Effects of seismic shooting on local abundance and catch rates of cod (<i>(Gadus morhua)</i> and haddock <i>)(Melanogrammus aeglefinus)</i>

Abstract

To determine whether seismic exploration affected abundance or catch rates of cod (Gadus morhua) and haddock&#13;\n(Melanogrammus aeglefinus), acoustic mapping and fishing trials with trawls and longlines were conducted in the central&#13;\nBarents Sea 7 days before, 5 days during, and 5 days after seismic shooting with air guns. Seismic shooting severely affected&#13;\nfish distribution, local abundance, and catch rates in the entire investigation area of 40 ´ 40 nautical miles.Trawl catches of&#13;\ncod and haddock and longline catches of haddock declined on average by about 50% (by mass) after shooting started, which&#13;\nagreed with the acoustic abundance estimates; longline catches of cod were reduced by 21%. Reductions in catch rates were&#13;\nobserved 18 nautical miles from the seismic shooting area (3 ´ 10 nautical miles), but the most pronounced reduction occurred&#13;\nwithin the shooting area, where trawl catches of both species and longline catches of haddock were reduced by about 70% and&#13;\nthe longline catches of cod by 45%; a relatively greater reduction was found (in catches and acoustic estimates) for large&#13;\n(&gt;60 cm) than for small fish. Abundance and catch rates did not return to preshooting levels during the 5-day period after&#13;\nseismic shooting ended.