the acceptance limit 6 h after defrosting in herring samples and after 12 h in sardines. During the entire experiment TMA-N and TVB-N concentrations in sardines were above the tolerance limit. The defrosting method usually applied in tuna farms is unsuitable for maintenance of a high quality food supply. Low quality baitfish can cause reduced weight gain as well as induce health problems and mortality in farmed tuna ( Thunnus thynnus) populations. [ABSTRACT FROM AUTHOR]

Diplodus puntazzo is a species characterized by a rudimentary hermaphroditism, with a low level of protandry. The study found that the overall sex ratio was one male to 2.03 females, diverging significantly from 1 : 1, and that there was a ratio of one male to 0.11 transitional fish. The sex ratio varied with season: during the reproductive period the ratio was 1 : 1.86 (male : female), significantly lower than in the non-reproductive period in which the sex ratio was approximately 1 : 2.26. Both sexes had similar size distributions; however, females were predominant in all size intervals, especially in the larger ones. No significant difference in mean total length (TL) between females (330 mm), males (319 mm) or transitionals (321 mm) was found. The smallest functional female and male analysed were 159 and 157 mm TL, and the largest were 520 and 510 mm TL, respectively. No significant difference in length at first level of maturity, attained at the second year of life, was found between males (281 mm) and females (292 mm), respectively. A protracted spawning season was identified for the species: from September to February, with a peak in November. GSI values followed the same pattern for males and females, with values of females being similar to those of males; the highest values occurred between September and December, with a maximum in November. Occurrence of transitional fish was significantly higher during the month with highest values of GSI than in the resting period. The study found that vitellogenesis did not begin synchronously for all females, and the simultaneous presence of oocytes in all stages of development indicated an asynchronous mode of ovarian development. The presence of postovulatory, together with tertiary yolk vesicle oocytes, indicated that the species is a multiple spawner. [ABSTRACT FROM AUTHOR]

This study describes otolith marking of brown trout ( Salmo trutta L.) larvae by immersion in different solutions of alizarin red S (ARS). The best results were obtained after marking with ARS at a concentration of 150 mg L−1. To evaluate the efficiency of stocking with brown trout fry, 10 000 20-day-old larvae were marked in years 2002 and 2003 with ARS and released 2 weeks later into sections of a river with natural brown trout reproduction. Electro-fishing surveys carried out 2 months after stocking in 2002 revealed that only 4.8% of all caught young-of-the-year trout originated from stocking; in 2003 the percentage was 8.9%. Based on the substantial natural reproduction and the low ratio of stocked to wild trout, it was recommended to discontinue stocking. [ABSTRACT FROM AUTHOR]

The population structure, age, growth, mortality and harvest intensity of the oyster Crassostrea madrasensis were examined in the Moheskhali Channel, Bangladesh between June 2003 and May 2004. The channel is a representative habitat for the area. C. madrasensis monthly length frequency data were analyzed using FiSAT software for estimating population parameters, including asymptotic length ( L ∝), growth co-efficient ( K) and recruitment pattern to assess the status of the stock. Asymptotic length ( L∝) and growth co-efficient ( K) were 20.88 cm and 0.35 year−1, respectively. The growth performance index (ϕ′) was calculated with 2.18. The growth pattern showed negative allometric growth ( b < 3), with an asymptotic weight ( W ∝) of about 1124.6 g. The oyster attained an average length of 6.17 cm at the end of 1 year. Total mortality ( Z) by length-converted catch curve was estimated at 1.78 year−1, fishing mortality ( F) at 0.77 year−1, and natural mortality ( M) at 1.01 year−1. The exploitation level ( E) of C. madrasensis was 0.43, while the maximum allowable limit of exploitation ( Emax) was 0.45 for the highest yield. The recruitment pattern was continuous, displaying a single major peak event per year. Habitat temperatures were 25.5–31.0°C (mean ± SD, 29 ± 1.62°C); salinity range was from 12.36 to 26.0 ppt (mean ± SD, 19.6 ± 4.7 ppt). The exploitation level (0.43) indicated that the oyster stock was exploited at almost maximum yield in this channel. [ABSTRACT FROM AUTHOR]

