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Comprehensive Description

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Description: Body wide and relatively thick with a sloping forehead and a large round eye and large terminal mouth. Dorsal-fin base long and anal-fin base short. Prominent dorsal, anal, and pelvic-fin spines and a large non-serrated preopercular spine.

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Look Alikes

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Pretransitional mostly-unmarked stage, usually from 10-15 mm SL: Body: Pretransitional larvae can have a few melanophores on the body just below the dorsal fin base where the future bars will develop: at the mid-spinous dorsal fin, the end of the spinous dorsal fin and under the mid-soft dorsal fin. There is a patch of melanophores along the anterior third of the dorsal midline of the caudal peduncle and a full-length band of melanophores along the ventral midline of the caudal peduncle extending forward and ending just before a single large melanophore underlying the pterygiophores of the last anal-fin rays. A bar pattern begins on the lower caudal peduncle as a patch without melanophores between two bars. There are a few deep melanophores at the very end of the lateral midline of the caudal peduncle. Head: Melanophores on the head consist of a patch overlying the brain and on the surface braincase and small melanophores around the tips of both the upper and lower jaw (in similar numbers). The opercular area is covered in iridescence extending down to the pelvic-fin insertion. The inner cleithral surface of the gill cavity is speckled with large melanophores and there are internal melanophores lining the dorsal aspect of the peritoneum extending down to the vent and overlain by a silvery camouflage layer. Fin Spines: The dorsal and anal-fin spines are relatively stout, with prominent internal reticulations. There are fine serrations along the anterior aspect of the anal-fin spines at this stage, but disappearing during transition. Fins: Melanophores on the dorsal-fin membranes are concentrated between the third and eighth dorsal-fin spines, predominantly on the distal half of the fin-ray membranes and typically sparing the membranes adjacent to the base of the fin. Some individuals have melanophores spreading down to meet the dorsal midline, but only behind the fourth and fifth spines and later the ninth and tenth spines (at the site of the future dark bars on the body). On the anal fin, there are melanophores along the base of the spines and membranes, spreading almost half-way up the second and third anal-fin spines. There are melanophores on the lower portion of the membrane between the last anal-fin spine and the first ray and the next membrane or two, followed by melanophores at the base of the membrane for the next few rays. There can be a few melanophores between the bases of the uppermost of the lower segmented caudal-fin rays and also on the lowest two or three segmented rays, often extending out along the rays. Pretransitional analogues: Pretransitional larvae (mostly-unmarked stage, usually from 10-15 mm SL) are separated from some other Lutjanus by having distinct serrations persisting on the anterior profile of the anal and dorsal-fin spines (but shared by L. griseus and L. jocu). L. apodus larvae are distinguished from the L. griseus type at this stage by having the dorsal-fin membrane melanophores concentrated on the distal portion of the membranes, only a small patch on the anterior third of the dorsal midline of the caudal peduncle, usually an incipient bar pattern on the lower caudal peduncle, similar numbers of melanophores on the tip of the upper and lower jaws, and often pigmentation along the longest pelvic-fin membrane. It is likely that pretransitional L. jocu cannot be separated from L. apodus.

