茜素络合物浸泡标记秦岭细鳞鲑发眼卵及仔鱼耳石

采用茜素络合物(ALC)在秦岭细鳞鲑(Brachymystax lenok tsinlingensis)发眼卵和仔鱼阶段进行浸泡标记试验,为确定合适浸泡浓度和持续浸泡时间,试验设置了6个的浓度组和4个时间梯度组.结果显示:在荧光显微镜下观察被浸泡的仔鱼和经浸泡处理的发眼卵而出膜后的仔鱼,其耳石都出现橘红色荧光标记.浸泡...     

Biomass and production of the euphausiid Euphausia pacifica along the coastal waters off north-eastern Japan

ABSTRACT:   Biomass and production of Euphausia pacifica off south-eastern Hokkaido (41–43°N), Sanriku (38–41°N), and Joban (36–38°N) were investigated every two months from March 1997 to February 1998. High biomass was found in summer–autumn off south-eastern Hokkaido, and in the late winter–early summer off Sanriku and Joban. Annual mean biomass was 381, 314 and 258 mg C/m² off south-eastern Hokkaido, Sanriku, and Joban, respectively. The total production (sum of flesh, moults and eggs) during the survey period off south-eastern Hokkaido (3829 mg C/m²) was comparable with that off Sanriku (3872 mg C/m²); both were much higher than that off Joban (2243 mg C/m²). Somatic production during the survey period contributed the highest proportion (51.5–70.9%) to the total production in each coastal area. The somatic production–biomass ratio in each coastal area (5.2–6.9) was an intermediate value among 25 populations of 16 euphausiid species previously reported. This effect resulted from the negative factor of stagnated growth of adults during summer–winter, coupled with positive factors including continuous occurrence of larvae which show high growth rate throughout the year off Sanriku and Joban, and the numerous larvae occurring in October off south-eastern Hokkaido.     

Naupliar copepod concentrations in the spawning grounds of Japanese sardine, Sardinops melanostictus, along the Kuroshio Current

Naupliar copepods were distributed at similar concentrations over the waters inshore and offshore of the Kuroshio Current off central Japan in early spring 1993 and 1994, overlapping with the distribution of early feeding larvae of Sardinops melanostictus . Although N, P, Si and chlorophyll a concentrations were higher in the waters inshore of the Kuroshio axis than in the offshore waters, the mean concentrations of nauplii were not statistically different between the two waters. Food availability for larval S. melanostictus did not seem to be different between the two waters in terms of the mean food concentrations. Using the critical food concentration (>9 nauplii L^–1) for 25% survival during 3 days after first feeding derived from a rearing experiment, percentages in number of stations or water samples with nauplii concentrations >9 nauplii L^–1 were higher in the inshore waters than in the offshore waters in both years examined. Considering that fish larvae may depend on small-scale patchiness of food for their survival, the inshore waters seemed to be more favourable for first-feeding larvae than the offshore waters.     

Mass-marking of coregonid larvae and fry by tetracycline tagging of otoliths

Abstract. Larvae and juveniles of two species of Coregouns sp. were immersed in tetracycline (TC) solutions (200–800)mg/1) and fluorescent marks in the otoliths from fish were identified under a UV-light microscope. Whitefish. Coregonus Iavaretus (L.). juveniles (average weight 191 mg) immersed in TC solution retained their marking until the 127th day, hut 40% of the population lost their TC marking after wintering. Whitefish and peled. C. peled Gmelin, larvae retained TC marking from the TC solution (400 mg/1) if water temperature was higher than 5°C, Whitefish juveniles retained clear marking in the otolith after 120 days of post-immersion rearing. Peled larvae immersed in TC solution were grown in a pond and the fluorescent otolith centre of 55·4-g fish was well visible after processing. Nearly 100% of peled larvae grown for 176 days can he identified based on fluoresceent marks observed under a UV-lighl microscope.     

