76 FISHES OF AUSTRALIA. 



and up to about 14 or 15 inches, being called "Hardgut." 

 The name "Hardgut-Mullet" is also made to apply in many 

 cases to all, from the smallest size up to that just mentioned ; 

 while "Sea Mullet" is the generally-accepted name for the 

 adult. Notwithstanding what has been written in the past, 

 there are still some who are under the false impression that 

 the Sea Mullet and the Hardgut-Mullet are distinct species. 

 For convenience sake it is often desirable to make use of 

 the latter term when speaking of the young, and there can 

 be no harm in so doing provided that their true specific iden- 

 tity is always borne in mind. Along the coast of Queensland 

 "Hardgut" are known as "Mangrove-Mullet." 



Up to the size of maturity, this species is a constant 

 dweller in the lakes, harbours and rivers ;* but, after maturity 

 has been reached, each year there is a migration seawards ; 

 and, after the sea is reached on our eastern and western 

 coasts northward. This migration is solely in connection 

 with spawning operations and takes place about May, June 

 and July. The reason of this movement in a northerly 

 direction, which has been so much noticed along the New 

 South Wales coast and about which so many curious and 

 wonderful stories have been woven, is as follows : The egg 

 of the Sea Mullet is a free-floating or pelagic one. That 

 being so, if the shoals of Mullet were simply to go straight 

 out of, say, Port Jackson, and there deposit their eggs, the 

 latter would be swept slowly along towards the south while 

 the development of the embryo was in progress ; and, as 

 there would be no corresponding northward movement of 

 the young Mullet, the habitat of the species would be gradu- 

 ally generation after generation moved farther and far- 

 ther south until it would disappear altogether from the 

 coasts of Australia. As it is, with the present northward 

 migration of the parent Mullet at the spawning time, it is 

 not improbable that many of the baby Mullet find their way 

 into the waters that their parents have recently vacated. In 

 addition to this, of course, it is highly probable that a large 

 number of the eggs are spawned within, or very near to, 



* Instances are on record in which shoals of Hardgut Mullet have 

 been found at sea ; but these are extraordinary cases brought about usually 

 by exceptional local conditions. 



