Sheepshead Status in Florida Waters
Florida Fish and Wildlife Conservation Commission,Florida Marine Research
100 Eighth Ave SE, St. Petersburg, Florida 33701-5020
This assessment is the third reliable analysis of the effect of 1995 and 1996 management actions on the status of sheepshead in Florida, after those performed by Murphy and Macdonald (2000) and Munyandorero et al. (2006). The current assessment timeframe was 1982-2009.
There was an average of 39-49% decrease in commercial landings of sheepshead on both coasts of Florida between the periods 1982-94 and 1996-2009. Nearly all landings are now made using cast nets or hook-and-lines. Throughout the period 1982-2009, few fishermen landed large amounts of sheepshead in any year. Sizes of landed sheepshead increased after implementation of the minimum-size limit and most landed sheepshead now are over 12" total length.
The recreational catch of sheepshead has historically fluctuated year-to-year but the annual catches on each coast since 1996 have been well below peak catch levels. The length of sheepshead landed has increased with a large decrease in the numbers of small fish (less than 10" fork length) killed. In addition, the bag-limit has been effective in reducing the kill of sheepshead. Before the bag limit, about 17-21% of the catch was made by anglers keeping more than 15 fish per trip, now that catch represents about 2-3% of the landings made on each coast.
The combined statewide harvest of sheepshead in Florida during 2009 was 1,204,000 fish or 2,554,000 lbs. The majority of sheepshead harvest was taken by the recreational fishery: 77% and 92% of the total Atlantic and Gulf coast landings by weight, respectively.
The estimated abundance of sheepshead ages 0 and older during 1982-2009 varied similarly on both coasts: it increased until the mid-1990s, declined and leveled off since 1996. Atlantic coast abundance was always smaller than Gulf coast abundance. Estimated abundance for these ages in 2009 was 10.5 million fish on the Atlantic coast and 13.8 million fish on the Gulf coast.
Recruitment of sheepshead was above average in 1983-1993, 2000, 2008, and 2009 on the Atlantic coast and in1984-199, 1993, 1997, and 2009 on the Gulf coast.
Under the current low harvest rates for young sheepshead, the fisheries are operating at well below the maximum yield-per-recruit (YPR) and even below the yield-per-recruit associated with F0.1. If sheepshead were managed for YPR at F0.1, the YPR at current F would increase by 28% upon doubling current F on the Atlantic coast and by 12% with 1.5 times current F on the Gulf coast.
Transitional spawning potential ratios (tSPR) have trended upward on both coasts since 1996. Their estimates on the Atlantic coast were 17% in 1995 and above 30 % after 2001. On the Gulf coast, tSPR's were below 19% from 1989 through 1997, but increased thereafter to reach 29% in 2009. Recent trends in year-specific, static SPR estimates indicate that the tSPR will continue to increase in the near future on the Atlantic coast and may level off on the Gulf coast.
Atlantic coast and Gulf coast stocks of sheepshead in Florida appear abundant to produce adequate supplies of new recruits but the gulf coast population shows overfished and overfishing signals.
For a more precise assessment of sheepshead, additional data needs include: 1) direct samples from landings for age composition 2) direct observations of discards from all fisheries and estimates of related size and age 3) estimates of release mortality and 4) coast-specific sex-ratio and maturity-at-age schedules.