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Copper, zinc, calcium, magnesium and phosphate in the gonads and livers of Sockeye salmon (Oncorhynchus nerka) during spawning migration
COPPER, ZINC, CALCIUM, MAGNESIUM AND PHOSPHATE IN THE GONADS AND LIVERS OF SOCKEYE SALMON (ONCORHYNCHUS NERKA) DURING SPAWNING MIGRATION* G. L. FLETCHER
Marine
Sciences
Research
and M. J. KING
Laboratory. Memorial University of Newfoundland. Newfoundland AIC 5S7. Canada (Received
3 August
St. John’s,
1977)
Abstract-l. Concentrations and total amounts of Cu”. Zn’+. Ca”, Mg’+ and PO:were measured in gonads and livers of Sockeye salmon during spawning migration. increased during migration, while total testicular 2. Total ovarian Zn”, Ca’+, Mg*+ and PO:Zn’ + declined. 3. Salmon do not eat during migration; therefore the essential elements incorporated by the ovary must have been absorbed from the water or released from storage within the body. 4. It is hypothesized that almost all of the ovarian Zn’+ and most of the Cal+, Mg’+ and PO:was obtained from body stores other than the liver. INTRODUCTION
During the Sockeye spawning grounds,
salmon migration the blood plasma
killed by a blow on the head and the gonads and livers removed and frozen on dry ice in washed plastic bags. Fork length, body weight, gonad weight and liver weight were recorded for each fish. Gonad and liver samples (2-5 g wet wt) were weighed into pre-weighed digestion tubes. dried at 90-100°C for 2-3 days, re-weighed and digested with nitric acid. Following the addition of the acid, digestion was allowed to proceed at room temperature or 4’C for several days, then heated gently until digestion was complete. The digests were diluted to 25-50ml with distilled water. Digestion blanks were included in each run of samples. The total Cu2+. Zn”. Ca”, Mg*+ and PO:content of the gonads and livers was computed as a function of the salmon’s total body weight @g or mg per IOOg body wt). However, the body weights of both sexes decline during the migration (Idler & Clemens, 1959; Watts, 1973) thus rendering estimates of body compartments based on body weight somewhat misleading. Therefore, assuming that the body length does not change significantly during the migration, the total element content of the livers and gonads was computed for a 63-cm fish (mean length of the salmon collected). The calculations were carried out as follows. The weight of a 63-cm fish was computed from the relationship Y = ax”, where Y is the body weight (g) and X the body length (cm). The 959,, confidence limits were computed around this weight according to Hays & Winkler (1970). The liver and gonad weights were computed for the 63-cm fish using the gonad-somatic index (g/lOOg body wt), and the 955; confidence limits were approximated using the limits computed for the body weight. The concentration of each of the elements in the liver and gonad was not correlated with body weight or length. Therefore the liver and gonad element content was estimated from the organ weights (mean +95”; confidence limits) and the average element concentration. Concentrations of the four metals were determined by flame atomic absorption (Varian-Tectron, Model AA5) coupled to a Varian A-25 recorder. An air-acetylene flame was used to determine Cu” and Zn” and a nitrous oxideeacetylene flame for Ca* + and Mg’ +. Both Ca’+ and Mg’+ were determined in diluted digests using 5000 pg/ml KCI as an ionization suppressor. A standard curve was run with each analysis. Zn’+ absorbance was corrected for the depressing effect of Mg” in the digests.
to the Chilco concentrations
of Cu*+ and Zn’+ decline to 3&50x of the values observed in seawater animals (Fletcher et al., 1975). Available information suggests that fish normally obtain these essential trace elements from dietary sources rather than directly from the water (Pentreath, 1973a). Therefore, since the Sockeye salmon does not eat during the migration up river, it was postulated that the copper and zinc were being removed from the plasma by developing tissues such as the gonads. In a recent study (Fletcher & King, 1977) evidence was presented to suggest that female Winter flounder store Zn2+ during summer feeding to be utilized for ovarian development during their winter post-feeding period. One possible store of zinc for the post-feeding ovarian development was the liver. The present investigation was carried out to quantitate the accumulation of five essential elements (Cu’+, Zn2+. Ca2+, Mg*+, PO:-) by the gonads during the spawning migration of the Sockeye salmon, and to determine whether the liver could serve as a possible source of these elements for the gonads. MATERIAIS
AND METHODS
Sockeye salmon (Oncorhynchus nerka) were caught at two points along their migratory route to the Chilko River (British Columbia) spawning grounds. The first collection was made on August IO, 1976 in seawater off Lummi Island, Washington State. U.S.A. 56km from the mouth of the Fraser River. The second collection was made on September 17. 1976 at Chilko River at the outlet of Chilko Lake. This collection was made at the time of spawning. None of the fish used in this study had initiated spawning. The salmon were caught by reef net at the seawater site, and by beach seine at the freshwater site. The fish were * Mark 2x0.
