Changes in the Body Composition with Age of Go

Changes in the Body Composition with Age of Go J. F. Craig, K. Srniley', and I. A. Babaluk Department sf Fisheries and Oceans, Central and Arctic Region, Freshwater Institute, 50 1 University Crescent, Winnipeg, Man. 613 % 2/46

Craig, j. F., K. Smiley, and 1. A. Babaluk. 1989. Changes i w the body composition with age of goldeye, Hiodsn alssoides. Can. 1. Fish. Aquat. Sci. 46: 853-858. Male goldeye, Hiodon aiossides, grew faster, matured earlier, and had a shorter lifespan than females as did exploited compared with unexploited populations. Instantaneous growth rates sf the body organs and tissues were usually higher in the male than in the female. The proportion of fat to the total constituents in the muscle, liver, gut, and carcase of female and the gut and carcase of male goldeye declined with age while that in the ovary increased. The proportion of protein in the body tissues and organs sf both sexes remained approximately constant with age. Ash content increased in the carcase of older females and males. Glycogen concentration in the liver varied extensively and was considered as indicator of stress and unrelated to aging processes. Between the ages of 10 and 16 yr the energy content of the female soma increased by 44% whereas the energy content of the ovary increased by 12%%. The ovary selected essential fatty acids at the expense sf the soma. Les Iaquaiches miles, Hiodon aiossides, snt une croissance plus rapide, arrivent plus t6t akt stade adulte et vivent moins longtemps que les femelles, c'est aussi le cas des populations exploitees par rapport aux population nsn exploitees. Les vitesses de eroissance instantanees des orgawes et des tissus de i'organistme etaient generalement plus elevees chez les miles que chez les femelles. On a observe une diminution avec I'ige de ia proportion de gras par rapport abax constituawts totaux presents dans Be muscle, Be foie, I'intestin et la carcasse des femelles ainsi que dans Ifintestin et la carcasse des laquaiches mdles; on a observe bane augmentation de cette proportion dans les ovaires. La proportion de proteines dans les tissus et les organes des deux sexes est restee pratiquement constante avec I'ige. O n a constate une augmentation de la teneur en cendres dans la cascasse des femelles et des miles plus ages. La concentration de glycoghe du foie etait tres variable et on estime qu'il spagissaitd'un indicateker du stress independant du processus de vieillissernent. On a constate un accroissement de la teneur 6nergetique du soma de femelles dg6es de 18 3 16 an et un accroiswment de 121 % de la teneur energetique des ovaires. Les ovaires ont choisi des acides gras essentiels aux dkpends du soma. Received )rs%g/ 4, 1988 Accepted January 10, 1989

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n fish there is histological and physiolsgicd evidence for aging (Craig 1985) but there have been few studies on changes in the allocation of energy for anabolic and catabolic processes. Orton" theory (Orton 1929) that over-production can lead to death states that the dloeation of energy for reprduction increases with age at h e expense of the soma. The bdmce between reproductive output and somatic maintenance has been s u m k z e d by Cdow (1985). The way energy is partitioned between metabolic demands is likely to have a profaand effect on time to md between breeding events, survivorship, and fecundity of the adult fish. Biological csrganisation is continuously being impaired; to remain viable the impaired stmcrtaEres must be replaced or repaired. For example, the energy for protein synthesis makes up about 25% 'sf the fasting metabolic rate (Waterlow 8 988). Alternatively reproductive investment may be at the expense of these maintenance processes. The basic biology of goldeye, Hiodon alosoides, was recorded by Kennedy and Spmles (1967) but little has been published on their ecology. They are almost unique among freshwater fish species in producing a semi-buoyant egg. Also the mount of milt produced by the mde is very small and 'Alberta EnviPsnmentd Centre, Vegreville, Aka. TOB 4LO. Can. J. Fish. Aqeeat. Sci., Voh. 46, 1989

indicates that the male must be in very close proximity to the female during spawning. However, the spawning act has not k e n observed since it takes place in turbid waters (Scott and Crossman 1973). Spawning occurs soon after the break up of ice and gonadal recrudescence starts i diately after spawnby the end of the spew water season (Parkurst et al. 1986). This development of the gonad is unlike that in the majority sf temperate freshwater fish which store energy in the soma and then gradually transfer it to the gonads (Craig 1977). As a result the allocation of energy intake to the various body tissues and organs in the goldeye is easier to measure. Other studies on perch, Berm fluviatiltas (Craig 1977), and Baltic cod, G ~ Ucallarias S (Bogoyavlenskaya and Ve19tishcheva 1972), appear to provide support far Orton9stheory. The present study was designed to directly test this theory.

