The Brown Shrimp's Breeding Times. 237 



As to the period of spawning, the fishermen's stock phrase 

 runs : " we gets them in berry all the year round." Strictly 

 speaking there is an underlying truth in this assertion. Though 

 when cross-questioned they admit that during the three autumn 

 months merging into beginning of winter very few indeed are 

 berried. This we find is the actual state of things, based on our 

 examination of series of specimens at different times. 



The subjoined gives an approximate idea of the relative per 

 centage numbers carrying eggs on their swimmerets, during 

 different months in the Thames estuary. 



Jan. ... 12% 20% May ... 60% 70% Sept. ... 8%-10% 



Feb. ... ? June ... 50% Oct. ... 1% 2% 



March ... 51% July ... 27% 30% Nov. ... 3% 5% 



April ... 54% 65% Aug. ... 15% 18% Dec. ... 7%- 10% 



These figures demonstrate that March, April, May and June 

 are the months when the great majority of the brown shrimps 

 are berried. In July and August there is a considerable drop 

 in numbers. Still more so in September, and in October the 

 minimum is reached. By November there is an apparent in- 

 crease, though still the per centage is very low. From Decem- 

 ber to February there is a steady rise, and a leap up in March 

 if the weather is favourable. 



We qualify the preceding by adding that the observations 

 (as tabulated) were not made consecutively throughout a single 

 year. For example, as a rule April and May are the culminat- 

 ing months ; but in one May trip a sample of the catch showed 

 no more than half the ordinary run. On some occasions samples 

 were merely hand picked roughly from the catch without being 

 riddled. Others were the residue of one sifting, fresh condition. 

 Still others cooked, that is those retained after being sieved 

 twice. It consequently follows that the more the sifting and 

 elimination of the immature, the higher becomes the ratio of 

 spawn carriers. Whichever the month, a touch of cold weather 

 reduces the numbers of large mature shrimps, with decrease of 

 their ratio. Hence with seasonal variation, the apparent 

 number of spawners notably fluctuates, and otherwise per 

 centage data cannot be strictly relied on. 