Sciemes
Research
Laboratory.
Contribution
No,
127
G. L. ELI
128
r(‘HFK
and M. .I. KI>~,
The validity of the above methods was checked several times using the method of standard additions (Christian & Feldman. 1970). In all cases the results obtained by the two methods did not differ significantly. Inorganic phosphorus was measured using the method of Fiske & Suhbarow (1925) (kit No. 670-C. Sigma Chemlcal Co.. St. Louis. MO). ,AII glasswnrc v.as washed. soaked ovcrmghr in 50”(, nitric acid and rinsed thoroughlq with dlstilled water. All acids used for digestion \ccrc of .Aristar grade (BDH Chcmlcals Ltd)
RESC
LTS
During the spawning migration the ovaries increased in size from a mean of 2.97”,, body weight to 15.3”,,. The testes showed no significant increase in percentage of body weight during the same period. The concentrations of 01”. Zn’+ and PO:- were significantly lower (P < 0.05) in mature ovaries than in ovaries obtained at the initiation of the spawning migration. Concentrations of Ca’+ and Mg” did not differ between the two groups. The total amounts (per 1OOg body wt) of ZII’ ‘. Ca”. Mg” and PO:in the ovaries were significantly greater (P < 0.05) at the end of the spawning migration than at its initiation. The total amount (per IOOg body wt) of copper in the ovaries did not differ significantly (P > 0.05) between the seawater and freshwater groups. In the testes. the concentrations of Zn”. Mg’+ and PO: declined. Ca’ + increased and Cu’ + showed no change during the freshwater spawning migration. The total testes Zn’+ (per 1OOg body wt) declined during the migration while the total Ca” increased. Total testes Cu’ -. Mg” and PO:did not differ between the two groups. Calculations based on the weight of a 63-cm fish suggest that both sexes lost weight during the migration from Lummi Island to Chilko Lake. The ovary weight increased during this time while the testes Table
‘yyF’
“;,‘:;;
Females Body wt (g) Ovary (g) Ovary 01” (mg)
Ovaq Zn’+ (mg) Ovary Ca’ ’ (mg) Ovary Mg’+ (mg) Ovary PO:(mg) Males Body wt (g)
(g) Cu” Q_ig, Zn’ i (jig) Ca’ + (mg) Testes Mg” (mg) Testes PO:- (mg)
and total amounts of Cu’+_ Zn’ ‘, rn Ihe gonad\ of Socke,ye salmon caught m seawater (Lummi Island) a1 the mltlatlon of spawning migration. and in freshwater (Chilko Lake) Just prior to spawning. Values arc plotted as means i-95”,, confidence limits. Fig. I. Concentrations
remained unchanged (Table I). The changes in total gonad Cu”. Zn’ ‘. Ca’ ‘. Mg’ ’ and PO: of a 63-cm fish were qualitatively similar to those computed per 100 g body wt. The ovaries showed sigweight
Chilko Lake (freshwater)
3365 2 123 * x.07 * 6.0 * 74.0 f 72.0 + 1270+
573 15.6 1.02 0.76 9.39 9.13 I60
2177 315 7.12 7.x3 171 173 2670
3369 64.3 19.7 910 1.77 12.0 967
430 x.21 2.52 116 0.23 1.53 127
2481 * I059 52.1 * 22.2 12.2 * 5 7’ 300 * 12X 2.30 * 0.9X X.0X + 3.44 8.54 _+ 364
& f * It f + f
]
C-a’*. Mg’ + and PO:
I. Changes in body wt. gonad wt and quantities of gonad C‘u’ ‘. Zn’ +. (‘a’ Mg’ ’ and PO: in a 63-cm Sockeye salmon during spawning migration
Lummi Island (seawater)
Testes Testes Testes Testes
[
Values are means +95”,, confidence limits. NS = not significant change based on overlapping
;\mount accumulated durmg migration
* 374 * 54.2 + I.?’ i_ 1.35 Ifr 29.5 + II.7 + 460
95”,> confidence
.-XXX(NS) 12.2 (NSI 7 5 (NS) hl0 0.53 (NS) --392(NS) -II’
Ilmlt\
‘.
Gonads and livers of Sockeye salmon during migration nificant increases in Zn2+, Ca’+, Mg2+ and PO:during the migration, while testes Zn2+ decreased (Table 1).