An application of a new automated fish counting device – the Riverwatcher System (RW) – was used to monitor upstream fish movements in a pool-and-weir fish pass in the River Zêzere, Portugal, for 141 days from June 2002 to May 2003. Fish populations were also collected downstream using multimesh gillnets (5 different mesh sizes ranging from 30 mm to 85 mm knot to knot; ratio between mesh sizes of about 1.30) and electrofishing for comparison with fish records produced by the RW. More than 3000 individual Iberian nase Chondrostoma polylepis ascended the fish pass and moved through the RW during the study period. However, only 18% of the records produced by the RW contained silhouettes similar to fish; no individual smaller than 15 cm TL was recorded by the counter. Most seasonal movements (73.9%) occurred in spring and were associated with reproduction. Displacements seemed to occur independently of time of day. Water temperature (range: 12–22°C) was the only significant environmental variable (P < 0.01) influencing upstream movements of this species. Further development of hardware and software will be necessary to improve performance of the counter, particularly in Mediterranean rivers, where more turbid waters and a greater proportion of small-size species are present. [ABSTRACT FROM AUTHOR]

The article discusses the elevated rearing densities necessary for profitable aquaculture operations are generally related to declining water quality, which may affect fish welfare and juvenile quality. The motivation for this research was to provide information on the potential effects of chronic exposure to ammonia on juvenile Atlantic cod raised in recirculating aquaculture systems since ammonia build up is frequently reported in such systems. Ammonia can significantly reduce growth, and can adversely affect different organs and functions.

The goal of this study was to determine the basic haematological profile of common carp ( Cyprinus carpio L.) spawners of eight breeds reared under identical conditions and sampled in spring after overwintering. Significant differences were found among the breeds for haemoglobin level (Hb), haematocrit value (PCV), mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) values. The number of red blood cells (RBC), mean corpuscular haemoglobin concentration (MCHC), number of leukocytes (WBC) and leukocyte differential count (WBC DIFF) did not differ significantly among the respective breeds. The highest Hb, PCV and MCH values were found for Ropsha scaly carp (ROP) and Amur wild carp (AS) (Hb 109 ± 17 and 106 ± 15 g l−1; PCV 0.40 ± 0.06 and 0.40 ± 0.06 l l−1; MCH 69 ± 7 and 69 ± 9 pg, respectively). The AS specimens and breeds that originated [ROP, Ukraine scaly carp (US), and Northern mirror carp (M72)] showed significantly higher values of Hb (P < 0.01), PCV (P < 0.01), MCV (P < 0.05) and MCH (P < 0.05), compared to the other four breeds: Hungarian mirror carp (M2), Israeli mirror carp (Dor 70), South Bohemian mirror carp (BV) and Tata scaly carp (TAT). Males showed significantly higher PCV, Hb and RBC values within individual breeds. This study demonstrated that Amur wild carp and breeds originating from it had significantly higher values of erythrocyte profile in comparison with the other breeds studied. [ABSTRACT FROM AUTHOR]

Models for estimating food consumption in fish by analysing changes in stomach fullness over time are invariably based on a stomach evacuation rate obtained when the fish is fasting, on the assumption that this rate also applies to when the fish is feeding. However, this often is not the case in fish that feed on small particles. A new modelling approach was therefore tested, which is based not only on stomach fullness but also on gut contents. To eliminate errors arising from assimilation in the gut, titanium(IV) oxide (TiO2) was used as an indigestible marker. When applied to a dataset obtained from tilapia given several equal doses of pelleted feed over a 2.5-h period, the new approach gave a closer true consumption estimate than a conventional model. The evacuation rate proved to be a more sensitive parameter than the ingestion rate, but the former was no longer required by the new approach for estimating ingestion, thus liberating the food consumption estimate from any errors and dependencies inherent in the evacuation rate. The new approach assumes that the digesta of previous feedings can be distinguished from those of the feeding phase being analysed and therefore needs further refinement for those cases when this does not apply. Suggestions for such refinements are also given. This new approach is expected to be equally suitable for estimating consumption in stomachless fish. [ABSTRACT FROM AUTHOR]

The article discusses the characteristics of synechogobius hasta. This has been identified as a species destined for diversification of Chinese marine aquaculture. The development of high quality formulated feed, based on the nutrient requirements of the species, will help improve economical and environmental sustainability of aquaculture in the country. Dietary lipids play not only important roles as potential sources for energy, essential fatty acids and fat-soluble vitamins, but also have important physiological functions.

