Fear the Mussel?

Fear the Mussel?

Well, maybe not…

But there could be reason to keep an eye out.  We are not talking about the common ribbed or hooked mussels we found in the Pensacola Bay area.  We are talking about an invasive species called the green mussel (Perna viridis).

The green mussel differs from the local species by having a smooth shell and the green margin.
Photo: Maia McGuire Florida Sea Grant

Why be concerned?

 

By nature, invasive species can be environmentally and/or economically problematic.  In this case, it is more economic – which is unusual, most are more environmental concerns.  The big problem is as a fouling organism.  Like zebra mussels (Dreissena polymorpha), green mussels grow in dense clusters, covering intact screens to power plants, intact pipes to water plants, and can displace native spaces by competing for space.  It has been determined they can grow to densities of 9600 mussels / m2 (that’s about 10 ft2) and they can do this on local oyster reefs – displacing native, and economically important, oysters.  They grow quickly, being sexually mature in just a few months, and disperse their larva via the currents.  To make things more interesting, they may be host to diseases that could impact oyster health.

 

So, what is the situation?

 

They are from the Indo-Pacific region, found all across southeast Asia and into the Persian Gulf.  In this part of the world they are an aquaculture product.  There was interest in starting green mussel aquaculture in China, and in Trinidad-Tobago.  After they arrived in Trinidad, they were discovered in Venezuela, Jamaica, and Cuba – it is not believed this was due to re-locating aquaculture, but rather by larva dispersal across the sea… they got away.

This cluster of green mussels occupies space that could be occupied by bivavles like osyters.

It would be an easy jump from Cuba to Florida – and they came.  The first record was in 1999 in Tampa Bay.  They were found while divers were cleaning an underwater intake screen.  Dispersal could have happened via larva transport in the currents, but it could have also occurred via ship ballast discharge at the port – this is how folks think it got there, they really do not know.  From there they began to spread across the peninsula part of the state.  They have been reported in 19 counties, most on the Gulf coast, and there is a record from Escambia County – however, that one was not confirmed.

 

How would I know one if I saw it?

 

They prefer shallow water and are often found in the intertidal zones – attached to pilings, seawalls, rocks.  As mentioned, they grow in dense clusters and should be easy to find.  They are long and smooth, with a mean length of 3.5 inches.  There was one found in Florida measuring 6.8 inches, which they believe is a world record.  Mussels differ from oysters in that they attach using “hairy” fibrous byssal threads – in lieu of cementing themselves as oysters do.  As mentioned, the shell is smooth and may have growth rings, but it lacks the “ribbed” pattern we see on the local ribbed and hooked mussel.  It will have a green coloration along the margin – hence its name, and the interior of the shell will be pearly white.

The shell at the far right is the common ribbed mussel native to our local salt marshes. Just to the left is the invasive green mussel. Can you tell them apart?
Photo: Maia McGuire Florida Sea Grant

They prefer salinities between 20-28‰, which would be the lower portions of the Pensacola Bay system (Santa Rosa Sound, Big Lagoon, maybe portions of Pensacola Bay).  They are not a fan of cold water.  They do not like to be in water at (or colder) than 60°F.  Some biologist believe it is too cold in the panhandle for these bivalves, but we should report any we think may be them – to be sure.

 

What do we do if found?

1)      Get a location and photos.  Pull some off and get up close photos of an individual.

2)      Report it.  You can do this by contact the Escambia County extension office (850-475-5230 ext.111), or email me at roc1@ufl.edu.

3)      If there is a method of removing all of them, do so.  But this should be done only after the identification is verified.  When removing try to collect all the shell material.  The fertilized gametes within, if left, can still disperse the animal.

4)      They are suggesting boat owners check their vessels when trailering.  Avoid transporting them from one body of water to another.

5)      I would recommend that marina owners do the same – check boats and pilings.

It appears the mean temperature of the Gulf is increasing.  With this change it is possible some of the tropical species common in south Florida could disperse to our region, and that could include the green mussel.  The most effective (and cheapest) way to manage an invasive species is catch them early and remove them before they can become established.

