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 Acoustic Tagging Project The Snapper - Grouper Complex The Snapper-Grouper complex is an integral part of the commercial and recreational fishing industry. Stock assessments suggest that many snapper and grouper species are declining regionally. Currently, the South Atlantic Fisheries Management Council (SAFMC) regulations limit recreational catch to only 10 Snapper and 5 Grouper caught per person per day. Several species have even stricter regulations, such as only being able to collect 2 gag grouper per person per day. For more information check the recreational regulations on the SAFMC website. The following provides a brief description of the three fish species being studied in the Gray’s Reef Acoustic Tagging Project.
Red snapper are light red in color and have a laterally compressed body form (meaning it is compressed from side to side) with a pointed anal fin. The anal fin is the fin on the bottom side on the fish, located the furthest from the mouth or right behind the anus. Their irises are also red. They resemble other snapper species in the shape of their bodies. Young red snapper commonly have a dark spot below the dorsal fin and a dark edge around the caudal tail (the back fin on the fish). These dark colors completely fade by the time they are adults. Red snapper can reach up to about 91cm (just under 3 feet) in length and have been recorded to live up to 50 years. Red snapper are gregarious and will school with other fish of their species that are similar in size. They congregate around reefs, hard bottom, ledges, artificial reefs, wrecks, platforms (such as oil rigs), and any other under water structure they can find. They are usually found at depths between 30 and 200 feet, but can occasionally be found deeper. Gray’s Reef is between 55 and 75 feet deep, so red snapper can be found near or on the reef. Red snapper have canine teeth attached to both the upper and lower jaw. These sharp teeth allow the snapper to be an opportunistic feeder, meaning they will eat anything they can, such as other fish, benthic crustaceans, squid, and other options that may be available. Some studies have suggested that red snapper feed close to the reef but in sand or mud habitats, while other studies suggest that they feed in the reef habitats.
Gag (Mycteroperca microlepis) Gag are a pale to dark gray fish with dark box-shaped spots. They also have dark fins with whiteish edges. The peropercle, a bone at the end of the cheek but in front of the gills, has a bony angle that is very distinct in this fish. Gag lack the other distinguishing characteristics that other groupers have, such as the streamer-points on the tail fin and the yellow color around the mouth. They can reach size of 96cm (3 feet). Gag are commonly found in and around Gray’s Reef. They aggregate in harems. Studies suggest that the largest, most aggressive, female undergoes sexual transformation to a male, probably due to behavioral triggers when males are not present. This behavior is called protogynous hermaphrodism. Similar to other grouper species and to red snapper, gag like to congregate around underwater structures.
Scamp (Mycteroperca phenax) Scamp are similar to yellowmouth grouper in appearance. They are light gray or brown with reddish-brown side spots. The spots tend to be aggregated into lines on the side of the scamp. The edge of a scamp’s mouth does not have the yellow coloring, like the yellowmouth grouper does. They can reach 60 cm (about 2 feet) in length. The reproductive behavior of scamp is similar to gag, they practice protogynous hermaphrodism. This sexual transformation occurs with age. Scamp differ from gag in their social behavior. Instead of being found in large aggregations, scamp roam individually or in small groups.
Red Grouper (Epinephelus morios) Red grouper are a brownish-red color with occasional white spots on the side. They are not considered to be overfished or experiencing overfishing, but they are both recreationally and commercially important. Due to this importance, red grouper are still managed by both the South Atlantic Fisheries Management Council and the Gulf of Mexico Fisheries Management Council. They can reach 125 cm (about 4 ft) in length and live for about 29 years. Similar to gag and scamp, red grouper are also protogynous hetmaphrodites. The sexual transfer usually happens between 7 and 15 years of age. Red grouper also spawn frequently, which can be up to 26 times per year. Red grouper are opportunistic feeders that do not specialize in any prey item. They have a very large mouth that they use to suck large amounts of water into and over the gills. Any prey in the water at the time will be "sucked" into the mouth as well. Adult red grouper prefer habitats with rocky or limestone reefs, caverns, or flat rock with many holes. These habitat types are found in Gray's Reef National Marine Sanctuary. In the past, these fish were not commonly observed at Gray's Reef, but are becoming more and more prevalent. The increase in numbers is of interest to scientists. Therefore when one was caught during the 2009 Nancy Foster cruise, scientists took advantage of the opportunity to learn something about this species and tagged and released the fish. |
Red Snapper (Lutjanus campechanus)