Transitional stage: Early transitional L. apodus develop a pattern of bars on the body, beginning at the lower caudal peduncle where two dark bars first separate and then bars progressively develop from the caudal peduncle anteriorly. Each bar starts below the base of the dorsal fin and extends down with development. The mid-body bars begin with three patches of melanophores: the first under the fourth to sixth dorsal-fin spines, the second under the last two dorsal-fin spines and first dorsal soft rays and the third under the middle of the soft dorsal fin. Melanophores are limited to the outer half of the spinous-dorsal-fin membranes at first, but progressively extend down during transition. Before any stripes develop on the head, the tips of the upper and lower jaws are similarly speckled with small melanophores. Even on lightly-marked transitional larvae, there are some small melanophores on the thorax and the pelvic fin membranes. Early transitional larvae have serrations on the anterior aspect of the first two anal-fin spines, but these are usually lost midway through transition. Late transitional larvae have melanophores covering much of the body, but now the bars are made up of alternating areas of smaller and larger melanophores. The lower caudal peduncle at this stage has filled-in with melanophores and no longer has bars separated by non-pigmented skin. By this point, melanophores have advanced down the spinous-dorsal-fin membranes and do reach the base where they merge with the melanophores of the darker bars. On the head, a stripe develops between the eye and the tip of the upper jaw and two stripes diverge behind the eye. Small melanophores fill in and uniformly speckle the cheek, operculum, and thorax as well as the pelvic fins. Transitional analogues: Transitional L. apodus larvae develop bars on the body with no lateral spot, distinguishing them from the spotted species. In the early stages of transition, L. apodus larvae can be separated from L. griseus by having incipient melanophore bars forming on the lower caudal peduncle (vs. uniform) and having melanophores mostly on the distal half of the spinous-dorsal-fin membranes (vs. proximal and base). Late transitional L. apodus larvae differ from L. griseus by having distinct vertical bars of larger melanophores on the body vs. uniform speckling over the upper body (and lighter over the lower half of the head and abdomen) or indistinct bars at most on the upper half of the body, numerous melanophores speckling the cheek, thorax, and pelvic fins (vs. those areas relatively lightly-marked). Transitional recruits of L. jocu can overlap in appearance and can show a similar bar pattern to that of transitional L. apodus, although the lighter bars are narrower and the bar pattern becomes less distinct with development. There is also some overlap in appearance when both have a mostly-uniform speckling pattern, although uniform L. apodus have large melanophores and L. jocu have a fine speckling of melanophores (for example, in the space below the eye, there are about 100 melanophores in an area equal to the pupil in L. jocu vs. about 10 in L. apodus). Transitional recruits of L. apodus and L. griseus can sometimes overlap in appearance. If the bars are distinct from the base of the dorsal fin down to the anal fin, it is L. apodus; when L. griseus have bars, they are apparent on the upper body but fade towards the anal-fin base. As they grow, L. griseus develop distinct striping patterns on the lower body that do not occur on L. apodus.

Juveniles: Juvenile L. apodus have prominent vertical bars and no lateral spot. Rare individuals have a uniform pattern with only indistinct bars, but, notably these individuals do not show any striping pattern. Juvenile analogues: The absence of a lateral spot separates L. apodus from most other juvenile snappers ((L. analis, L. mahogoni, L. synagris, and the deep-water snappers). Virtually all juvenile L. apodus have prominent vertical bars which are absent or indistinct in L. jocu, L. griseus, and L. cyanopterus. Rare individuals of L. apodus that have a uniform appearance or indistinct bars can be difficult to separate from juvenile L. jocu, but juvenile L. griseus of the same size would show some evidence of body stripes. Juvenile L. cyanopterus are narrower-bodied, have a wider caudal peduncle, and do not share the blue line under the eye.

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Diagnostic Description

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Diagnosis: Modal fin-ray counts of D-X,14 A-III,8 are shared among most of the regional Lutjanus species, including L. analis, L. apodus, L. cyanopterus, L. griseus, L. jocu and the deep-water snappers L. buccanella, L. campechanus, and L. vivanus. Transitional and juvenile L. apodus have a prominent pattern of vertical bars without a lateral spot. (DNA)

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Principal threats

provided by EOL authors
Studies at the Saba Reef, one of the richest fish assemblages in the Caribbean Basin, have indicated the chief threats to the dogtooth snapper and other reef fishes are overfishing and the residual impacts of the particular chemical dispersant used by the USA in the aftermath of the Deepwater Horizon oil spill; this chemical has high persistence and known toxicity to a gamut of marine fauna. Studies by Burke et al. suggest that concentrations of dispersant and other water pollutants are of particular concern in critical lagoon nurseries; these studies suggest that the toxicity of residual dispersant may be much more significant to reef fishes than the actual petroleum release of an underwater oil spill.
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Encyclopedia of Earth
bibliographic citation
Mark McGinley. 2011. Schoolmaster. topic ed. C.Michael Hogan. Ed.-in-chief Cutler J.Cleveland. Encyclopedia of Earth. National Council for Science and Environment. Washington DC
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C. Michael Hogan (cmichaelhogan)
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Diagnostic Description

