Research Document - 2008/067

Status of NAFO Division 4T American plaice, February 2008

By R. Morin, S.G. LeBlanc, G.A. Chouinard, D.Swain

Abstract

Landings of NAFO 4T American plaice declined to 339 tonnes in 2005 and 369 tonnes in 2007, the lowest recorded level for this stock. The annual quota has been 750 tonnes since 2003. Much of the decline in landings can be attributed to reduced fishing effort, particularly since the early 1990s, following closure of the cod fishery. Management measures introduced in the 1990s may have also contributed to declining effort (e.g. increased mesh sizes, restrictions on the capture of small plaice and on the bycatch of other groundfish species, and area closures for spawning stocks). The market demand for plaice and the price paid to harvesters have affected fishing effort on plaice. The resource is mainly exploited by mobile gears (seines and trawlers) with the under 45-foot vessels the most active fleet sector. A telephone survey of active fishers, conducted yearly since 1995, indicates that the abundance of the resource was viewed positively throughout the 1990s, but is less favourable in this decade. Research trawl surveys conducted yearly since 1971 show that the stock reached its highest level of abundance in the late 1970s, but has declined nearly tenfold since then. Trawl survey data indicate persistent low recruitment of year classes since the early 1970s. The sentinel mobile gear survey, begun in 2003, shows a similar declining trend in 4T plaice abundance. A population model was used to estimate the biomass of 4T American plaice, spawning stock biomass, natural mortality and fishing mortality. The resulting view of the 4T plaice stock is one of declining biomass, with high natural mortality (0.55) and low exploitation rate (1% in 2007). Given its low productivity and current level of abundance, the prospects for improvement in the abundance of this stock are poor in the short term.

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