Language selection

Search

Research Document - 2012/053

The status of NAFO Division 4T winter flounder (Pseudopleuronectes americanus), February 2012

By R. Morin, D.P. Swain, and S.G. LeBlanc

Abstract

Annual winter flounder landings in NAFO 4T reached over 3,000 tonnes in the 1960s, but varied widely due to unreliable catch statistics up to the 1990s. Landings have declined through the 1990s to less than 200 tonnes in 2007 and 2008. Approximately 300 tonnes were landed in the 2010 and 2011 fisheries. Landings have been consistently below 500 tonnes for the past 10 years, well below the average of 1,481 tonnes since 1960 and the annual TAC of 1,000 tonnes that was introduced in 1996. The fishery is increasingly concentrated around the Magdalen Islands where there is a high demand for winter flounder as bait for lobster fishing. Otter trawls and gillnets are the dominant gear used to capture 4T winter flounder. Despite low harvest levels in recent years, there is no evidence that the resource is rebounding anywhere in the southern Gulf. Survey catch rates were highest before the mid-1980s and then underwent a decline. For the past two decades, winter flounder abundance has fluctuated near the 41-year average of survey catches, but stock biomass has continued to decline to its lowest point in 2011. Data from the mobile gear sentinel program indicate a declining trend since 2003. The size distribution of 4T winter flounder in surveys has shifted to smaller sizes, with fewer large-bodied fish in the population. The size and weight at age have declined over time. The dynamics of 4T winter flounder since 1973 are described using an age structured population model for the first time. The spawning stock biomass (SSB) has peaked at intervals, but exhibits a downward trend over the past 20 years. The age composition of the SSB has shifted from older spawners (age 6+ years) to 3 to 5-year-old fish. Recruitment at age-3 increased sharply in the 1980s to a peak in the 1990s and early 2000s, but has declined since then. Natural mortality (M), estimated for two age groups, is high and appears to drive the dynamics of the 4T winter flounder stock. High M, declining SSB and recruitment, combined with a loss of productivity due to changes in the size composition and declining growth rate, make the prognosis for stock recovery low in the short term.

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.

Date modified: