326 



Appendices to Fifth Annual Report 



APPENDIX F. — No. X. 



NOTES ON THE FOOD OF YOUNG GADID.E. 

 By George Brook. 



During the months of July, August, and September young forms of 

 various species of Gadidse were plentiful near low water in East Loch 

 Tarbert, in the north bay at Barmore, and in other suitable localities in 

 Loch Fyne. They were most abundant amongst the Zostera beds, just 

 below low-water mark. In August thousands of young cod and saith 

 could be captured with one haul of the seine-net in almost any suitable 

 locality. The cod were usually from 2 to 3 inches in length, and were 

 nearly all banded with reddish brown, the lighter patches appearing as 

 irregular blotches along the lateral line. The saith were usually a little 

 larger, the majority being from 3J to 4 inches long. 



A number of the young cod were sent to Rothesay Aquarium, where 

 many still survive. I also recognised a few lythe and whiting amongst 

 those captured, but they were far from numerous. 



I was struck by the great abundance of the young cod and saith 

 amongst the Zostera beds, and their comparative scarcity in other localities, 

 and as it seemed probable that this choice of locality might be dependent 

 on the food devoured by the immature forms, a large number of stomachs 

 were examined, and their contents noted. A few particulars relating to 

 the food of the young cod and saith will, I think, be of interest. 



Cod. — On the 14th of August, thirty-seven stomachs of young cod were 

 examined. The fish were obtained at low water in the sandy bay in front 

 of the Tarbert Laboratory. They varied in size from \\ to 3 inches in 

 length. All the stomachs were found to be full of food. Those of the 

 smaller fish were filled with Copepods, to the exclusion of almost every 

 other kind of food. The stomachs of the larger specimens contained, in 

 addition to the Copepods, a considerable number of Amphipods (£a?ftmar«s?) 

 and also a fair quantity of young Mysidae, probably Mysis inermis, young 

 specimens of which abound amongst the Zostera at this season. 



The majority of the Copepods belonged to the Ccdanidce ; the Harpacti- 

 cidce contributed a good many specimens, while the Cyclopidce were also 

 represented. 



Amongst the Calanidce the genus Centropages appeared to contribute 

 the greatest number of individuals, but others occurred which were not 

 identified. 



Amongst the other groups, Oithona spinijrons, Diosaccus tenuicornis, Ida 

 fureata, and Thalestris longimana, w T ere the only species which were 

 identified. 



On the 18th of August, eleven specimens were examined from another 

 locality. These were taken in the north bay at Barmore, and the speci- 

 mens ranged from 2 \ to 3 inches in length. The food consisted of Copepods, 

 Amphipods, Isopods, and Schizopods. The Copepods formed about half 

 the food (in bulk), and consisted mainly of Calanidce. The Amphipods, 

 Isopods, and Schizopods occurred in about equal quantities, and consisted 

 mainly of Gam mar idee, young Idotea, and young Mysis. 



A number of the stomachs were nearly empty. 