Lake sturgeon ( Acipenser fulvescens) population characteristics and migration patterns were evaluated in the Manistee River system, Michigan. Sturgeon (n = 102) were captured using gillnets, tagged and released in the system between 2001 and 2005. Biological data (weight, length, age, sex and spawning status) were collected to calculate length–weight relationships and relative condition factor ( K n), determine age structure, and estimate the annual spawning population size. Sturgeon were also implanted with radio and sonic transmitters, and migration patterns of 22 sturgeon were determined. The weight–length equation for sturgeon in the Manistee River system was log10 W = 3.17log10TL−5.52 and did not differ by sex. K n equaled 0.72 and did not differ by sex or spawning status. Ages ranged from age 5 to age 54. Sexually mature male and female sturgeon were captured over the course of the study, and the size of the spawning population ranged from 21 to 66 spawners. Sturgeon migration movements up and down the Manistee River varied with date, water temperature, and discharge. The sturgeon appeared to use two different spawning sites in the Manistee River. The Manistee River system supports a remnant lake sturgeon population; the presence of a wide range of age classes and availability of a limited number of suitable spawning sites suggest continued recruitment to the population. [ABSTRACT FROM AUTHOR]

The purpose of this study was the identification and quantification of biochemical parameters over a 1-year cycle and to provide a detailed picture of seasonal changes in plasma metabolites and enzymes. Using the novel methods of machine learning techniques, the authors created and generated for the first time comprehensible classification models for exploring the importance of blood chemistry parameters, strength, mutual interactions or dependencies, and reliability of particular parameters within the seasonal groups. [ABSTRACT FROM AUTHOR]

Understanding the nutritional condition and survival of fish larvae is of primary importance in mass larva culture because intensive mortality is concentrated during the larval period. In order to estimate growth and nutritional status based on biochemical indices of slime flounder, Microstomus achne, larvae reared under starved and fed conditions in the hatchery for 58 days and the changes of RNA, DNA, and protein contents were described with the progress of growth and developmental. DNA contents increased gradually throughout the experimental period until 12 and 58 days post-hatching (DPH) in starved and fed groups respectively. Although they fluctuated and decreased around 12 and 46 DPH, the RNA contents of the fed group increased gradually after hatching; however, in the starved group, they decreased after yolk absorption and 7 DPH. Subsequently, the RNA/DNA ratios in the starved group remained constant until 6 DPH and then decreased rapidly. In the fed group, this decreased slightly from hatching to 14 DPH, then increased gradually until the end of the experiment, except at the lower level of around 46 DPH. Namely, temperature shocks (around 14 DPH) and the dramatic changes in body shape (around 46 DPH) were accompanied by the decrease of the RNA/DNA ratios. Total protein/DNA in both groups decreased rapidly during yolk absorption 0–7 DPH, then decreased continuously until death in the starved group; in the fed group total protein/DNA increased again with feeding. It is suggested that the changes in these biochemical values reflect yolk absorption, feeding, morphogenetic changes, growth, and environmental conditions. [ABSTRACT FROM AUTHOR]

This study evaluated the growth performance and body composition of Oreochromis niloticus fingerlings (average initial weight 16.53 ± 0.44 g) fed 9 experimental diets (A, B, C, D, E, F, G, H and I) containing three different levels of protein (26, 31 and 36 g 100 g−1) at three different gross energy (GE) levels (16, 19 and 22 MJ kg−1) for a period of 64 days. Significant differences were observed in the feed consumption, body weight gain, specific growth rate (SGR), condition factor ( k), feed conversion ratio (FCR), protein efficiency ratio (PER), net protein retention (NPR) and apparent net energy retention (ANER) values of fish when the energy level of diet was increased at different protein levels. The maximum weight gain, SGR and k were observed on diet F containing 36% protein and an energy level of 19 MJ kg−1 of dry feed with a protein to energy (P/E) ratio of 18.96 (g protein MJ−1 GE). A further increase in the energy content of the diet (22 MJ kg−1) at the same protein level (Diet I) did not produce any improvement in the growth performance. Lowering the energy level at the same protein level significantly affected the growth performance. Fish fed diet B containing 31% protein and a lower energy level of 16 MJ kg−1 with the same P/E ratio of 18.61 as diet F showed significantly lower weight gain and growth performance than diet F. Diets E and H containing 31% crude protein at all three energy levels produced similar results as diet B. The poorest FCR was observed when the diet contained both lower levels of protein and energy. Fish fed diet G, containing 26% protein at high energy level (22 MJ kg−1), showed the best PER and NPR values. The PER and NPR were the poorest on diet C containing 36% protein at low energy level (16 MJ kg−1). The body moisture content at all protein levels decreased (P < 0.05) with the increasing level of dietary energy whereas the body fat content increased (P < 0.05). Similar trends were observed in the body ash and energy content. Increasing the dietary energy content at lower protein levels did not show any difference (P > 0.05) in body protein content. Our results indicated the optimum P/E ratio for O. niloticus as 18.96 g protein per mega joule of gross energy at 36% dietary protein level and a dietary gross energy value of 19 MJ kg−1. [ABSTRACT FROM AUTHOR]