129
LIVER
I
Liwr During the spawning migration the male livers increased in size from a mean of 1.05% of body weight to 1.723;. The female livers showed no significant change during the same period. The concentrations of Cu’+, Zn2+, Ca’+, Mg*’ and PO:- in female livers did not differ significantly between Lummi Island and Chilko Lake. In ttie male livers the concentrations of Cu2+ and Ca’+ aeclined (P < 0.05) during the migration, and the remaining elements showed no significant changes. The total amounts (per IOOg body wt) of Zn’+. Mg’+ and PO:- in the male livers increased signilicantly (P < 0.05) during the migration, whereas Cu” and Ca’+ showed no change. No significant changes occurred (per 1OOg body wt) in the element content of the female livers. Calculations based on the weight of a 63-cm fish suggest that the liver of female Sockeye salmon declined in weight during the migration (Table 2). In addition, the liver Cu’+. Zn*+. Ca’+, Mg’+ and PO:content of a 63-cm fish also declined. There appeared to be no significant changes in liver weights or element content of 63-cm male salmon during the migration. DISCUSSION
During the course of the spawning migration Sockeye salmon stop eating, complete gonad development and undergo a number of physical and chemical changes associated with sexual maturation and the energy costs of the migration (Idler & Clemens, 1959; Robertson & Wexler, 1960: Vladykov. 1962). The results of this study indicate that the Sockeye salmon ovary incorporated Zn*‘, Ca*‘, Mg*’ and PO:- during the course of the spawning migration. Since the salmon do not eat during the migration (Idler & Clemens. 1959) these elements must have
Fig. 2. Concentrations and total amounts of 01”. Zn”. Ca”, Mg” and PO:- in the liver of Sockeye salmon caught in seawater (Lummi Island) at the initiation of spawning migration. and in freshwater (Chilko Lake) just prior to spawning. Values are plotted as means +95O/, confidence limits. been absorbed directly from the water or released from storage within the salmon. Available evidence suggests that marine fish normally obtain Zn’+ from dietary sources rather than by direct accumulation from the water (Hess, 1964;
Table 2. Changes in liver wt and quantities of liver Cu’+, Zn”. Ca’+% Mg” PO:- in a 63-cm Sockeye salmon during spawning migration
Lummi Island (seawater) Females Liver (g) Liver Cu’+ (mg) Liver Zn” (mg) Liver Cal+ (mg) Liver Mg*+ (mg) Liver PO:- (mg) Males Liver (g) Liver Cu2+ (mg) Liver Zn” (mg) Liver Ca’+ (mg) Liver Mg’+ (mg) Liver PO:- (mg)
Chilko Lake (freshwater)
47.7 7.39 2.13 2.93 11.6 520
* + + i f +
8.08 1.25 0.36 0.50 1.97 88
30.6 4.22 1.43 1.93 8.08 302
+ + i * & +
5.27 0.73 0.25 0.33 1.39 52.0
35.4 14.1 1.81 1.62 6.41 303
+ + + + + *
4.52 1.80 0.23 0.21 0.82 38.7
42.7 10.2 2.24 1.39 8.16 331
f * + + + +
18.2 4.35 0.95 0.59 3.48 141
Amount accumulated during migration
- 17.1 -3.17 -0.7 - 1.0 - 3.52 -218 + 7.3 (NS) - 3.9 (NS) 0.43 (NS) - 0.23 (NS) 1.75(NS) 28.0 (NS)
Values are means +95% confidence limits. NS = not significant change based on overlapping 95’,, confidence limits
,
R P
fdl ?A -”
and
130
L.
FLLT(.HtK
Pentreath. lY73a. b. 1976). Pentreath (lY73a) estimated that plaice accumulated Zn”’ from seawater ([Zn’ ‘1 15 /(g/l) at a rate of 0.867 rig/g per day. This rate does not differ substantially from the rate of uptake expected if the fish retained all of the Zn-” taken in by drinking. Similar rates of Zn’ +-accumuIation arc not available for freshwater fish. However. if the plaice “Zn fluxes arc used in conjunction with a water concentration of 2Okcg/l~ a high mean value for the Fraser River (Hall er al.. 1974). -to compute the uptake of Zn’ ’ by the salmon. it would take approximately 450 days to obtain the 1.X3 mg of Zn’+ required by the ovary. Since the time between sampling at Lummi Island and Chilko Lake was on11 3X days it would appear that Zn” must have been removed from stores within the body to be deposited in the ovaries during the migration. This zinc requircment of the developing ovary may be one of the reasons for the declining zinc-protein ratios observed in the plasma (Fletcher ~‘r al.. 1975). One possible storr of Zn’+ which could have been utilized by the developing ovary is the Iivcr. Total liver Zn’+ appeared to decline 0.7 mg (Table 2) during the migration. This