EECKNT REPORTS OF FISHERY AUTHORITIES. 367 



the height of the barometer — the temperature, density, and other 

 observations being taken at the beginning and at the end of the 

 trawling; that is to say, at each end of the station; (6) the nature of the 

 pelagic fauna, collections being made by means of tow-nets at surface 

 and bottom, and occasionally at intermediate depths ; (7) the number of 

 each species of fish, and the length of each individual caught in the 

 trawl ; (8) the nature and relative abundance of the invertebrate 

 organisms found in the trawl, which form a large portion of the food of 

 the bottom-living fishes." 



"Summary and Conclusions. 



" Wliile the trawling experiments of the Garland in the Firth of 

 Forth and St. Andrews Bay have been productive of a great body 

 of scientific knowledge respecting the reproduction, spawning areas, 

 and tlie natural history generally of the food-fishes, the immediate 

 practical object in view was to ascertain the influence which the 

 cessation of beam-trawling would have upon the relative abundance of 

 the food-fishes within the closed areas. The method adopted for this 

 purpose has been already explained, namely, the periodic examination 

 of certain selected stations in each of the areas, the enumeration 

 and measurement of the fishes caught, and the comparison of the 

 statistics thus obtained from month to month and year to year. A 

 question which confronts one at the outset is whether the period during 

 which the experiments have been carried on is sufficiently long to 

 enable definite conclusions to bo formulated with certainty. It is 

 evident, on the one hand, that if trustworthy conclusions in regard 

 to the influence of beam-trawling can be drawn from the ten years' 

 experiments in the Firth of Forth and St. Andrews Bay, it is un- 

 necessary that they should be continued there. On the other hand, it 

 would be obviously unwise to terminate them until definite conclusions 

 are obtained, since so much depends upon them. 



" The problem is complex, inasmuch as the natural causes, which are 

 of course by far the most important in producing fluctuations in the 

 abundance of the food-fishes in any given area, are very variable 

 and very obscure. There is in the first place the group of physical 

 influences, such as the weather, storms, currents, and temperature, 

 acting directly upon the fishes themselves at all stages of their life, from 

 the floating egg onward to the adult condition, and upon the organisms 

 upon which they feed ; and in the second place, a group of biological 

 causes, such as variations in reproductive activity, migrations from 

 the closed area to the outer waters, and vice versa, and the presence, 

 or absence, of other fishes upon which particular species feed, e.g., the 

 herring. For example, it was discovered by the fine-meshed nets of 



