Friday, May 17, 1946 THE FISHERMAN Page Three Scientist Proposes New Herring Catch Regulation On West Coast Present Situation A study of catch statistics shows that the average annual catch during recent years for the west coast of Vancouver Island as a whole and for Barkley Sound in particular has been less than In the early years of the fishery when fishing was practically confined to Bark-ley Sound: The decreased catch might be explained by (1) reduced fishing effort, (2) reduced availability, (3) catch limitations during the recent period, or (4) decreased population abundance. (1) Fishing effort has been greater in the recent than in the early period- While the number of boats has averaged about the same, there has been an increase in the efficiency of fishing, plant capacity and duration of the fishing season. (2) Fluctuations in availability may be assumed to average out over a period of nine or ten years. Spawning reports have not indicated any pronounced abundance of spawning fish during years of low abundance during the fishing season. (3) Excluding Quatsino sound, a newly-exploited area with an obviously small population, sub-quota restrictions limited the catch in only two years (1936-37, Barkley and Kyuquot sounds; 1937-38, Barkley sound), and the reduced blanket quota limited the catch in only one year (1945-46). It may be shown that had fishing not been restricted in these three years, very large catches would have had to be made (for Barkley sound of the order of 75,000 tons in eaoh year) to bring the average catch for the recent period up to that of the early period. These catches Avould be larger than the estimated size of the spawning population. (4) It Is concluded that the decreased catch of recent years is due mostly to decreased population abun-dance- DECREASEn RECRUITMENT When fishing of a virgin population commences, some decrease in population abundance must take place. The initial decrease is at the expense of the accumulated stock which has maintained the virgin population in a state of natural balance or equilibrium. It may be shown that in the case of the west coast herring, at the present estimated level of fishing intensity, the accumulated stock would be used up in about six years and that the average catch over an initial nine-year period would decrease by about nine percent. Decrease in the case of Bark- itTniniiinintuniiiHiiiitruiiiiniiii mnnniTni iniiiiuinHitiinHniniinnimiimHinmiHiiiHiiiusiiiiniimmnirRiismtiiini mtntniTinTniiii nHTinnnHiifiintnifunnniniuitinnuEHiiiuHniJtu With the permission of Dr. Foerster of the Nanalmo Pacific Biological Station, arranged through Jack Deane, a member of the Fisheries Research Board of Canada, we are presenting here a brief on the herring fishery of Vancouver Island's west coast- The brief, prepared by Dr. A L. Tester of the station^ who is in charge of the herring investigation for the department,' summarizes present knowledge of the effect of fishing on the herring stock. In addition, four possible methods for determining the effect of fishing activity on recruitment are suggested. The one favored by Dr. Tester would involve removal of all restrictions, except for closed areas, during two years, followed by complete closure the third year, for four cycles (12 years) over the whole west coast A committee, headed by "Pop" Foster, has been set up by the United Fishermen and Allied Workers Union to study Dr. Tester's brief. All herring fishermen are urged to give full consideration to the memorandum and the suggestions contained in it Letters and discussion of the brief are welcomed by The Fisherman. f ► ► ► ► DUSENBURY MACHINE SHOP Pender Harbor wOld established business, com-i Tplete overhauls, Engine, Drum.j PGurdy, etc ^ ► ► ► INSTALLATIONS Electric Welding, Acetyline Workmanship Guaranteed iiiiraiiiniiiiiiiiiiiiiiiiiiiiiiHfflaaisii ley sound has been much greater, about 65%. Therefore the removal of accumulated stock cannot account wholly for the decrease in catch. It seems reasonable to conclude that the decreased catch is due mostly to decreased recruitment of young fish. It is known that there are annual fluctuations in recruitment due to "natural" factors. For example, conditions for survival of the young must have been exceptionally favorable in the case of the 1943 year clas3, for despite being derived from a light spawning, this year class was exceptionally abundant and was responsible for the spectacular fishing of the past season (1945-46). However, extreme fluctuations such as this are the exception rather than the rule. Usually, annual variation is not particularly great; in fact, it would be classed as fairly uniform in comparison with that in othei major herring fisheries of the world. Has decreased recruitment resulted from decreased spawning, which has in turn been caused by fishing activity? This is the crux of the problem. The Problem The goal of the herring investigation is to determine and apply the greatest level of fishing intensity which will produce maximum sustained catch. If an approximately constant supply of young is assumed, it may be shown from a consideration of rate of growth and rate of natural mortality, that the greatest yield will result from the greatest possible fishing intensity- Thus, in the words of Dr. W. F. Thompson, "the intensity should be as great as is consistent with the maintenance of the supply of young, and as is economically feasible in view of the fall of returns to the indi v'jdual fisherman." From the biological viewpoint, emphasis is thus thrown on maintenance of the supply of new recruits. It seems reasonable to assume that within certain limits of fishing intensity, recruitment will remain approximately constant, despite a decrease which must occur in the stock of spawning fish. This should result from an increase in survival rate from egg to recruitment stage because of a reduction in "population pressure" (less overcrowding, iess competition for food, etc). However, this compensation cannot FRED E. MARCHESE, Mgr. Moderate Rates and Centrally Located PAc 8374 — PAc 8875 444 CarraU Street Vancouver, B.C. BREAD. SEHRU BAKERIES LTD.! proceed indefinitely. There must be'' a certain level of abundance at which rate of survival of young is a maximum, and beyond whioh further decrease in the abundance of the spawning population will cause a decrease in recruitment. The attainment of the goal of maximum sustained catch thus depends on maintaining the population at this critical level of abundance. The indications are that the abundance of the west coast population has decreased below this critical level, but the evidence is open to question. The immediate problem, therefore, is to obtain reliable information concerning the effect of fishing activity on recruitment Stated more specifically, the immediate problem is this: Can fishing activity, at a level of intensity which can be reached in practice, cause a decrease in recruitment? If not catch