Larval Development and Rearing of Longtooth Grouper Epinephelus bruneus in Jeju Island, Korea

Eggs and sperm were obtained from a female (6.3 kg/BW) and a male (8.4 kg/BW) longtooth grouper Epinephelus bruneus following HCG injection in July 2003. The eggs were fertilized artMcially with the sperm and incubated in one of two 50-m³ tanks after washing the fertilized eggs. The fertilized eggs were 830–950 pn (average 900 ± 2 μm) in diameter and the respective fertilization and hatching rates were 97.7 ± 0.6% and 96.8 ± 0.5% at a water temperature of 25.0 ± 0.5 C. With this regime, the survival rate by day 93 was 7.5% in the 50-m³ tank. The elapsed time from hatching to opening the mouth was 3 d at 25 C. The initial mouth size (z) of the larvae was 0.22–0.23 mm. The newly hatched larvae were 2.02 ± 0.02 mm TL; this increased to 4.12 ± 0.09 mm TL by day 11. By day 54, the larvae had metamorphosed into juveniles and reached 41.12 ± 1.20 mm TL, and by day 93 the juveniles reached 93.78 ± 1.98 mm TL. In all, 49.5% of the larvae were malformed and the type of malformation was diverse.     

Mass-marking of grayling, Thymallus thymallus (L.), larvae by fluorochrome tagging of otoliths

Abstract Larvae of grayling, Thymallus thymallus (L.) were immersed in tetracycline hydrochloride (TC) and alizarin red S (AL) solutions for 3–4 h at concentrations of 300 and 70 ppm, respectively. Fluorescent marks on the otoliths from the marked fish were identified using a UV-light microscope. Results obtained with AL were superior to TC in marking otoliths. Fish kept in an aquarium retained good marks for 842 days. Stocking of the Carpathian River Ochotnica with marked grayling larvae revealed good mark retention for 128 days and a survival rate of approximately 12.2%.     

Can calcein and alizarin complexone be used for double immersion marking of juvenile qingbo <Emphasis Type="Italic">Spinibarbus sinensis</Emphasis>?

Calcein (CAL) from 50 to 250 mg/l and alizarin complexone (ALC) from 100 to 300 mg/l were used for double immersion marking of juvenile qingbo Spinibarbus sinensis. With the exception of the scales, double immersion for 24 h produced detectable double marks in otoliths (sagittas and asterisci), barbs, fin rays (dorsal, pectoral, ventral, anal, and caudal), and fin spines (dorsal, pectoral, ventral, and anal) after 90 days in a laboratory growth experiment. Green fluorescent rings produced by CAL were considerably closer to the inside of the bony structures (including otoliths, barbs, fin rays, and fin spines) than red fluorescent rings produced by ALC. Sagittas, asterisci, and barbs showed acceptable fluorescent marks at higher concentrations (250 mg/l CAL and ≥ 200 mg/l ALC, ≥ 200 mg/l CAL and 300 mg/l ALC, 150–250 mg/l CAL and 250–300 mg/l ALC, respectively). Fin rays and fin spines treated by 200 mg/l CAL and 250 mg/l ALC and 250 mg/l CAL and 300 mg/l ALC simultaneously had both acceptable CAL and ALC marks. There was no statistically significant difference on the survival or growth of marked fish compared to the controls throughout the experiment (p > 0.05). The results suggest that double immersion with CAL and ALC is suitable for double mass-marking of juvenile S. sinensis, and these double marks are useful in the experimental development of biological research or restocking methodologies.     

Preliminary investigations on the effects of dietary lipid on the spawning performance and egg quality of black sea bass Centropristis striata L

Adult black sea bass Centropristis striata broodstock ( N =162) were fed three different dietary treatments: two commercially prepared diets with 45% protein and two different lipid levels (12% and 20%) (diets 1 and 2), and a diet of frozen Atlantic silversides Menidia menidia (SS, diet 3). Broodstock were held under controlled photothermal conditions and induced to spawn with an LHRHa pellet (72 μg kg⁻¹ bw). Dietary lipid had pronounced effects on spawning performance and egg quality. Diet 3 (SS) produced a significantly ( P <0.05) higher fertilization success (22.4%) than diets 1 (0.6%) and 2 (4.8%). The hatching success of fertilized eggs was similar in all diets (range=40–58.6%), but only two spawns from diet 1 (12% lipid) yielded viable yolk-sac larvae (YSL). Diet 3 (SS) also produced significantly more YSL per female (21.8 × 10³) than the diet 1 (0.3 × 10³). Eggs from diet 3 (SS) contained a significantly greater proportion of n-3 series fatty acids, with docosahexaenoic acid (DHA) as the largest fraction. Eggs from commercially prepared dietary treatments contained significantly more n-6 fatty acids. The poor spawning performance of fish fed diet 1 (12% lipid) may be related to higher levels of linoleic acid and lower levels of DHA in the diet.     

