Recent British Columbia Spring and Coho Salmon Tagging Experiments, and a Comparison with Those Conducted from 1925 to 1930
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BU'JJETIN-No. lI� Recent British Columbia spring and coho salmon tagging experiments, and a comparison with those conducted from 1925 to 1930 By D. J. MILNE Fisherw8 Research Board 01 Canada Biological Station, Nanaimo, B.C. PUBL ISHED BY THE FISHERIES RESEARCH BOARD OF CANADA UNDER THE CON TROL OF THE HONOURABLE THE MINISTER OF FISHERIES fTAWA, 1957 fer50'cents ��, ----------------------------------� BULLETIN No. 113 Recent British Columbia spring and coho salmon tagging experiments, and a comparison with those conducted from 1925 to 1930 By D. J. MILNE Fisheries Research Board of Canada Biological Station, Nanaimo, B.C. PUBLISHED BY THE FISHERIES RESEARCH BOARD OF CANADA UNDER THE CONTROL OF THE HONOURABLE THE MINISTER OF FISHERIES OTTAWA, 1957 w. E. RICKER N. M. CARTER Editors (ii) Bulletins of the Fisheries Research Board of Canada are published from time to time to present popular and scientific information concerning fishes and some other aquatic animals; their environment and the biology of their stocks; means of capture; and the handling, processing and utilizing of fish and fishery products. In addition, the Board publishes the following: An A nnual Report of the work carried on under the direction of the Board. The Journal of the Fisheries Research Board of Canada, containing the results of scientific investigations. Atlantic Progress Reports, consisting of brief articles on investigations at the Atlantic stations of the Board. Pacific Progress Reports, consisting of brief articles on investigations at the Pacific stations of the Board. The price of this Bulletin is 50 cents (Canadian funds, postpaid). Orders should be addressed to the Queen's Printer, Ottawa, Canada. Remittance made payable to the Receiver General of Canada should accompany the order. All publications of the Fisheries Research Board of Canada still in print are available for purchase from the Queen's Printer. Bulletin No. 110 is an index and list of publications of the Board and is priced at 75 cents per copy postpaid. (iii) 91243-l! CONTENTS PAGE ABSTRACT.. .. .. .. .. .. .. .. .. .. .. .. (vii) INTRODUCTION.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 1 ACKNOWLEDGMENTS. 2 METHODS........................................................ 2 REVIEW OF THE 1925-30 TAGGING EXPERIMENTS.. 7 Spring salmon...... , . 7 Coho salmon. 7 SUMMARY OF THE 1949 TAGGING EXPERIMENTS.. 9 Spring salmon.. .. .. .. .. .. .. .. .. .. .. .. .. 9 Coho salmon. 10 SPRING SALMON EXPERIMENTS FROM 1950 TO 1952. .. .. .. .. .. .. 11 Queen Charlotte Islands. .. .. .. .. .. .. .. .. .. ... 11 West coast of Vancouver Island-Northern part.. .. .. .. ... 11 -Southern part. .. .. .. ... 14 COHO SALMON EXPERIMENTS IN 1950 AND 1951 ............ , .. .. .. 18 Queen Charlotte Islands.. .. .. .. .. .. .. .. .. .. ... 21 West Coast of Vancouver Island-Northern part..... .. .. .. .. 22 -Southern part.. ...... ... ... .. 23 COMPARISON OF THE EARLY AND RECENT TAGGING EXPERIMENTS. .. .. 25 Spring salmon.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 25 Coho salmon........................................ : .. .. 30 SUMMARy........................................................ 33 REFERENCES.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 34 ApPENDIX.. .. .. .. .. .. .. .. .. .. .. .. .. .. 35 (v) ABSTRACT From 1949 to 1952 a total of 1,222 spring (chinook) salmon and 2,190 coho salmon were tagged off the coast of British Columbia to demonstrate the ocean migrations and the rivers of origin of fish exploited by the offshore troll fishery. These represent the Canadian part of a coastwide tagging program carried out from Alaska to California through the coordination of the Pacific Marine Fisheries Commission. Most spring salmon were on long spawning migrations, travelling in a southeasterly direction along the continental shelf towards the larger rivers, such as the Columbia and Fraser. Offthe southwestern part of Vancouver Island many small imma ture fish were tagged and recovered from various directions during the next two years. All coho salmon were on shorter spawning migrations, travelling in many directions from offshore waters towards the numerous small coastal streams. Similar experiments carried out from 1925 to 1930 involved 6,457 spring salmon and 7,126 coho salmon. A comparison between the experiments conducted offthe west coast of Vancouver Island in the two periods revealed the following: For spring salmon, the percentages returned were the same (12.9). However small fish appear to provide fewer returns than large fish and more small fish were caught and tagged in recent years. Also more of the tagged fish were recaptured in the recent period off British Columbia (71% compared