Sheepshead – Where are they all coming from?

SheepsheadCool weather means the convicts are loose and on the move! This annual winter migration of sheepshead to congregate along structure makes for great fishing of these striped and toothy bait stealers. It also leads to the annual questions: Where did they all come from? And, where is that underwater prison that holds them the rest of the year? Before I attempt to answer, first let’s explore a few facts about the life history of sheepshead.

The sheepshead, Archosargus probatocephalus is a member of the porgy and seabream family (Sparidae).  Worldwide Sparidae includes about 120 species. Within Archosargus probatocephalus there are three subspecies.  A subspecies means that there are differences within a species, usually due to geographic isolation, but those differences are not significant enough to identify them as separate species. In these cases scientist add a subspecies name to recognize the differences. For sheepshead, A. p. probatocephalus includes the northern form occurring from Canada south to Cedar Key off the Florida gulf coast (our sheepshead); A. p. oviceps occurs in the Gulf of Mexico from St Marks, Florida to the Campeche Bank, Mexico; and A. p. aries ranges from Belize to Brazil.

Sheepshead live about 11-14 years here, but in areas to our north they can live much longer (20 years Louisiana, 18 years Georgia, and 19-23 years in South Carolina). Sheepshead reach sexual maturity around 2 years of age and there appears to be little difference in age of maturity between sexes. Like many other fish species, sheepshead on the Atlantic coast tend to have faster growth rates than those on the Gulf coast and northern sheepshead have growth rates that exceed those in the southern part of the sheepshead range. Regardless of which coast you are on or which latitude you are at, size is not a good determinate of sheepshead age.

Populations of sheepshead spawn offshore primarily in the early spring (February-March). Prior to heading offshore adults group up in large numbers generally in deep water and around structure.  Anglers are seeing this now. Temperature triggers this annual migration to spawn. Females may produce from 1,100 to 250,000 eggs per spawning event and it appears the further offshore a female goes, the more eggs she releases per spawn. Some adults spawn daily others may only spawn once every 20 days. Sheepshead eggs and larvae are transported into estuaries by tides and currents where they settle out and grow. Very young sheepshead are most abundant in seagrass flats and above mud bottoms where they feed on copepods and algae. At around 2 inches they begin to show up on structure.

So back to the question, where are all of the sheepshead coming from? After a spawn, adult sheepshead come into the estuary but are dispersed and in areas most people are not looking for them. Post spawn sheepshead can be found in the open estuary, back bay waters, rivers, creeks and canals. According to Tim MacDonald, a fisheries expert with FWC’s Fish and Wildlife Research Institute in St. Petersburg, adult sheepshead are caught in their 600 foot seines throughout the year. They catch them in a variety of habitats including seagrass beds and along mangrove shorelines. Sheepshead are also found on and around oysters and mixed in with juveniles around pilings and under docks, boats, and other structure. In essence sheepshead are not “locked up” but instead are here, on the loose, and hiding in plain sight all around us.

Another thing that is important to note about sheepshead this time of year is that they are probably eating more as they store up the reserves needed to get them through the spawning season. As such they may be much easier for anglers to catch since they are probably less discerning in their food choices. Other species, snook for example also feed more leading up to reproduction making them more susceptible to capture. This is why we have a closure to correspond with their spawning activity.

One final thought on sheepshead, many anglers have reported that this year there seems to be far more sheepshead than prior years at this time and have asked “what’s up with that?” Interestingly in 2013, FWC recorded abnormally high abundances of young of the year sheepshead. Those fish may now have entered the fishery which could explain these higher abundances observed by anglers.

 

Sources:

Dutka-Gianelli and D.J. Murie. 2001. Age and growth of sheepshead, Archosargus probatocephalus (Pisces: Sparidae), from the northwest coast of Florida, Bulletin of Marine Science, 68(1): 69–83.

C.J. McDonough, C.A. Wenner & W.A. Roumillat. 2011. Age, Growth, and Reproduction of Sheepsheads in South Carolina, Marine and Coastal Fisheries, 3:1, 366-382, DOI: 10.1080/19425120.2011.632234

G. Poulakis, D. Blewett, and T. MacDonald. 2016. Email correspondence.

J.H. Render & C.A. Wilson. 1992. Reproductive Biology of Sheepshead in the Northern Gulf of Mexico, Transactions of the American Fisheries Society, 121:6, 757-764, DOI: 10.1577/1548-8659(1992)121<0757:RBOSIT>2.3.CO;2