provided by Fishbase
Snout long and pointed, mouth large. One of the upper pairs of canine teeth notably enlarged, visible when mouth is close. Preopercular notch and knob weak. Pectoral fins long, reaching the level of anus. Scale rows on back parallel to lateral line, at least anteriorly. Olive gray to brownish on upper back and sides, with eight narrow, pale vertical bars which may be faint or absent in large adults. A solid or broken blue line which may disappear with growth, runs under the eye.
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Susan M. Luna
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Morphology

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Dorsal spines (total): 10; Dorsal soft rays (total): 14; Analspines: 3; Analsoft rays: 8
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Trophic Strategy

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Occurs in shallow, clear, warm, coastal waters over coral reefs. Often near the shelter of elkhorn corals and gorgonians (Ref. 9710). Juveniles are encountered over sand bottoms with or without seagrass (Thalassia), and over muddy bottoms of lagoons or mangrove areas. Young sometimes enter brackishwaters. Sometimes forms resting aggregations during the day. Feeds on fishes, shrimps, crabs, worms, gastropods and cephalopods. Carnivore (Ref. 57616).
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Biology

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Adults occur in shallow, clear, warm, coastal waters over coral reefs. Often near the shelter of elkhorn corals and gorgonians (Ref. 9710). Juveniles are encountered over sand bottoms with or without seagrass (Thalassia), and over muddy bottoms of lagoons or mangrove areas. Young sometimes enter brackish waters. Sometimes form resting aggregations during the day. Feed on fishes, shrimps, crabs, worms, gastropods and cephalopods. Considered a good food fish, it is marketed fresh or frozen (Ref. 55). Maximum length for female taken from Ref. 3093.
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Importance

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fisheries: commercial
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Diagnostic Description

provided by Plazi (legacy text)

MZUSP 65929 (2, 142-138), Bahamas , San Salvador Island.

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Rodrigo L. Moura, 2007, A new species of snapper (Perciformes: Lutjanidae) from Brazil, with comments on the distribution of Lutjanus griseus and L. apodus., Zootaxa, pp. 31-43, vol. 1422
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Schoolmaster snapper

provided by wikipedia EN

The schoolmaster snapper (Lutjanus apodus), also known as the dogtooth snapper, is a species of marine ray-finned fish, a snapper belonging to the family Lutjanidae. It is found in the western Atlantic Ocean. Like other snapper species, it is a popular food fish.

Taxonomy

The schoolmaster snapper was first formally described in 1792 as Perca apoda by the German physician, naturalist and taxonomist Johann Julius Walbaum with the type locality given as the Bahamas.[3] Walbaum's description was based on an illustration which omitted the fish's pectoral fins, so he gave it the specific name apoda meaning "footless".[4]

Description

The schoolmaster snapper has a moderately deep body which is robust and slightly compressed[5] with a long. pointed snout and a large mouth. One of the upper pairs of canine teeth is clearly larger than back teeth in the lower jaw and can be seen when mouth is closed. The vomerine teeth are arranged in a chevron or crescent shaped patch with a line of similar teeth extending from the middle of the patch towards the rear. The preoperculum has a weakly developed incision and knob.[6] This species has a protrusible upper jaw which is mostly covered by the cheek bone when the mouth is closed and both pairs of nostrils are simple holes. The dorsal fin is continuous with a slight incision separating the spiny part from the soft rayed part. The dorsal fin has 10 spines and 14 soft rays while the rounded anal fin contains 3 spines and 8 soft rays.[2][7] The interior scale rows on back are parallel to lateral line. The caudal fin is slight emarginate or truncate. The pectoral fins are longer than the distance from longest point of the snout to tail edge of preopercle, reaching the level of anus.[6] The color is olive gray to brownish on upper back and upper sides, with yellow to reddish mite around the head. The lower sides and belly are lighter; there is no dark lateral spot below the anterior part of soft dorsal fin. There are 8 narrow, light vertical bars on the side of the body which may be faded or absent in large adults. A solid or broken blue line runs beneath the eye; it may also disappear with growth. From the upper jaw to the tip of the fleshy opercle, the line is often broken into parts that resemble dashes and spots. The fin and tail is bright yellow, yellow green, or pale orange, and the snout contains blue stripes.[5] This fish attains a maximum fork length of 79.1 cm (31.1 in), although 35 cm (14 in) is more typical, and the maximum published weight is 10.8 kg (24 lb).[2]

