EFFECTS OF SEISMIC SHOOTING ON LOCAL ABUNDANCE AND CATCH RATES OF COD(GADUS-MORHUA) AND HADDOCK (MELANOGRAMMUS-AEGLEFINUS)

To determine whether seismic exploration affected abundance or catch r ates of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus), aco ustic mapping and fishing trials with trawls and longlines were conduc ted in the central Barents Sea 7 days before, 5 days during, and 5 day s after seismic shooting with air guns. Seismic shooting severely affe cted fish distribution, local abundance, and catch rates in the entire investigation area of 40 x 40 nautical miles. Trawl catches of cod an d haddock and longline catches of haddock declined on average by about 50% (by mass) after shooting started, which agreed with the acoustic abundance estimates; longline catches of cod were reduced by 21%. Redu ctions in catch rates were observed 18 nautical miles from the seismic shooting area (3 x 10 nautical miles), but the most pronounced reduct ion occurred within the shooting area, where trawl catches of both spe cies and longline catches of haddock were reduced by about 70% and the longline catches of cod by 45%; a relatively greater reduction was fo und (in catches and acoustic estimates) for large (>60 cm) than for sm all fish. Abundance and catch rates did not return to preshooting leve ls during the 5-day period after seismic shooting ended.