amount would onl) account for 38”,, of the ovaries’ requirements; the remainder must have been supplied from the other stores. In Winter flounder. the evidence suggested that the liver could supply “‘,, of the ovaries post-feeding rcquiremcnts for Zn’ + (Fletcher & King. 1977). The changes which occurred in gonad Ca” and PO: concentrations during the migration were similar to those observed by Watts (1973). The one exccption was testicular PO: ~. which showed no change during the migration in the present study but was observed to increase by Watts (1973). The ovarian requirements for Ca’+. Mg” and PO: wcrc considerably greater than for Zn’ + (Table I) and could not be met by liver stores (Table 2). Although Ca” (Simmons. 1971) and possibly PO:could be obtained from the water. Watts (1973) obtained data which suggested that the Ca”’ and PO: requirements of developing tissues such as the ovaries. teeth. premaxilla. vertebrae and jawbones could be supplied by resorbing bones (Tchernavin, 193X) and declining muscle mass (Greene, 1924; Idler & <‘lcmcns. 1959). Muscle tissue contains relatively high concentrations of Mg’ I (Vinogradov. 1953); thcrcforc. it is also possible that the ovarian requirecould have been obtained from ments for Mg’ muscle stores. A recent study (Zeitoun or ul.. 1976) indicated that the developing trout embryo derived all of its PO;-. Cu” and most of its Zn’ ’ and Mg’ * from the unfertilized oocytc. If this result is applicable to the salmon. the present study suggests that essential elements such as rinc are stored (actively or passively) in the body for oocyte development well in advance of spawning. /~rkno,~lc~d~o,~r,~r.\ ~~I would like IO thank the International Pacific Fisheries Commission for permission to collect the samples. and Elspeth McGowan for organizing and collecting the samples. I would also like to thank Alice
and
M. J. Ki\\c,
Cadigan for her excellent help m the ;~nal~s~s, and beth Mulatl for the diagram\.
t~hla-
CHKISTIAK G. D. & F~I.I)MA~ f,. _) I 1970) .4rotwc~ -Ihorptiorl SpWro.scop_r. Appllcutior~ln .A~qricltlture, Bioloq~~ uutl Mvdicirw. Wiley-Interscience. New York.
Frxr C. H. & SL~BBAROU' Y (1915) The colorimctric determination of phosphorus. .I. htol. (‘l~rtr~. 66, 37-%4(X). FLETCHER G. L.. WATTS E. G. & KIN<; M J. (1975) Copper. zinc. and total protein Icvcls in the plasma of Sockeye salmon (Oncorhynchu.\ ,~c,rktr) during their spawning migration. J Fish. Rm. Hd Cm. 32. 7X X2. FLt.rCHEK G. L. 6i K~uc; M J. (197X) Seasonal dcnamlcs of C-u: -. Zn’ I. Ca’. and Mg’ ’ 111gonads and hccr of Winter flounder (P.\~,ur/opl~urot~~,~rl~.\umwcmus): Lvidence for summer storage of Zn-’ lor winter gonad dcvelopment in females. CUJI. ./. %n0/. In Press. GKI.EN~ C. W. (1924) The ph>siologJ of spawning migration. Ph~siol. Rw. 6. 201 241 HALL K. H.. KOCH F. A. & Y~SALI I. (1974) Further ~nvestigations into water qua111~ conditions in the lower Fraser River slstcm. We\twatcr Re\. Centrc. Tech Kept No. 4. HA) ES W. L. & WlhLLf K R L (1970) S’rtrrr.\r~~~\:Prohahlllr~~ I+wm~ and Decision. \‘ol. 2 Holt Reinhart. Toronto. Hoss D. E. (1964) Accumulatmn of rinc-65 by flounder d/,1. Fi\/l sot. 93. of the genus Parulichrh~ \. Trclur 364 36X.
D. R. & CLEME&S W -2. (195Y) The cncrg) cxpcndlture of Fraser River Sockeqc during spawning mlgrations to Chilko and Stuart Lakes. lnt. Pocif: Sdmm Fidl.
IDLER
Cower.
Proyr.
Rep.
and lrctcntlon PFN~R~ATH R. J. (197%) Th e accumulation of ‘
Washington. PrFrKI:ArH R. J. (1976) Some further studies on the accumulation and retention of “‘Zn and “Mn by the plaice. Plcuronrcrr~~ plut~~~str L .I L’\,‘. ,nur. Biol. El,of. 21, 179-
I x9.
RoUtRrsox 0. H. & WIXI.IK B. C‘. (1960) Histological changes rn the organs and tissues of migrating and spawning Pacific salmon (genus Orlc,orh~,rlchlc\,. Etdoc~rinology 56, 222~ 239.
VLAII~.~(OVV. D. (1962) Osteological studies on pacltic salmon of the genus O,~c~oril~~n~hfr\. Art// F&I. Rm. Bd Cot!. 136. I- 172. WArrs F. G. (197.7) Colclum and calcltonin studies In pacv tic salmon. genus Oncor/~~nclllr.\. and rainbow trout. S~lnro ycCdrwrl. PhD theslr. llnl\crslty of British C‘olumhia. Vancouver. B.C. ZFI~O~IN I. H.. LILLRI:~ D. E. BIH(;I h W. G. & MAC;E.I W. T. (1976) Mineral metabolism during ontogenesis of Rainbow trout (Srrlrno yrrrrtlrwri). J Fish. Rcs. Bd Cm. 33, 2587 2591.
