Publication Abstract

The effects of a synthetic pyrethroidpesticide on some aspects of reproduction in Atlantic salmon (Salmo salar L.)

A. Moore and C.P. Waring

The synthetic pyrethroidpesticide cypermethrin, a known contaminant of tributaries supporting spawning salmonidfish, had a significant sublethal impact upon the pheromonal mediated endocrine system inmature male Atlantic salmon (Salmo salar L.) parr. Previous studies havedemonstrated that ovulated female salmon release a priming pheromone in their urine(considered to be the F-type prostaglandin, PGF_α which is subsequently detected by the olfactory system of maturemale salmon parr and results in increased levels of plasma sex steroids and expressiblemilt. Exposure of mature male parr for a 5 day period to a water concentration of<0.004 µg l^-1 cypermethrin significantly reduced or inhibited the olfactoryresponse to PGF_α. In addition, exposure of male parr to cypermethrin significantly reduced theirability to respond to the priming effect of the pheromone. The priming effect on milt andplasma 17,20beta -dihydroxy-4-pregnen-3-one levels were abolished at water concentrationsof <0.004 and 0.028 µg l^-1 cypermethrin, respectively. The effect ofcypermethrin on the priming response did not appear to be due to a direct effect on thetestes, since the ability of testes to respond to pituitary extract stimulation in vitrowas not impaired in males exposed to cypermethrin. In addition, exposure of salmon miltand eggs to a concentration of 0.1 µg l^-1 cypermethrin during fertilisationsubsequently reduced the number of fertilised eggs. The results of the study suggest thatlow levels of cypermethrin in the aquatic environment may have a significant effect onAtlantic salmon populations through disruption of reproductive functions.

Reference:

A. Moore and C.P. Waring, 1994. The effects of a synthetic pyrethroid pesticide on someaspects of reproduction in Atlantic salmon (Salmo salar L.). Aquatic Toxicology, 52(1):1-2.