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1.
Eleven Arctic charr (Salvelinus alpinus) (370–512 mm) and eight sea trout (Salmo trutta) (370–585 mm in length) were tagged externally or internally with depth‐ and temperature‐measuring data‐storage tags (DST) before they were released into the sea in the Alta Fjord in north Norway in June 2002. All sea trout were recaptured after they spent 1–40 days at sea, while all Arctic charr were recaptured after 0.5–33 days at sea. On average, trout preferred water about 0.6 m deeper and 1.3°C warmer than Arctic charr. Arctic charr spent >50% of their time between 0 and 1 m depth, while trout spent >50% of their time between 1 and 2 m depth. Both species spent >90% of their time in water no deeper than 3 m from the water surface. However, sea trout dove more frequently and to greater depths (max. 28 m) than Arctic charr (max. 16 m), and these deep dives were most frequently performed at the end of the sea migration. Arctic charr demonstrated a diel diving pattern, staying on average about 0.5 m deeper between 08:00 hours and about 15:00 hours than during the rest of the 24 h, even though there was continuous daylight during the experiments. When comparing data obtained from the DSTs with temperature measurements within the fjord system, the two species were observed to select different feeding areas during their sea migration, the sea trout choosing the inner and warmer parts of the fjord, in contrast to the Arctic charr that preferred the outer, colder parts of the fjord. The observed differences in migration behaviour between the two species are discussed in relation to species preferences for prey and habitat selection, and their optimal temperatures for growth.  相似文献   

2.
To determine the efficacy of passive integrated transponder (PIT) tags for marking rohu Labeo rohita (Ham.) in the selective breeding programme, a series of experiments has been carried out at the Central Institute of Freshwater Aquaculture (CIFA) under the Indo–Norwegian project of ‘Selective breeding of rohu’. Six groups of rohu fingerlings with weight ranging from 2 g to 20 g were tagged with PIT tags to determine a suitable size range for tagging. Fingerlings weighing 8–15 g were found to be quite suitable for tagging with a PIT tag. Recovery of the PIT tag depends upon the survival of tagged fish under field conditions. Rejection of the PIT tag by rohu was observed to be only 0.05%. Through effective management practice, the survival of tagged fish increased up to 95%, and thus tag loss was minimized.  相似文献   

3.
Abstract –  Winter growth and survival of wild individually tagged juvenile Arctic charr (1+ age) from a riverine anadromous stock, were studied in a small ice-covered (∼6 months) ground water brook (temperature ∼1 °C) connected to Skibotnelva in subarctic northern Norway. The overall winter survival was estimated to be 68% from late October 2005 to early May 2006. The recaptured charr were not significantly different in initial length or weight compared with the nonrecaptured fish suggesting low size-dependent mortality. The majority (98%) of the recaptured charr showed significant increase in size, with a mean increment of 62% from their initial bodyweight and 12% of the charr parr had more than doubled their weight. The mean specific growth rate was calculated to be slightly lower (0.27) than estimated values from a growth model (∼0.35). In addition, the condition factor increased significantly during the field experiment. These results are the first individual growth data on riverine anadromous Arctic charr parr under natural winter conditions, and indicate that charr can grow relatively fast during periods with low temperature and also that ground water brooks can be good over-wintering habitat for juvenile Arctic charr. These results suggest that the winter period is perhaps a less severe bottleneck than previously recognised for the cold-adapted Arctic charr.  相似文献   

4.
Over 3 years, 32,444 age‐0 group Atlantic salmon (Salmo salar) parr tagged with passive integrated transponder tags throughout the River Frome catchment were assigned to one of three groups, nonmigrants, autumn migrants and spring smolts, depending on the detection and the timing of detection at downstream tag readers (situated 8.6 km above the tidal limit). We examined the effect of density at the time of tagging (n·m?2), distance upstream from the tidal limit (km), fish length (mm), Fulton condition index, habitat type (divided into two types, main river and carrier), days after 1 September that each fish was tagged and year (replication) on the proportions of fish in each of the migration groups. Distance upstream from tidal limit was strongly negatively related to the proportion of autumn migrants and positively related to the proportion of spring smolts. Nonmigrants had a lower average body size than migrants, although there were no differences in the sizes of autumn migrants and spring smolts in September prior to migration. Fish density had no effect on migration strategy. A lower proportion of fish migrated as autumn migrants from the smaller carrier habitats than the main river channel. There is some evidence that those parr destined to become autumn migrants underwent a lower mortality rate during September before tagging than those destined to become spring migrants indicating possible physiological or behavioural differences between these two groups of fish at that time. More research into the factors responsible for initiating the autumn migration is required.  相似文献   

