Length measurement accuracy of adaptive resolution imaging sonar and a predictive model to assess adult Atlantic salmon ( Salmo salar ) into two size categories with long‐range data in a river

2020 ◽  
Vol 97 (4) ◽  
pp. 1009-1026
Author(s):  
Jani Helminen ◽  
Guillaume J. R. Dauphin ◽  
Tommi Linnansaari
2019 ◽  
Vol 70 (10) ◽  
pp. 1459 ◽  
Author(s):  
Leonhard Egg ◽  
Joachim Pander ◽  
Melanie Mueller ◽  
Juergen Geist

Dyke-based pumping stations have been linked with high fish mortalities during pumping events. Behavioural barriers like electric fish fences have been proposed as a promising solution to prevent entrainment of fish into pumps. In order to test the effectiveness of such barriers, the intake of a pumping station was equipped with a new generation electric fish fence while fish behaviour was observed with an adaptive resolution imaging sonar (ARIS) during non-electrified (reference) and electrified (treatment) operation modes. This study revealed the functionality of the fish fence as a behavioural barrier, with a fish turning rate of up to 72% at a mean water temperature of 4.3°C and a mean current velocity of 0.05ms–1. These field results suggest that new-generation electric fish fences may be a promising solution to reduce the effects of pumping stations on fish.


2020 ◽  
Vol 96 (4) ◽  
pp. 655-678
Author(s):  
Jeffrey D Plumlee ◽  
Kaylan M Dance ◽  
Michael A Dance ◽  
Jay R Rooker ◽  
Thomas C TinHan ◽  
...  

Quantitative surveys of fishes associated with artificial reefs in the northwest Gulf of Mexico were conducted over a 4-yr period (2014–2017). Artificial reefs surveyed were comprised of three types: concrete structures, rig jackets, and decommissioned ships. All reefs were surveyed using vertical long line (VLL), fish traps, and Adaptive Resolution Imaging Sonar (ARIS 1800). Mean fish abundance did not significantly differ using VLL [1.7 ind set –1 (SD 2.2)] among the three reef types. However, relative abundance among all fishes collected was significantly highest on rig reefs using traps [6.2 ind soak–1 (SD 3.8)], while results from sonar surveys indicated that the mean relative fish density was highest on concrete reefs [15.3 fish frame–1 (SD 26.8)]. Red snapper (n = 792), followed by gray triggerfish (n = 130), pigfish (n = 70), tomtate (n = 69), and hardhead catfish (n = 57) were the most numerically abundant species using VLL and traps; red snapper comprised 90.7% of total catch using VLL and 43.9% using traps. Mean Brillouin's diversity (HB) was highest on ships using VLL [0.41 (SD 0.14)] and highest on rigs using traps [0.87 (SD 0.58)] compared to the lowest diversity found on concrete [VLL 0.07 (SD 0.11); traps 0.36 (SD 0.32)]. Findings from this study can be used to inform the planning of future artificial reefs and their effect on the assemblages of reef-associated fishes. Additionally, these results highlight the value of using multiple gear types to survey reef fish assemblages associated with artificial reefs.


2017 ◽  
Vol 191 ◽  
pp. 190-199 ◽  
Author(s):  
Suzan Shahrestani ◽  
Hongsheng Bi ◽  
Viacheslav Lyubchich ◽  
Kevin M. Boswell

2021 ◽  
Vol 243 ◽  
pp. 106092
Author(s):  
Robyn E. Jones ◽  
Ross A. Griffin ◽  
Richard K.F. Unsworth

2001 ◽  
Vol 32 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Sjofn Sigurgisladottir ◽  
Margret S. Sigurdardottir ◽  
Helga Ingvarsdottir ◽  
Ole J. Torrissen ◽  
Hannes Hafsteinsson

2005 ◽  
Vol 68 (7) ◽  
pp. 1336-1339 ◽  
Author(s):  
L. L. NESSE ◽  
T. LØVOLD ◽  
B. BERGSJØ ◽  
K. NORDBY ◽  
C. WALLACE ◽  
...  

The objective of our experiments was to study the persistence and dissemination of orally administered Salmonella in smoltified Atlantic salmon. In experiment 1, salmon kept at 15°C were fed for 1 week with feed contaminated with 96 most-probable-number units of Salmonella Agona per 100 g of feed and then starved for 2 weeks. Samples were taken from the gastrointestinal tract and examined for Salmonella 1, 2, 8, 9, 15, and 16 days after the feeding ended. In experiment 2, Salmonella Agona and Montevideo were separately mixed with feed and administered by gastric intubation. Each fish received 1.0 × 108, 1.0 × 106, or 1.0 × 104 CFU. The different groups were kept in parallel at 5 and 15°C and observed for 4 weeks. Every week, three fish in each group were sacrificed, and samples were taken from the skin, the pooled internal organs, the muscle, and the gastrointestinal tract and examined for the presence of Salmonella. The results from the two experiments showed that the persistence of Salmonella in the fish was highly dependent on the dose administered. Salmonella was not recovered from any of the fish that were fed for 1 week with the lowest concentration of Salmonella. In the fish given the highest dose of Salmonella, bacteria persisted for at least 4 weeks in the gastrointestinal tract as well as, to some extent, the internal organs. The present study shows that under practical conditions in Norway, the risk of Salmonella in fish feed being passed on to the consumer of the fish is negligible.


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