48 SALT-WATER FISHES 



embarked, may throw tresh light on the mystery of the 

 spawning-grounds of valuable species, particularly of the plaice, 

 in that area. We want to know the spawning-grounds in order 

 that we may avoid them and induce others to do likewise. 

 Only a few general facts have been so far ascertained, and even 

 these must be regarded as subject to any rebutting evidence that 

 may possibly be brought forward. We know, for example, that 

 some fishes approach our coasts for spawning purposes, but 

 that the majority repair to deeper water. Those which spawn 

 in deep water may come inshore as soon as the spawning is 

 over — when they are technically known as " spent " — but that 

 is in order that they may recoup their lost strength with 

 abundant food. Many of the valuable fishes, such as the plaice 

 {Pkuronectes) and pilchard [Clupea), deposit their spawn at a 

 considerable distance from the land, and pilchards with roe are 

 notably far less common than herrings in the same condition. 

 Others, on the other hand, like cod and whiting, spawn near 

 the shore. In the case of the herring, it is thought that the 

 distinct summer and winter " races " of that fish, which will be 

 explained in a later chapter, have different preferences in this 

 respect, the former spawning out in deep water, while the 

 latter choose the brackish inshore water for the same purpose. 

 Among the smaller, comparatively valueless fishes the inshore 

 spawning habit is very common. The eggs of the father- 

 lasher (Cottus), for instance, lie partly exposed among the weeds 

 at low water, and the same may be said of those of the lump- 

 sucker {Cyclopterus). In sticklebacks {Gasterosteus) the eggs are 

 sheltered in a seaweed nest among the inshore rocks. It is 

 quite evident that these small shore-loving forms are compelled 

 in self-preservation to produce heavy, or demersal, eggs, else 

 these would, if they were to float, have no chance in the shallow, 

 broken water. In this instance, at any rate, the object of the 

 demersal egg is not difficult to understand. 



The terms " larval " and " post-larval " have already been 

 explained. After the end of the post-larval stage, and when the 