5.
Abstract –  The round goby ( Neogobius melanostomus Pallas) is an invasive species in North America and Europe. We evaluated the efficacy of passive integrated transponder (PIT) tags for marking round gobies and tracking their movements with a portable underwater antenna in shallow areas (≤1 m) of a lake. Tagging did not markedly decrease growth of fish <105 mm; however, growth decreased unexpectedly for tagged fish ≥105 mm during the final sampling period. Nevertheless, tagging did not increase mortality regardless of size class, and tag retention was 100% for caged fish. Tagged round gobies in a 20 × 20-m2 block net avoided detection by the portable underwater antenna, and a high proportion of fish probably escaped from the net, suggesting that round gobies may be more mobile than previously reported. In conclusion, PIT tags are a viable method for individually marking round gobies, but detecting tagged round gobies with a portable underwater antenna, given current technology, does not appear promising in shallow areas with low habitat complexity.  相似文献   

6.
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.  相似文献   

7.
8.
This study tested different tags for each size of farm-reared gilthead sea bream, Sparus aurata L. juveniles, used in enhancement programmes. The following tags were tested: dye mark, fingerling tag, opercular tag, anchor tag A (filament diameter of 1.20 mm) and anchor tag B (0.85 mm). Tag/mark retention, wounds produced by the tag, ease of application, ease of detection and cost were examined. Epidermal dye marks had poor retention and detection rates. Of the tags tested, retention was greater for the anchor tag A (80–100%) after 7 months; anchor tag B showed a retention rate of only 20% after 3 months. The fingerling tag had a retention rate of 27.5% after 12 months. The opercular tag had a retention rate of 44% after 20 days but fractured the opercular bone in many cases. Tag incisions and wounds persisted in some fish for the duration of the experiment.  相似文献   

9.
Abstract –  In 2000, the Atlantic salmon ( Salmo salar L.) stock in the river Signaldalselva, North Norway was found to be infected with the monogenean Gyrodactylus salaris (Malmberg). This river system has a multispecies fish community of nine species in total. Low densities of Atlantic salmon parr were found during electrofishing in October (2003) with a prevalence of 94% and a mean abundance of 848 G. salaris. This watercourse also holds a riverine stock of anadromous Arctic charr ( Salvelinus alpinus ), which is not common in Norway. Among the parr of Arctic charr, 64% were infested with an abundance of 23 parasites per fish. The most heavily infected 0+ and 1+ juvenile Arctic charr had 469 and 534 parasites, respectively, indicating that the parasites are able to reproduce on Arctic charr in the wild. There was little variation in the rates of infestation of Arctic charr along the studied stretch of the river, even in areas with very low densities of Atlantic salmon parr. The parr of anadromous Arctic charr seem to be suitable as long-term hosts for G. salaris . Moreover, a few (22%) infested adult sea-running Arctic charr were captured after ascending the river in the autumn, which shows that large fish may also act as carriers of G. salaris . However, no parasites were recorded on potential anadromous Arctic charr before descending during early spring (April 2003 and April 2004). Thus, it is still not clear whether anadromous Arctic charr are able to disperse the parasite between watercourses. So far, it is uncertain whether G. salaris may increase the mortality rates of Arctic charr and thereby be a threat to these unusual occurring riverine anadromous Arctic charr stocks.  相似文献   

10.
为了开发适宜牙鲆(Paralichthys olivaceus)苗种放流的标志技术,利用编码金属标签(CWT)对不同规格牙鲆苗种进行了标记实验,并从标记死亡率、脱标率、适宜标记鱼规格等方面评价了CWT的标记效果.结果显示,CWT标记3种规格的牙鲆苗种后,脱标均发生在标记后的4d内,其后未再发生脱标现象.小规格苗种[全长为(5.92±0.41)cm]死亡率较高(13%),中规格苗种[全长(8.92±0.36) cm]死亡率为2%,大规格苗种[全长为(12.06士0.62) cm]死亡率为1%.小规格、中规格和大规格苗种脱标率分别为3.3%、2.4%和0.7%.建立了标记死亡率(M)与苗种全长(TL)、体厚度(BT)的关系模型:M=0.7254 TL2-15.3220TL+79.4260 (R2=0.9601);M=1.3627 BT2-15.5610 BT+ 44.4330 (R2=0.9645),为适宜苗种规格选择与标记效果评价提供了依据.今后利用CWT标签进行牙鲆苗种标志放流时,建议选择全长6 cm以上的苗种进行背部肌肉标记,标记对苗种游泳行为和生长无影响,表明CWT是一种适宜在牙鲆大规模标志放流中应用的理想标志方式.  相似文献   