Methods Collection Goldeye were collected by multi-mesh gillnets from the Battle River, Alberta, from July to November, 1983. Since it

FIG. 1. Map showing the sites used for goldeye collections.

was not possible to collect prespawning fish in the spring from the Bdtle River, additiond samples were taken from Dauphin Lake, Manitoba, in May 1984 and I985 (Fig. I). Samples for comparison with the Battle River goldeye were collected from Dauphin Lake in July, September, and November 1984 and 1985. Further samples were gathered from the Red River, Manitoba, in January, March, April, and May during 1984 and I985 for growth measurements. Goldeye in the Battle River undergo very little exploitation while those in Dauphin Lake (light commercial) and particularly those in the Red River (heavy angling) are exploited. Fish age was detemined by counting bands on opercula. These bands appear on n e b n e s mainly in June (J. F. Craig, unpubl. data) and were used to backcalculate growth. After weighing (to nearest gram) and measuring the fish (fork length in millimetres), the goldeye were dissected m d divided into muscle fillets, liver, gonad, gut (minus its contents), md carcase (composed of the remaining tissues m d organs). These items were weighed to the nearest 0.001 g except the cxcase which was weighed to the nearest 0.1 g. A separate sample of femde fish was collected during September, October, and November I983 from the Battle River. TXe eggs of these fish were stored in Gilson9sfluid. The eggs were later counted for fecundity estimates. Body Composition The proximate cornpsition of tissues was determined, mainly from the Battle River fish. Water content was measured by feeze-drying (mean - 57OC, range - 50 to - 60°C). Drying was continued until constant weights were achieved. Lipid determinations were based on a modified Bligh and Dyer method using chforofom and methanol (Hmson and Olley 2963; Craig 1977). A muffle furnace set at 600°C was used to estimate ash content. Ash content of the testes was not determined owing to small sample size. Total nitrogen was measured by the K j e l d d method (AOAC 1960). Protein content was estimated by assuming that 16% sf the nitrogen was nonprotein $54

TABLE1. Values for the statistics of the Vonr Bertalanffy equation, age at which 95% of the growth is complete (A,,,, yr) oldest age of fish caught (yr) and first age of maturity (yr) for female and male goldeye from the Battle River (BR), Dauphin Lake (DL), md the Red River

(RW. Male

Female

BR

DL

La

375

355

K

8.28 -0.39 B0

0.29 -0.30 10 10

80

A.95 Oldest caught First age of maturity

16

5

5

WR

BR

DL

RR

318 346 327 292 0.33 8,32 0.35 8.47 -0.39 -0.25 -0.20 -0.11 9 9 8 6 8 14 12 6 4

4

4

3

and multiplying the remaining protein nitrogen by a factor of 6.25 (Craig 197'7). The protein content of testes and livers of the males was not determined. The energy values of extracted lipids obtained by pooling samples fmm Dauphin Lake over the whole study period for the various tissues and organs were estimated by calorimetry using a B m macrobomb calorimeter. An analysis using phenol and sulphuric acid (Montgomeq 1957) was carried out to determine the glycogen content of some of the livers. The fatty acid composition of tissues and organs was determined by the following procedure (M. Yurkswski, pers. eomrn.). Lipids were obtained as for energy content deteminations. The lipids were transesterifid by heating for 90 min at 770°C in 5% methanslic HCL. The fatty acid methyl esters were purified (silica gel H thin-layer plates, 25 mrn thick; toluene solvent). Fatty acids were analysed by capillary gas chromatography (Brarim Aerograph ckomatograph, model 2 100, modified for capillary columns; Supelcowax 10 glass columns, outside diameter). The injector and detector temperatures were 250°C a d the oven temperature was 193'C. Peak areas were measured m d converted to weight percent by a computing integrator (Shimadm Chromatopac, model CCan. J. Fish. A q u a Sci., VoE. 46, 6989

TMLE2. (i) Values of regression coefficient (b) and intercept (a) for log weight (grams) s f body organ on log length (millimetres) for male md female goldeye. The carrelation coefficient (r) is given plus statistics from which 95% CL can be estimated. (iji) Weights of body organs of a goldeye of fork length of 327 m h r n the Battle River. Percentages are given in brackets, The carpcase weights of Dauphin Lake (DL) fish are dso presented. (9 Mde

Muscle

Liver

Testes*

Gut

Carcase

fish from the same month, area (Battle River and Dauphin Lake), and sex. Tests of covariance were p d o m e d on these analyses between months a d areas. Where there were no significant differences between slopes or intercepts data were combined. The results are sum&sed in Table 2. Also given in the table are weights of the various tissues for each sex for a standard fork length of 327 nun (the average size of female caught) for fish from the Battle River. Tests of significance between slopes of each sex indicated that only the liver was significant @ pB0.05). The carcase weights of both the male a d female goldeye from the Battle River were significantly heavier than those from Dauphin Lake. The gut weight of mdes from the Battle River was nearly twice that of mdes from Dauphin Lake. The mature o v q represents 8.0-9.5 % (Battle River md Dauphin Lake females, respectively) of the total body weight compared with the mature testes of 0.9-1.196 body weight. Fecundity was estimated from the following relationship: log Fecundity = - 3.4672 - 3.0202 log Length (p