Seals

Current Research Projects

Blue Crab Bait

Highly valued for commercial and recreational fishing, over 90 thousand metric tons of blue crab (Callinectes sapidus) were landed in the United Stated in 2010.  However, most in the Gulf of Mexico was caught using Atlantic menhaden (Brevoortia tyrannus).  Ecological concern is growing over the depletion of the Chesapeake Bay Atlantic menhaden stocks and the potential negative impacts on food chains and the environment. Over the last 50 years, cost per pound, shipping costs, and demand have Crab bait increased for B. tyrannus.  While it becomes harder and more expensive to get Atlantic menhaden, Louisiana creates large quantities of waste from their many marine commercial fisheries including blue crab, oysters, shrimp, and finfish.  We have begun researching ways to utilize this waste in the creation of an artificial bait to reduce fishing pressure on B. tyrannus and add value to current waste products from the Louisiana seafood industry. See a video summary

Blue Crab Disease

Research on the prevalence of blue crab (Callinectes sapidus) diseases and parasites in the Gulf of Mexico has been limited and sporadic. Without consistent, population specific prevalence data, future correlation between increased disease and parasite prevalence and decreased commercial landings in the Gulf is nearly impossible. The selected seven diseases and parasites for this study include Loxothylacus texanus, shell disease or shell rot, Vibrio spp., Lagenophrys callinectes, Hematodinium perezi, Urosporidium crescens, and Whispovirus spp. All of these diseases and parasites are known to occur in Gulf blue crabs, whether through observational reports or infrequent scientific surveys. This project will begin the process of establishing disease and parasite prevalence for blue crabs along Louisiana’s Gulf Coast in order to better understand the current health of the blue crab population. Large juvenile and adult crabs (greater than 11 cm carapace width) will be collected along the Louisiana Gulf Coast and from commercial shedding facilities throughout 2013. In order to determine prevalence, disease or parasite diagnosis will be conducted via PCR, histology, bacterial plate streaking, and visual gross diagnosis.

Derelict Crab Traps & Ghost Fishing

Crab traps become derelict due to vandalism, severing of buoy lines, inclement weather, and improper disposal of retired traps.  As part of a larger outreach and cleanup project, we created a lost trap reporting website that allowed fishermen to easily report lost traps anonymously.  After Hurricane Isaac in August 2012, over 3,000 traps were reported lost to the database.  A field study in 2012 and 2013 is determining blue crab mortality associated with ghost fishing using a combination of monthly visits to experimental derelict traps and mark-recapture techniques.  We initiated the field study to further investigate the impact of derelict blue crab traps on fishery resources in Louisiana.

Additionally, citizen scientists have collected ghost fishing data from the crab traps collected as part of our Crab Trap Rodeo program. This data is providing instantaneous ghost fishing rates at sites across Louisiana each year.

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Black Spot in Louisiana Shrimp

Black spot, or melanosis, is caused by enzymes that are naturally present in the shrimp. Upon removing shrimp from the waters of the Gulf of Mexico, these enzymes react with the air and chemically transform colorless compounds in the shrimp into complex brown pigments near the shrimp surfaces and shell. These initial color changes are NOT an indication of bacteria spoilage. However, even though we eat with our mouth, we buy with our eyes. Black spot is a color defect, and negatively affects quality perception and purchase by the customer.

Sulfite (metabisulfite, sodium bisulfite) is commonly used in Louisiana as a dip for shrimp to prevent the development of black spot.  However, sulfites are a known allergen and must be on all product labels.  Alternative products, such as Everfresh (powder) and Prawnfresh (liquid), have entered the market to replace sulfite treatments.  These products use an organic compound derived from kiwis to reduce black spot development.  This allows for producing “sulfite free” shrimp without black spot, which do not then require a sulfite statement on the package label. These products allow for targeting previously untapped markets where customers want sulfite-free shrimp.

While these alternative products were developed elsewhere for other species, we have been testing Prawnfresh and Everfresh with Louisiana White Shrimp for efficacy and recommended usage in Louisiana.

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