BULLETIN OF THE UNITED STATES FISH COMMISSION. Page 65
Coal Ashes as a means of raising mackerel in purse seines.
Sometimes, when there is a large school of mackerel in the seine, they are heavy on the bottom of the seine, so that it canot be easily handled. In such a case, heave a bucket of coal ashes in the seine, and that will being the mackerel to the surface. Captain Coas, of schooner John S. McQuinn, told me he had three hundred barrels of mackerel in his seine and they lay so heavy on the twine that he could not move the seine with twelve men hauling on the twine. He threw a bucket of coal ashes in it, the mackerel came to the surface, and they could then easily haul the seine. All the vessels that have tried it say it works well. The cook saves the coal ashes.
[Note: Ashes have been used, so Mr. Merchant tells me, for several years, but is thrown outside of the seine instead of into it, as Captain Martin thought. The object is to frighten the fish by making the water white, when they rise to the surface. The same result is obtained by the menhaden fishermen by giving a few quick turns of the propeller. The fishermen call it "whirling them up." -- J.W. Collins]