A comparison of five external marks for Atlantic salmon, Salmo salar L.

Five external marks (Panjet, visible implant tag, hot brand, anal finclip and fluorescent pigment) were compared for retention and effect on marine survival in Atlantic salmon, Salmo salar L., ranching experiments aimed at complementing coded wire tagging. Only fluorescent pigment marks and Panjet marks were found to be effective, with retention rates of 76.9% and 90.0% respectively, after one year at sea. The Panjet was the only mark to significantly reduce marine survival ( P < 0.001) compared with controls.     

Relative catch ability and performance of three strains of rainbow trout, Salmo gairdneri Richardson, in a small fishery

Abstract. The performances of two strains of rainbow trout, Salmo gairdneri Richardson, and a hybrid were assessed in a put-and-take fishery against stock from the normal supplier. The three batches of experimental fish were reared to the size usually stocked in the fishery and they and two batches of the normal stock fish were given distinctive dye-marks using a Panjet inoculator. Anglers’ returns were analysed and demonstrated that there were significant differences in the catchability of the various types of fish throughout the trial period. There was no apparent difference between strains in their susceptibility to the fly-fishing methods employed, nor between their growth rates whilst in the fishery, despite the clear superiority of some genotypes under fish-farm conditions. These factors are discussed in relation to the management of put-and-take trout fisheries.     

Validation of daily increment formation in otoliths of immature and adult Japanese anchovy <Emphasis Type="Italic">Engraulis japonicus</Emphasis>

In order to validate daily increment formation in otoliths of immature and adult Japanese anchovy Engraulis japonicus, three rearing experiments using chemical marking of otoliths were conducted on adult anchovy in summer 2004 and immature anchovy in summer 2005 and in winter 2006. In the two experiments conducted in summer, the number of otolith microincrements between alizarin complexone (ALC) marks showed that microincrements were formed daily. In the summer 2005 experiment, immature anchovy under conditions of reduced daily food rations also showed daily microincrement formation. Average increment width was 0.9 μm in adults and 1.8–3.1 μm in immature anchovy. In contrast, no clear increments were observed between ALC marks on the otoliths from the experiment in winter 2006, and scanning electron microscope (SEM) observations failed to confirm clear increment formation. We consider that low water temperatures (<13–14°C) restricted otolith growth and lowered the contrast between the discontinuous and the incremental zones of the otolith increments. For age estimation of Japanese anchovy, clear increments wider than about 1 μm in the otolith can be regarded as daily increments. However, daily age estimation of immature and adult anchovy that experience low water temperatures in winter may be difficult due to the obscurity of the increments.     

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.     

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.     

Mass marking of stocked European glass eels (Anguilla anguilla) with alizarin red S

This study describes a mass marking method suitable for European glass eel Anguilla anguilla, avoiding osmotic shock and reducing fish stress. During a single day, 360,000 glass eels intended for a stocking operation were bathed into an alizarin red S (ARS) solution, at a density of 346 ind.·l^?1 before being released into a freshwater marsh along with unmarked glass eels. After 15 days, examination of marked and unmarked eels kept in enclosures in the marsh showed 100% of otoliths had been successfully marked and that no excess deaths related to marking process had occurred. Seven months after stocking, results from biometric measurements and otolith analysis, carried out on a sample of 53 elvers caught by electrofishing and belonging to the size class of the 0⁺ cohort, suggest that: (i) the proportions of marked and unmarked remained unchanged, hence suggesting that the marking process had not caused excess mortality, (ii) there was no difference in length, body mass or condition factor between marked and unmarked individuals, demonstrating that marking had caused no harmful effect after 7 months, and (iii) ARS marks in otoliths remained clearly visible. The benefits of this ARS mass marking technique are discussed through a stocking operation.     

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%.     

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.     

