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FISHERIES RESEARCH BOARD OF CANADA Translation Series No By E.M. Krokhin

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FISHERIES RESEARCH BOARD OF CANADA Translation Series No Effect of size of escapement of sockeye salmon spawners on the. phosphate content of a nursery lake By E.M. Krokhin Original title: Vliyanie
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FISHERIES RESEARCH BOARD OF CANADA Translation Series No Effect of size of escapement of sockeye salmon spawners on the. phosphate content of a nursery lake By E.M. Krokhin Original title: Vliyanie razmerov propuska proizvoditelei krasnoi na fosfatnyi rezhim nerestovykh ozer. From: Izvestiya Tikhookeanskogo Nauchno-Issledovaterskogo Instituta Rybnogo Khozyaistva i Okeanografii, Vol. 57, p Translated by R.E. Foerster Fisheries ReseaAh Board of Canada Biological Station, Nanaimo, B. C. 1968 This is a preliminary translation prepared for the use of the Fisheries Research Board of Canada. It is not a definitive English version of the article, and it has not been checked or approved by,the author. 1. Effect of size of escapement of sockeye salmon spawners on the phosphate content of a nursery lake By E.M. Krokhin. Some 30 years ago Juday, on the basis of hi s studies at Karluk Lake, which was the most important place for production of sockeye salmon in Alaska, expressed the view that carcasses of spawned-out sockeye constitute a unique form of fertilizer since they supplemented the supplies of biogenic substances in the lake (Juday and others, 1932). To this he attributed the abundance of plankton in Karluk Lake. However Juday did not provide any positive evidence for this hypothesis. At the beginning of the 1930's it was observed in the Bolshaya River, that the carcasses of spawned-out pink salmon had a marked effect on the hydrochemical regime of the river (Krokhin and Krogius, 1937). Studying this question as it applied to Cultus Lake, British Columbia, Ricker (1937) came to the conclusion that the carcasses of spawned-out fish could not play a significant role in the biogenic balance since the number of such fish in the lake was too small in comparison with the volume of the lake (in Karluk Lake there was an average of 500 fish, but in Cultus only around 50 per 10 6 m 3 ); and the sockeye did not enter the lake every year because in some seasons all the maturing fish were taken for artificial propagation. However Ricker did not completely rule out all effect of the spawned-out carcasses on the lake's regime; in a later paper (Ricker, 1938) he stated that after years of large escapements of spawning sockeye to the 'lake very rich crops of plankton Crustacea were observed to occur. In Ricker's opinion fertilization of the lake with supplies of essential minerals from the - 2- spawned-out carcasses through the action of bacteria was too slow and inefficient a path, and the effect of the spawned-out carcasses on the development of plankton Crustacea could be explained only through the direct consumption of the decomposing sockeye carcasses by these Crustacea. In 1947 the question of fertilization of lake areas by the carcasses of spawned-out salmon was investigated by the author in several lakes in Kamchatka. As a criterion 500 fish per 10 6 ma were selected, for such a concentration of fish had a marked effect. It was noted that in the Paratunka lakes (Blizhnee, and especially Dalnee) even a minimum escapement for that period must have had an effect approximately equal to the average for Karluk Lake. At Lake Kurile, on the contrary, the maximum upriver run during this period (3.2 X 10 6 fish) would have about half the effect of the average for Karluk Lake; in the case of small escapements [page 32] the effect of this factor in Lake Kurile could be disregarded (Krokhin, 1948). Later an analysis was made of the average annual phosphate balance in Lake Dalnee. It was found that prior to 1950 there was a positive phosphorus balance, on account of what was brought in by the carcasses of the spawned-out salmon. This element of the balance amounted to about onequarter of the incoming portion, on the average. In the spawning lakes Blizhnee and Dalnee, by the method of hydrobiological productivity of the water, it was established that phosphorus was not a factor limiting the production of phytoplankton. At the same time, from a comparison of data on the concentration of phosphates in the water of lakes where sockeye spawn, with those where they do not spawn, it was found that waters of the first group were very much richer in phosphates than in the second group (Krokhin, 1957). - 3 - Rounsefell (1958) published a paper on the factors which caused the decline in abundance of sockeye in Karluk Lake. In it consideration was given to the possible effect of a decrease in the food supply of the lake resulting from a decline in the quantity of phosphate brought in in carcasses of sockeye. On the one hand, the author of this paper considered that more phosphate entered the lake from watershed run-off than from the fish and