 

For more information on green mussels in Florida read https://edis.ifas.ufl.edu/pdffiles/SG/SG09400.pdf.

Crawfish!

Crawfish!

Crawfish boils are popular in the springtime. Crawfish are generally harvested from aquaculture operations. Photo credit: Libbie Johnson, UF IFAS Extension

You get a line, I’ll get a pole, we’ll go down to the crawdad hole, honey, baby, mine“…there are lots of great zydeco songs singing the praises of crawfish (aka crayfish, crawdads, mudbugs). They are in season now, and while crawfish festivals all around the southeast are canceled due to concerns over COVID-19, they are still available and make for great eating. Most of us would recognize a cooked one alongside a feast of corn and potatoes, but would you know an actual crawfish hole if you came up on it?

Last fall, our office welcomed about 500 kids (over several days) to the 4-H camp in Barrineau Park for a field trip. I showed every single one of them a small muddy mound with an opening in the top, and asked if anyone could tell me what it was. Not a single kid knew! Now, I make sure I point crawfish mounds out to anyone I happen to be walking with, as they are fascinating little structures. Also referred to as crawfish chimneys due to their upright, open construction, they are built by a crawfish in a muddy area, often near a creek or other water source.

Crawfish mounds are constructed using small pellets of mud, and the opening connects down to a burrow. Photo credit: Carrie Stevenson, UF IFAS Extension

The industrious invertebrate uses its legs and mouth to create pellets of mud as it digs its burrow. It places mud up above the ground, using the mud balls like small bricks. Bricking up the entrance to its burrow (as opposed to placing discarded mud elsewhere) also protects a crawfish from exposure to predators on open soil. The crawfish chimneys can be 6 inches tall (or more!) and connect down to a burrow that may reach 3 feet deep, some straight down and others with side tunnels extending different directions.

Since the crawfish lives in wetland areas, it is theorized that these chimneys extending above the soil allow for better oxygen flow in the burrow. During a drought, crawfish will plug the opening of their mounds with mud, to keep water in the burrow from evaporating.

Crawfish in the wild are rarely harvested, although some folks do fish for them like the song referenced earlier. For the vast majority of crawfish harvested in commercial production, two species are the most popular–the white river crawfish (Procambarus zonangulus) and red swamp crawfish (Procambarus clarkii). They are typically farmed in coordination with rice, as both commodities thrive in flooded conditions. Most aquaculture operations are associated with Louisiana, but at least five other southern U.S. states farm crawfish. To learn more about this industry, check out LSU AgCenter’s informative video.

New List Provides Assistance Options for Florida Coastal Businesses

New List Provides Assistance Options for Florida Coastal Businesses

Florida Sea Grant is maintaining a curated list of disaster assistance options for Florida’s coastal businesses disrupted by COVID-19.

Boats at dock in harbor

Boats at calmly at rest in Massalina Bayou, Bay County, Florida.

The list contains links to details about well- and lesser-known options and includes “quick takeaway” overviews of each assistance program. Well-funded and widely available programs are prioritized on the list. The page also houses a collection of links to additional useful resources, including materials in Spanish.

 

“There is a lot of information floating around out there,” says Andrew Ropicki, Florida Sea Grant natural resources economist and one of the project leaders. “We are trying to provide a timely and accurate collection of resources that will be useful for Florida coastal businesses.”

 

Ropicki and others on the project team stress that the best place to start an application for disaster aid is to visit with your bank or lender and the Florida Small Business Development Center (SBDC). They also suggest contacting local representatives by telephone or email and not to just rely on internet-based applications.

Overview of Selected Disaster Assistance Programs Benefiting Florida Small Businesses including Agriculture, Aquaculture, and Fisheries (COVID-19)

The project team — which includes experts from Florida Sea Grant, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Extension, and the UF/IFAS Center for Public Issues Education — reviews the page regularly for accuracy and to include new options.

