Effects of passive integrated transponder tags on short‐term feeding patterns in European perch (<scp><i>Perca fluviatilis</i></scp>)

Chrysafi, Anna; Jepsen, Niels; Villar-Guerra, Diego del; Larsen, Mette Voldby; Skov, Christian

doi:10.1111/jfb.14887

Cited by 3 publications

(2 citation statements)

References 34 publications

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“…Nonetheless, in the case of such low growth as seen here, a comparison of growth is not a very good indicator of sublethal tagging effects. Some studies have indicated that a reduced feeding/growth may be caused by the simple fact that an implanted object takes up a significant part of the body cavity, thus reducing appetite (Chrysafi et al, 2021), but the data here show no difference in growth between tagged and control fish.…”

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confidence: 80%

Survival, growth and tag retention of juvenile European eel (Anguilla anguilla L.) with implanted 12 mm passive integrated transponder tags and acoustic tags

Jepsen¹,

Richter

Pedersen³

et al. 2022

Journal of Fish Biology

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To evaluate the efficiency of tagging juvenile European eels with implanted 12 mm passive integrated transponder (PIT) tags or Eel/Lamprey acoustic transmitters (ELATs), the authors studied tag retention, survival and growth of eels (7-25 g).Experimental eels were obtained from an eel farm, tagged and then released in a series of shallow dug-out ponds with a surface area of c. 200 m 2 . Tagged and control eels were distributed evenly, with 50 tagged and 50 control eels in each of four ponds, giving a total of 200 tagged and 200 control eels mixed. After 76 days, the ponds were drained, and eels were sampled and measured. A total of 344 eels (86%) were recaptured, indicating high survival. Tag retention was 99% as only one of the recaptured PIT-tagged eels had lost the tag and none of the ELAT tagged. The results demonstrated that tagging juvenile eels >16 cm with these small tags is indeed feasible. The growth of tagged and control fish was differentiated but generally low in length and negative in mass but did not differ between the three groups.seminatural ponds, tag expulsion, tagging effects, telemetryThe European eel population has been declining since early 1980s, and the current recruitment of glass eel is 1. 2%-8.4% of the 19602%-8.4% of the -19792%-8.4% of the reference level (ICES, 2021. To aid recovery of the eel stock,

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confidence: 80%

Survival, growth and tag retention of juvenile European eel (Anguilla anguilla L.) with implanted 12 mm passive integrated transponder tags and acoustic tags

Jepsen¹,

Richter

Pedersen³

et al. 2022

Journal of Fish Biology

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“…The tagging procedure may affect fish behaviour in the first days after tagging [ 52 ], and newly tagged fish in the current year would bias the distribution of breeding fish due to the cumulative effect of tagging during season. Therefore, only fish tagged in previous breeding seasons were considered in the analysis of a given year.…”

Section: Methodsmentioning

confidence: 99%

Diverse environmental cues drive the size of reproductive aggregation in a rheophilic fish

et al. 2023

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Background Animal migrations are periodic and relatively predictable events, and their precise timing is essential to the reproductive success. Despite large scientific effort in monitoring animal reproductive phenology, identification of complex environmental cues that determine the timing of reproductive migrations and temporal changes in the size of reproductive aggregations in relation to environmental variables is relatively rare in the current scientific literature. Methods We tagged and tracked 1702 individuals of asp (Leuciscus aspius), a large minnow species, and monitored with a resolution of one hour the size of their reproductive aggregations (counts of sexes present at the breeding grounds standardized by the sum of individuals in the season) over seven breeding seasons using passive integrated transponder tag systems. We examined the size of reproductive aggregations in relation to environmental cues of day number within a reproductive season (intra-year seasonality), water temperature, discharge, hour in a day (intra-day pattern), temperature difference between water and air, precipitation, atmospheric pressure, wind speed and lunar phase. A generalized additive model integrating evidence from seven breeding seasons and providing typical dynamics of reproductive aggregations was constructed. Results We demonstrated that all environmental cues considered contributed to the changes in the size of reproductive aggregations during breeding season, and that some effects varied during breeding season. Our model explained approximately 50% of the variability in the data and the effects were sex-dependent (models of the same structure were fitted to each sex separately, so that we effectively stratified on sex). The size of reproductive aggregations increased unimodally in response to day in season, correlated positively with water temperature and wind speed, was highest before and after the full moon, and highest at night (interacting with day in a season). Males responded negatively and females positively to increase in atmospheric pressure. Conclusion The data demonstrate complex utilization of available environmental cues to time reproductive aggregations in freshwater fish and their interactions during the reproductive season. The study highlights the need to acquire diverse data sets consisting of many environmental cues to achieve high accuracy of interpretation of reproductive timing. Graphical abstract

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Ethohydraulic Experiments Investigating Retention Rates of an Electrified Bar Rack

Haug

Frees

Brinkmeier³

et al. 2022

Water

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Bar racks at water intakes of hydropower plants serve mainly to protect the turbines from floating debris. Additionally, they can be utilized to protect downstream migrating fish in order to prevent a potentially harmful turbine passage. The Bar Rack FishProtector consists of a common bar rack equipped with electrodes mounted on the upstream side of the bars. The application of a low voltage current at the electrodes creates an electric field in the water which is actively avoided by fish. Thus, a hybrid barrier consisting of a mechanical barrier and a behavioral barrier is formed. An unscaled model of a Bar Rack FishProtector (bar spacing sb = 50 mm, bar thickness tb = 20 mm) was used in field experiments to investigate the retention rate in an experimental setup with only one possible migration route (downstream, rack passage) and an average flow velocity of 0.43 m/s. Ethohydraulic experiments were performed with three indicator species barbel (Barbus barbus), bream (Abramis brama) and roach (Rutilus rutilus) and additionally perch (Perca fluviatilis) in selected trials. The twelve trials included four reference trials without electric field present (Nday = 2, Nnight = 2) and eight trials with electric field (Nday = 6, Nnight = 2). The results show that the experimental retention rate could be increased significantly by the application of an electrical field during the night and during the day with an even more pronounced effect during the night. The differences between the functionality of the system during the day and at night as well as other influencing parameters are discussed. No significant influence of the applied voltage on the electrodes or significant influence of fish size could be identified.

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Effects of passive integrated transponder tags on short‐term feeding patterns in European perch (Perca fluviatilis)

Cited by 3 publications

References 34 publications

Survival, growth and tag retention of juvenile European eel (Anguilla anguilla L.) with implanted 12 mm passive integrated transponder tags and acoustic tags

Survival, growth and tag retention of juvenile European eel (Anguilla anguilla L.) with implanted 12 mm passive integrated transponder tags and acoustic tags

Diverse environmental cues drive the size of reproductive aggregation in a rheophilic fish

Ethohydraulic Experiments Investigating Retention Rates of an Electrified Bar Rack

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