Common Snook Aquaculture Research
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| Snook — prized by anglers for decades because of their acrobatic leaps on the end of a fishing line and their ability to evade capture more often than not — are one of the most important catches in Florida's saltwater recreational fishing industry. Their popularity, however, has a downside: fishing pressures have placed them on the state's list of "species of special concern" and resulted in the need for fishing restrictions and careful monitoring.
Such considerations have led Mote to focus on growing snook (and other marine species) in captivity so they can be released to help replenish wild fish stocks. |
| Background Mote began developing the technology to culture common snook (Centropomis undecimalis) in the 1980s. We initially focused on catching wild snook during the spawning season and then transferring them to tanks at our City Island facility. These fish were induced to spawn soon after capture and researchers collected the fertilized eggs. This approach led to limited larval survival and in 1996 we began collecting and fertilizing eggs from wild, naturally spawning fish in Sarasota Bay. This strategy was more successful and provided good quality eggs for larval growth and production studies for stock enhancement. |
| Wild Spawning Studies To collect snook eggs, a group of eight to 10 staff deploy a 400-foot-by-10-foot seine net from a boat. Netting sites are chosen based on knowledge of snook spawning behavior and the feasibility of deploying and collecting snook in the large seine net safely. In Southwest Florida, snook spawn from May through September, congregating near passes and inlets to bays following new and full moons. Although there are many sites that snook congregate for spawning, the currents or topography of a site may be too difficult to net. After the fish are collected in the seine, they are then separated by sex into floating pens, or hapas. Milt - sperm - is taken from the males and eggs are taken from the females and the fish are released alive and unharmed. Eggs and milt are then combined with seawater and the eggs are fertilized then carefully packed and transported to Mote where they were stocked in larval-rearing tanks and maintained for growth and other studies. |
| Captive Spawning Studies In 2006, Mote began developing year-round maturation and spawning techniques for snook held at Mote Aquaculture Research Park. Each 14,348-gallon (54.3 m3) snook broodstock tank and its associated filtration system is designed to hold approximately 14 adult snook (up to 50 kilograms of fish). In 2006, we successfully matured and spawned snook in captivity during the natural spawning season. In 2007 and 2008, we successfully matured and spawned snook two months before the natural spawning season - a first for this species held in captivity. Current research is focused on determining if enriching the broodstock diet with vitamins and fatty acids — specifically arachodonic acid or ARA — results in improved egg quality. |
| Larval Production Research Snook larval and juvenile research at Mote is focused on improving survival in larval rearing and nursery culture. Snook start off their lives as very small larvae - approximately 0.06 inches (1.5 mm). This small size means that they require extremely small food. Larval snook are initially fed rotifers, a small zooplankton approximately 0.00039 inches (100 micrometers). Rotifers are fed algae for survival and to enhance their nutritional profile. Before they're fed to snook, we also add enrichments to increase their fatty acid content. Larval survival is not optimal on an initial rotifer diet and research is ongoing to identify alternative first feeds for larval snook. Other larval research is evaluating survival at low and high salinities, optimal egg disinfection methods and the effect of live food enrichment on larval survival. Read more. |
| Juvenile Production Research Juvenile, or nursery culture, research is focused on increasing the numbers of healthy juvenile snook produced for stock enhancement. Reducing cannibalism, determining optimal diet and reducing the incidence of deformities (such as lordosis) are key factors being studied. Aggression When snook metamorphose from larvae to nursery stage fish 25-30 days after hatching, they are highly cannibalistic. Snook are so aggressive that they will even try to swallow a fish of the same size. This aggression among juvenile snook makes it necessary to routinely grade the fish based on size - that is, keeping smaller and larger fish in separate tanks. However, even with frequent size grading, the snook's aggressive behavior makes it difficult to rear these animals in high densities. Research is ongoing to determine if culture conditions can be modified to reduce aggression in nursery culture systems. Deformities The incidence of lordosis, or bent-back syndrome, in hatchery-reared snook varies from year to year. Research conducted to date suggests that this deformity either results from nutritional deficiencies in commercial fish diets or from high currents in culture tanks. Research is ongoing to determine whether we can reduce the occurrence of lordosis in juvenile snook through modifications in the nutritional makeup of the diet or modifications in current. |
| Learn more about snook restocking at Mote Read a Mote Magazine story about this topic |
YOU CAN'T TELL A SNOOK BY IT'S COVER. The snook, just another fish in the sea to some, is actually one of the most popular game fish in Florida waters. With your support, we can make sure there'll always be plenty to catch. |
About Us
Mote Marine Laboratory has been a leader in marine research since it was founded in 1955. Today, we incorporate public outreach as a key part of our mission. Mote is an independent nonprofit organization and has seven centers for marine research, the public Mote Aquarium and an Education Division specializing in public programs for all ages.