Spawning habitat of the Atlantic menhaden in Onslow Bay, North Carolina

The Continuous, Underway Fish Egg Sampler (CUFES) was used to sample pelagic eggs of the Atlantic menhaden ( Brevoortia tyrannus ) from 3-m depth off North Carolina in winter 1993–94 and 1994–95. Simultaneous measurements were made of temperature, salinity, and the concentration of chlorophyll a . The maximal concentration of eggs was 346 eggs m⁻³. Eggs were highly aggregated in patches which occurred between the Gulf Stream and mid-shelf fronts (17–23°C, 36.0–36.4‰). Unexpectedly, eggs were found almost exclusively in water of 20–60 m (mode 20 m) bottom depth. Thus, spawning appears related to bathymetry as well as hydrography. Variograms for egg concentration indicated a mean (± SE) patch scale of 3.6 ± 1.7 km and a high degree of spatial variance explained by CUFES sampling. Lagrangian modelling of particles moving in response to tides, winds, and a prescribed flow from the north indicated that the region of observed, maximal occurrence of eggs is favourable for the retention of eggs and larvae on the shelf adjacent to inlets used to enter nursery areas.     

Preliminary investigations on husbandry, nutrition and growth of glass eels and elvers, Anguilla anguilla L.

Abstract. Some effects of husbandry and feeding on growth of glass eels and elvers of the European eel. Anguilla anguilla L., were investigated. In the first 7 months after arrival the recorded mortality amounted to 34% of the initial population. due to escapes and possibly cannibalism the observed survival after 7 months was only 21% of the initial population.
Mean growth rate of the whole population was 7.1 g day⁻¹ kg^−0.8. Growth proved to be highly variable. Growth rate was clearly affected by feeding level but not by initial stocking density.
Maximum growth rate was approximately 8g day, ¹ kg^−0.8 with feed conversions of 1.7–2.0. An optimal feeding level of 7.5g day¹ kg^−0.8 resulted in feed conversions of 1.3–1.6.     

Reproductive Performance of Pigmented and Albino Female Channel Catfish Induced to Spawn with HCG or Ovaprim

Reproductive performance of albino and pigmented channel catfish ( Ictalurus punctarus ) females was compared when spawning was induced with HCG (human chorionic gonadotropin) or Ovaprim ³ (domperidone and [d-Ala⁶, Pro⁹ NEt]-luteinizing hormone-releasing hormone). In 1985, only HCG was used to induce spawning. Albino females required more injections, had a longer latency period from time of first injection to spawning, and had lower spawning success (30%) than pigmented females (77%). No differences were observed between albino and pigmented females for time-of-day of spawning, number of eggs obtained by manual stripping, and number of eggs/kg body weight. In 1988, HCG, Ovaprim, and saline (control) were used to induce spawning. HCG induced spawning in 80% of albino and 71% of pigmented females. Ovaprim induced 67% of pigmented females to spawn, but only 2 of 5 albino females spawned. One of four pigmented females injected with saline spawned. Albino females yielded 40–50% fewer eggs/kg body weight than pigmented females. Other performance characteristics for albino and pigmented females were similar whether injected with HCG or Ovaprim. High temperatures encountered during the 1985 spawning season my have had a differential effect on albino and pigmented fish and may account for some differences in spawning success.     

Optimal protein level in a semipurified diet for juvenile greenlip abalone Haliotis laevigata

To optimize dietary protein level in relation to growth, semipurified diets with an essential amino acid profile similar to that of the soft body profile were fed for 59 days to young greenlip abalone, Haliotis laevigata (initial shell length, 15–25 mm). Animals were housed in 10-L acrylic tanks, with flow-through seawater supplied at 1 L min^–1 (20 °C, salinity= 36 g L^–1). Protein level of feeds ranged from 122 g kg^–1 to 461 g kg^–1 crude protein (CP) on an 'as is' basis. Second-order polynomial regression analysis of specific growth rate indicated that maximal growth occurs at 270 g kg^–1 CP. The protein and energy components of the feed were estimated to have a digestibility of 71.7% and 55.6%, respectively.     

