sea-fisheries laboratory. 279 



Ftsh Eggs in Bay. 



Floating' fish eggs (containing embryos) begin to 

 make their appearance early in April in the bay and 

 remain low in number (mostly under ten per haul) up to 

 the middle of the month. There is a sudden rise in the 

 Eockling eggs on April 18th (to 43 per haul), followed 

 by a -much more marked rise on the 22nd, and the 

 numbers remain relatively high until the 25th (reaching 

 a maximum of 500 per haul on the 23rd), after which 

 they fall off rapidly and remain low in number and 

 occasional in occurrence throughout the summer and 

 autumn until September. The other fish eggs in the bay 

 follow much the same course as the Rockling eggs, 

 appearing at the same date, remaining low for the same 

 period, rising at the same time, though to a much less 

 degree — the maximum being 76 per haul — and then 

 falling off rapidly to a low level which remains through- 

 out the summer. 



VERTICAL DISTRIBUTION. 



We have already shown above that our weighted open 

 tow-net, ranging from about ten fathoms up to the surface 

 during fifteen minutes, usually captured a larger quantity 

 of plankton than the exactly similar surface nets hauled 

 at the same time within a foot or two of the surface. 

 This weighted net also, in most cases, caught more than 

 the two vertical closing nets " Hensen " and " Nansen " 

 (which, however, are not exactly comparable in size, either 

 with the open tow-nets or with one another, see p. 230) 

 hauled up as a rule through the zone of water from twenty 

 fathoms to ten and then closed. In those cases, early in 

 April, when either the Hensen or Nansen net showed a 

 larger catch than the weighted net, the great bulk is seen 