Commercial seafood is a large part of Florida’s economy and culture.
Photo: Rick O’Connor

“[I] really appreciate the outstanding work that you and FSG have done on consolidating the various types of aid available to fishermen due to the virus,” said Bill Kelly, executive director of the Florida Keys Commercial Fishermen’s Association, in a recent email. “I’ve been searching for a comprehensive listing and you just provided it.”

Aquatic Weed Control – Common Salvinia

Aquatic Weed Control – Common Salvinia

Common Salvinia Covering Farm pond in Gadsden County
Photo Credit – Shep Eubanks UF/IFAS Gadsden County Extension

Close up of common Salvinia
Photo Credit – Shep Eubanks UF/IFAS Gadsden County Extension

Aquatic weed problems are common in the panhandle of Florida.  Common Salvinia (Salvinia minima) is a persistent  invasive weed problem found in many ponds in Gadsden County. There are ten species of salvinia in the tropical Americas but none are native to Florida.  They are actually floating ferns that measure about 3/4 inch in length.  Typically it is found in still waters that contain high organic matter.  It can be found free-floating or in the mud.  The leaves are round to somewhat broadly elliptic, (0.4–1 in long), with the upper surface having 4-pronged hairs and the lower surface is  hairy.  It commonly occurs in freshwater ponds and swamps from the peninsula to the central panhandle of Florida.

Reproduction is by spores, or fragmentation of plants, and it can proliferate rapidly allowing it to be an aggressive invasive species. When these colonies cover the surface of a pond as pictured above they need to be controlled as the risk of oxygen depletion and fish kill is a possibility. If the pond is heavily infested with weeds, it may be possible (depending on the herbicide chosen) to treat the pond in sections and let each section decompose for about two weeks before treating another section. Aeration, particularly at night, for several days after treatment may help control the oxygen depletion.

Control measures include raking or seining, but remember that fragmentation propagates the plant. Grass carp will consume salvinia but are usually not effective for total control.   Chemical control measures include :carfentrazone, diquat, fluridone, flumioxazin, glyphosate, imazamox, and penoxsulam.

For more information reference these IFAS publications:

Efficacy of Herbicide Active ingredients Against Aquatic Weeds

Common salvinia

For help with controlling Common salvinia consult with your local Extension Agent for weed control recommendations, as needed.

Wild Versus Farmed

Wild Versus Farmed

Laura TIu

Scallops and shrimp over grits.

I have been involved in the aquaculture industry since the late 1980’s when I got my first job out of college on a tropical fish farm in Plant City, FL. As you can imagine, the industry has changed a lot since then.  When folks find out I have worked in aquaculture, the same question seems to arise: “Is farm-raised fish safe to eat as wild caught?”  I would like to say that I don’t understand where this question comes from, but over the years I have seen a bewildering number of mass media headlines touting misinformation about farm-raised fish and not enough touting the benefits.  In fact, I saw a post this week on Facebook actually claiming that tilapia have no skin or bones and cannot be found in the wild, both not true.  It is no wonder people are so confused.  Many of the claims made are not research-based and a quick review of the scientific literature will disprove the statements, but who has time for that?

Aquaculture currently supplies over fifty percent of all seafood consumed and will expand in the future due to a limit on the amount of wild fish that can be sustainably harvested, and increasing demand by a growing population. Sustainable, responsible aquaculture is needed to fill that gap. Fish are farmed using a variety of production methods including ponds, raceways, recirculating land-based systems and in ocean net pens.  Each one of these fish species and production methods comes with pros and cons, similar to the production of livestock and fruits and vegetables.  Each species can be evaluated based on its environmental impact, production method and even country of origin.

The American Heart Foundation recommends eating fish (particularly fatty fish rich in Omega-3s) two times per week. We currently only consume about half of that.  This recommendation includes a variety of farm-raised and wild-caught fish.  Both are crucial to meet current and future demand for seafood and omega-3 fatty acids.  A common misconception is that farmed fish is not as healthy or nutritional valuable as wild caught fish although this claim has been largely disproven.  One recent paper (Trushenski et al, 2017) compared the nutritional values of wild-caught and farmed bluegill, largemouth Bass and hybrid striped bass and concluded that the farmed fish provided more long-chain polyunsaturated fatty acids (LC-PUFAs) per portion that wild fish, however both are excellent sources of high quality protein and nutrients.

