Fisheries, Subsistence, and Habitat
Publications Searchable Database
Search Again| Division: | Sport Fish |
| Title: | Evaluation of a dual-frequency imaging sonar for estimating fish size in the Kenai River |
| Author: | Burwen, D. L., S. J. Fleischman, and J. D. Miller |
| Year: | 2007 |
| Report ID: | Alaska Department of Fish and Game, Fishery Data Series No. 07-44, Anchorage |
| Abstract: | Experiments were conducted with a DIDSON (Dual frequency IDentification SONar) acoustic system to evaluate the potential for estimating fish size from images of tethered and free-swimming fish in two Alaskan rivers. DIDSON is a recently developed imaging sonar that incorporates a sophisticated lensing system to improve image quality. In the first experiment, DIDSON images were collected from six Chinook salmon Oncorhynchus tsawytscha and four sockeye salmon O. nerka tethered in the center of the DIDSON’s multibeam array. In the second experiment, 130 Pacific salmon Oncorhynchus and Dolly Varden Salvelinus malma Walbaum were allowed to swim freely through the DIDSON multibeam array after being released from a weir live-box. Length estimates from DIDSON images of tethered fish were subject to a positive bias that increased with range of the fish from the transducer (approximately 1.3 cm/m of range). Measurements from free-swimming fish did not demonstrate the same size bias with range. Possible causes for the differing results are discussed, as well as the performance of the DIDSON with respect to detecting fish, determining direction of travel, and tracking fish at high densities. |
| Keywords: | multibeam sonar, imaging sonar, DIDSON sonar, fisheries acoustics, Chinook salmon, Oncorhynchus tshawytscha, sockeye salmon, Oncorhynchus nerka, hydroacoustic assessment, Kenai River, riverine sonar |