Marine
Sciences
Research
and M. J. KING
Laboratory. Memorial University of Newfoundland. Newfoundland AIC 5S7. Canada (Received
3 August
St. John’s,
1977)
Abstract-l. Concentrations and total amounts of Cu”. Zn’+. Ca”, Mg’+ and PO:were measured in gonads and livers of Sockeye salmon during spawning migration. increased during migration, while total testicular 2. Total ovarian Zn”, Ca’+, Mg*+ and PO:Zn’ + declined. 3. Salmon do not eat during migration; therefore the essential elements incorporated by the ovary must have been absorbed from the water or released from storage within the body. 4. It is hypothesized that almost all of the ovarian Zn’+ and most of the Cal+, Mg’+ and PO:was obtained from body stores other than the liver. INTRODUCTION
During the Sockeye spawning grounds,
salmon migration the blood plasma
killed by a blow on the head and the gonads and livers removed and frozen on dry ice in washed plastic bags. Fork length, body weight, gonad weight and liver weight were recorded for each fish. Gonad and liver samples (2-5 g wet wt) were weighed into pre-weighed digestion tubes. dried at 90-100°C for 2-3 days, re-weighed and digested with nitric acid. Following the addition of the acid, digestion was allowed to proceed at room temperature or 4’C for several days, then heated gently until digestion was complete. The digests were diluted to 25-50ml with distilled water. Digestion blanks were included in each run of samples. The total Cu2+. Zn”. Ca”, Mg*+ and PO:content of the gonads and livers was computed as a function of the salmon’s total body weight @g or mg per IOOg body wt). However, the body weights of both sexes decline during the migration (Idler & Clemens, 1959; Watts, 1973) thus rendering estimates of body compartments based on body weight somewhat misleading. Therefore, assuming that the body length does not change significantly during the migration, the total element content of the livers and gonads was computed for a 63-cm fish (mean length of the salmon collected). The calculations were carried out as follows. The weight of a 63-cm fish was computed from the relationship Y = ax”, where Y is the body weight (g) and X the body length (cm). The 959,, confidence limits were computed around this weight according to Hays & Winkler (1970). The liver and gonad weights were computed for the 63-cm fish using the gonad-somatic index (g/lOOg body wt), and the 955; confidence limits were approximated using the limits computed for the body weight. The concentration of each of the elements in the liver and gonad was not correlated with body weight or length. Therefore the liver and gonad element content was estimated from the organ weights (mean +95”; confidence limits) and the average element concentration. Concentrations of the four metals were determined by flame atomic absorption (Varian-Tectron, Model AA5) coupled to a Varian A-25 recorder. An air-acetylene flame was used to determine Cu” and Zn” and a nitrous oxideeacetylene flame for Ca* + and Mg’ +. Both Ca’+ and Mg’+ were determined in diluted digests using 5000 pg/ml KCI as an ionization suppressor. A standard curve was run with each analysis. Zn’+ absorbance was corrected for the depressing effect of Mg” in the digests.
to the Chilco concentrations
of Cu*+ and Zn’+ decline to 3&50x of the values observed in seawater animals (Fletcher et al., 1975). Available information suggests that fish normally obtain these essential trace elements from dietary sources rather than directly from the water (Pentreath, 1973a). Therefore, since the Sockeye salmon does not eat during the migration up river, it was postulated that the copper and zinc were being removed from the plasma by developing tissues such as the gonads. In a recent study (Fletcher & King, 1977) evidence was presented to suggest that female Winter flounder store Zn2+ during summer feeding to be utilized for ovarian development during their winter post-feeding period. One possible store of zinc for the post-feeding ovarian development was the liver. The present investigation was carried out to quantitate the accumulation of five essential elements (Cu’+, Zn2+. Ca2+, Mg*+, PO:-) by the gonads during the spawning migration of the Sockeye salmon, and to determine whether the liver could serve as a possible source of these elements for the gonads. MATERIAIS
AND METHODS
Sockeye salmon (Oncorhynchus nerka) were caught at two points along their migratory route to the Chilko River (British Columbia) spawning grounds. The first collection was made on August IO, 1976 in seawater off Lummi Island, Washington State. U.S.A. 56km from the mouth of the Fraser River. The second collection was made on September 17. 1976 at Chilko River at the outlet of Chilko Lake. This collection was made at the time of spawning. None of the fish used in this study had initiated spawning. The salmon were caught by reef net at the seawater site, and by beach seine at the freshwater site. The fish were * Mark 2x0.
Sciemes
Research
Laboratory.
