Red grouper
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Red grouper ( Mycteroperca rubra ) |
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| Mycteroperca rubra | ||||||||||||
| ( Bloch , 1793) |
The red grouper ( Mycteroperca rubra ) is a benthic predatory fish of the genus Mycteroperca from the grouper family ( Epinephelidae ). It is native to the coasts of the Eastern Atlantic from Portugal to Angola and on the southern coast of the Mediterranean area.
General
Mycteroperca rubra was first described by Marcus Élieser Bloch in 1793 . This is currently the official species name. The species is also known by other synonyms. These include Epinephelus ruber (Bloch, 1793), Cerna macrogenis (Sassi, 1846), Mycteroperca scirenga (Rafinesque, 1810), Serranus armatus (Osório, 1893), Serranus emarginatus (Valenciennes, 1843), Serranus nebulosus (Cocco, 1833), Serranus tinca (Cantraine, 1833) and Sparus scirenga (Rafinesque, 1810).
features
M. rubra has a bilaterally symmetrical , elongated and robust body and has a standard length (SL) of 59 cm, but can grow to a total size of approx. 85 cm. However, observations should even allow sizes of up to 95 cm. The main characteristics of the species are listed in the United Nations FAO Species Catalog and are described below.
The head is longer than the body height and the height is included 2.8-3.2 times in the body length. The head length is included 2.5-2.7 times the total length. Other features include a convex interorbital area and elongated spines on the preoperculum that are enlarged at the angle and form a rounded flap that is delimited by a depression directly above. The width of the upper jaw (maxilla) is 3.8 - 4.5% of the SL in individuals with 17 - 37 cm SL and 4.8% of the SL in individuals with 59 cm SL. The nostrils are unequal in juvenile fish and in adults the posterior ( posterior ) nostrils are about twice as large as the anterior (anterior) nostrils.
The dorsal fin (dorsalis) has 11 dorsal fin spines with clearly indented membranes and 15–17 dorsal soft rays (D XI + 15–17), all of which are connected by a membrane and the posterior part of the fin is rounded. The anal fin consists of 3 hard rays and 11–12 soft rays (A III + 11–12). The pectoral fins (pectoralis) have 16 or 17 rays. The rear edge of the caudal fin (caudalis) is convex in juveniles below 20 cm SL, especially in individuals with 20 - 50 cm SL and finally concave in adults from 50 cm SL. The scaly body has along the lateral line 69-76 scales and 94-108 shed dorsoposterior to the side line.
The species is usually uniformly red-brown in color and sometimes with black or gray-white spots. There are irregular black stripes over the maxilla . A distinguishing feature of juveniles is also a black saddle point on the base of the tail.
distribution and habitat
The red grouper occurs in the eastern Atlantic along the coast from Portugal to Angola , as well as on the coasts in southern parts of the Mediterranean , the Aegean , the Ionian and southern parts of the Adriatic .
In general, the red grouper is a benthic species that lives on the continental shelf and lives there at depths of 15 - 200 m, but mostly in the range of 15 - 50 m. There it is preferably restricted to sandy and rocky soils as a habitat and usually swims 0.1 - 5 m above the ground. Along the coasts of the eastern Mediterranean, it is often found at shallower depths of less than 40 m.
Originally it was wrongly assumed that the species also lives in other areas. The individuals observed on the coasts in parts of the western Atlantic were subsequently identified as Mycteroperca acutirostris . In addition, other allegedly observed individuals near Madeira , the Azores , the Canary Islands and Cape Verde were identified by Heemstra as Mycteroperca fusca .
behavior
Red groupers usually live solitary or in small groups of up to 10 individuals. They are diurnal and retreat to caves and holes in the rocky habitats at night. Smaller individuals up to 10 cm live all year round in shallower rocky coastal areas at shallow depths of less than 10 m.
nutrition
The red grouper is a carnivorous predatory fish that feeds mostly on small fish, but also on mollusks (probably cephalopods ). Its prey is primarily the rabbit fish ( Siganus spp.), Which makes up about 2/3 of the identified prey.
It is therefore plausible that the rabbit fish makes a significant contribution to the establishment of large populations of the red grouper in the eastern Mediterranean. This prey fish is invasive in the Mediterranean and has migrated due to anthropogenic factors. Since the opening of the Suez Canal , this new and abundant source of food has enabled a large increase in the population of the red grouper. As a result, this species has become the grouper most commonly found in the eastern Mediterranean, while it is significantly rarer in other areas of the Mediterranean.
