Conuma River Salmon Enhancement Facility - New Developments and Programs

Conuma Seapens

SEAPEN REARING:

Seapen rearing is where salmon smolts are transported to large open water pens or cages. Our seapens are mainly located in Moutcha Bay, which is adjacent to the Conuma River estuary. Before releasing the smolts, they are fed in the seapens until they are almost double in size (8 gm). This gives them an advantage over enhanced river released smolts by allowing them to better acclimate to the marine environment before release which helps them to avoid predation. Another benefit to seapen rearing is that it helps to minimise competitive interaction with their wild counterparts.

Seapen rearing of enhanced Conuma chinook has resulted in a dramatic increase in the number of adult chinook returns and catches.

MACKEREL PREDATION:

In the spring of 1992 and 1993, back to back El Ninos (warm water ocean currents) resulted in the migration of massive schools of non-native mackerel to the West Coast of Vancouver Island. These mackerel prey upon the wild and enhanced chinook, chum and coho smolts. This resulted in a dramatic decrease of returning adult salmon in 1996-97. Another El Nino Mackerel attack was apparent in the spring of 1998. This particular attack has reduced the number of returning adult salmon in the years 2000 and 2001.

Seapen Translocation

During the spring seasons of 1996 to 1998, a predator avoidance release strategy was conducted to minimise mackerel predation in which a seapen of enhanced Conuma chinook smolts was towed through Tlupana Inlet to Nootka Sound (this has been termed "Translocation") and released closer to open ocean. The hope was to help avoid the predation bottleneck problem within the narrow constraints of the inlet during a Mackerel event. Results of this strategy are yet to be analysed.

Chinook Seapen

Another strategy to avoid mackerel predation in the spring of 1998 was carried out where enhanced chinook fry were kept for a longer period at the facility and released in the spring of 1999 as yearling chinook smolts. Results are still to come.