Distribution

The schoolmaster snapper is found in the western Atlantic Bermuda and the southeastern coast of the United States from Cape Canaveral in Florida southwards to the Bahamas and into the Gulf of Mexico where its range runs from the Florida Keys as far north as Tampa, Florida then from Alabama westwards along the coast of the Gulf to the Yucatan Peninsula and northwestern Cuba. It occurs throughout the Caribbean Sea. It has been recorded as far north as Massachusetts but these records involve juveniles that cannot survive the winter. Its is typically found at depths between 1 and 50 m (3 ft 3 in and 164 ft 1 in), with one record at 89 m (292 ft).[1] Adults usually stay near shore shelter around elkhorn and gorgonian coral. Large adults are sometimes found on the continental shelf. Typical depths are up to 4 m (13 ft). reported that at night, schoolmaster snapper may increase their range to twice the daytime range, mostly by visiting seagrass beds.[8]

Biology

The schoolmaster snapper forms large resting schools during the day which disperse to forage at night,[2] these schools frequently sheltering in beds of sea grass.[5] These aggregations are defensive and are adopted by the fishes to minimise the chance of any one of them being predated. These fish spend 84% of the day swimming, 13% resting, 2% eating and less than 0.5% in other behaviors.[9]

Feeding

Studies have reported that the diet of the schoolmaster snapper changes ontogenetically, small individuals, less than 70 mm (2.8 in) in length have a 90% of their diet made up of crustaceans, specifically amphipods and crabs. Larger specimens preferred smaller fish. these making up more than 50% of their diet by weight, and also ate crabs, shrimp, and stomatopods. These differences in diets were attributed to the ability of the bigger fish to open their jaws wider for bigger prey.[10]

Reproduction and growth

Schoolmaster snapper are gonochorist, meaning males and females are separate. They spawn over most of the year, with the majority of the spawning happening during middle to late summer. They spawn during April–June off Cuba. They reproduce by spawning in open water with both male and female fish releasing their gametes at the same time. The fertilized eggs then settle to the bottom, where they are left unguarded.[9]

The schoolmaster snapper is a slow growing, long lived species which has a maximum recorded age of 42 years.[9]

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Weight:length relationship for schoolmaster snapper L. apodus[11]

As fish grow longer, they increase in weight, but the relationship is not linear. The relationship between length (L) and weight (W) for nearly all species of fish can be expressed by an equation of the form:

W = c L b {displaystyle W=cL^{b}!,} W=cL^{b}!,

Invariably, b is close to 3.0 for all species, and c varies between species. A weight-length relationship based on 100 schoolmaster snapper ranging in length from 2 to 7 in (50 mm to 180 mm) found the coefficient c was 0.000050015 and the exponent b was 2.9107. This relationship suggests a 12.5-inch schoolmaster snapper (320 mm) will weigh about 2.2 lb (1 kg).[11]

Commercial and recreational use

Schoolmaster snapper, along with other snapper species, are sought by both recreational and commercial fishermen. but the schoolmaster snapper is not as frequently targeted by commercial fisheries as other sympatric Lutjanus snappers.[1] Their food quality is reported to be excellent.[6] However, the consumption of this species has been linked to ciguatera poisoning in humans.[2]

Fishing regulations in US state waters are specific to each state, but they have similarities. For example, the minimum length in Florida for schoolmaster snapper is 10 in (250 mm) total length with a catch limit of 10 per fisherman per day. However, the 10-fish limit is an aggregate for all species of snapper.[12]