A test of two methods for marking larvae and postlarvae of the giant freshwater prawn, Macrobrachium rosenbergii

This paper describes the successful use of two tagging systems, both produced by Northwest Marine Technology Inc., on larval and postlarval giant freshwater prawns, Macrobrachium rosenbergii. Visible implant (VI) elastomer tags (a coloured liquid that solidifies under the epidermis) were used on stage XI larval prawns (mean weight 0.01 g) and postlarval prawns (mean weight 0.07 g). VI alphanumeric tags (small biocompatible plastic labels also inserted under the epidermis) were tested on postlarval prawns (from a weight of 0.5 g). Tags were inserted using clove oil as anaesthetic, and survival, mortality and growth rates of tagged animals were compared with those of controls that were handled but not anaesthetized or marked. Twenty per cent of the larval prawns (the smallest of the group) died just after tagging, but thereafter the remaining prawns survived well, as did all the tagged postlarval prawns. Visibility of the VI elastomer tags in larval prawns deteriorated with time, though 79% of marks were still visible to the naked eye 70 days after tagging. VI elastomer tags in the postlarval group remained clearly visible for up to 100 days. Visibility of the VI alphanumeric tags fell shortly after tagging, but remained adequate thereafter. Moult rates in control and tagged animals were the same in larvae with VI elastomer tags and postlarvae with VI alphanumeric tags, but the moult rate in the postlarval prawns given elastomer tags was slower than in controls. Rates of growth were similar in tagged (elastomer and alphanumeric) and control postlarval prawns, once the size‐dependent mortality of tagged larval prawns was taken into account. We conclude that VI elastomer tags could be used to mark small numbers of individual larval and immediately postlarval prawns for periods of several months, and that VI alphanumeric tags could be used to mark an unlimited number of individuals from a size of approximately 0.5 g.     

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.     

Use of temperature to manipulate circulus patterns on scales of silver perch, Bidyanus bidyanus (Mitchell), for the purpose of stock discrimination

Abstract  Controlled temperature variation was used to induce marks on scales of silver perch, Bidyanus bidyanus (Mitchell), for stock identification. Genetically similar fish were held in tanks at three temperatures for a period of 4 weeks. Circulus spacing information was acquired using automated video digitizing equipment. Discriminant function analysis was used to classify fish into their respective rearing temperatures. Fish held at 30°C were classified with high accuracy (94–96%). Classification inaccuracies increased in fish held at the lower temperatures. Fish growth at each temperature was examined and classification accuracies were a reflection of growth differences. The use of temperature variables to induce marks on scales offers scope for batch-marking pre-stocked fish.     

Evaluation of a stable‐isotope labelling technique for mass marking fin rays of age‐0 lake sturgeon

Abstract The effectiveness of marking age‐0 lake sturgeon, Acipenser fulvescens Rafinesque, pectoral fin rays with a stable strontium isotope was evaluated. Age‐0 lake sturgeon were reared in water spiked with 0 (control), 25, 50 or 100 μg L^{?1 86}SrC0₃ for 10 and 24 days; fish from each treatment group were retained for up to 120 days post‐labelling to assess mark retention. Enriched‐isotope marks imparted to fin rays were distinct from fin ray ⁸⁸Sr/⁸⁶Sr ratios of control fish immediately following marking, with the 100 μg L^{?1 86}SrCO₃ treatments consistently yielding the highest rate of marking success (83–92%). Lower marking success (25–69%) was observed with the 25 and 50 μg L^{?1 86}SrCO₃ treatments. Isotopic marks in fin rays were retained for 120 days post‐labelling. Immersion marking of juvenile fish pectoral fin rays with distinct strontium isotope ratios is possible and does not require sacrificing fish to check for marks.     

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.     

COLD BRANDING AS A SMOLT MARKING TECHNIQUE

Cold branding of smolts of Atlantic salmon has resulted in clearly visible marks on almost 94 per cent of the returning grilse. The technique is considered to be an improvement on fin-clipping for batch identification in that it involves no mutilation and has a much wider range of possible marks. A possible disadvantage of the technique is the ease with which JDranded fish may be overlooked in trap, net or rod catches, although this applies with almost equal force to fin-clipped fish.     

Is it possible to raise,offspring of the 25th generation of Litopenaeus vannamei (Boone) and 18th generation Litopenaeus stylirostris (Stimpson) in clear water to 40 g?