restrictions are unnecessary. If so, catch restrictions are necessary, and the further problem arises as to the severity of the restrictions and the best method of applying them- The problem is one of extreme complexity, in view of "natural" variation in recruitment, yet one which should be tackled if, there is a promising line of investigation. Until it is solved, thousands of tons of fish and hundreds thousands of potential dollars are apt to be wasted either because of needless restrictions or because of lack of adequate restrictions. The problem is general, applying not only to the west coast of Vancouver Island, but also to all herring fisheries of British Columbia which are subject to catch restrictions. Methods Of Attack If the problem is to be tackled, the west coast of Vancouver island is the logical scene of attack, for here there are indications, but no proof, that fishing has been sufficiently intensive to cause a decrease in recruitment. Intensified scientific investigations should therefore be inaugurated in this sub-district, directed primarily at a solution of the problem. The speed at which pertinent information can be obtained and the conclusiveness of this information will depend on what catch regulations are in force. These are discussed forthwith- J—Maintenance of the present quota system at a reduced quota for a iM'rifiH of vears. The obiect of auotas is to limit the catch. If the present quota were lowered to 10,000 tons, and this auantitv of fish were taken regularly over a five-year period, an increase to 15.000 tons would be justified. If this were taken regularlv over a further five-year period, an increase to 20,000 tons would be justified, and so on. This is essentially a trial and error system based on the assumption that flshinir activity can cause a decrease in recruitment, and that bv building up the spawning: nomilation through catch restrictions, eventually an average ouota can be arrived at which will vield maximum catch in peroetuitv. Its success depends on quotas being rigidly adhered to- With or without proof of the effect of fishing activity on recruitment, it is difficult for operators and fishermen to take the long-term view and to overlook temporary fluctuations in abundance which are bound to occur to some extent Some will deny the need for any restrictions. Others will admit the possible need, but will want the ideal system of regulation—a sliding quota system geared to varying recruitment from year to year. By intensive scientific Investigation it might be possible to work out such a system, but first the general relationship between the spawning stock and the resultant recruits must be determined. This relationship might eventually be worked out under the quota system, but it would take many years. Intense Research In the meantime, there would still be the question as to whether or not quotas are necessary, and there wsuld still be the perennial requests for extensions when fish remain on the fishing grounds after closure is enforced-^—Removal of all restrictions (except for closed areas on or adjacent to spawning grounds) for a period of years. If fishing intensity were maintained at a level as high or higher than that of recent years, this might be the quickest method of determining the effect of fishing activity on recruitment. This plan, if accompanied by intensive scientific work, would probably give an answer to the question as to whether or not catch restrictions were necessary within a relatively short period of time. If fishing activity caused a progressive decrease in recruitment, average catch would decline to a low value, considerably lower than the average for the past ten years despite the removal of restrictions. The quickest way of restoring the run would be absolute closure for a few years. This would be followed by the imposition of either a sliding or a steady quota, an approximation to the proper value having been determined during the course of the experiment McGavins on the Label Means Quality on the Table! keep McGAVIN'S BREAD aboard High. 0240 764 E. Hastings When in Vancouver, for your Health's sake, go to the . . . HASTINGS STEAM BATHS Vancouver, B.C. 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But at least it would be known that it was impossible at the highest possible practical level of fishing intensity to produce a steady decline in population and catch. There might also still be a question as to the optimum economic level of exploitation, and whether or not reduction in fishing effort (numbers of boats) would yield about the same catch at a lower cost. 3—Removal of all restrictions (except for closed areas on or adjacent to spawning grounds) during two years, followed by complete closure in the third year, for four cycles (12 years) for the whole west coast This plan is particularly suitable for scientific study. By imposing contrasting conditions of fishing intensity on the population it should be possible to determine the relationship, if any, between the number of spawners and the number of resultant recruits, and thus to determine the effect, if any, of fishing activity on recruitment. The spawning population would be made to fluctuate in a definite manner, with a large abundance during the closed year, an intermediate abundance in the first year of fishing and a low abundance in the second year of fishing in each cycle. If recruitment is independent of spawning stock, the spawning population, apart from these fluctuations, would remain approximately constant over the period at a level of abundance depending on the maximum possible intensity of fishing. If recruitment varies directly as the spawning stock, the spawning population apart from these fluctuations, would either steadily increase, or remain constant, or steadily decrease, the exact situation depending on the maximum possible intensity of fishing. Catch and age composition should also undergo fluctuations and trends of a definite pattern. Unless violent "natural" fluctuations in year class abundance take place, it should be possible to determine the effect of fishing activity on recruitment from a study of these fluctuations, supplemented by other scientific investigations. By mathematical reconstruction of the present west coast population, based on rough but (at present) best possible estimates of factors such as present rate of fishing mortality (40%), rate of natural mortality and rate of growth in weight, it is possible to calculate the hypothetical catches which would result according tc —Continued on Page 7 Boat Batteries * COYLE BATTERIES LTD. 276-390 Industrial Avenue VANCOUVER - YORK STREET NETS - We regret that we are unable to fill the ever increasing demand for York Street Nets. The mills are still short of machinery and skilled personnel, but eventually the shortage will be overcome. In the meantime, we suggest early orders. 134 Abbott Street P. LECKIE & CO. 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