1D4 



Vnrt III. — Eleventh Annual Report 



2. Common Dab. 



An examination of the Table on p. 188 will show the extent to which 

 the migration experiments throw light on the rate of growth of this fish. 

 Most of them exhibit very slight increase indeed, but one case is remarkable, 

 the second last entered in the Table. It was a female with ill-developed 

 roe (when re-caught), liberated on 10th November 1892, and re-captured on 

 4th February 1893, having therefore been in the water for 86 days. 

 When placed in the sea it was 7 inches long, and on re-capture it 

 measured 10^ inches — an increase of nearly 4 inches in less than three 

 months. Mr Scott, who measured the fish when it was liberated, has 

 verified the measurement from his original notes, and my note as 

 to its condition when it was sent to me is 'tail very little abraded.' 

 Although the dab, according to Cunningham* may grow to a length 

 of 5 \ inches in the first year, the rate of growth in the above case is so 

 exceptionally great, that one may surmise that a mistake has been made. 

 The experiments in the tanks show that the common dab grows more 

 rapidly than the plaice under precisely similar conditions. The following 

 specimens were kept in the same tank as the plaice tabulated on p. 193 : — 





No. 1. 



No. 2. 



No. 3. 



No. 4. 



Date. 



Length 



Weight 



Length 



Weight 



Length 



Weight 



Length 



Weight 





in 



in 



in 



in 



in 



in 



in 



in 





inches. 



lbs. oz. grs. 



inches. 



lbs. oz. grs. 



inches. 



lbs. oz. grs. 



inches. 



lbs. oz. grs. 



1892 



















Jan. 14 



8| 



0 4 40 



u 



0 If 30 



125 



0 13^ 20 



103 



0 8 80 



Feb. 2f. 



83 



0 4 A 90 



7l 



0 If 20 



12f 



0 1U 30 



llf 



o 91 50 



Mar. K) 



9 



0 S 0 





0 12 90 





0 14f 100 





0 91 GO 



May 5 



9i 



0 5f 20 





0 2 30 





1 0 40 



ii| 



0 10A 0 



July 0 



9f 



0 Gi 90 





0 21 0 







ni 



0 9A 30 



Sept. G 



10J 



0 7| 80 



8 



0 3 70 







12 



0 101 70 



Nov. 7 



10f 



0 8i 60 



8| 



0 4 0 







12| 



0 12 30 



1893 



















Jan. G 





0 9| 20* 



8$ 



0 U 0 









0 131 0 



Mar. (i 



io| 



0 10§ 0 



0 41 20 









0 141 30 



May (J 





0 101 60 



9 



0 4i 30 









0 141 40 



* Ovaries ripening. 



It will be observed that the dabs thrived well. No. 1 did not appar- 

 ently spawn in 1892 ; but in April and May this year it did. No. 4 

 spawned in June 1892, and the ovary began to enlarge at the end of De- 

 cember, and it was partially spent in May 1893. No. 2 did not exhibit 

 any distention, and is probably a male ; and No. 3 died. These speci- 

 mens lived in the same tnnk a? the plnice, and were subjected to entirely 

 the same conditions, and yet they grew much more rapidly. No. 1 in the 

 sixteen months increased by nearly 2h inches in length, and much more 

 than doubled in weight ; No. 2 grew nearly 2 inches longer, and also 

 more than doubled in weight ; No. 3, in the four months during which it 

 was under observation, added only one quarter of an inch to its length, 

 and nearly 4 oz. to its weight ; and No. 4 increased by over 1| inches in 

 length, and added 6 J oz. to its weight. Some of the marked specimens 

 in another tank also increased in length and weight, but more slowly. 

 Thus No. 1 (47) was 9 -J inches, 4h oz. and 60 grains on 14th January 1892, 

 exactly the same on 25th February ; the same length, but 20 grains less in 

 weight on 10th March ; 9| inches in length and 5| oz. in weight on 5th 

 May, and thereafter gradually increased to 10£ inches and 10J oz. on 6th 

 May 1893 (but the label had been removed earlier). Other specimens 

 bring out the same results ; details need nor he given. 



* Vide this Naturalist's papers in the Journal of the Marine Biological Assoc., 

 vol. ii., No. 2, p. 101 ; No. 4, p. 352 ; also Mr Williamson's paper on page 265 of 

 the present Report. 



