SEA-FISHERIES LABORATORY. 



Ill 



Size 





21 cms. 



22 



j? 



23 



55 



24 



55 



25 



55 



26 



55 



27 



55 



28 



55 



Weight. 



Size. 





94 grammes. 



29 cms. . . 



105-4 



30 „ 





120 



31 „ 





134-65 „ 



32 „ 





168-7 



33 „ 





186-15 „ 



34 „ 





198-5 



35 „ 





226-3 



36 „ 





Weight. 



253-5 grammes. 



262 



314-5 „ 



325-7 „ 



357-8 



393 



449 



484 



Condition of the Keproductive Organs. 

 None of the fish under 24 cms. in length, from the area 

 off Walney Island, had the reproductive organs developed to 

 such an extent that the sex could be recognised by naked 

 eye observation. The condition of maturity in the fish of 

 24 cms. and upwards was very irregular. There was no gradual 

 approach to a definite spawning time. Some of the fish caught 

 in September were no further advanced towards spawning than 

 many of those caught at the end of June. In the sample 

 examined on June 30th one spent female, 27 cms. long, and 

 one male, 30 cms. long, with the sperms flowing freely were 

 observed. The others were not more than half mature. One 

 spent female, 35 cms. long, was found amongst the fish examined 

 during July. The others over 24 cms. were mostly quite 

 immature. A few were just about half mature. The mackerel 

 examined in the first week of September were, with one excep- 

 tion (a spent female 31 cms. long) about half mature. The 

 spawning period varies greatly in different places. In the 

 Mediterranean spawning may begin as early as January, and 

 extend into May. In the South-west of Ireland the time stated 

 is May and June. Off Plymouth spawning takes place between 

 the end of May and the end of July. The reproductive organs 

 of the mackerel caught off Walney in 1913 were in quite a 

 different condition from those examined in previous years. 

 It has been quite a common occurrence to find them in a spent 



