Research Document - 2011/047

Recovery potential assessment of American Plaice (Hippoglossoides platessoides) in Newfoundland and Labrador

By Morgan, M.J., Bailey, J., Healey B.P., Maddock Parsons, D., and Rideout, R.

Abstract

Recent trends and status, as well as projected population size at different exploitation levels, were evaluated for the 3 populations in the Newfoundland and Labrador designatable unit (DU) of American Plaice. Projections were also evaluated for the DU as a whole.

For SA2 + Div. 3K, there has been some increase in the number of adults since 2005 but the average of the last 3 years remains at only 16% of the 1980-85 average. For Div. 3LNO, the number of adults has increased since the late 1980’s but the number in 2010 is estimated to be only 25% of the 1980-85 average. In Subdiv. 3Ps there has been some increase in population size and the average number of adults in 2007-09 is 30% of the 1983-85 average.

American Plaice in each of the 3 areas occupied most of the available habitat and 80% or more of the survey area was occupied in most years in all areas.

Projections of population size show that there is scope for management to facilitate recovery as all three populations (and for the DU combined) increase under scenarios of no fishing mortality (F). Current fishing mortality (average of last 3 years) is estimated to be 0.172 for Div. 3LNO, less than 0.001 for SA2+Div.3K and 0.025 for Subdiv.3Ps. Under current F a large number of the projection runs for American Plaice in Div. 3LNO do not reach B_lim by the end of the projection period (48 years). The maximum F that would result in reaching a level where the populations and DU no longer meet COSEWIC’s listing criteria was less than F=0.15 for Div. 3LNO, near F=0.06 for SA2+Div.3K and less than F=0.137 for Subdiv.3Ps.

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