Argyrosomus japonicus is a member of the family Sciaenidae, which are commonly known as drums and croakers. A. japonicus occurs in estuarine and nearshore Pacific Ocean and Indian Ocean waters surrounding Australia, Africa, India, Pakistan, China, Korea and Japan. The biology of A. japonicus is relatively well studied in South Africa, and more recently studied in Australia, but no information is readily available from other areas of its distributional range. The early life history distribution of A. japonicus may differ among regions, with their distribution in estuaries linked to salinity, turbidity, freshwater flows and depth of water. Studies in South Africa and Australia found that juvenile fish grow rapidly, attaining 35 cm TL in 1 year and 87–90 cm TL in 5 years. Sexual maturity also differs among regions and is attained at 2–3 years of age and >50 cm in eastern Australia, 5–6 years of age and >80 cm TL in western Australia and southern Africa. The maximum reported length and age of A. japonicus is 175 cm and 42 years, respectively. Spawning most likely occurs in nearshore coastal waters although there is evidence to suggest that it may also occur in the lower reaches of estuaries. Time of spawning varies among geographic localities and is probably linked to water temperature and oceanography. Juvenile fish (<2 years) appear to be relatively sedentary, but sub-adults and adults can move relatively long distances (>200 km) and such movements may be linked to pre-spawning migrations. A. japonicus is important in many recreational and commercial fisheries, but like other sciaenids, is prone to overfishing. It is classified as recruitment overfished in South Africa and overfished in eastern Australia. Although much research has been done to minimize the capture of juveniles in Australian prawn-trawl fisheries, greater protection of spawners and improved fishing practices to enhance survival of discarded juveniles, particularly from prawn trawling, may be required. An aquaculture industry is developing for A. japonicus in Australia and preliminary research on the impacts and success of re-stocking wild populations has begun in an attempt to arrest the apparent decline in populations. [ABSTRACT FROM AUTHOR]

This work focuses on reproductive biology aspects of Uranoscopus scaber from the coast of the Aegean Sea. In total, 175 U. scaber specimens were collected in Izmir Bay using trawl nets from January to December 2005. The reproduction period according to gonadosomatic index (GSI) values extents from March to September, with a peak in May (6.32 ± 1.2). Oocyte diameters taken from 59 mature gonads ranged from 62 to 1860 μm. Maximum batch fecundity (BF) was 58091 (mean: 11556 ± 1445) in large oocytes in May, and 8408 (mean: 2821 ± 945) in hydrated oocytes in September. The BF increased with total length and body weight, excluding the ovaries. Total length (TL)–BF relationships and fish weight–BF relationships were BF = 0.0034TL4.6248 ( r = 0.47) and BF = 59.166W−3101 ( r = 0.49), respectively, according to the oocyte size frequency method. There was a linear relationship between BF and fish size. [ABSTRACT FROM AUTHOR]

The article discusses the characteristics of capoeta capoeta capoeta. It is one of the subspecies of the genus Capoeta and it is distributed throughout southwest, south and central Asia. This subspecies is a popular taxon in the south Caspian Sea basin of Iran. The parasitological characteristics of khramulya have been studied in the Madarso stream of Golestan National Park. However, there is no published data on age and growth of C. c. capoeta in the southern Caspian Sea basin; the aim of present study was to investigate its age and growth characteristics from the Yasalegh stream in the Gorganrud basin.