Creation of artificial upwelling areas for brown trout, Salmo trutta, spawning in still water bodies

Abstract  Brown trout, Salmo trutta L., spawning sites were constructed by creating areas of artificial upwelling water, 252 ± 37 mL m⁻² min⁻¹ (95% CL), through appropriately sized spawning gravel substrate in 3 m² vessels buried in the bottom of a 150-m² pond. Natural spawning occurred in the vessels during autumn 2001–2004, with hatching and alevin swim up the following spring. In areas of upwelling, egg survival was 85–95%, while no live eggs were observed in areas without upwelling. In areas with upwelling, the maximum density of live eggs at the eyed stage was 570–1510 eggs m⁻². In spring 2004 and 2005, the density of alevins was estimated at 322 (±187) m⁻² and 567 (±217) m⁻², respectively, in areas with upwelling water, compared with 35.2 ± 25.4 m⁻² in areas without upwelling water in 2004.     

Factors affecting the susceptibility of Irish soft-water streams to forest-mediated acidification

Hydrochemical sampling was carried out at forty seven sites on upland soft-water streams in the eastern region of Ireland. The majority of sites were circum-neutral during dry weather but became episodically acidic during heavy or prolonged rainfall. Sensitive sites were characterized by low alkalinity (< 200 μeq L^–1) and low non-marine hardness (< 120 μeq L^–1) values and high levels of natural acidity (DTOC). These sensitive, naturally acidic waters were shown to be susceptible to acid inputs from forestry. The high acidity levels associated with some afforested catchments were attributed to inputs of sulphates, nitrates and hydrological factors.     

Effect of Ultraviolet Irradiation on Sperm of the Left-eyed Flounder, Paralichthys olivaceus

In this study, at proper dosage of ultraviolet (UV) irradiation (180   sec: 36,000   erg/mm²), sperm chromosomes of left-eyed flounder, Paralichthys olivaceus , were inactivated, while spermatozoa maintained ability to move and inseminate eggs. Gynogenetic haploids were detected by morphological observation, chromosome counting, and flow cytometer analysis. The ultrastructure of treated sperm was observed under scanning electronic microscope (SEM) and transmission electronic microscope (TEM). The results showed that after being irradiated at lower dosage of irradiation (0–180   sec: 0–36,000   erg/mm²), the surface structure of spermatozoa was not affected by UV irradiation, while the inner structures including membrane system and karyoplasm denseness of treated spermatozoa were little changed. However, obvious changes were observed in their membrane system, mitochondria, and nucleus if the dosage of irradiation increased to 240   sec: 48,000   erg/mm² or 300   sec: 60,000   erg/mm². The sperm survival rates did not change at the lower dosages of the UV irradiation (0–180   sec: 0–36,000   erg/mm²) but decreased as the irradiation dosage increased. The motility of treated sperm was lower than that of control group in general but did not change with UV irradiation dosage increasing at the certain range of 0–300   sec: 0–60,000   erg/mm².     

The relationship between stock and catch and the effect of bait on catch as determined for a UK recreational catch and release fishery

Abstract Twelve anglers fishing in a UK navigation canal for a total of 42 h caught 567 fish, mainly gudgeon, Gobio gobio (L.) ( n =306) and roach, Rutilus rutilus (L.) ( n =253) at an average catch rate of 13.4 fish angler-h⁻¹ or 128.5 g angler-h⁻¹. The species and size of fish caught were compared with the numbers determined by depletion estimates at six sections of canal using micromesh seine netting. Fifty four percent of fish caught in the net were < 60 mm FL. Gudgeon (60–99 mm) were over-represented in the anglers' catches whilst roach (60–99 mm) were under-represented. The size distribution of roach and gudgeon caught by anglers using two types of bait (small maggots and chironomid larvae) was examined and smaller fish were found to be caught using the latter.     

