Aquaculture, also known as aqua-farming, is the rearing of animals from egg to adult for food and/or stock enhancement.
Through conservation aquaculture, queen conch can be farmed for restocking wild populations. Queen conch farming can also be used to grow sustainable seafood.
These farms can be used for protecting or rebuilding adult populations to increase number of eggs laid. The eggs can also be used for hatcheries.
The most intensive stage for growing conch from eggs to larvae to tiny juveniles.
Rearing juveniles for up to 1-year-old stage, in a controlled environment with sand.
Large scale production that uses natural conditions.
Queen conch egg masses can be collected from wild populations or from an egg farm. An egg farm is an enclosure in the wild where adult conch are stocked to ensure a steady supply of egg masses.
Conch have separate sexes and are sexually mature at 4 years old. The male is on the left and female on the right.
Conch have internal fertilization and the male (right) and female (left) conch need to be at a density of at least 100 conch per hectare (2.2 acres) in order to find each other for mating.
Photo credit: Michiel van Nierop
Each female conch lays about 10 egg masses during the summer breeding season, which is typically April to September. Each egg mass contains about 500,000 eggs.
Small portions of the egg mass are collected from the female and brought back to the hatchery inside a bucket of salt water.
Queen conch eggs take 3-5 days to hatch and will hatch at 9:00 PM.
This video highlights the aquaculture techniques used to collect queen conch egg masses from the field, and how to incubate and hatch the egg masses in a hatchery. Florida Atlantic University Harbor Branch Oceanographic, research professor, Dr. Megan Davis takes you through each of the steps. This tutorial was produced for the fishers of the Naguabo Commercial Fishing Association as part of the Saltonstall-Kennedy NOAA Fisheries grant (Award Number NA19NMF4270029) Development of a Fishers Operated Pilot-Scale Queen Conch (Lobatus gigas) Hatchery and Nursery Facility for Sustainable Seafood Supply and Restoration of Wild Populations in Puerto Rico awarded to Megan Davis, Ph.D. (PI) Florida Atlantic University; Raimundo Espinoza, (Co-PI) Conservación ConCiencia; and Carlos Velazquez (collaborating organization), Naguabo Commercial Fishing Association. Queen conch are a regulated and managed species. It is prohibited to collect egg masses without the appropriate permits.
Spanish version: https://youtu.be/gKEcTCCbz9U
French version: https://youtu.be/LkLMMPMQJj8
Queen conch egg mass is one continuous strand that is covered in sand grains. The egg mass is about five inches long and has 500,000 eggs.
Using a microscope, you can see the tiny embryos inside the egg mass strand. For reference, those white pebbles are grains of sand! Once ready to hatch, the embryo's foot will have orange pigments, the velar lobes are visible and the embryo will steadily rotate in its egg capsule.
Newly hatched veligers have a distinct, elongated beak, two velar lobes, and a light-colored gut. The black eye spots and orange pigments on the foot are visible. Shell length is 350 – 370 µm and the shell has 1.5 whorls.
By day 4 the velar lobes have indented to form four lobes. The foot has expanded and the orange pigments multiply near the bottom portion of the foot. Phytoplankton makes the veliger digestive glands brown. The cilia on the lobes are used to aid the larvae in feeding, respiration and movement. Shell length is 440 – 470 µm and the shell has 2 whorls.
This 18 days old veliger has 6 lobes and a dark brown gut from feeding on phytoplankton. As the veliger approaches metamorphosis competency, the foot greatly expands, the adult operculum becomes visible and the orange foot pigment is starting to show dark spots. Some veligers exhibit swim-crawl behavior. The shell length is 830 - 1130 µm and has 3 whorls.
Around day 21 the veligers undergo metamorphosis. The conch veliger needs a metamorphic cue to settle. The metamorphosed conch absorbs its velar lobes and crawls with its foot. The eyes have migrated up the tentacles and the proboscis is used for grazing. The shell length two days after settlement is 1280 – 1760 µm.
This 1.5 cm (half an inch) juvenile conch is about 2 months old. In the wild, these juveniles would be buried and very hard to find!
It takes about 1 year for the conch to grow to 7 cm (3 inches). In the nursery they are fed prepared food from seaweed and chow.
Juvenile conch are ready to be stocked in grow out cages for ranching or released in the field for restoration at about 1 year of age at 7-9 cm (3-3.5 inches).
For the first month after metamorphosis the small juvenile conch are grown on mesh screens and fed flocculated diatoms.
Conch are extremely efficient gazers feeding on diatoms starting at a young age. As shown here they leave nothing behind (see top of image vs. bottom). In the wild, this function keeps seagrass beds healthy.
After the conch are one to two months old they are transferred to trays that are filled with sand. The sand helps the conch to develop their shells and mimics their natural environment.
Conch need to be 7-9 cm (3-3.5 inches) in shell length to be stocked for ranching or restoration. The largest conch in this photo is about 1 to 1.5 years old.
Ranch enclosures are used to grow the conch for food. The enclosures are secured to the sandy and seagrass substrate on the bottom and extend above the surface to limit predation.
The conch are stocked at 1-2 conch per square meter (10 square feet) in the pasture. The enclosure should be at least 25 meters (80 feet) in diameter. This density mimics that of the wild. If enclosures are stocked higher, then pasture rotation is necessary.
These conch range in age from 1 to 4 years old.
Size plays an important role in determining stocking and harvesting phases.
Photo Credit: H. Forrest Thomas
Juvenile conch are collected from the nursery tanks and relocated to the ranch enclosures via boat.
Conch are stocked into the wild for restoration by hand to ensure they are sheltered in the seagrass meadow.
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