III. A study on the growth of Herrings

E. Lea
1911 ICES Journal of Marine Science  
The study of the scale of the herring, which serves as means for the determination of the age and growth of each single individual, has become a very important branch of the international investigations. The main considerations which form the basis of the scale studies are: ( l ) , that the different growth-zones which can be observed on the scales correspond to regular epochs in the life of the herring, or more definitely, that a period of one year lies between the formation of two so-called
more » ... nter-rings, and (2), that the linear growth of the scale is approximately proportional to the longitudinal growth of the fish. . The number of the winterrings would thus give us information on the age of the fish and their relative distance from one another gives us a means of determining the length of the fish on the formation of the respective winterrings. Thai the so-called winter-rings are at least annual rings seems to me to have been suf'ficiently proved in the papers which have been published on this subject (see BROCH 1, DAHL 2 and LEA 3 ) . On the other hand, but few observations exist regarding the time for the formation of the different growth-zones of the herring scale, the broad, striated ,surnmer-belts(( and the narrow, clear ))winter-rings((. There is so little in the literature regarding these things, that G. SCHNEIDER {4) has considered himself justified in replacing the designation winter-ring with a more indifferent name ,age-ringa. DAHL'S ,summer-belt (( he calls ~scale-area((. Although the present author, through his work on the scales of herring taken from the most different localities and at different times of the year, has arrived at a subjective certainty with regard to the correctness of DAHL'S interpretation, yef he has thought 3% at Whatever the explanation may be, attention may be paid to the hint the phenomen gives regarding the use of the other data in the tables. For the first, spring samples the lengths and weights are too high. On studying the growth in length this error can be avoided by taking the increment outside the 2nd winter-ring ( t 8 : ) instead of the increment of the total length. In the first samples of the years, namely, this is so small that the influences of the above-mentioned conditions must be covered by the observation errors. On studying the augmentation in weight, on the other hand, we must endeavour to eliminate the influence of this phenomen in a more indirect way, regarding which more will be said later. The results of the chemical investigation serve to give an estimate of the physiological condition of the fish, and the temperature data give a picture of one of the outer conditions under which the fish live. Our first problem refers to the time of formation of the winterrings and summer-belts. The first sample from December 1909 consists of fish with 1 winter-ring far inside the margin of the at University of Michigan on July 13, 2015 http://icesjms.oxfordjournals.org/ Downloaded from 13 21 3 0 at University of Michigan on July 13, 2015 http://icesjms.oxfordjournals.org/ Downloaded from . This ex-standard deviation of the variates inumber of variates Standard-error of the mean = pression for the accuracy of the average is analogous to the standard deviation and gives the limits between which the mean or average will lie in about 7 of 10 cases. This should be used in preference to the inconvenient 0.6745 x standard-deviation fno. of variates probable error of the mean =If: at
doi:10.1093/icesjms/s1.61.35 fatcat:3s3oxpv72vdaja7tkjbgcnlkka