Effects of acidity and a metabolic inhibitor on incorporation of calcium and inorganic carbon into endolymph and otoliths in salmon Oncorhynchus masou

ABSTRACT:   To investigate the mechanisms of calcium carbonate formation of teleost otoliths, using the double labeling technique of ⁴⁵Ca²⁺ and H¹⁴CO₃^–, the effects of tissue elimination, a metabolic inhibitor (cyanide) and acidity on the incorporation of calcium and inorganic carbon into endolymph and otoliths were examined. Incorporation of calcium and inorganic carbon into otoliths was decreased to 36% and 45%, respectively, by removing the sacculus. In contrast, cyanide inhibited incorporation of inorganic carbon and calcium into endolymph and otoliths in a concentration-dependent manner. Acidity in the incubation medium decreased the accumulation of inorganic carbon within the endolymph and otoliths. Calcium incorporation was not affected by variation of pH in the medium. These results indicate that calcium and bicarbonate are actively transported to endolymph via the sacculus, and it is suggested that the transport is involved in the oversaturation state for calcium carbonate in the endolymph and regulates subsequent calcification of otoliths.     

Size-dependent predation on marine fish larvae by Ctenophores, Scyphomedusae, and Planktivorous fish

Size-dependent predation rates on marine fish larvae by the ctenophore Mnemiopsis leidyi , scyphomedusa Chrysaora quinquecirrha , and planktivorous fish Anchoa mitchilli were estimated via experiments in 3.2 m³ me-socosms. Predation rates on larvae of the goby Gobio-soma bosci were estimated in relation to 1) length of larval prey, 2) presence or absence of alternative < 1 mm zooplankton prey, and 3) a predator-prey interaction between the scyphomedusa and ctenophore. The consumption rate of larvae by the three predators generally declined as larval length increased. The ctenophore ate fewer (1.0 d^-1 per predator) larvae than did the medusa (7.8 d ^-1 per predator) or bay anchovy (4.0 d ^-1 per predator), but it consumed larvae in all size classes tested (3.0–9.5 mm SL). Predation by bay anchovy and the medusa was more size-dependent: 3.0–5.0 mm larvae were most vulnerable. Fewer larvae were eaten by the ctenophore and bay anchovy when zooplankton alternative prey was available, but predation on larvae by the medusa was not influenced by alternative zooplankton prey. Consumption rate of fish larvae by the medusa was reduced 20–25% when the ctenophore was present as its alternative prey. An encounter-rate model was developed and its parameters estimated from the experimental results. Model simulations indicated that the relationship between larval size and vulnerability is dependent on size, swimming speed, and behavior of both predators and larvae, and that bigger or faster-growing fish larvae are not always less vulnerable to predation.     

Mass Production of Striped Patao Eugerres brasilianus Juveniles in Cuba

Abstract.— Two spawning and larval rearing trials with striped patao Eugerres brasilianus were conducted at Tunas de Zaza, Cuba, to develop a method for experimental-scale mass production of juvenile fish. Mature striped patao were captured from coastal lagoons in September 1988 and January 1989. Sexually mature females and males were induced to spawn by treatment with human chorionic gonadotropin (HCG). After spawning, eggs were collected and placed in 1.2-m³ cylindroconical fiberglass incubators at densities of 150 and 200 eggs/L. About 1 h before hatching, eggs were transferred to 5–m³ concrete tanks. Larvae were fed a mixture of marine microalgae, rotifers, copepods, and Artemia nauplii; artificial food was supplied at 30 d post-hatch as a shrimp diet with 25% protein and 0.1–0.4 mm particles. Fourteen of 20 females spawned after 2 or 3 HCG injections (total dose = 6–10 IU/g body weight). Fecundity was 467–2,167 eggs/g body weight. Egg incubation time in seawater (38–39 ppt salinity) was 15–17 h at 29–30 C and 21–23 h at 25–26 C, with 98–100% hatching rate. The oil droplet and yolk sac were consumed by 3 to 5 d post-hatch and first food (rotifers) was eaten during second day. High larval mortalities began after the first month. Growth in 39- ppt seawater was faster (0.41 ± 0.01 md/d) at 29.1 ± 0.3 C than at 25.2 ± 0.2 C (0.27 ± 0.008 mm/d). Overall survival was 6–12.5% with tinal densities of 5–10 juveniles/L after 48–60 d. A total of 132,000 juveniles was harvested from the two rearing cycles.