I’ve been seeing lots of cobia pictures lately. I’m acutely tuned into seeing them because cobia is still a bucket list fish for me. And of course this is the time of year when we see them and when anglers are catching them. Recently my friend Robert ask if I knew why some cobia have prominent stripes and others do not. He knows juveniles have darker stripes and as a fish ages the stripes fade. But Robert said if you look at angler photos, you could have two large cobia both the same size and one will be dull and the other with more prominent striping. That was what had him perplexed. And to be honest, I didn’t know the answer. But, I do now!
Before I answer the stripe question, let’s look at this beautiful fish. Cobia, Rachycentron canadum, gets its name from its 7-9 pointed dorsal spines; rhachis is Greek for spine and kentron mean pointed. The first description of cobia occurred in 1766 by a scientist Linnaes who classified it as Gasterosteus canadus, and not from a Canadian specimen as the species name canadus would suggest; his cobia came from the Carolinas. Interestingly, cobia was reclassified and renamed 19 times before its current scientific name was settled on.
Sawfish are modified rays with a shark-like body. Sawfish get their name from their “saws”, which are used for defense and to locate, stun, and kill prey; mostly fish. The earliest sawfish arose about 200 million years ago. These sawfish were distant cousins of the ones we see today which appeared about 65 million years ago. At one time sawfish were abundant; however, they have experienced significant declines due to decades of unintentional overfishing, mostly the result of entanglements in fishing gear. Sawfish saws (scientifically called rostrums) have also been popular trophy items, but when they’re removed, they don’t grow back and sawfish are unable to feed normally or defend themselves. Today, all sawfish species (five) are endangered, including the smalltooth sawfish which occurs in our area. The smalltooth sawfish historically ranged from around North Carolina to central Brazil, and along the western coast of Africa. Now, smalltooth sawfish are only found in south and southwest Florida, and the Bahamas. With few remaining, it is important to learn about their life history, biology, and ecology so that conservation efforts will be successful.
In Southwest Florida, smalltooth sawfish research began in the early 2000s with most research efforts focused in the Caloosahatchee and Peace rivers; research data and angler observations indicate these areas still support juvenile sawfish. Last month I accompanied FWC-Fish and Wildlife Research Institute (FWRI) researchers on a directed sawfish trip in the Caloosahatchee River. FWRI’s sawfish research includes both random and directed sampling using a variety of net gear. We sampled in areas where anglers and shore observers had reported sawfish sightings (hence directed sampling).Sampling involved deploying a net and letting it soak for one hour. We had to check the net whenever anyone saw movement or after a half hour, whichever came first. Our first set resulted in nothing. We then cruised the shoreline looking for sawfish before setting a second net. We thought we were skunked a second time but finally at the end of our set, we got a sawfish!
It’s cownose ray mating season. It’s also the time of year when I’m frequently asked “what kind of fish is that swimming at the surface with two fins out of the water?” That fish is a female cownose ray and if one looks carefully they will see at least one male, often several, following her at a slightly deeper depth. When a female cownose ray displays her pectoral fin tips above water she is ready to mate.
In Charlotte Harbor, cownose ray mating behavior can occur between October and June but mating usually takes place from April to June. Like all sharks and rays, fertilization is internal. Female cownose rays have two ovaries, but only the left one is functional. Males have modified pelvic fins called claspers that they use to deposit sperm when mating. During mating, the male bites the female to hold onto her. This often leaves visible wounds along the pectoral fins. Sharks and other rays also exhibit this biting behavior. Don’t worry, the wounds heal quickly.
If you’ve spent any time fishing along shore or strolling in our parks along the shoreline of Charlotte Harbor, you’ve probably noticed all the green algae attached to the rocks and other intertidal structure. I walked along the shoreline at Bayshore Live Oak Park and noticed two species of filamentous green algae. One species was closer to the water than the other in what biologists refer to as resource partitioning. I suspect that the one closer to shore is probably better adapted to being periodically exposed at low tide. The other is probably better at competing in deeper water.
