2010 Spotted Seatrout Stock Assessment

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An assessment of the status of spotted
seatrout in Florida waters through 2009

Michael D. Murphy, Dave Chagaris, and Dustin Addis
Florida Fish and Wildlife Conservation Commission
Fish and Wildlife Research Institute
100 Eighth Avenue, Southeast
St. Petersburg, Florida 33701-5020
March 1, 2011

EXECUTIVE SUMMARY

This assessment update is for the spotted seatrout populations found within each of the northern and southern management units along the Atlantic and gulf coasts of Florida. Spotted seatrout fishing mortalities and abundances were estimated for males and females separately for the period 1982-2009.

Overall, annual commercial landings of spotted seatrout in Florida declined quite slowly during the period 1950 through the 1970s from almost 3.5 million to 1.8 million fish. During the 1980s, the decline accelerated, and current landings rarely exceed 30,000 fish. Declines in the number of commercial trips from the mid-1980s to recent years were over 90% on the Atlantic coast and nearly 99% on the gulf coast.

Estimates of recreational harvest (which includes live-release mortalities) averaged 6.3 million fish during the early 1980s but declined drastically to about 3.2 million fish during the early 1990s then down to an annual average of 2.6 million since 1996. The number of angler-trips made to catch spotted seatrout has generally increased in each region since 1996. However, in the Northeast region, this increase was relatively small, and in the Southeast region, fishing effort in 2008 and 2009 appeared to have declined substantially.

Monitoring data for young-of-the-year spotted seatrout and for older age groups appear to show some consistency with the appearance of strong or weak year-classes. Recent recruitment has been about average in the Northwest region but has remained consistently below average since 2005 in the Southwest region. There was greater year-to-year variability along the Atlantic coast, with recruitment declining from a peak seen in 2006-2007 in the Northeast region and fluctuating markedly since 2006 in the Southeast. Angler total-catch rates for spotted seatrout implied an increase in the abundance of females in all regions after 1988 or 1989 with a sustained plateau in abundance from the early 1990s onward. Males showed a similar pattern, except that the early 1990s abundance levels slowly declined until about 2000.

Fishing mortality estimates for spotted seatrout showed a decline in all regions for both sexes in the late 1980s, and recent estimates have remained low. Spotted seatrout abundance trends for both males and females showed an increase in the numbers of fish in the oldest age groups beginning in the early 1990s in the Southeast, Southwest, and Northwest regions and beginning in the late 1990s in the Northeast region.

Current (average for 2007-2009) estimated transitional spawning potential ratios (tSPR) exceed the Commission's 35% target in both regions of the northern and southern management units: 37% in the Northwest, 49% in the Southwest, 45% in the Southeast, and 67% in the Northeast region. Uncertainties about these estimates were evaluated with various sensitivity runs. The ranges for regional tSPR point estimates from the base model and all sensitivity runs for the 2005-2009 period were 20-40% in the Northwest, 38-50% in the Southwest, 34-48% in the Southeast, and 41-68% in the Northeast. Based on these estimates, there is strong evidence that the recent tSPR meets the Commission's 35% target level in all regions except for the Northwest, where there is a level of uncertainty about the current condition of the stock.