No abstract

Coronary arteriosclerosis was examined in cultured Atlantic salmon (Salmo salar L.) maintained on normal and cholesterol-enriched diets in both freshwater and saltwater during the period when they normally mature (June to December). The incidence of lesions was high (48% or greater) in all experimental subgroups (assigned according to diet, salinity, sex, and maturation status). The primary factor in the development of arteriosclerotic lesions was not established, but the high frequency of lesions in immature fish suggests that it was not maturation. However, maturation was associated with a significant increase in the incidence of lesions and was, therefore, an important secondary factor in the etiology of the disease. Furthermore, diet had a secondary influence on the development of lesions since the cholesterol supplement was also associated with an increase in the incidence of lesions. The cholesterol supplement significantly increased the total plasma cholesterol level in all subgroups; the low density lipoprotein fraction (total cholesterol minus the high density lipoprotein fraction) was also elevated in seven of eight paired subgroups. Plasma free fatty acids and triglycerides were unaffected by the cholesterol supplement. The elevated total cholesterol and low density lipoprotein levels resulting from the cholesterol-enriched diet and the associated increase in the incidence of lesions was most prominent in mature males and females held in freshwater. Salinity had no demonstrable effect on lesion incidence, but the severity of lesions tended to be greater in freshwater fish.

No abstract

Livers from brook trout (Salvelinus fontinalis) held in water containing 3.8 p.p.m. (mg/l) Corexit and in water containing 3.8 p.p.m. Corexit + 0.2 p.p.m. polychlorinated biphenyl (PCB) were firmer in texture than livers taken from control trout held in fresh water. The testes from the PCB-treated trout were darker in color, smaller in size, contained less spermatic fluid, and appeared to be regressed when compared with testes from the control fish. Only 72% of the eggs from PCB-treated trout hatched compared to 92% for control eggs when eggs were incubated in fresh water. Fertilized eggs incubated in water containing 0.2 p.p.m. PCB + 3.8 p.p.m. Corexit resulted in less than 1% of the eggs from the untreated fish and none of the eggs from PCB-treated fish being hatched. The young fish from the control group lived only a few days in the water containing PCB. PCB greatly stimulated the in vitro 11beta-hydroxylation of testosterone by trout testicular tissue. There was no significant change in 11-ketotestosterone blood levels in maturing brook trout after treatment with 3.8 p.p.m. Corexit or 3.8 p.p.m. Corexit + 0.2 p.p.m. PCB for 21 days during the final stages of maturation. It is thought that sublethal levels of PCB can interfere with the reproduction process in this species.

Non-frozen storage of sperm for several weeks was achieved by the use of buffered protective agents and low temperature. For example, sperm stored with 5% dimethyl sulphoxide at −4.5 C for 28 days gave 81% fertility; use of 5% ethylene glycol allowed storage at −3 C for 38 days, giving 70% fertility. It is suggested how these results may be employed for interspecific mating of salmonids. Attempts to employ glycerol as a protective agent were unsuccessful as were all attempts at freezing sperm.The necessity of providing an adequate air-space in vials used for short-term storage of undiluted sperm of Atlantic salmon is demonstrated.Although a rough correlation between motility of sperm and fertilization is reported, caution in the interpretation of motility as an indication of fertility is suggested.