11.
Arctic charr Salvelinus alpinus (L.) were individually tagged and maintained in circular tanks for 102 days in order to allow the development of dominance hierarchies. At the end of the trial period, the charr were anaesthetized in benzocaine and identified as dominant, beta (β) and subordinate according to a set of established criteria including size, coloration and bite marks. The gut contents were then collected and analysed for apparent digestibility coefficient of nutrients using the chromic oxide method. Subordinate fish had significantly lower specific growth rates and apparent nutrient digestibility coefficients of both dry matter and lipid compared with dominant fish. Although specific growth rate was significantly lower in the β fish compared with dominant charr, this did not influence the apparent digestibility coefficient of nutrients to any major extent.  相似文献   

12.
Abstract – The piscivorous behaviour in a brown trout ( Salmo trutta L.) population was studied in four discrete periods over seven decades (1917–94) in the hydroelectric reservoir Tunhovdfjord in Norway established in 1919. Piscivorous brown trout were extremely scarce prior to the introduction of two fish species Arctic charr ( Salvelinus alpinus L.) and European minnow ( Phoxinus phoxinus L.) in the 1920s. Brown trout started eating minnow at 17 cm and Arctic charr at 22 cm of length. In the 1950s, the brown trout predated extensively (60% of analysed trout) on Arctic charr and minnow. During the next four decades, the incidence of piscivorous brown trout declined to 15%, whereas the frequency of brown trout eating Arctic charr remained constant at 10%. The growth pattern, expressed as back-calculated length, demonstrated similarity in three periods (1920s, 1960s and 1990s) and improved growth in the 1950s. The improvement was addressed the impoundment of a reservoir upstream. We did not find any marked change in growth rate due to piscivority, but coefficient of variance of back-calculated lengths indicated significant variation in individual growth in age group ≥6 years from 1950 onwards. We accredit this variation to the rise of piscivorous brown trout.  相似文献   

13.
Abstract –  To address the dearth of information on tagging effects and long-term survivorship of tagged fish in native and introduced species, laboratory and field investigations were undertaken on three non-native fish species (pumpkinseed Lepomis gibbosus ; topmouth gudgeon Pseudorasbora parva ; pikeperch Sander lucioperca ) tagged with coded-wire (CW), passive integrated transponder (PIT), radio (RT) telemetry and/or acoustic tags (AT), with survivorship of native brown trout ( Salmo trutta ) examined in the field. Laboratory results revealed high survivorship following tag attachment/insertion and resumption of feeding within 24–48 h of tagging (all mortalities could be attributed to an unrelated outbreak of fungal infection), with retention rates being high in both pumpkinseed and pikeperch but low in topmouth gudgeon (excluded from field studies). In the field, short-term post-operation survival was high in pikeperch, pumpkinseed and brown trout. In pumpkinseed and trout, 100% of RT fish survived a 24–30 day tracking study, with 60% and 80%, respectively, recaptured alive at least 3 months post-tagging. Of PIT tagged pumpkinseed, 44% were recaptured (after 6–18 months), with small-sized, CW-tagged fish (0.38 g weight) captured up to 1 year after tagging. In pikeperch, all AT fish except one (the smallest specimen) survived their full expected tracking period (i.e. tag life) – the single lost specimen survived at least half of its expected tracking period (i.e. 6 month battery life). Overall, the tagging methods used were highly effective in pumpkinseed and pikeperch, showing good retention and survival, but PIT tagging of topmouth gudgeon was plagued by low survivorship and tag rejection.  相似文献   

14.
Telemetry tags are increasingly used in management to monitor the migration timing of Atlantic salmon smolts (Salmo salar L.). It has been postulated that (1) effects from tagging and handling may alter migration behaviour, and (2) that the selection of fish during sampling is not representative of all migrating smolts, yielding bias in migration timing estimates. In the River Dale (Vestland, Norway), five groups of wild Atlantic salmon smolts (N = 385) were tagged in April–May and recaptured in a wolf trap. Migration timing was then compared to the untagged population. Migration timing differed between tagged (12 mm PIT) and untagged fish for 4/5 groups. Only fish tagged at the first time point did not have significantly different timing of migration from untagged counterparts. The relationship between length and the timing of migration was different for initial length and length at recapture; initial length suggested earlier migration of longer fish, but the extra time spent in the river prior to migrating for smolts that were initially smaller compensated for the size difference. The tagging protocol is crucial to obtaining representative migration timing results. Smolts should be tagged as early as possible and include the entire size distribution.  相似文献   

