Tests of Some Batch-Marking Techniques for Rainbow Trout (Salmo gairdneri Richardson)

Freeze-branding and tattooing by Panjet were used as techniques for rapid application of batch marks to rainbow trout of stockable size. The subsequent performances of the marks produced were compared. Freeze brands took 2 weeks to become clear and thereafter remained wholly satisfactory for only 1 month. Pigments injected by Panjet were immediately visible but of the dyes tested only Alcian blue remained completely clear after a 3-month trial. These results are contrasted with those of other workers in trials with various species of freshwater fish.     

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%.     

Larval pigmentation, survival and growth of Penaeus indicus fed the nematode Panagrellus redivivus enriched with astaxanthin and various lipids

The highly unsaturated fatty acid (HUFA) content of the free-living nematode Panagrellus redivivus was successfully increased when three different lipid sources (cod-liver oil, marilla oil and capelin oil) from marine animals were used in the nematode culture medium. The lipid enrichment significantly increased the ω3 HUFA content, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), of the nematodes compared with lipid non-enriched nematodes. Penaeus indicus larvae fed the lipid-enriched nematodes had significantly ( P < 0.05) greater larval survival (69–77%) until metamorphosis than those fed non-enriched nematodes (54%).
This nematode species was also enriched with astaxanthin to determine the effects of this carotenoid on pigmentation, survival and growth during the larval development of P. indicus . The pigment, delivered via nematodes, significantly ( P < 0.05) improved larval coloration and survival (88%) compared with that of placebo-pigmented nematodes (78%). However, there was no strong evidence to show the benefit of either pigment and/or lipid enrichment on larval growth and development of P. indicus .
This study has shown that the nutritional value of the nematodes can be enhanced by the addition of fish oil into the culture medium. Supplementation of EPA and DHA, together with synthetic astaxanthin, allow the nematodes to be used as a sole diet for the larval culture of P. indicus .     

Evaluation of Fluorescent Pigment Marking of Brown Trout (Salmo trutta L.) and Atlantic Salmon (Salmo salar L.)

Fish farm and field trials have been conducted into the longevity and reliability of fluorescent pigment spray marking on brown trout and Atlantic salmon. These have shown that the technique produces high quality marks for a minimum of 20 months for brown trout and 7 months for Atlantic salmon. In addition a minimum size of 6.8 cm for the successful marking of brown trout fry has been established. High mortalities were found when the technique was used on fish which were subject to stress. Causes of stress are discussed and mortality rates of <1% have now been achieved.     

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.     

Tagging of juvenile lobsters (Homarus gammarus (L.)) with visible implant fluorescent elastomer tags

Visible implant fluorescent elastomer (VIFE) tags were implanted beneath the epidermal layer within the abdomen of 25 juvenile lobsters. After three molts the tag retention was 100% and the total survival 92%. The results suggest that VIFE tags could be an effective tool when assessing the feasibility of enhancing natural lobster stocks.     

色素添加对咖啡金黄水母体色影响的初步研究

在人工繁殖水母的饵料中添加食用性人工合成色素、人工合成荧光色素、天然虾青素、铁元素和饲喂含有色素的海蜇等,测定水母采食饵料后感官指标、酪氨酸酶活力和总类胡萝卜素含量的变化,分析添加物质对水母生理机能的影响。试验结果显示,4种人工食用色素均能大大提升水母的观赏性,但颜色保持时间短,3 h后,所有水母均恢复原来的体色,水母状态未发现改变。水母注射水溶性荧光色素,10 h后才能通过水循环扩散到全身,荧光色维持时间可达30 d。水母饲喂天然虾青素、铁元素和含有色素的海蜇1个月后,肉眼观察,海蜇组的水母比对照组的水母颜色深,而虾青素组、FeSO_4组与对照组差异不明显。各组酪氨酸酶活力和总胡萝卜素含量均较低。组内个体间酪氨酸酶活力差异较大,但各组间差异均不显著(P>0.05)。总胡萝卜素在450 nm处吸收值最高。海蜇组水母的酪氨酸酶活力和总胡萝卜素含量均最高,分别为0.133 U/mL和251.01 mg/kg。虾青素组酪氨酸酶活力最低,为0.109 U/mL。食用色素组总胡萝卜素含量最低,仅为158.83 mg/kg,酪氨酸酶活力仅高于虾青素组,可能与色素并未在表皮和中胶层形成色素沉淀有关。试验结果表明,人工添加色素能获得颜色各异的水母,水溶性荧光色素能长期保存在动物体内,可作为体色调控色素。水母的色素合成与酪氨酸酶活力和总胡萝卜素含量有关。     

