NATURE 



THURSDAY, DECEMBER lo, 1908. 



BIOLOGICAL RESEARCH ON THE LANCA- 

 SHIRE COAST. 



Report for 1907 on the Lancashire Sea-Fisheries 

 Laboratory at the University of Liverpool and the 

 Sea-Fish Hatchery at Piel. Drawn up by Prof. 

 \V. A. Herdman, F.R.S., assisted by Mr. Andrew- 

 Scott and Mr. James Johnstone. No. xvi. Pp. 

 406; with illustrations. (Liverpool, 1908.) 



ABOUT half the bulk of this report is devoted 

 to a monograph on the edible crab by Mr. 

 Joseph Pearson. Excellent features of this work, 

 which is illustrated with twelve plates and numerous 

 diagrams in the text, are the methodical arrangement 

 of the matter and the clearness and simplification of 

 the descriptions. Hitherto, students who aspired to 

 more than a general knowledge of the anatomy and 

 development of the crab have had to search out 

 and abstract for themselves the numerous original 

 memoirs scattered in various scientific journals in 

 different languages, a labour which only specialists 

 care to undertake. It is, therefore, extremely useful 

 to have all these researches carefully epitomised and 

 brought together in one volume. Again, although the 

 general features of the anatomy and development are 

 fairly well known to readers of text-books, the average 

 student knows very little about the habits of the 

 crab, partly because the literature of this part of 

 the subject is mainly of recent growth, and partly 

 because the original memoirs dealing with it are 

 contained in reports which have a somewhat limited 

 circulation. Accordingly, much of the information 

 contained in the section of this work which deals 

 with " Bionomics," namely, such matters as the mi- 

 grations, spawning habits, rate of growth, age and 

 size at maturity, frequency of casting, " autotomy " 

 and limb-regeneration, &c., will be new to those 

 readers who have not consulted the more recent 

 annual reports of the Fishery Board for Scotland and 

 other journals. Altogether, Mr. Pearson's mono- 

 graph maintains the high standard of excellence char- 

 acteristic of the series of '" L.M.B.C. memoirs " of 

 which it is the latest number. This series of mono- 

 graphs can only be described as a boon both to general 

 students and specialists. 



.•\ voluminous and important contribution to this 

 report is given by Prof. Herdman, assisted by Mr. 

 -Andrew Scott, under the title of " An Intensive Study 

 of the Plankton around the South End of the Isle 

 of Man." The thorough nature of this investigation 

 may be gathered when it is stated that the numbers of 

 every species of organism obtained in more than 800 

 separate gatherings of plankton were carefully esti- 

 mated — a vast labour in itself. More than 600 of these 

 samples were collected within a very restricted area in 

 the neighbourhood of Port Erin, simultaneous hauls 

 being made with various kinds of pelagic nets both of 

 the horizontal (tow-net) and vertical type, and these 

 were worked in different depths of water. These 

 .samples were collected every week and almost every 

 day during a full yearly period. 

 NO. 2C4I, VOL. 79] 



One feels justified in accepting with confidence con- 

 clusions which are based on observations the fre- 

 quency of which in time and space is so great. On 

 this secure basis Prof. Herdman discusses the seasonal 

 changes in the abundance of plankton as a whole and 

 of its various constituents, and arrives at important 

 general conclusions regarding its vertical and hori- 

 zontal distribution. Thus, it has been found, here 

 as elsewhere, that diatoms reach their maximum 

 development in April, and rise again to a second but 

 less important and less constant maximum in autumn ; 

 dinoflagellates rise to a maximum later than the 

 diatoms, and have also a sudden periodic increase 

 in autumn ; copepods attain their maximum in early 

 summer after the diatoms have died down, and 

 again in late autumn they follow the phytoplankton. 

 The distribution of particular species is also ex- 

 haustively discussed and illustrated by means of fre- 

 quency curves. Of more general interest is the 

 evidence that the zone of most abundant life is not 

 at the surface, but is generally a few fathoms 

 below. This observation is of decided importance 

 in connection with the depth at which certain 

 plankton-feeding fishes such as the mackerel and 

 herring swim. As regards the horizontal distribu- 

 tion, it is found that while some organisms have 

 a very regular and uniform distribution over a con- 

 siderable area, others are distributed very unevenly, 

 including those which markedly tend to congregate 

 in shoals. 



" The horizontal distribution is consequently liable 

 to be very variable and irregular, and although its 

 characteristic constitution at different times of the 

 vear may be described, it is very doubtful whether 

 any numerical estimate can be framed which will 

 be applicable to wide areas." 



This conclusion appears rather to discount the 

 efforts of certain German naturalists to arrive at a 

 census of pelagic organisms in whole seas on the 

 basis of the numbers caught in hauls with specially 

 designed quantitative apparatus. 



Considerable light on the movements of plaice, and 

 on the intensity with which the fishing for this 

 species is carried on on the Lancashire and Welsh 

 coasts, is thrown by the results of marking experi- 

 ments reported on by Mr. James Johnstone and 

 illustrated by means of two charts. These experi- 

 ments bring to light a marked tendency on the part 

 of small plaice to leave the estuaries and bays of 

 this coast and move seawards in the summer months. 

 The older fishes apparently leave the district for good. 

 Some of these were found to have crossed the Irish 

 Sea, while others had entered the Firth of Clyde. 

 From 25 to 30 per cent, of the fishes liberated were 

 returned by fishermen, but Mr. Johnstone has good 

 reasons for believing that many more are re-captured 

 than are returned. This represents a considerable 

 intensity of fishing in the eastern part of the Irish 

 Sea, and it is further interesting to note that by far 

 the greatest numbers of marked plaice were re- 

 caught by first-class sailing trawlers. There is still, 

 however, a good deal of obscurity as to the exact 

 direction of the movements of the plaice in this district 



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