FISHERY BULLETIN: VOL. 73, NO. 4 



data are presented here without statistical com- 

 parisons or extensive discussion so that com- 

 parisons can be made with the results on body lipid 

 resen'es. After removal of the gonads, the bodies 

 of the fish were extracted to remove lipids. The 

 procedure used to measure body fat content has 

 been previously described (de Vlaming, Sage, 

 Charlton, and Tiegs 1974; de Vlaming et al. in 

 press). Basically this technique consists of ex- 

 tracting in a methanol:chloroform:ether solution 

 (1:1:1). Body fat content is expressed as a function 

 of drj^ body weight. 



RESULTS 

 Preparatory Season 



The effects of pinealectomy on body lipid 

 resen'es were first examined during the gonadal 

 preparatory period (January). The results of this 

 experiment are summarized in Table 1. 



Body lipid reserves were significantly depleted 

 in both male and female sham operated fish main- 

 tained at 25°C (whether on a long or short pho- 

 toperiod) compared to the initial January controls. 



Table l.-The effects of pinealectomy on body lipid reserves in 

 Notemigonus maintained on various photoperiod-temperature 

 regimes during the gonadal preparatory season (30-day treat- 

 ment). 



'Dry lipid index = mg lipid, less gonadal lipids/g dry body wt. 

 'Gonosomatic index = wt of gonads (g)/g body wt x 100. 

 'Significantly (P<0.05) different than sham operated controls 

 maintained under same photoperiod-temperature regime. 



In both sexes of sham operated fish exposed to the 

 long photoperiod-low temperature regime body 

 Hpid stores were maintained at the initial levels. 

 Short photoperiod-low temperature treatment, 

 however, caused a significant increase in fat stores 

 in sham operated females, but not in sham oper- 

 ated males. 



In sham operated control fish maintained on a 

 long photoperiod, body lipid levels were sig- 

 nificantly higher in the group at 12°C than in the 

 group at 25°C. Fat levels were also significantly 

 greater in sham operated Notemigonus main- 

 tained at 12°C than at 25°C on a short photoperiod. 

 These data suggest that low temperatures, 

 regardless of daylength, either maintain or favor 

 body lipid deposition in this species. 



At 12°C, a short photoperiod was more effective 

 in maintaining or stimulating lipid deposition 

 than a long photoperiod. Specificially, body fatness 

 (in both sexes) was significantly greater in sham 

 operated fish exposed to the short photoperiod-low 

 temperature regime than in animals maintained 

 on the long photoperiod-low temperature regime. 

 Thus, short daylengths seem to compliment the 

 effects of low temperatures on fat deposition. 

 Body lipid levels were significantly lower in sham 

 operated animals maintained on the short pho- 

 toperiod-warm temperature regime than in fish 

 exposed to the long photoperiod-warm tempera- 

 ture regime. Body fat depletion in Notemigon iis at 

 warm temperatures is therefore accentuated by 

 short daylengths. 



In animals maintained on the 15.5L/8.5D-25°C 

 regime, body lipid levels were significantly lower 

 in the pinealectomized group than in sham 

 operated group. Pinealectomy also retarded fat 

 deposition in female fish exposed to the 9L/15D- 

 12°C regime. In contrast, body fat levels were 

 significantly greater in the female pinealec- 

 tomized fish than in the sham operated females 

 maintained on the long photoperiod-low tempera- 

 ture regime. Body lipid levels in pinealectomized 

 fish did not differ significantly from lipid levels in 

 control sham operated animals under any of the 

 other experimental conditions. These data suggest 

 that the effects of pinealectomy on lipid me- 

 tabolism depend on photoperiod and temperature 

 conditions. 



The effects of pinealectomy on reproductive 

 function are discussed elsewhere (de Vlaming 

 1975). One should note, however, that pinealec- 

 tomy retarded the stimulatory effects of the 

 15.5L/8.5D-25°C regime on gonadal maturation; 



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