Survival of Brown Trout (Salmo trutta L.) Stocked as Summerlings and Autumn Fingerlings in Two Northern Ireland Lakes

The survival of 0+ brown trout, spray-marked with fluorescent pigment and stocked in two angling lakes as summerlings and autumn fingerlings, was assessed by netting exercises. About twice as many autumn fingerlings as summerlings survived the first winter after stocking, and in one lake the percentage survival of the two groups was estimated at 31.0% and 15.2% respectively. Survival to age 2+ was estimated to be in the range 5.7–9.7% for summerlings, and from 15.1% to 16.6% for autumn fingerlings. The best survival for both groups was obtained in the most productive lake, where condition factors and growth rates were the highest. The results were assessed in economic terms, and the cost per 2+ fish in each lake was more expensive from both summerling and autumn fingerling stocking than from direct introductions of fish-farm, two-year-old trout.     

三疣梭子蟹的两种标记技术

本研究采用注射可视嵌入性荧光、剪附肢两种手段对不同期别的三疣梭子蟹进行标记,以研究标记的适用性及对个体生长的影响。对不同发育阶段三疣梭子蟹进行两个部位荧光注射,统计蜕壳后可识别率。结果显示,Ⅱ、Ⅲ期幼蟹适合腹面区域注射,Ⅳ期以后幼蟹适合游泳足基节和头胸甲背面的薄膜关节注射;标记后,经过两次蜕壳,识别率在80％以上,但经3次蜕壳后,识别率较低;根据标记组、未标记组生长数据,通过单因素方差分析发现,标记对三疣梭子蟹个体生长无显著性影响。Ⅶ期以后的幼蟹,更适合剪附肢法,该法操作简单、识别率高,对个体生长、存活无显著性影响（P〉0．05）。     

Use of Chlorella vulgaris as a carotenoid source for rainbow trout: effect of dietary lipid content on pigmentation, digestibility and retention in the muscle tissue

Apparent digestibility, deposition and retention of carotenoids in the muscle of rainbow trout, Oncorhynchus mykiss, were investigated comparing the feeding of pigments from Chlorella vulgaris against commercially available pigments at two different total lipid contents (15% and 20% lipid). Algal biomass (ALG) was included in rainbow trout diets and muscle pigmentation was compared to that obtained in trout fed diets containing a 5:3 mixture of canthaxanthin and astaxanthin (MIX) (reflecting the relative concentrations of these carotenoids in the dry alga) or those fed a diet containing astaxanthin only (AST). Apparent digestibilities of pigments and nutrients were determined by the indirect method, using Cr2 O3 as indicator, and the colour intensity and pigment concentration were assessed in the muscle, using the Roche colour card for salmonids and UV-vis spectrophotometry. After 6 weeks feeding, colour intensity was similar for the various pigment sources, achieving levels 12 to 13, yet significantly higher in fish fed the diet with the higher lipid content ( 20%) (p<0.05). Pigment concentration in the muscle was also higher in the fish fed the high-fat diet. Muscle pigment concentrations were similar for fish fed diets ALG and MIX, and over 1.5 times higher than for diet AST (p<0.05) after 6 weeks. Apparent digestibility of dry matter, crude protein, lipid, total energy and specific carotenoid concentrations were also measured. Increased dietary fat content was shown to increase the deposition and the retention of carotenoids in muscle, and the difference increased with time (deposition increase of 10–20% at week 3 and 30–40% at week 6 and retention increase of 10–15% at week 3 and 30% at week 6). Pigment digestibility also apparently increases (10–20%) under those conditions despite the fact that no significant effects in terms of apparent digestibility increase were found for dry matter, protein, lipids or energy. © Rapid Science Ltd. 1998     

