FLUCTUATIONS IN THE SUPPLY OF HERRING (CLUPEA 
PALLASII) IN SOUTHEASTERN ALASKA 1 
By George A. Rounsefell, Ph. D., Junior Aquatic Biologist, United States Bureau of Fisheries 
J- 
CONTENTS 
Page 
Introduction 15 
Factors other than abundance affecting 
the catch 16 
Changes in the season 16 
Effect of regulations 16 
Changes in the unit of fishing effort. 19 
Changes in the purse seine 
vessels 19 
Changes in the purse seines 23 
Effect of impounding on the 
unit of effort 23 
Capacity of the herring plants 23 
Analysis of catch records 25 
Changes in average size of catch 25 
Changes in number of deliveries 28 
Page 
Analysis of catch records — Continued. 
Changes in average weekly catch 29 
Levels of abundance in different 
areas 33 
Decline of older fishing grounds 34 
Biological evidence of depletion 36 
Conclusions 38 
Recommendations 38 
Fundamental considerations 38 
Specific recommendations 39 
Explanation of specific recommen- 
dations 39 
Definitions of areas for which specific 
recommendations are made 41 
Bibliography 56 
INTRODUCTION 
A knowledge of the changes in relative abundance of the herring populations at 
different times and on different fishing grounds is necessary if the herring fishery is so 
to be regulated as to produce an optimum yield. By optimum yield is meant the 
maximum yield that can be taken without endangering the supply and which allows 
the population to maintain that level of abundance that will permanently produce 
either the greatest quantity or the greatest value of fish. In a previous report 
(Rounsefell, 1930, pp. 305-309) an analysis of the total catch figures was made, but 
no definite conclusions concerning abundance were reached for southeastern Alaska. 
The trends of abundance depended on too many factors to be determined by such a 
simple method. Therefore it has been necessary to use more exact methods. 
As shown previously (Rounsefell, 1930, p. 272) several populations of herring 
are being dealt with, each of which conceivably has its own trend of abundance and 
therefore deserves to be studied as a unit. It is difficult, however, to determine the 
abundance of a single race of herring from the data of a composite fishery. Assuming 
that this initial difficulty be overcome, the determination of the trend of relative 
annual abundance is still rendered difficult by variations in the numerical strength of 
the annual increments to the population which may cause temporary fluctuations 
in abundance (Rounsefell, 1930, p. 299; 1930a). Aside from their influence on the 
1 Approved for publication Jan. 5, 1931. 
15 
