252 



RATE OF GROWTH OF SOME SEA FISHES. 



weiglits ascertained by myself from the specimens taken at Plymoutli 

 on November 3rd, 1891. 



30-55 grms. 



59-60 



55-50 



74-70 



69-40 



84-40 



84-85 



16-2 cm, 



18-6 „ 



19-0 „ 



19-4 „ 



19-7 „ 



21-4 „ 



21-8 „ 



It will be seen that the differences between the proportions observed 

 by me, and those taken from Pouchet, are not very great, the lengths 

 in the latter being a little too small in proportion to the weight. 

 However, we may take the lengths of the fish corresponding 

 to the number to a box, as given above, to be approximately cor- 

 rect, and interpreting the annual records in Pouchet' s reports by their 

 means, we may try to discover what are the biological facts 

 underlying the industrial statistics. 



But before offering my own interpretations and criticisms, I must 

 quote those of Pouchet himself, who devotes a special short 

 appendix in the Report for 1888 (Annexe D) to the subject of the 

 growth and the age of the sardine. Pouchet regards this question, 

 as he regards all others concerning the life history of the sardine, 

 from the most sceptical point of view possible, insisting that no 

 calculation, without the observation regularly followed of the same 

 individuals, can give us exact information concerning the growth of 

 any species of animal, as the growth, whether in weight or length, 

 may describe the most irregular curves. He refers to what he said 

 in the previous Report, for 1887 as to the probability that the 

 sardine de rogue is about one year old, that it has never spawned, 

 and that from October onwards it begins to show indications of the 

 development of the genital organs. He then discusses the apparent 

 increase in size of the fish in the same locality, as shown by the 

 industrial records. This gradual increase presents itself more fre- 

 quently in the Bay of Douarnenez as though the fish which 

 entered the bay remained there and grew ; but, on the other hand, 

 sudden changes of size show that the fish even there very often 

 depart and give place to new shoals. Pouchet takes the records 

 of the years in which this gradual increase was most regular, and 

 translating the figures into weight and lengths of individual fish, 

 compares the results with one another, with the following i*esults : 



DOUAENENEZ, 1888. 



15 to box to 9 to box. 



166 grms. to 27 grms, = 11 grms. 



12-5 cm, to 14-8 cm. =2-3 cm. 



15th August to 10th October. 

 56 days. 