Evaluation of techniques for marking juvenile barramundi, Lates calcarifer (Bloch), for stocking

To monitor the success of stockings of hatchery-reared barramundi, Lates calcarifer (Bloch), in tropical Australian waters a series of laboratory and field experiments were undertaken to evaluate a range of marking techniques. Juvenile fish of stocking size 30-85 mm total length were first used in laboratory experiments and then some were stocked into a freshwater impoundment for field evaluation. Marking techniques evaluated were fin crimping, fin removal, cold branding, polyethylene streamer (ags and coded-wire tags. The results showed that dorsal fin crimping and pelvic fin removal were relatively ineffective methods of marking, with only 53% and 63% of marks in each respective group being recognizable after 3 months. The polyethylene streamer tags were quickly shed, with 100% loss after only 77 days. Cold brands faded rapidly and were not considered to be of value as long-term marks. Coded-wire tags, inserted into the cheek musculature, were considered to be the most successful of the techniques assessed. Coded-wire tags were implanted at a rate of 250-270 tags per hour with an immediate success rate of 95-97%. These tags had no significant detrimental effect on either growth or survival and tag retention in the 2-month laboratory trials was 93%. Longer-term field studies, where fish had been stocked for about a year, also suggested little effect of coded-wire tags on growth or survival and no evidence of shedding.     

Beak microstructure analysis as a tool to identify potential rearing stress for Octopus vulgaris paralarvae

Octopus vulgaris is a viable candidate for commercial aquaculture, but rearing procedures might stress individuals and result in diminished growth and survival. This study investigated the relationship between possible stress sources (tank transposition and syphoning) when rearing O. vulgaris paralarvae and the deposition pattern of growth increments in their beak microstructure. Light intensity at the facility was heterogeneous, and accounted for with an experimental design consisting of blocks without replicates. Growth and survival were estimated and possible effects of handling were tested for both parameters. Increments and stress marks were counted in 120 paralarval upper jaws (UJ), and the number of UJs with a mark on the day of stress application (day 8) was quantified. Differences in light intensity, diet quantity and total number of marks in the UJ were also compared between treatments. Growth and survival were statistically similar between treatments, although the control treatment showed a tendency for higher survival rates. Age at first increment deposition coincided with day 1 of experiment, and a 1 increment day^?1 deposition rate was validated for the experiment duration. The number of stress marks was significantly different between the control and other treatments, indicating that handling might cause stress and that marks can be used as a biomarker for stress, although the occurrence of stress marks on day 8 was not significantly different. Light intensity and diet might have also been relevant stressors and confounded the results. The results herein presented are important for improving rearing conditions for O. vulgaris paralarvae.     

Intertidal Growth and Survival of Northern Quahogs Mercenaria mercenaria (Linnaeus 1758) and Atlantic Surf Clams Spisula solidissima (Dillwyn 1817) in Georgia

This work reports on the effects of intertidal planting heights upon the growth and survival of the northern quahog, Mereenaria mercenaria (L.) and the Atlantic sod clam, Spisula solidissima (Dillwyn), in the castal waters of Georgia. Quahogs (N = 100 per cage) at 19.5 mm in shell length were planted in replicate cages (N = 3) placed at the spring (SLW), mean (MLW), one (+1), two (+2), and three (+3) hours above mean low water mark. Surf clams (N = 200 per cage) at 41.5 mm in shell length were placed in replicate cages (N = 3) deployed, as above, in all sites except +3. Quahogs grown at the SLW mark after 15 months were significantly larger than clams planted at other tidal heights. Quahogs planted at the MLW mark were significantly greater in shell length than those planted at the +3, +2, and +1 marks. Clams at the upper three sites were not significantly different in size. An inverse relationship between clam growth and intertidal planting height was evident among surf clams. Surf clams grown at the SLW mark for six months were signplificmtly larger than those at the MLW mark which were larger than those grown at the +1 above MLW mark. No significant differences in quahog survival were detected between intertidal planting sites. There was no significant difference in surf clam survival between SLW (77.5%) and MLW (61%) marks, but there was significantly lower survival at the +1 mark (15%) and no survival at the +2 mark.     