to 16%) and in the Fraser River (12% compared to 5%) while less were caught in United States waters (29% compared to 82%) and in the Columbia River (16% compared to 60%). This implies that the trollers are now fishingmore intensively near the tagging areas and on stocks which spawn in British Columbia rivers rather than on the Columbia River stocks which have decreased greatly in size and import ance in recent years. For coho salmon, the percentages returned were higher recently (9.2 compared to 6.1) owing to an increase in the fishing intensity, particularly in United States waters. The outside troll fishery of British Columbia has been shown to catch a mixture of fish from many streams along the Pacific coast. For this reason certain conservation measures for spring and coho salmon should be considered on an international basis. (vii) INTRODUCTION In 1948 the Pacific Marine Fisheries Commission resolved to undertake an extensive offshore tagging program along the coast of California, Oregon and Washington to determine the movement of chinook or spring salmon (Oncorhynchus tshawytscha) and coho salmon (0. kisutch) at sea and the rivers of origin of the fish exploited in various areas. Preliminary results of the 1948 and 1949 tagging experiments by the three states have been reported by the Commission in its Bulletin No.2 (1951). Both Alaska and Canada cooperated to make the program coastwide. It was hoped that by this means the inter national mixing of stocks could be assessed and, where necessary from a conservational viewpoint, common regulations could be formulated. Since the Biological Board of Canada had tagged extensively off British Columbia from 1925 to 1930 (Pritchard, 1933) a repetition of these experiments would also afford an opportunity to assess any differences in fishing drain which had occurred over the last twenty years. In recent years the British Columbia troll fleet has increased in size and efficiency and both the fishermen and industry have expressed a growing concern over the conservation of the spring and coho salmon stocks. In 1949 a commercial trolling vessel was chartered by the Fisheries Research Board of Canada to tag salmon off the weat coast of Vancouver Island. Pre liminary results have been reported by Neave (1951). A brief summary of the final results will be given, which include a few late returns. In 1950 tagging operations on a red�ed scale were repeated off the west coast of Vancouver Island by purchasing live fish from commercial trollers for tagging purposes. All fish tagged were small, less than 8 pounds in weight, with an average length of 25 inches. Tagging locations were off Barkley Sound in the south and off Kyuquot Sound in the north. In 1951 two tagging experiments were conducted offeach side of the northern end of Vancouver Island and the northern end of Queen Charlotte Islands. Later in the fall, coho salmon were tagged off the southern tip of Vancouver Island from Sooke traps. In the summer of 1952 spring salmon were tagged from Sooke traps. The results of the experiments from 1950 to 1952 will be discussed in detail. 1 91243-2 ACKNOWLEDGMENTS The success of the tagging program has been due to the excellent cooperation which has been received from the fishermen and those connected with the fishing industry, who conscientiously returned tags and to others who assisted in the actual tagging operations. In particular, sincere thanks are extended to the following trollers: Messrs. L. Ives, S. Olsen, W. Taylor, G. Holden, L. Ochs, A. Oswald, C. Lindrupson, E. Akerley, and ]. Stace-Smith; to the Fishermen's Co-operative Association and to ]. H. Todd & Sons, Ltd. for assistance rendered. To the taggers, Messrs. W. G. Calderwood (Barkley Sound, 1950), E. A. R. Ball (Kyuquot Sound, 1950 and Sooke, 1951), V. R. Taylor (Quatsino Sound, 1951), W. J. Mitchell (Queen Charlotte Islands, 1951) and D. Denbigh (Sooke, 1952) much appreciation is also due. Mr. E. A. R. Ball and Miss M. Philp were responsible for tabulating many of the data obtained. METHODS The majority of the tagged spring and coho salmon were caught by trolling gear; a few of each species were obtained from the traps at Sooke. The former resulted in lower returns than the latter, probably because the former fish were caught by hooks and hauled up from considerable depths by the trolling gear. Trolling is the only fishing method employed in the ocean, on the feeding grounds and along the migration routes; most net fisheriestake place on mature fish either near or on the way to the spawning rivers. The present trolling areas adjacent to British Columbia (Fig. 1) show the places of capture of these two species of salmon. All areas are within 50 miles of shore and 100 fathoms or less in depth, and are either along the continental shelf or in inside waters. Most coho salmon are caught in the top 10 fathoms and