Contribution
No,
127
G. L. ELI
128
r(‘HFK
and M. .I. KI>~,
The validity of the above methods was checked several times using the method of standard additions (Christian & Feldman. 1970). In all cases the results obtained by the two methods did not differ significantly. Inorganic phosphorus was measured using the method of Fiske & Suhbarow (1925) (kit No. 670-C. Sigma Chemlcal Co.. St. Louis. MO). ,AII glasswnrc v.as washed. soaked ovcrmghr in 50”(, nitric acid and rinsed thoroughlq with dlstilled water. All acids used for digestion \ccrc of .Aristar grade (BDH Chcmlcals Ltd)
RESC
LTS
During the spawning migration the ovaries increased in size from a mean of 2.97”,, body weight to 15.3”,,. The testes showed no significant increase in percentage of body weight during the same period. The concentrations of 01”. Zn’+ and PO:- were significantly lower (P < 0.05) in mature ovaries than in ovaries obtained at the initiation of the spawning migration. Concentrations of Ca’+ and Mg” did not differ between the two groups. The total amounts (per 1OOg body wt) of ZII’ ‘. Ca”. Mg” and PO:in the ovaries were significantly greater (P < 0.05) at the end of the spawning migration than at its initiation. The total amount (per IOOg body wt) of copper in the ovaries did not differ significantly (P > 0.05) between the seawater and freshwater groups. In the testes. the concentrations of Zn”. Mg’+ and PO: declined. Ca’ + increased and Cu’ + showed no change during the freshwater spawning migration. The total testes Zn’+ (per 1OOg body wt) declined during the migration while the total Ca” increased. Total testes Cu’ -. Mg” and PO:did not differ between the two groups. Calculations based on the weight of a 63-cm fish suggest that both sexes lost weight during the migration from Lummi Island to Chilko Lake. The ovary weight increased during this time while the testes Table
‘yyF’
“;,‘:;;
Females Body wt (g) Ovary (g) Ovary 01” (mg)
Ovaq Zn’+ (mg) Ovary Ca’ ’ (mg) Ovary Mg’+ (mg) Ovary PO:(mg) Males Body wt (g)
(g) Cu” Q_ig, Zn’ i (jig) Ca’ + (mg) Testes Mg” (mg) Testes PO:- (mg)
and total amounts of Cu’+_ Zn’ ‘, rn Ihe gonad\ of Socke,ye salmon caught m seawater (Lummi Island) a1 the mltlatlon of spawning migration. and in freshwater (Chilko Lake) Just prior to spawning. Values arc plotted as means i-95”,, confidence limits. Fig. I. Concentrations
remained unchanged (Table I). The changes in total gonad Cu”. Zn’ ‘. Ca’ ‘. Mg’ ’ and PO: of a 63-cm fish were qualitatively similar to those computed per 100 g body wt. The ovaries showed sigweight
Chilko Lake (freshwater)
3365 2 123 * x.07 * 6.0 * 74.0 f 72.0 + 1270+
573 15.6 1.02 0.76 9.39 9.13 I60
2177 315 7.12 7.x3 171 173 2670
3369 64.3 19.7 910 1.77 12.0 967
430 x.21 2.52 116 0.23 1.53 127
2481 * I059 52.1 * 22.2 12.2 * 5 7’ 300 * 12X 2.30 * 0.9X X.0X + 3.44 8.54 _+ 364
& f * It f + f
]
C-a’*. Mg’ + and PO:
I. Changes in body wt. gonad wt and quantities of gonad C‘u’ ‘. Zn’ +. (‘a’ Mg’ ’ and PO: in a 63-cm Sockeye salmon during spawning migration
Lummi Island (seawater)
Testes Testes Testes Testes
[
Values are means +95”,, confidence limits. NS = not significant change based on overlapping
;\mount accumulated durmg migration
* 374 * 54.2 + I.?’ i_ 1.35 Ifr 29.5 + II.7 + 460
95”,> confidence
.-XXX(NS) 12.2 (NSI 7 5 (NS) hl0 0.53 (NS) --392(NS) -II’
Ilmlt\
‘.
Gonads and livers of Sockeye salmon during migration nificant increases in Zn2+, Ca’+, Mg2+ and PO:during the migration, while testes Zn2+ decreased (Table 1).