The suitability of VIE tags to assess stock enhancement success in juvenile European lobsters (Homarus gammarus)

Assessments of stock enhancement programmes for European lobsters (Homarus gammarus) require mark‐recapture analysis of stocked individuals. However, established tag technology is deemed unsuitable for extensive use by many current lobster hatcheries, particularly upon the early juvenile stages. We tested the suitability of fluorescent Visible Implant Elastomer (VIE) tags for use in 5‐month‐old juvenile lobsters. Three treatment groups comprising 348 cultured lobsters in total were used to examine survival, growth and tag retention, and to assess mobility, shelter use and moulting behaviours. Tagging had no significant effect on lobster survival, growth, mobility, shelter use or moult frequency. Survival over 7 weeks was 75% among lobsters tagged with two elastomers, 76% in those with one elastomer and 74% among untagged controls. Mortality during moulting did not increase in tagged (6%) compared to untagged lobsters (9%). We found no evidence that VIE tags cause any negative effects that would be expected to inhibit survival upon wild release, but tag loss had reached 12% in both tagged treatments after 7 weeks and showed no sign of abating. Our study suggests that VIEs effectiveness in discerning cultured lobsters long after wild release may be limited when used in smaller juveniles.     

Stocking location and predation by marine fishes affect survival of hatchery‐reared Atlantic salmon smolts

Abstract Release strategies of hatchery‐reared Atlantic salmon, Salmo salar L., smolts were compared by studying survival and migration of smolts (n = 99) and their predators (Atlantic cod, Gadus morhua L., n = 8; and saithe, Pollachius virens (L.), n = 2) during the first 37 km of the marine migration using acoustic telemetry. Survivorship was higher in smolts released at the river mouth (30%) compared with smolts released in the river (12%). This was likely due to mortality or reduced migratory behaviour in fresh water. The marine mortality was 37% during the first 2 km after leaving the river (at least 25% mortality because of predation from marine fishes), and total marine mortality over 37 km was 68%. Detection‐depth data were useful for evaluating whether the tagged smolts were alive or predated; mortality during the first 2 km of outward migration would have been underestimated at 26% instead of 37% without the analysis of depth detection. Transmitters from consumed post‐smolts remained in predators for up to 47 days (average 29 days).     

Food habits and marine survival of juvenile Chinook and coho salmon from marine waters of Southeast Alaska

Little is known about the food habits of juvenile Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon in marine environments of Alaska, or whether their diets may have contributed to extremely high marine survival rates for coho salmon from Southeast Alaska and much more modest survival rates for Southeast Alaskan Chinook salmon. To address these issues, we documented the spatial and temporal variability of diets of both species collected from marine waters of Southeast Alaska during summers of 1997–2000. Food habits were similar: major prey items of both species included fishes, crab larvae, hyperiid amphipods, insects, and euphausiids. Multivariate analyses of diet composition indicated that the most distinct groups were formed at the smallest spatial and temporal scales (the haul), although groups also formed at larger scales, such as by month or habitat type. Our expectations for how food habits would influence survival were only partially supported. As predicted, Southeast Alaskan coho salmon had more prey in their stomachs overall [1.8% of body weight (BW)] and proportionally far fewer empty stomachs (0.7%) than either Alaskan Chinook (1.4% BW, 5.1% empty) or coho salmon from other regions. However, contrary to our expectations, coho salmon diets contained surprisingly few fish (49% by weight). Apparently, Alaskan coho salmon achieved extremely high marine survival rates despite a diet consisting largely of small, less energetically‐efficient crustacean prey. Our results suggest that diet quantity (how much is eaten) rather than diet quality (what is eaten) is important to marine survival.     

