GREA T BRIT A IN. 95 



night ; in fact, at Penzance, drift-nets have frequently 

 brought 100 tons in a single night in May. 



Breeding. In the spring of the year the roe of the 

 mackerel may be observed to be growing very fast, and 

 in Britain it is mostly shed about May, June, or July, at 

 some leagues from the shore and at the very surface of the 

 waves, where a great quantity of these fishes may often be 

 met with engaged in spawning. The ova of these fishes 

 shed in the Brighton Aquarium has been observed to float. 



low temperature exercises great influence in postponing 

 >reeding, and fish in roe are occasionally seen even in 

 anter. Harmer found 546,681 ova in a female 18 oz. 

 weight, 430,800 in a second of 20 oz. weight, and 454,961 

 in a third of similar size, all having been captured in the 

 tonth of June ; while Bloch counted 540,000 in one he 

 examined. Mackerel quickly recover from the effects of 

 spawning. 



Although this fish is generally a very rapid grower, such 

 must greatly depend on whether suitable food abounds, or 

 the reverse. In Cornwall, where spawning occurs in May 

 or June, young about 3 to 5 inches long are plentiful 

 in the bays about August and September, leaving for the 

 leep sea in November, when they are from 6 to 7 inches 

 in length, and re-appearing the following June about 8 or 9 

 inches in length. In fact, the young at the commencement 

 of winter are small, and their growth is slow up to the 

 following spring. 



Hermaphrodites. Couch observed upon having noticed 

 these in the form of a lobe of roe lying between the usual 

 pair of lobes of milt ; while A. Malm likewise describes and 

 figures such. 



Diseases. The nipper crab, Polybius Henslowii, which 

 swims near the surface, has been known to kill mackerel. 