that as a result of the weakening of the influence of the latter factor, the phosphate supplies in the lake might have been reduced by some 10-15% over the last 75 years. On the other hand, he recommended that studies be made of the efficacy of introducing artificial fertilizers into the lake, in amounts consistent with the size of the lake, i.e. he definitely did not deny a possible influence, on the biogenic regime which had been observed over the last two decades, of the insufficient escapement of spawning sockeye to Karluk Lake. In the late 1950's preliminary results were reported of a comparison of data on the escapement of sockeye to Lake Dalnee and the phosphate content of the waters of the lake for the period In the second half of this period ( ) the comparison showed a concurrence of low level phosphate concentration with a marked reduction in the number of sockeye entering the lake to spawn (Krokhin, 1959). However, since the phosphate introduced through the carcasses of spawned-out sockeye amounted only to about one-quarter of the incoming portion of the phosphate balance and the main portion of this income was from run-off waters (Krokhin, 1957), it was not quite clear to what degree the change in phosphate content might have been due to fluctuations in run-off during this same period, and whether or not the coincidence of reduction in phosphate concentration with a decrease in the number of sockeye spawning in Lake Dalnee might have been accidental. - 4 - In order to ascertain the real factors of cardinal importance in evaluating the level of the food resources in a lake, it was necessary to compute as closely as possible all the elements of the phosphate balance for each year for the whole period from 1937 to This was the more necessary because a simple comparison of the changes in average concentration of phosphate between the two halves of this period with the calculated average amounts of phosphate brought into the lake in the same two halves ( and ) in the carcasses of fish, indicated a marked discrepancy (the change in average phosphate concentration was equal to 40 mg P 2 0 5/m 3, whereas the change in average quantity of phosphate brought in by the fish amounted to a total of 5-6 mg P 2 0 5/ m 3 ). In order to calculate the phosphate balance. it is necessaryto have knowledge of the water balance of Lake Dalnee, and also of the annual escapement of sockeye salmon to the lake, the seaward migration of their young, and the loss of biotic material down the Dalnee River. [page 33] Calculation of discharge In order to compute the naturally-incoming part of the water balance of Lake Dalnee (in the Paratunka River system) it is necessary to bring together the data on the amount of sediment discharging into the lake from the watershed area (11.3 km 2 ). However the available information for the period from 1937 to 1960 is extremely scarce, as indicated in recently-published reports on the flow of Kamchatka rivers by hydrologist M.G. Vaskovskii (1959). An attempt to compute the inflow through precipitation showed that, in this instance, for almost all years the inflow of water into the lake from its watershed was less than the discharge from the lake through the River Dalnee. Since the level of Lake Dalnee for the period in question had, to all practical degree, remained unchanged, one must assume that the incoming and outgoing parts of the water balance were in equilibrium. The basis for such assumption is the relative stability of the lake level: the minimum average monthly level of the lake fluctuates within limits of 2-3 cm, which, under the circumstances, may be considered as very close to zero. Howyer the assumption of a zero value for the water balance does not necessarily indicate a zero value for the phosphate balance (without counting the phosphates brought in in sockeye carcasses), since the income to the lake is composed of three parts, differing quite appreciably in their to the lake is composed of three parts, differing quite appreciably in their phosphate content and having quite unequal relative importance in different years: ground-water flow, surface flow, and precipitation falling on the surface of the lake. First of all it is necessary to compute the flow down the Dalnyaya River, for which one can use a relationship that has been determined between the levels of the river and its discharge per second (Fig. 1 and Table 1), and on this basis calculate firstly the monthly and then the yearly size of the flow of the river. 