The use of alizarin complexone for immersion marking of the otoliths of embryos and larvae of the turbot, Scophthalmus maximus (L.): dosage and treatment time

The purpose of this work was to determine the efficacy of marking turbot, Scophthalmus maximus (L.), eggs and larvae with alizarin complexone (ALC) for use in enhancement programmes and in studies of the ecology and behaviour of the species. The main aim was to determine the optimum dosage and treatment time for large batches of larvae destined for release into the sea.Eggs and larvae were immersed in a range of ALC concentrations (0–60 mg L^–1) for various times (3–24 h). On day 8 after hatching, eggs marked with the different ALC dosages had 99% marking success and had mainly good-quality or very-good-quality marks, whereas larvae achieved 100% success and had mainly very-good-quality marks. The best results were obtained after marking larvae with ALC at 60 mg L^–1 for 6–24 h.During the first months after marking, the fluorescent rings formed in the otoliths were easily detected when directly examined with a UV microscope, no prior preparation of the otoliths was necessary, but after 7 months the marks become faint as the otoliths get thicker, so it is necessary to cut or polish the otoliths before examination.     

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.     

The Effect of Potassium Concentration in Inland Saline Water on the Growth and Survival of the Western King Shrimp,Penaeus latisulcatus Kishinouye, 1896

Abstract

The survival, growth, and condition of the western king shrimp, Penaeus latisulcatuswere measured for 42 days when grown in marine water and inland saline water with four different concentrations of potassium: 100%, 80%, 60% or 40% of the concentration of potassium in marine water (IS100, IS80, IS60, and IS40). Shrimp survival and cannibalism frequency decreased with decreasing potassium concentration, with final shrimp survival in IS100 significantly higher (P < 0.05) than in IS60 and IS40 and significantly higher (P < 0.05) in MW and IS80 than in IS40. Specific growth rate (SGR), moult increment, and diet ingestion rate of shrimp were significantly higher (P < 0.05) in shrimp grown in marine water than the other water types. At the conclusion of the trial, exoskeleton mineral content of shrimp in IS100 and IS80 was significantly higher (P < 0.05) than in IS60 and IS40. Tail muscle moisture content of shrimp in IS60 and IS40 was significantly higher (P < 0.05) than in the other water types, suggesting a depletion of tail muscle energy reserves in IS60 and IS40. This trial demonstrates the necessity of fortifying potassium-deficient inland saline water to allow the culture of western king shrimp. Furthermore, a potassium concentration greater than approximately 76% of that in marine water and a Na/K ratio of less then 39 appear to be necessary to maintain a comparable level of shrimp survival, as in marine water. However, the slower growth and reduced molt increment of shrimp in inland saline water with 100% and 80% potassium compared to shrimp in marine water demonstrates the presence of other limiting factors.     

Dorsal aorta cannulation: a method to monitor changes in blood levels of astaxanthin in voluntarily feeding Atlantic salmon, Salmo salar L.

This study was undertaken to assess dorsal aorta cannulation as a method to evaluate alterations in diet composition and feeding protocol on pigment retention in salmonid fish. Temporal changes in blood astaxanthin concentrations of dorsal aortacannulated Atlantic salmon, Salmo salar L., were followed in relation to variations in dietary pigment concentration and fish-feeding husbandry protocol. The fish were held individually in 200-L fibreglass tanks supplied with running sea water. Each fish was forced to swim at 0.5 body lengths s^?1 and was fed daily by hand to satiation. The fish had an average growth rate of 1% day^?1. Blood astaxanthin concentrations were noted to be highly correlated (r= 0.995) with dietary levels of astaxanthin, but not as well correlated (r= 0.71) with total gut content of this pigment. Marked variations in blood astaxanthin concentration were noted between individual fish at each dietary pigment concentration, but the ranking of the fish was generally unaffected between each dietary pigment level. After cessation of feeding a diet supplemented with 75 mg of astaxanthin kg^?1, salmon fed a diet with no pigment showed more-rapid blood pigment clearance than those that were starved. Likely, feed remaining in the alimentary tract of the starved fish functioned as a reservoir of pigment for the blood until the intestinal tract was empty. Blood pigment levels were not depressed in salmon fed a diet supplemented with 75 mg of astaxanthin kg^?1 once daily instead of twice daily.