The article discusses the invasive round goby Apollonia melanostoma Trematodes. Four species comprise this genus in North American waters. N. umbellus is the sole species that has been described to parasitize fishes in Lake Erie of the Great Lakes. The metacercariae of N. umbellus are located in the muscles of relatively small-sized fishes. The skin, fins, gills, muscles, brain, eyes, gut, liver, spleen, kidneys, body cavity, and mesentery were examined for metazoan parasites. The metacercariae were first isolated from cysts. Parasite

Length and weight descriptive statistics are reported for 29 demersal fish species caught off the Madeira archipelago during three yearly surveys (1997, 2004 and 2005) using bottom long-lines from depths of 25–1150 m. Weight–length relationships were estimated for 18 of these species. The parameter b ranged between 2.737 in Polyprion americanus and 3.674 in Benthodesmus simonyi. Additionally, in 11 species, parameter a was calculated setting b = 3. To the authors’ knowledge all weight–length relationships presented herein are recorded for the first time from the Madeira area, and in the cases of Deania profundorum, Muraena helena and B. simonyi, are the first references worldwide. [ABSTRACT FROM AUTHOR]

Totals of 284 Hemigrammocapoeta kemali specimens were caught during 1998 in the Işıklı Lake, Turkey. Their ages, lengths and weights were determined to estimate length–weight relationships and age composition. Fecundity and oocyte diameter were also determined. The sex ratio was 1 : 1.29. Fork length and total weight of specimens ranged from 3.4 to 8.2 cm and from 0.5 to 6.9 g, respectively. Maximum age observed was 4 years. The length–weight relationship for all fish was best described by the equation W = 0.0121*L3.06; the von Bertalanffy growth equations for length and weight were Lt = 8.73[1−e−0.401(t + 0.947)]; Wt = 9.17[1−e−0.401(t + 0.947)]3.06. Oocyte numbers varied from 220 to 1159 and oocyte diameters ranged between 450 and 900 μm. [ABSTRACT FROM AUTHOR]

The present study determined whether puffer Takifugu rubripes and T. xanthopterus larvae use selective tidal stream transport (STST) for migration into the nursery area. The influence of the tidal cycle on the vertical distribution of Thkifugu larvae was investigated during a 24 h sampling period at one location off Shimabara Peninsula in Ariake Bay. Samples were collected in three depth layers, from near the sea floor to near the surface (5, 20 and 30 m depth). The change in vertical distribution in relation to tidal phase was not observed. This data did not support STST hypothesis. Diel vertical migration was observed irrespective of tidal phase, where larvae migrated to the middle layer during the night, and sank to the bottom layer during the day, however, larvae hardly emerged into the surface layer during the study period. In Ariake Bay, the residual current leads to a layered vertically stratified structure, in which surface water flows towards the mouth and the middle-bottom water flows toward inner part of the Bay. It is suggested that Takifugu larvae use not STST but residual currents for transport into the nursery ground, namely, undergoing nocturnal diel vertical migration in the water column between the middle layer and the bottom layer where the net flow is northward. [ABSTRACT FROM AUTHOR]

On 7 November and 15 December 2006, two specimens of the Lessepsian migrant Fistularia commersonni were caught in trammel nets off the coastal waters of Tricase Porto (southwestern Adriatic, Italy) and Sveti Andrija (southeastern Adriatic, Croatia), respectively. These represent the first records of this species in the Adriatic Sea. [ABSTRACT FROM AUTHOR]

Weight–length relationships (WLR) are reported for 20 fish species from the mangroves of Guadeloupe (Lesser Antilles). The fishes were collected using fishing hoop nets. In the present study, the regressions were calculated after separating juveniles and adults. The b coefficient in the WLR varied between 2.37 and 3.85, with a mean of 3.15 ± 0.15. [ABSTRACT FROM AUTHOR]

The article discusses the characteristics of a lumpsucker Cyclopterus lumpus Linnaeus. It is a pelagic and solitary species distributed on both North Atlantic Ocean coasts. The spawning behaviour and curious parental care of this species is well-known. Lumpfish migrate from the open ocean toward shallow coastal waters during the spawning season. Females lay eggs that adhere to rocks in the seaweed beds. The presence of this species in Galician latitudes is actually occasional, but regular, mainly in the first half of the year.

The length–weight relationship of 21 species of fish from a coastal lagoon in the southwestern Gulf of California was estimated. These species were obtained as bycatch from the artisanal shrimp fishery. A total of 8522 specimens were used to estimate the parameters of the relationship, as well as at least 100 organisms per species. Differences between sexes were not found in any species. The slope ( b) showed values between 2.5 and 3.5. [ABSTRACT FROM AUTHOR]