Diurnal variation in the catch of salmon in drift gillnets in Lynn Canal, Alaska
Ericksen RP and Marshall RP. 1997. Diurnal variation in the catch of salmon in drift gillnets in Lynn Canal, Alaska. Alaska Fishery Research Bulletin. 4(1):1-11
Operators of 4 commercial drift gillnet vessels kept logbooks of their 1991 fishing effort and catch of sockeye Oncorhynchus nerka, chum O. keta, coho O. kisutch, and chinook O. tshawytscha salmon in Lynn Canal, Alaska. Mann-Whitney tests were used to determine if catch per unit effort (CPUE) for each species varied significantly by ambient light phase (day vs night). Two definitions of day and night were employed: one relative to sunrise and sunset and another relative to civil twilight. All data were temporally stratified into 3 fishing periods of 5 or 6 weeks each. Logbook fishers caught 7,840 sockeye, 6,330 chum, 3,579 coho, and 187 chinook salmon in 1,060 sets between June 16 and October 2. Chinook salmon were only caught incidental to other species, and 82% were classified as small (£8 lb) fish. The chinook harvest rate was significantly higher at night than at day, except during the final (fall) strata when very few chinook salmon were caught. During the peak of directed fisheries for sockeye salmon (mid July through August), CPUE for sockeye salmon was highest during the day. During September, CPUE for chum salmon was also higher during the day. Results provide a solid indication that considerable savings in chinook salmon could result from night closures in drift gillnet fisheries of inside marine waters.
- Type
- Journal Article
- Authors
- Ericksen, R; Marshall, R
- Units
- GLBA , KLGO , SITK
- Keywords
- Anadromous Fish, Coastal/Marine Systems, Commercial Fishing, Fish/Ichthyology, Fishery Management, Lynn Canal, Salmon