6 40 '' ;4 re aa 1,g 13 1,4 1,6' 1,8 2,0 Pacx118,41 3/cem Fig. 1 [page 33]. Relationship between the water level and the amount of discharge of the Dalnyaya River. Ordinate - Water level in cm. Abscissa - Discharge in m3/sec. - 7 - During winter the Dalnyaya River is observed to have rises in level of short duration. This is a result of the fact that sometimes after heavy snowfalls with strong winds the actual cross-section of the river in the neighbourhood of the water-measuring gauge often became completely clogged with snow. Such rises in level would not indicate an increase in the outflow of the river and consequently in calculating the outflow they were not considered. [page 34] table 1. Outflow of the Dalnyaya River (in ma/sec) at levels CM CM GO O 0,195 0,150 0,91(,39 1, ,216 0,492 0,960, ,135 0,237 0,531,01 ;49' --L ,258 0,576,06, ,145 0,279 0,6)8, 1 1,60 '5 0, ,660,I6, ,157 0,330 0,710, 2!, ,163 0,360 0,760, ,170 0,390 0,810,30, ,182 0,420 0,860,35,85 -- Table 2. Year Flow Year Flow Year Flow Year Flow ,9 1191,7 1090,0 1501,0' 1252,7 1175, ,1 980,1 918,6 1290,0 1103,0 973,1 1258, ,3 1140,1 826,8 1008,0.1212,0 1520,3 908,2' CpeRtie ,3 999,8 1147,2 1202,0 1118,0 1156,0 - 8 - The calculated annual flow of the Dalnyaya River (in 10 4 ma/year) for the years 1937 to 1960 is shown in Table 2. From the data of Table 2 it is apparent that the average yearly coefficients of the flow down the Dalnyaya River: discharge GO 31.5 x 108 x 11.3 (km2 fluctuate from 23.2 (1953) to 43.6.? //sec x km2 ) (1951) and on the average equal ,/sec x km2 ); they never reach the t/sec x km 2 ) attributed to the Paratunka River by M.G. Vas'kovsky. According to the data of Table 2 the annual discharge of the Dalnyaya River will fluctuate from x 10 4 to 1549 x 10 4 ma per year. On the average it amounts to 1156 x 10 4 per year. For the first half of this period it was somewhat higher than for the second. The flow in the lake, which in magnitude is equal to the discharge of the Dalnyaya River, can be divided into its three components. The portion of the flow ascribable to precipitation falling on the lake's surface may easily be determined from the ratio between the area of the watershed (11.3 km2 ) and the area of the lake's surface (1.36 km 2 or 12% of the watershed). From this it is easy to calculate that the fraction of the precipitation falling on the lake is 12% of the annual flow. [page 35] In order to compute the ground water flow, it is assumed In all calculations of the water balance no consideration was given to amount of condensation or evaporation, since data on these features were completely lacking. Since they affect the water balance in opposite ways, they can be considered as mutually cancelling out each other. -e 9 that this is represented by the minimum intensity of the flow during the year; it is considered that at this time the discharge is fed only by groundwater sources, and that the ground-water flow is relatively constant during the year. Minimal intensities of such flow, under Kamchatka conditions, occur during the winter months. Multiplying the minimal monthly flow by 12 gives the yearly flow. The difference between the total flow and the sum of the ground-water flow and the flow attributable to precipitation over the surface area of the lake, evidently must represent the surface discharge [from land]. The results of calculation of the various components of the flow in general are given in Table 3 and in Fig. 2 (10 4 ma per year) I-- aao...,,.g. v. 1 ri \---: / Ov ' -... / i )(-- r \ e.,, -it., 400 -,, 4. s,...,, \ 2 % t..,- Y,e I li t e, %,' %., e F I,, t--, se _ _: ,..--C2L ::::_--_e_::-.7._ c ,_z. : A ` - D I t I J T t t I I II I ,1 I J I t I t SZ fait Fig. 2. Components makin'g up the flow of water into Lake Dalnee: 1 - Ground-water supply; 2 - Surface run-off; 3 - Precipitation on the lake; 4 - Long-term average flow Ordinate - flow, 10 4 ma - years Abscissa Table 3. Year ' Precip tation on the lake 145,4 143,8 130,9 180,1 150,4 140,0 173,0 137,0 117,5 113, ,9 151 I 186,0 Flow ground surfa 566,0 566,0 566,0 740,0 472,0 403,0.505,0, 510,0 527,0 '92,0 487,0 546,0 584,0 737,0 695,0 500,5 485,2 393,1 580,9 630,3 542,6 764,1 495,1 335,6 3'* ,1 424,6 272,3 370,1 668,3 Year Precipitation Flow on the ground surface lake ,8 528, ,0 606, ,2 587, ,3 587; ,3 737, ,0 606, ,7 606, ,0 546, ,8 566,0 CpeAHee ,2 539, ,0 610, ,0 577,0 A75, ' 299,8 479,7 601,0 293,2 177,6 333,8 443,4 520,0 ' 382,0 445,0 About 50% of the flow in Lake Dalnee, on the average, is made up of ground-water flow; the remainder comes from the surface run-off (40%) and the ' precipitation falling on the lake surface (10%). In particular years these average proportions will vary. Thus, in 1941, 1942 and 1943, the surface'runoff was much greater than the ground water; in 1953, on the contrary, the ground-water outflow rose to 70%, while the intensity of the surface run-off dropped to 14%. The portion made up by precipitation falling on the lake surface [page 36] was not large in total amount, and was relatively stable. Comparatively speaking,the changes in the ground-water discharge were also small. Fluctuations in total inflow of water to Lake Dalnee are associated predominantly with the variability of the surface run-off from the watershed. It is quite evident that changes in the ratio between these separate components of the inflow must be reflected in the intake of phosphates by the lake. 1 1 - Computation of the phosphate balance in Lake Dalnee The incoming part of the phosphate balance consists of the phosphate brought in with the surface run-off, ground-water and precipitation, and also that carried in in the bodies of sockeye