Closest to shore I saw Enteromorpha flexuosa. If it has a common name I don’t know what it is. Enteromorpha means “intestine-shape,” and this algae resembles hollow tubes much like intestines. Enteromorpha is light green, unbranched, and only about four to five inches in length, often shorter. It grows in clumps or tufts at or near the low-tide line and is often found on rocks, mangrove roots, or other woody debris. This species of algae has a wide salinity range and can be found in almost any shallow-water brackish or marine environment.
News from FWC:
Recent changes to the buoys marking the Boca Grande Channel will affect tarpon anglers and others fishing in Boca Grande Pass during the months of April, May, and June.
Southwest Florida has a long tradition of commercial fishing in its rivers, bays, and Gulf waters. In 2015 over 22 million pounds of wild harvested fish and shellfish including shrimp, blue and stone crab, grouper, mackerel, and mullet among others were harvested by commercial fishermen and landed in the seven-coastal counties of Southwest Florida. In addition, approximately 285 wholesalers and 750 retailers bought and sold seafood in this region contributing to Florida’s multi-billion dollar seafood industry.
The fisheries in Southwest Florida are monitored and managed at the state level by the Florida Fish and Wildlife Conservation Commission, and federally by the Gulf of Mexico Fishery Management Council. Closed areas and seasons, size and daily limits, trip tickets, and limited access into a fishery are all tools commonly used to manage Florida’s fisheries. In addition, managers establish annual catch limits and accountability measures to ensure the long-term health of the fisheries they manage. Fishermen use a variety of gear and methods to harvest their catch and they must also follow rules to minimize impacts to the surrounding environment and marine life.
Invasive Indo-Pacific Lionfish were introduced by aquarium hobbyists to waters off the southeast coast of Florida in the 1980s. Over the past ten years, these beautiful, ornate fish have rapidly spread across the entire tropical western Atlantic, from North Carolina to Venezuela, throughout the Caribbean and the Gulf of Mexico. The population sizes in the invaded range commonly exceed those from their native habitats by several orders of magnitude. With a seemingly insatiable appetite for our native fishes, and a lack of local predators and disease to keep them in check, Lionfish can have detrimental effects on the invaded marine ecosystem. In this talk, we will review the history of the invasion, discuss the biology and ecology that has allowed them to be so successful, highlight some damaging impacts they can have, and finish with what scientists are doing to combat the problem.
On Thursday, March 3rd, UF/IFAS Extension, Florida Sea Grant at Weedon Island Preserve welcomes Dr. Chris Stallings, University of South Florida College of Marine Science, to present “Salty Topics: A Thorny Matter: Invasion of the Indo-Pacific Lionfish in the Western Atlantic”. The educational program is intended for adult and high school age audiences.
Shellfish aquaculture is a relatively new pursuit in Florida. It began in the 1970s in the Indian River Lagoon when attempts were made to culture hard clams as a means of taking pressure off declining wild populations. Techniques for producing seed clams had been developed 20 years prior and Harbor Branch Oceanographic Institution (HBOI) developed early grow-out technologies based on culture methods already used in the Northeast but modified for Florida’s subtropical and subtidal conditions.
If you love seafood and want to savor a taste of Florida’s history, then you don’t want to miss the annual Cortez Commercial Fishing Festival (February 13 & 14, 2016).
Cortez village represents one of the last working waterfronts on Florida’s Gulf coast that is dedicated to commercial fishing. Each year, tough and ingenious Cortezians join together to celebrate and share the history and proud heritage of their community at the Cortez Commercial Fishing Festival. This two-day event allows festival-goers to enjoy live music, clog dancing, boat rides, marine life exhibits, nautical arts & crafts, beautiful waterfront vistas – and of course, plenty of delicious local seafood! Trust me, you do not want to miss out on the mullet hot dog. This year’s Festival marks its 34th anniversary.
Cortez has been a center of commercial fishing since the Spanish colonial era, and prior to that, Native Americans depended upon the region for its abundant marine life. This little village has withstood the test of time, surviving hurricanes, red tides and storms of regulations, habitat degradation and economic upheavals. The annual festival showcases how the pioneering spirit of fishermen past continues today in the industrious locals who carry on the community’s legacy.
Cool 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.