With the Lenten season upon us, a time of a traditional increase in seafood consumption, what is an easy way to choose wild and farm-raised seafood?   One website and smartphone app that I find easy to use is Seafood Watch (www.seafoodwatch.org).  Seafood Watch uses an extensive evaluation system using research and a panel of experts to label seafood products as green (best choice), yellow (good alternative) and red (avoid) depending on the variety’s sustainability.

With this information and a little bit of homework, I hope you come to the same conclusion that I have. Both farm-raised fish and wild-caught fish are delicious, nutritious and great additions to your diet.

Baked tilapia, rice and vegetable medley.

Meanwhile, Back at the Oyster Ranch…

Meanwhile, Back at the Oyster Ranch…

Sorting and re-caging take place on-site at the lease

Photo: Erik Lovestrand

There are a number of parallels than can be drawn between shellfish farming and traditional forms of agriculture that take place on the land. The most obvious similarities are the amount of hard work, grit and faith that are required of the farmer on land or sea. In spite of this there are many “salty” farmers in the Florida Panhandle who have mustered the faith requirement and are now putting in the hard work necessary to help build this budding industry in the Southeastern U.S.

Market demand for quality oysters has continued to outstrip available supplies for several years of late. This has been due in part to better marketing strategies employed by growers as well as clientele becoming aware of the health benefits of fresh oysters; a great supply of important vitamins and minerals, including vitamin C and B vitamins, zinc, selenium and iron. However, supply/demand ratios are not the only important factor in developing a thriving oyster aquaculture industry. Also required, is the necessary infrastructure to support the grower’s equipment needs, enough sources of baby oyster “seed”, a reliable refrigerated transportation network for live shellfish, and the support of regulatory agencies in making water leases available in suitable growing areas.

Fortunately, the stars seem to be aligning for many of these industry-growth necessities and the business of oyster farming is gaining a firmer foundation to build upon. One of the important milestones for Florida was the approval of “full-water-column” leases, which allows the use of floating oyster cages or bags. Previously, oysters were required to be grown on the bay bottom and this made them susceptible to higher levels of predation from crabs and snails and severe biofouling (barnacles and algae) on the exterior of the mesh bags. Heavy biofouling reduces the water flow through the oyster’s growing environment, thus the available food for this filter feeding bivalve.

One critical need for this industry is the availability of quality “seed” (baby oysters) to put in the growing waters. Seed oysters are supplied by hatcheries where oyster brood stocks are spawned and babies are raised to the necessary age for grower needs. Some growers use baby oyster larvae that have not settled and attached yet. These “eyed larvae” are put in a tank with old oyster shell and allowed to attach on the shells, which are then deployed at a lease site. Other growers use seed that has already attached to a small particle of crushed shell and are sold as individual oysters to be placed in grow-out bags or cages. The more recent development of oyster stocks with 3 sets of chromosomes (triploids) have provided growers with an oyster that gets to market size faster. Triploid oysters are infertile and do not use energy for spawning, thereby putting more energy into shell and tissue growth. Federal and state laws also govern where growers can buy their seed in an effort aimed at stopping the spread of shellfish disease from one body of water to another (i.e. Atlantic to Gulf of Mexico, etc.).

Even if all of the hardware and infrastructure is in place, there is still one other factor that plays a significant role in whether an oyster farmer will be successful. Just like the dairy farmer, the cattle rancher, the cotton or peanut grower, or the blueberry producer; backbreaking labor is necessary for many stages of the production cycle. Oyster growers work their leases either bending over the gunnels of a boat or actually being in the water, lifting heavy bags or cages of shellfish, sorting by size, re-caging, and moving lots of materials to and from the lease area. True grit and a dogged determination to stay on top of things, regardless of unpleasant conditions, are vital to raising a successful crop of oysters. And by the way, don’t forget that Mother Nature will have the final word. As all farmers know, they are required to be a good listener when she speaks.