THE OCCURRENCE AND SPAWNING OF CULTURED ATLANTIC SALMON (SALMO-SALAR)IN A CANADIAN RIVER

The New Brunswick Bay of Fundy salmon aquaculture industry expanded fr om 6 t in 1980 to 16 380 t in 1995. With the growth of the industry ca me an increase in the frequency of escaped cultured salmon entering an d spawning in fresh water. Since 1992, the Magaguadavic River, located in the centre of the New Brunswick salmon aquaculture industry, has b een monitored to show changes in the proportions of wild and escaped c ultured salmon entering the river. Wild salmon numbers steadily declin ed over 5 years, whereas cultured salmon numbers generally increased. Cultured salmon entered the river later than wild salmon and the major ity of cultured salmon were sexually immature. Present ratios of multi -sea-winter to one-sea-winter for wild salmon are 0.4:1, compared with 2:1 a decade earlier. Eggs were sampled from 20 redds in the Magaguad avic River in 1993. Analysis of carotenoid pigments revealed that 45% of the redds were made by females of definite wild origin, at least 20 % by females of definite cultured origin, and the remaining 35% contai ned eggs with pigments indicating a possibility of cultured origin. Th us, redds of cultured escapees could be as high as 55% of the total ex amined. The location of the Magaguadavic River, and the availability o f data on wild and cultured salmon in the river dating back to 1992, m ake this an ideal site for a Canadian reference river to monitor inter actions between wild and cultured salmon.