Lake trout rehabilitation in Lake Ontario, 2013

Each year we report on the progress toward rehabilitation of the Lake Ontario lake trout (Salvelinus namaycush) population, including the results of stocking, annual assessment surveys, creel surveys, and evidence of natural reproduction observed from all standard surveys performed by USGS and NYSDEC. No lake trout from the 2011 year class were stocked into Lake Ontario during October 2011 or May 2012; therefore, no stocked age-2 lake trout were available to bottom trawls during 2013. The catch per unit effort of adult lake trout in gill nets increased each year from 2008-2013, recovering from historic lows recorded during 2005-2007. Adult abundance in 2013 exceeded the level of the 1999-2004 mean which at the time appeared to be the new stable abundance following from the 1993 stocking cuts. The 2013 rate of wounding by sea lamprey (Petromyzon marinus) on lake trout caught in gill nets was 2.26 fresh (A1) wounds per 100 lake trout and was slightly above target (2 wounds per 100 lake trout). Estimates from the NYSDEC fishing boat survey indicated 2013 angler catch and harvest rates were the highest estimated in more than 10 years. Adult lake trout condition (indexed from annual length–weight regressions) increased in 2007-2009 from relatively low values observed during 2000-2006, remained nearly constant during 2010-2012 at the highest values observed for the 30 year time-series, but declined in 2013. The low condition values observed for juvenile lake trout during 2010-2012 continued during 2013. Reproductive potential for the adult stock, determined from the annual egg deposition index, rebounded from the 2007-2008 values that were the lowest observed since 1985 and stabilized during 2009-2013 at a mean value of 20.7. In 2013, five age-1 and three age-2 naturally produced lake trout were collected from trawl survey catches providing first evidence of a 2012 year class and continued evidence of a 2011 year class.