spawners. Since there are no data on the fluctuations in the yearly concentration of phosphates in the waters of different origins entering Lake Damée, one must assume that it is relatively stable. On the basis of hydrochemical studies in the lake basin, the following yearly average quantities of phosphates from the several different sources were accepted: from precipitation - 20, from ground-water discharge - 100, from the surface run-off - 50 mg P2 05 /m3. In order to calculate the phosphates in the fish, the content of. P2 05 in Lake Dalnee sockeye was set at 0.28% (Kizevetter, 1942). Since the average weight of Lake Dalnee sockeye, over many years, has been 1.88 kg, then one fish contains 5.3 g P2 Q5. Data on the number of sockeye spawning in the lake from 1937 to 1960 are given in Table 4, and presented graphically in Fig. 3. Table 4. miv. ui 1.11S-1,. V.I.._-.1.1i1.1. u3. - 4,11teXag pawnin spawni g pawnin no. o ockeye ockey sockey sockey in in in in Year 's Year 1000' Year 1000' Period 1000' , , , , , ,1 ' Meeesteem ceikm. - if:ge1/ / / V.....,...:5 iy; ;:...:.:,...:*, ,..e.,.,...,:iw iv.;, w e,,,.....,,.,. 6,. WY,O,,, 7 *He tie» zer,ierfeele ederie e SO 00 Cie hi m /re lttlk 90 Fig. 3 [page 36]. Escapements of sockeye into Lake Dalnee and phosphate concentration of the lake waters. Left ordinate - escapement of spawners, in thousands Right ordinate - P 2 0à, Abscissa - years concentration in mg/m3 Single-angled line area - phosphate Double-angled line area - escapement Top broken line - average phosphate Lower line - average escapement From Table 4 and Fig. 3 it is apparent that the period from 1937 to 1960 may be divided into two parts in respect to the number of sockeye escaping to Lake Dalnee. During the first 12 years ( ) the escapement was on the average approximately 7 times greater than in subsequent years ( ). [page 37] Similarly the analysis of phosphate balance is broken down into these two periods. The average phosphate content of the Dalnyaya River outflow for the computation of the outgoing discharge of phosphate, on the basis of many years' hydrochemical analysis, is taken to be 85 mg/m 3. The P05 content of sockeye smolts migrating from Lake Dalnee, according to I.V. Kizevetter's data, amounts to 0.49% of their live weight. Data on the total biomass of migrating sockeye smolts of all age - 13- groups for each year (with the exception of 1960) Of the study. period are shown in Table 5. In conform.j..ty with the reduced number of spawning sockeye during the second period ( ) the average biomass of smolts for was approximately three times that for Table 5 [page 37]. iomass Biomas 3iomas Bioma: of smolts cf smol s ojf smols of smo: ts Year kg Year kg Year kg Year. kg CpeRion ' ? The last component of the outflowing part of the phosphate balance to be considered in the present calculation is the biotic material present in the water. We must assume that in the Dalnyaya River there occurs plankton only from the upper 10-metre stratum. However data concerning the abundance of plankton organisms in this stratum for Lake Dalnee are extremely scarce. More or less detailed information is available for Crustacea constituted the main biomass of the lake's plankton; thé biomass of the remaining organisms was very mall, therefore may be disregarded.' On the basis of our data we accept the following average wet weights (in mg) per 100 plankton crustaceans (Krogius and Krokhin, 1948; Krokhin, 1948): Cyclops strenuus 6.2, Diaptomus anqustilobus 10.8, Daphnia lonespina 11.0, nauplii of Copepoda 0.6. Calculating the average yearly quantity of plankton crustaceans in - 14- the 0-10 m stratum for 1949, and multiplying by the corresponding wet weight, we can determine the average yearly biomass of plankton crustaceans in this stratum (in mg/m3 ). The Peb content of this biomasse according to I.V. Kize- vetter (1948), amounts to 0.09%. Therefore, calculating on the basis of the average data for 1949, in the 0-10 m stratum there would be found the following numbers of plank- ton Crustacea: Nauplii of Copepoda 2600 per m3 or 156 mg/me Cyclops Diaptomus Daphnia Total biomass 1086 It was indicated above that in this biomass there would be 0.09% P2 00 therefore in 1949 in the average outflow of biomass there would be roughly 1 mg P24 per m3. Since the vertical distribution of the plankton [page 38] is subject to little change from year to year, we may take for granted that the average biomass of plankton in the 0-10 m stratum is proportional to the average annual biomass for the whole lake, which we know already, and on this basis we may compute the average annual biomass of crustaceans in that stratum and, consequently, the quantity of phosphorus anhydride contained in it for any year in relation to its plankton content. The average annual quantity of P2 0 (mg/m3 ) flowing down the Dalnyaya River in the form of plankton is presented in Table 6. Table 6 Year P20,; Year Pao& Year P20 6 Year P30. -A 937 1,5(?) 943 0, , , , , , ,3(?) 938 0, , , ,0(?) 940 0, , , ,4(?) 911 0, , , ? 942 0,
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