Detailed study of the cod shoals also showed that their composition was continually changing: in some years the shoal is composed of younger or older fish than the average and with this latter variation there are changes in the quantities of oil yielded per t,000 fish.
Towards the mainland the water shoals, and the best anchorage is under the lee of the island.
These fish frequent rocky shoals off the eastern coast and are caught in numbers outside Port Jackson for the Sydney market.
Its most extreme point is called Buddon Ness, off which are the dangerous shoals locally known as the Roaring Lion, in consequence of the deep boom of the waves.
But it frequently happens that the dam at the head of the Hindieh is carried away, and, a free channel being thus opened for the waters of the river to the westward, the Hillah bed shoals to 2 or 3 ft., or even dries up altogether, while the country to the west of the river is turned into lakes and swamps.