In the laboratory and field, American eels (Anguilla rostrata) showed a strong avoidance of white strobe light . Eels avoided low light intensities for all strobe flash frequencies tested, and showed no behavioural adaptation to the light source over a prolonged time period . A strobe light barrier was 65-92% effective in repelling upstream migrating eels at Saunders GS on the St . Lawrence River. All size classes of eels were repelled, but effectiveness appeared to be reduced for smaller eels . IntroductionMaterials and methods

The effectiveness of a Hidrostal pump in the live transfer of American eels (Anquilla americana) was investigated under laboratory conditions. Eel survival 72h after passage through the fish pump was high, averaging approximately 98% over all test conditions. There was no significant increase in mortality observed with an increase in pump impeller speed (890-1204 r.p.m.) or eel density (low-high). The Hidrostal pump shows promise for application at hydro-electric facilities in the passage of eels.

No abstract

: This study examined the spatial and temporal variation of dissolved inorganic radiocarbon in the East Sea. Five vertical profiles of radiocarbon values were obtained from samples collected in 1999 in three basins (Japan Basin, Ulleung Basin, Yamato Basin) of the East Sea. Radiocarbon values decreased from 63-85‰ at the surface to about -50‰ with increasing depth (up to 2,000 m) and were nearly constant in the layer deeper than 2,000 m in all basins. Radiocarbon values did not show significant basin-to-basin differences in the surface and the bottom layers. In the intermediate layer (200-2,000 m), however, they decreased in the order of Japan Basin > Ulleung Basin > Yamato Basin, which is consistent with the suggested circulation pattern in the intermediate layer of the East Sea. Radiocarbon was found to have decreased at ~2%/year in the surface water of the East Sea. In contrast, in the interior of the East Sea, radiocarbon values have increased with time in all three basins. In the Central Water, the annual increase rate was about 3.3‰, which is faster than the rates in the Deep and Bottom Waters. The radiocarbon in the Deep and Bottom Waters had increased until mid-1990s, after which time it has been almost constant.

Investigations were conducted in the laboratory on the accuracy in terms of range resolution of a commercial sonar system (420 kHz) in detecting underwater targets. Accurate range resolution of fish is necessary for reliable estimates of numbers and for detecting the presence and behaviour of fish near the bottom. Results indicated that the existing sounder was limited in target separation below 25 cm at a transmitted pulse of 0.1 ms under laboratory conditions. Modifications to equipment resulted in an improved range resolution (to approximately 10 cm) of targets in both vertical and horizontal tank experiments.