28 



temperatures were observed from the Heads to the jetty at 

 Knysna : 60 -2°, 60 -2°, 60 -2°, 60 -2°, 61°, 61 -2°, 61°, 61 -2°, 61°, 

 61°, 61°, 61°. 



For some four or five days pre\'ious to the occurrence there 

 was a fairly strong south-east wind and, on the day immediately 

 preceding (Friday), it blew very strongly. On the day suc- 

 ceeding the above observation a north-west wind sprang up, 

 and it was then found that the water in the lagoon (at high 

 tide) was quite normal (72°), though at sea beyond the Heads 

 the temperature was still 60°. From the signal-station at the 

 Heads the cold water (recognised by its colour) could be seen, 

 stretching along the shore in both directions as far as the eye 

 could reach, while, at about a distance of two or three miles 

 out to sea, the warm water (blue) could be seen with the same 

 sharp line of distinction between them as observed in the lagoon. 

 The signalman had noted the occurrence of the cold water and, 

 on visiting the beach on Saturday, had observed " thousands 

 of dead fish." On Sunday I could find only a few (about half- 

 a-dozen) of these, the rest having been washed out by the tide, 

 or eaten by sea-birds. The signalman further stated that 

 such occurrences were frequent in January and February, and 

 the dead fish could easily be seen at sea from his look-out, and 

 that the cold water appeared as a muddy-looking band, stretch- 

 ing along the shore, as in the present instance. It appeared 

 generally after a continuous or strong south-east wind, which 

 he states blows along the shore, but is more associated with 

 the direction of the inshore current ; this, he says, is usually 

 from west to east, but, with cold water, it is reversed and flows 

 to the west. This westerly current is usually associated with 

 south-east winds, but not always, as he has observed occasion- 

 ally a strong westerly current of cold water with no accom- 

 panving south-east wind. This easterly current is alwaj^s 

 warm. 



The species of fish affected by this cold current is of signifi- 

 cance in this enquiry being mostly shore-frequenting forms, 

 such as Poeskop, Hottentot, Roman, Dasje, Dageraad, Michael 

 or Red Stumpnose, and the Kraai-bek {Chrysophrys sp., 

 Cantharus blochii, Chrysophrys cristiceps, Sargus capensis, 

 Chrysophrys gibbiceps, Hoplegnathus conwayi). The species not 

 affected include Kabeljaauw, Bontrok, Seventy-four (here 

 called silver fish), Galjoen, Harder, etc. (Sciaena hololepidota, 

 Sargus cervinus, Dentex undulatus, Dipterodon capensis, 

 Mugil spp.) 



Whatever the origin of the cold water may be, it 

 apparently comes up from the lower or deeper regions of 

 the sea, and would thus cut off the rock and shore-frequenting 