Reproduction
The red grouper is a protogynous hermaphrodite . The fish are initially female and from a certain age and a certain size they reach sexual maturity, at which point some individuals develop into males.
A study in Israeli waters has shown that the fish are sexually mature from the age of two years and a size of 35-36 cm. The breeding season takes place in the period from February / March to the end of May, when large numbers of red groupers gather in certain areas. During the entire period, up to 500 individuals gather in intervals of 1 - 2 weeks in complex rocky habitats that offer a lot of protection during reproduction. It is also believed that female fish have offspring several times in a season.
Three different color patterns were observed in one study at the mating season gatherings of the red groupers. These include a dark, a dotted and a light pattern. In the course of the investigations, however, no significant changes in the behavior pattern of the fish could be observed, so that the exact function of the different color patterns is largely unknown. However, it is well known that the frequent changes in color morphology of closely related Serranids at gatherings during the mating season is an important aspect of the sexual communication of fish. One can therefore assume that the color patterns also play a role in the reproduction of M. rubra .
Parasites
A prominent parasite of M. rubra is the diplectanid monogenic Pseudorhabdosynochus regius , as well as Pseudorhabdosynochus Yamaguti , 1958, which was not described in detail.
These parasitic gill parasites live on the fish's gills and have been found on individuals caught off the coasts of Senegal, Tunisia, and Libya. It can therefore be assumed that the parasite is found on the gills of the red grouper in southern parts of the Mediterranean and on the west coast of Africa.
Fisheries and threats
M. rubra has some commercial utility as it is caught as a food fish in some areas in the Mediterranean Sea and along the west coast of Africa. However, the species is often found as bycatch on Moroccan fish markets. Ciguatera poisoning can occasionally occur when the fish is consumed, depending on the fishing area.
Another threat to the species is spear fishing, especially on the Israeli coast, which is increasingly taking place during the gatherings in the breeding season of the fish.
The red grouper was last rated on November 22, 2016 by the World Conservation Union (IUCN) as “Least Concern” (LC). Exact population data are not known, but M. rubra is particularly common in the eastern waters of the Mediterranean , which is particularly due to the new source of food made possible by anthropogenic influences. However, exposure to intensive fishing is possible in areas with large congregations of individuals during breeding seasons.
Web links
Individual evidence
- ↑ a b c d e f g h i j k Whitehead PJP, Bauchot M.-L., Hureau J.-C., Nielsen J. & Tortonese E. 1986 ed .: Fishes of the North-eastern Atlantic and the Mediterranean . Volume 2. Bungay (United Kingdom): Unesco, ISBN 92-3-002308-6 , pp. 787-788 (English).
- ^ A b c Neumann V, Paulus T. 2005. Mediterranean Atlas. Melle: MERGUS Verlag GmbH, 1011-1012. ISBN 3-88244-061-9
- ↑ http://www.marinespecies.org/aphia.php?p=popup&name=citation (2019). World Register of Marine Species. Available from http://www.marinespecies.org at VLIZ. Accessed 2019-12-19. doi: 10.14284 / 170
- ↑ a b c d e f g h Aronov, A., Goren, M. 2008. “Ecology of the mottled grouper (Mycteroperca rubra) in the Eastern Mediterranean”. Electronic Journal of Ichthyology
- ↑ Heemstra, PC, Randall, JE 1993. FAO species catalog. Vol. 16: Groupers of the world (Family Serranidae, Subfamily Epinephelinae). An annotated and illustrated catalog of the grouper, rockcod, hind, coral grouper and lyretail species known to date. Rome: FAO, 275-276. ISBN 92-5-103125-8
- ↑ a b c d e f Froese R, Pauly D. 2009, eds. Fishbase. https://www.fishbase.de/summary/Mycteroperca-rubra.html, accessed December 16, 2019
- ↑ a b c Marine Species Identification Portal 2019 Mycteroperca rubra . http://species-identification.org/species.php?species_group=fnam&id=1876&menuentry=soorten, accessed December 16, 2019
- ↑ a b c d Chaabane, A., Neifar, L., Justine, J. 2015. “Pseudorhabdosynochus regius n. Sp. (Monogenea, Diplectanidae) from the mottled grouper Mycteroperca rubra (Teleostei) in the Mediterranean Sea and Eastern Atlantic ". DOI: 10.1051 / parasite / 2015005
- ↑ a b Pollard, DA & Francour, P. 2018. Mycteroperca rubra . The IUCN Red List of Threatened Species 2018: e.T14054A42691814. http://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T14054A42691814.en. Downloaded on December 19, 2019.