15.
Abstract  Atlantic salmon, Salmo salar L., reared from two Baltic strains were released around the islands Bornholm and Møn in the Baltic Sea between 1995 and 1999. A total 600 000 reared salmon were released from net pens using the delayed release technique, keeping the salmon in net pens for approximately 3 months after smolting, and 208 000 were released directly from the hatchery. Of these, 15 958 were tagged with Carlin tags. Additionally, 65 300 coded wire tagged salmon were released as delayed release salmon close to Bornholm in 2000. Recaptures from the five years of Carlin tagged releases varied between 2.8% and 21.2% (average 13.1%). Most recaptures were from within the Baltic Sea (average 98%), but some were recaptured outside the Baltic Sea, either in the sea (1%) or in fresh water (1%). Recaptures outside the Baltic Sea and in fresh water were higher for releases at Møn in the western part of the Baltic, than releases at Bornholm. Straying rates from the releases into six rivers on the Swedish west coast were estimated using information from capture in traps and sport and broodstock fisheries. The proportion of straying salmon in rivers on the Swedish west coast was about 3.8% of the salmon run, but with large variations between rivers. Releases were discontinued because of possible deleterious effect on the local wild salmon populations.  相似文献   

16.
Two different colours (red and green) of visible implant elastomer (VIE) were used in Nile tilapia (Oreochromis niloticus). The visibility, location and retention of the VIE tags was investigated and any adverse effects on fish survival and growth determined. The use of VIE tags for monitoring individual fish during a bacterial challenge with either Streptococcus agalactiae or S. iniae was also studied. The results showed that VIE treated fish were lighter but not shorter than the non‐tagged control fish and that tagging caused no mortality. The retention of tags was better at the base of pectoral fin followed by the nasal area, lower abdomen, upper abdomen and branchiostegal rays inside the operculum. During the bacterial challenge experiment individual animals could be easily identified using the VIE tags. In this preliminary study, VIE tagging appears suitable for Nile tilapia research, as with other fish species, and could be a novel method to identify individual animals during microbial pathogenesis studies.  相似文献   

17.
2011年9月底至2012年5月,采用可见植入荧光标记(VIE)和编码金属标(CWT)标志全长为(28.06±1.79)cm的达乌尔鳇(Huso dauricus),检验了VIE和CWT的标志保持率及其对达乌尔鳇生长和存活的影响。结果显示,经过210 d实验,VIE标志达乌尔鳇吻部腹面,CWT标志达乌尔鳇背部前(第1~2块背骨板间下方肌肉)、中(第6~7块后背骨板间下方肌肉)、后(第11~12块背骨板间下方肌肉)的标志保持率分别为:95.83%、92.00%、92.59%、92.59%。实验中VIE出现破碎、脱落或迁移致使标志可识别性下降;CWT背部中这一标志部位操作最为简便。标志30 d,VIE标志组的保持率较CWT背部不同部位标志组及对照组低,且差异显著(P<0.05),此后31~210 d并无显著性差异。VIE和CWT背部不同部位标志对达乌尔鳇的生长无显著性差异。结果表明,VIE和CWT均可用于标志达乌尔鳇。进行短期大规模达乌尔鳇的标志放流可使用成本相对较低的VIE标志。  相似文献   

18.
The study examined the effect of PIT tagging and size on the growth, survival, food conversion, tag retention and wound healing in juvenile European whitefish. Three size classes of juvenile whitefish (class S—body weight (b.w.) approx. 4.0 g; class M—b.w. approx. 8.0 g; class L—b.w. approx. 13.6 g) were tagged with PIT implanted intraperitoneally (TROVAN®, United Kingdom). These groups formed S‐P, M‐P and L‐P respectively. Fish from the control groups (groups S‐C, M‐C and L‐C) were not tagged. Whitefish from the tagged and control groups were reared for 28 days in recirculating aquaculture systems. Only in the fish from the smallest group (group S‐P) was tagging confirmed to have a negative impact on growth rate and survival, which, after 28 days, was 70% in comparison with 94.4% in group S‐C. The rate of wound healing in all whitefish groups was similar. After 28 days following PIT implantation, all wounds were healed. Short‐term PIT retention (28 days) for all the groups was > 90%, and no differences were noted among groups. In summary, it is recommended that whitefish be PIT‐tagged using the intraperitoneal method after they have attained a body weight > 8 g. Tagging smaller specimens of this species leads to higher mortality.  相似文献   

19.
The effects of four different tagging methods (PIT, anchor T‐tag, Carlin tag and dummy radio transmitter) on survival, behaviour and growth of Atlantic salmon smolts during their downstream migration were examined in semi‐natural circular channels during a natural migration period in spring. Survival of smolts was high and tagging wounds healed well in all tagging groups. Tag loss rates were generally low, being the highest (2.5%) in the dummy radio transmitter group. Total length and body mass of the tagged and untagged smolts did not differ at the end of the experiment. Migration activity of smolts generally showed similar patterns among the treatments. However, Carlin‐tagged smolts started their migration slightly later than the PIT‐tagged fish, and smolts tagged with Carlin tag or dummy radio transmitter showed less overall migration activity than fish with PIT tag.  相似文献   

20.
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.  相似文献   

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