129
LIVER
I
Liwr During the spawning migration the male livers increased in size from a mean of 1.05% of body weight to 1.723;. The female livers showed no significant change during the same period. The concentrations of Cu’+, Zn2+, Ca’+, Mg*’ and PO:- in female livers did not differ significantly between Lummi Island and Chilko Lake. In ttie male livers the concentrations of Cu2+ and Ca’+ aeclined (P < 0.05) during the migration, and the remaining elements showed no significant changes. The total amounts (per IOOg body wt) of Zn’+. Mg’+ and PO:- in the male livers increased signilicantly (P < 0.05) during the migration, whereas Cu” and Ca’+ showed no change. No significant changes occurred (per 1OOg body wt) in the element content of the female livers. Calculations based on the weight of a 63-cm fish suggest that the liver of female Sockeye salmon declined in weight during the migration (Table 2). In addition, the liver Cu’+. Zn*+. Ca’+, Mg’+ and PO:content of a 63-cm fish also declined. There appeared to be no significant changes in liver weights or element content of 63-cm male salmon during the migration. DISCUSSION
During the course of the spawning migration Sockeye salmon stop eating, complete gonad development and undergo a number of physical and chemical changes associated with sexual maturation and the energy costs of the migration (Idler & Clemens, 1959; Robertson & Wexler, 1960: Vladykov. 1962). The results of this study indicate that the Sockeye salmon ovary incorporated Zn*‘, Ca*‘, Mg*’ and PO:- during the course of the spawning migration. Since the salmon do not eat during the migration (Idler & Clemens. 1959) these elements must have
Fig. 2. Concentrations and total amounts of 01”. Zn”. Ca”, Mg” and PO:- in the liver of Sockeye salmon caught in seawater (Lummi Island) at the initiation of spawning migration. and in freshwater (Chilko Lake) just prior to spawning. Values are plotted as means +95O/, confidence limits. been absorbed directly from the water or released from storage within the salmon. Available evidence suggests that marine fish normally obtain Zn’+ from dietary sources rather than by direct accumulation from the water (Hess, 1964;
Table 2. Changes in liver wt and quantities of liver Cu’+, Zn”. Ca’+% Mg” PO:- in a 63-cm Sockeye salmon during spawning migration
Lummi Island (seawater) Females Liver (g) Liver Cu’+ (mg) Liver Zn” (mg) Liver Cal+ (mg) Liver Mg*+ (mg) Liver PO:- (mg) Males Liver (g) Liver Cu2+ (mg) Liver Zn” (mg) Liver Ca’+ (mg) Liver Mg’+ (mg) Liver PO:- (mg)
Chilko Lake (freshwater)
47.7 7.39 2.13 2.93 11.6 520
* + + i f +
8.08 1.25 0.36 0.50 1.97 88
30.6 4.22 1.43 1.93 8.08 302
+ + i * & +
5.27 0.73 0.25 0.33 1.39 52.0
35.4 14.1 1.81 1.62 6.41 303
+ + + + + *
4.52 1.80 0.23 0.21 0.82 38.7
42.7 10.2 2.24 1.39 8.16 331
f * + + + +
18.2 4.35 0.95 0.59 3.48 141
Amount accumulated during migration
- 17.1 -3.17 -0.7 - 1.0 - 3.52 -218 + 7.3 (NS) - 3.9 (NS) 0.43 (NS) - 0.23 (NS) 1.75(NS) 28.0 (NS)
Values are means +95% confidence limits. NS = not significant change based on overlapping 95’,, confidence limits
,
R P
fdl ?A -”
and
130
L.
FLLT(.HtK
Pentreath. lY73a. b. 1976). Pentreath (lY73a) estimated that plaice accumulated Zn”’ from seawater ([Zn’ ‘1 15 /(g/l) at a rate of 0.867 rig/g per day. This rate does not differ substantially from the rate of uptake expected if the fish retained all of the Zn-” taken in by drinking. Similar rates of Zn’ +-accumuIation arc not available for freshwater fish. However. if the plaice “Zn fluxes arc used in conjunction with a water concentration of 2Okcg/l~ a high mean value for the Fraser River (Hall er al.. 1974). -to compute the uptake of Zn’ ’ by the salmon. it would take approximately 450 days to obtain the 1.X3 mg of Zn’+ required by the ovary. Since the time between sampling at Lummi Island and Chilko Lake was on11 3X days it would appear that Zn” must have been removed from stores within the body to be deposited in the ovaries during the migration. This zinc requircment of the developing ovary may be one of the reasons for the declining zinc-protein ratios observed in the plasma (Fletcher ~‘r al.. 1975). One possible storr of Zn’+ which could have been utilized by the developing ovary is the Iivcr. Total liver Zn’+ appeared to decline 0.7 mg (Table 2) during the migration. This amount would onl) account for 38”,, of the ovaries’ requirements; the remainder must have been supplied from the other stores. In Winter flounder. the evidence suggested that the liver could supply “‘,, of the ovaries post-feeding rcquiremcnts for Zn’ + (Fletcher & King. 1977). The changes which occurred in gonad Ca” and PO: concentrations during the migration were similar to those observed by Watts (1973). The one exccption was testicular PO: ~. which showed no change during the migration in the present study but was observed to increase by Watts (1973). The ovarian requirements for Ca’+. Mg” and PO: wcrc considerably greater than for Zn’ + (Table I) and could not be met by liver stores (Table 2). Although Ca” (Simmons. 1971) and possibly PO:could be obtained from the water. Watts (1973) obtained data which suggested that the Ca”’ and PO: requirements of developing tissues such as the ovaries. teeth. premaxilla. vertebrae and jawbones could be supplied by resorbing bones (Tchernavin, 193X) and declining muscle mass (Greene, 1924; Idler & <‘lcmcns. 1959). Muscle tissue contains relatively high concentrations of Mg’ I (Vinogradov. 1953); thcrcforc. it is also possible that the ovarian requirecould have been obtained from ments for Mg’ muscle stores. A recent study (Zeitoun or ul.. 1976) indicated that the developing trout embryo derived all of its PO;-. Cu” and most of its Zn’ ’ and Mg’ * from the unfertilized oocytc. If this result is applicable to the salmon. the present study suggests that essential elements such as rinc are stored (actively or passively) in the body for oocyte development well in advance of spawning. /~rkno,~lc~d~o,~r,~r.\ ~~I would like IO thank the International Pacific Fisheries Commission for permission to collect the samples. and Elspeth McGowan for organizing and collecting the samples. I would also like to thank Alice
and
M. J. Ki\\c,
Cadigan for her excellent help m the ;~nal~s~s, and beth Mulatl for the diagram\.
