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2006 Sheepshead Stock Assessment

This assessment is the second reliable analysis of the effect of 1995 and 1996 management actions on the status of sheepshead in Florida (through 2004).

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An assessment of the status of sheepshead in Florida waters through 2004


Florida Fish and Wildlife Conservation Commission,
Florida Marine Research
100 Eighth Ave SE, St. Petersburg, Florida 33701-5020

IHR 2006-009
May 2, 2006

Executive Summary

This assessment is the second reliable analysis of the effect of 1995 and 1996 management actions on the status of sheepshead in Florida. The previous assessments (Murphy et al. 1997; Murphy and MacDonald 2000) were conducted with access to only one year and four years, respectively, of post-regulation data.

There was an average of about a 57% decrease in commercial landings of sheepshead on both coasts of Florida between the periods 1982–1994 and 1996–2004. Nearly all landings are now made using cast nets or hook-and-lines. Throughout the period 1982–2004, few fishermen landed large amounts of sheepshead in any year. Sizes of landed sheepshead increased after implementation of the minimum-size limit. Most landed sheepshead now are over 12-inches fork length.

The recreational catch of sheepshead has historically fluctuated year-to-year but the annual catches on each coasts 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-inches 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 is represents about 2–4% of the landings made on each coast.

The combined statewide harvest of sheepshead in Florida during 2004 was 1,217,000 fish or 2,734,000 pounds lbs. The majority of sheepshead harvest was taken by the recreational fishery: 81% and 94% of the total Atlantic and gulf coast landings by number, respectively.

The trend in estimated abundance of sheepshead ages 0 and older during 1982–2004 was steady on the Atlantic coast and varied erratically on the gulf coast. Estimated abundance for these ages in 2004 was 11.5 million fish on each coast.

Recruitment of sheepshead has varied without trend during 1982-2004, with occasional strong year classes seen on the Gulf coast in 1990, on the Atlantic coast especially in 2000 and 2004.

Under the current low harvest rates for young sheepshead, the fisheries are operating at well below the maximum yield-per-recruit and even below the yield-per-recruit associated with F0.1. If sheepshead were managed for yield, a moderate increase in fishing mortality for sheepshead on both coasts would allow for a large increase in yield-per-recruit.

Transitional spawning potential ratios (tSPR) have tended up on both coasts since 1996. Their estimates on the Atlantic coast were about 40% in 1995 and above 60 % after 2001. On the gulf coast, tSPR’s were below 0.25 from 1989 through 1997, but increased through the late 1990s and early 2000 to reach 30% in 2004. 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.

Both Atlantic coast and gulf coast stocks of sheepshead in Florida appear abundant enough to produce adequate supplies of new recruits while maintaining the current levels of harvest.

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.

Prior to July 1, 2004, the Fish and Wildlife Research Institute was known as the Florida Marine Research Institute. The institute name has not been changed in historical articles and articles that directly reference work done by the Florida Marine Research Institute.