Peneid shrimp are commonly reared in clear‐water aquaria or tanks for short‐term studies of 4–6 weeks during controlled experiments, such as nutrition studies to estimate dietary nutrient requirements. Recently, in line with the genetic program at Centre Océanologique du Pacifique (COP), experimental clear‐water facilities were tested for the first time over a longer rearing period. Environmental conditions used to maintain animal growth in clear‐water system using a well‐balanced diet were defined. After 100 days, shrimp growth rates tended to decrease and only by adjusting the diet could shrimp complete their life cycle and reach maturation size of around 40 g. This paper presents information on stocking density, diet quality and husbandry linked to reproduction that must be considered to successfully rear animals from PL's to breeder size in clear water. By following these protocols a minimum amount of breeders can be used to meet production goals. Moreover, by isolating a small group of individuals, genetic diversity can be preserved, thereby allowing specific crosses for selective breeding purposes. Length of trials, amount of feed, composition of feed, growth performances and maturation success are reported and should encourage further studies to optimize rearing conditions in clear‐water rearing.     

Age validation and growth variability of Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> off the Pacific coast of northern Japan

ABSTRACT:   This study examined age and growth of Japanese flounder Paralichthys olivaceus off the Pacific coast of northern Japan, and determined whether the growth patterns of male and female fish in northern (40–41°N) and southern (37–38°15'N) waters differ. In total 8095 specimens were collected between January 1999 and December 2005. Zonation consisting of opaque and translucent bands on the otolith was evident. Within each opaque band a thin and clear check (ring mark) was observed in all specimens examined. Monthly change in the frequency of appearance of a ring mark on the outer margin of the otolith indicates that ring marks form between July and August. The von Bertalanffy growth model showed a sexual dimorphism in growth, as females grew faster and reached a larger size than males. The growth patterns obtained by tracking the observed total length for monthly collections showed a rapid increase in total length between August and October. Spatial variation in the growth pattern of male and female fish between northern and southern waters was evident, as southern fish were significantly larger than northern counterparts during 1.25–3.00 years post hatch.     

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...     

Spawning of the broad-finned Galaxias, Galaxias brevipinnis Günther (Pisces: Galaxiidae) in coastal streams of southeastern Australia

Abstract— The broad-finned galaxias, Galaxias brevipinnis , spawned during high flows in mid autumn. Spawning took place over inundated riparian areas where eggs were laid amongst substrate, mainly in the interstices of cobbles and pebbles. Between subsequent high flows, eggs were out of water for days or weeks, lying up to 7 m from the water's edge. When exposed, eggs and streamside substrate remained damp, shaded by surrounding forest. Hatching would only occur when eggs were inundated by a subsequent flood. In the field, most eggs had hatched within 30 days of the spawning period, but some remained unhatched for up to 60 days. In the laboratory, eggs remained unhatched for up to 57 days under moist conditions but out of water, and up to 120 days when kept in water. However those kept under drier conditions died. It would appear that riparian cover may be important in providing shaded and moist conditions for the survival of eggs in the wild. Evidence of some adult mortality following spawning was noted. Newly hatched larvae were carried to sea during high flows. Predation on eggs by both adult G. brevipinnis and introduced brown trout Salmo trutta Linnaeus was found to occur.     

From whaling to whale watching: Identifying fin whale critical foraging habitats off the Chilean coast

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Effect of habitat conditions on reproduction of the European anchovy (Engraulis encrasicolus) in the Strait of Sicily

The aims of this study were to describe the reproductive cycle of the European anchovy (Engraulis encrasicolus) off the south coast of Sicily and determine whether intra‐ and inter‐annual reproductive trait variations, if any, are adaptive responses which maximize reproductive success under environmental fluctuations. Biological data were collected from purse seine and mid‐water pelagic trawl commercial catches landed in Sciacca (Sicily) over 6 yr (1997–2002) at fortnightly intervals, analysing a total of 84 581 individuals. No inter‐annual changes in length at first reproduction were observed, with a mean pooled value of 11.26 cm for both sexes being found. Spawning intensity, indicated by gonadosomatic index, condition factor and length–weight relationships, seem to be governed by food availability prior to spawning. Anchovy reproductive investment was limited by the area's low primary production. There was a synchrony between reproductive cycle and temperature. Water warming marks the onset of a period of high water stability in the area, and its later cooling marks the onset of a period with low water stability. The relationship between reproductive cycle and temperature is therefore probably a reproductive strategy having evolved to ensure that spawning takes place during the period of the year when water column stability is higher, favouring food concentration and egg and larval retention in the spawning areas.