Migratory Routes of Adult Sockeye Salmon, 

 Oncorhynchus nerka, in the Eastern Bering Sea 



and Bristol Bay 



RICHARD R. STRATY- 



ABSTRACT 



The stocks of sockeye salmon, Oncorhynchus nerha, in Bristol Bay, Alaska, are produced 

 in the lakes and streams of 10 major river systems, which discharge into the bay over a shoreline 

 distance of 193 km. 



The establishment of fishing areas, the determination when fishing may be permitted, and 

 the effect of exploiting simultaneously several stocks of sockeye salmon require knowledge of 

 the migratory pattern of the individual stocks comprising the run to Bristol Bay during spaw- 

 ning migration. Various mark-and-recapture experiments and exploratory fishing in the 

 eastern Bering Sea and Bristol Bay provide a picture of the migratory pattern of Bristol Bay 

 sockeye salmon from approximately long. I70°W to the head of Bristol Bay. 



The main migration route of all stocks of Bristol Bay sockeye salmon is in the offshore 

 waters of the southern half of the entrance to the bay and in the southern half of the bay itself. 

 All stocks remain in the offshore waters until within 32 to 80 km of their home-river systems. 

 Segregation according to river of origin apparently began in the offshore waters as much as 200 

 km from the mouths of the home-river systems and appeared to progress to the head of Bristol 

 Bay. 



INTRODUCTION 



Salmon management in the Pacific Northwest has 

 long been based on the premise that salmon homing to 

 various river systems or principal tributaries of river 

 systems constitute individual production units or 

 stocks.' Because of its reproductive isolation and 

 attendant adaptive processes, each stock has its own 

 unique requirements for spawning, incubation of eggs, 

 and rearing, and therefore must be managed separate- 

 ly insofar as it is practical to do so. 



Thus, management of stocks of Pacific salmon, On- 

 corhynchus, in North America has resulted in a mul- 

 tiplicity of regulatory districts, each of which is 

 associated with a major river, bay, or strait. Ideally, 

 the times and places that salmon are taken would be 

 controlled within each district so that individual 

 stocks would be harvested independently of others, 

 each in accordance with its own requirements and 

 level of productivity. In pursuit of this ideal, fishery 



'Based in part on a thesis submitted to the graduate school of 

 Oregon State University, Corvallis, in partial fulfillment of the re- 

 quirements for the degree of Doctor of Philosophy, June 1969. 



'Northwest Fisheries Center, Auke Bay Laboratory, National 

 Marine Fisheries Service. NOAA, Auke Bay, AK 99821. 



'The term "stock" as used in this paper is applied to the popula- 

 tion of salmon of a given species inhabiting a specific river system 

 or main tributary during the spawning and rearing stages of the life 

 cycle. This use of the term is, for the most part, consistent with 

 current management practices. 



biologists have directed their efforts toward deter- 

 mination of the routes and times of the spawning 

 migrations of major stocks. These efforts have reveal- 

 ed that most salmon stocks are completely separate 

 from others only when they become segregated in the 

 spawning tributaries. 



The establishment of fishing areas, the determina- 

 tion of times when fishing may be permitted, and the 

 assessment of the effects of exploiting simultaneously 

 several salmon stocks having differing levels of 

 productivity remain especially vexing problems. This 

 is particularly true for the important stocks of sockeye 

 salmon, 0. nerka, of Bristol Bay, Alaska where five 

 districts are designated for management and regula- 

 tion of the fishery — Togiak, Nushagak, Naknek- 

 Kvichak, Egegik, and Ugashik. The Togiak, Egegik, 

 and Ugashik districts have single-river systems,^ 

 which discharge into Togiak, Egegik, and Ugashik 

 Bays; the Nushagak district has four major river 

 systems which discharge into Nushagak Bay; and the 

 Naknek-Kvichak district has three river systems 

 which discharge into Kvichak Bay (Fig. 1). 



Over the years the boundaries of each district have 

 undergone a number of changes which have generally 



'Each lake or group of connected lakes and its outlet to the ocean 

 is termed a "system" and designated in this report by the name of 

 the outlet or trunk river. For example Coville, Grosvenor, Brooks, 

 and Naknek lakes are connected to the ocean through the Naknek 

 River, and the system is therefore called the Naknek. 