t~hla-
CHKISTIAK G. D. & F~I.I)MA~ f,. _) I 1970) .4rotwc~ -Ihorptiorl SpWro.scop_r. Appllcutior~ln .A~qricltlture, Bioloq~~ uutl Mvdicirw. Wiley-Interscience. New York.
Frxr C. H. & SL~BBAROU' Y (1915) The colorimctric determination of phosphorus. .I. htol. (‘l~rtr~. 66, 37-%4(X). FLETCHER G. L.. WATTS E. G. & KIN<; M J. (1975) Copper. zinc. and total protein Icvcls in the plasma of Sockeye salmon (Oncorhynchu.\ ,~c,rktr) during their spawning migration. J Fish. Rm. Hd Cm. 32. 7X X2. FLt.rCHEK G. L. 6i K~uc; M J. (197X) Seasonal dcnamlcs of C-u: -. Zn’ I. Ca’. and Mg’ ’ 111gonads and hccr of Winter flounder (P.\~,ur/opl~urot~~,~rl~.\umwcmus): Lvidence for summer storage of Zn-’ lor winter gonad dcvelopment in females. CUJI. ./. %n0/. In Press. GKI.EN~ C. W. (1924) The ph>siologJ of spawning migration. Ph~siol. Rw. 6. 201 241 HALL K. H.. KOCH F. A. & Y~SALI I. (1974) Further ~nvestigations into water qua111~ conditions in the lower Fraser River slstcm. We\twatcr Re\. Centrc. Tech Kept No. 4. HA) ES W. L. & WlhLLf K R L (1970) S’rtrrr.\r~~~\:Prohahlllr~~ I+wm~ and Decision. \‘ol. 2 Holt Reinhart. Toronto. Hoss D. E. (1964) Accumulatmn of rinc-65 by flounder d/,1. Fi\/l sot. 93. of the genus Parulichrh~ \. Trclur 364 36X.
D. R. & CLEME&S W -2. (195Y) The cncrg) cxpcndlture of Fraser River Sockeqc during spawning mlgrations to Chilko and Stuart Lakes. lnt. Pocif: Sdmm Fidl.
IDLER
Cower.
Proyr.
Rep.
and lrctcntlon PFN~R~ATH R. J. (197%) Th e accumulation of ‘
Washington. PrFrKI:ArH R. J. (1976) Some further studies on the accumulation and retention of “‘Zn and “Mn by the plaice. Plcuronrcrr~~ plut~~~str L .I L’\,‘. ,nur. Biol. El,of. 21, 179-
I x9.
RoUtRrsox 0. H. & WIXI.IK B. C‘. (1960) Histological changes rn the organs and tissues of migrating and spawning Pacific salmon (genus Orlc,orh~,rlchlc\,. Etdoc~rinology 56, 222~ 239.
VLAII~.~(OVV. D. (1962) Osteological studies on pacltic salmon of the genus O,~c~oril~~n~hfr\. Art// F&I. Rm. Bd Cot!. 136. I- 172. WArrs F. G. (197.7) Colclum and calcltonin studies In pacv tic salmon. genus Oncor/~~nclllr.\. and rainbow trout. S~lnro ycCdrwrl. PhD theslr. llnl\crslty of British C‘olumhia. Vancouver. B.C. ZFI~O~IN I. H.. LILLRI:~ D. E. BIH(;I h W. G. & MAC;E.I W. T. (1976) Mineral metabolism during ontogenesis of Rainbow trout (Srrlrno yrrrrtlrwri). J Fish. Rcs. Bd Cm. 33, 2587 2591.