How bubbles can throw off the sound Alaska uses to count its fish

Scientists don't just net Alaska's fish to count them — they listen for them. Research ships map the seafloor and estimate fish stocks by pinging the water with sound and reading the echoes that bounce back. A new federal grant takes aim at something that can distort that picture: bubbles.

The problem is called bubble sweep.

In rough or ice-strewn seas, wave action forces air beneath a ship's hull, and the trapped bubbles scatter the acoustic beams the vessel depends on — blurring its read of both the seafloor and the fish below.

In Alaska, where sound-based surveys help underpin the management of the nation's largest fisheries. The $400,926 grant from the National Science Foundation will fund an engineering evaluation of how badly bubble sweep affects the acoustic systems aboard the R/V Sikuliaq, the 261-foot ice-capable research ship UAF operates, along with a range of other instrument upgrades.

The evaluation is diagnostic — it will measure the extent of the problem rather than fix it — and runs through mid-2027. Cleaner data is something the fishing industry has pushed for, too; as commercial fishing representative Dustin Delano told a congressional hearing last year, "we can always do better, and we need to do better before it's too late."