Light spinning and baitcasting tackle are used to fish for schoolmaster snapper. Live shrimp and baitfish, as well as shrimp pieces and cut bait, are the best natural bait. While jigs make for the best artificial bait, artificials are rarely used and rarely successful.[13]

Conservation

The IUCN lists this species as being of Least Concern because it is not routinely targeted by commercial fisheries and separate commercial catch statistics are unavailable. The juveniles are common in mangroves and on shallow reefs which may be threatened by coastal development, as well as the impacts of climate change. In Colombia, illegal dynamite fishing in the Rosario Islands led to the near extirpation of this species. In some areas, minimum sizes and bag limits have been introduced to conserve the stocks of schoolmaster snapper. Fishing pressure could lead to a decrease in numbers and make the defensive aggregations of these fish more vulnerable to predation, so it has been suggested that no-take zones be introduced to reduce the amount of fishes killed by fisheries.[1]

References

  1. ^ a b c d Lindeman, K.; Anderson, W.; Carpenter, K.E.; Claro, R.; Cowan, J.; Espinosa-Perez, H.; Padovani-Ferreira, B.; Rocha, L.A.; Sedberry, G.; Zapp-Sluis, M. (2016). "Lutjanus apodus". IUCN Red List of Threatened Species. 2016: e.T155152A726254. doi:10.2305/IUCN.UK.2016-1.RLTS.T155152A726254.en. Retrieved 19 November 2021.
  2. ^ a b c d e Froese, Rainer; Pauly, Daniel (eds.) (2021). "Lutjanus apodus" in FishBase. February 2021 version.
  3. ^ Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Species in the genus Lutjanus". Catalog of Fishes. California Academy of Sciences. Retrieved 31 May 2021.
  4. ^ Christopher Scharpf & Kenneth J. Lazara, eds. (5 January 2021). "Order LUTJANIFORMES: Families HAEMULIDAE and LUTJANIDAE". The ETYFish Project Fish Name Etymology Database. Christopher Scharpf and Kenneth J. Lazara. Retrieved 30 May 2021.
  5. ^ a b c "Schoolmaster". Mexican Fish. Retrieved 30 May 2021.
  6. ^ a b c Gerald R. Allen (1985). FAO species catalogue Vol.6. Snappers of the world An annotated and illustrated catalogue of lutjanid species known to date (PDF). FAO Rome. pp. 56–7. ISBN 92-5-102321-2.
  7. ^ "Species: Lutjanus apodus, Schoolmaster snapper". Shorefishes of the Greater Caribbean online information. Smithsonian Tropical Research Institute. Retrieved 31 May 2021.
  8. ^ Steven Hitt. "Nocturnal migration patterns of two Caribbean reef fishes, Haemulun sciu and Lutjanus apodus" (PDF). Center for Marine and Environmental Studies, University of the Virgin Islands. Retrieved 20 February 2012.
  9. ^ a b c "Lutjanus apodus (Schoolmaster Snapper)" (PDF). The Online Guide to Animals of Trinidad and Tobago. University of the West Indies. Retrieved 31 May 2021.
  10. ^ Rooker, JR (1995). "Feeding ecology of the schoolmaster snapper, Lutjanus apodus' (Walbaum), from southwestern Puerto Rico" (PDF). Bulletin of Marine Science. 56 (3): 881–894.
  11. ^ a b Valentine-Rose L, Layman CA, Arrington DA, Rypel AL (2007). "Habitat fragmentation decreases fish secondary production in Bahamian tidal creeks" (PDF). Bulletin of Marine Science. 80 (3): 863–877.
  12. ^ "Florida fishing regulations for snapper species". myfwc.com. Retrieved 31 May 2021.
  13. ^ "Schoolmaster Snapper". Florida Fishing Information. Retrieved 31 May 2021.

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Schoolmaster snapper: Brief Summary

provided by wikipedia EN

The schoolmaster snapper (Lutjanus apodus), also known as the dogtooth snapper, is a species of marine ray-finned fish, a snapper belonging to the family Lutjanidae. It is found in the western Atlantic Ocean. Like other snapper species, it is a popular food fish.

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Distribution

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Western Atlantic: Bermuda, as far north as Massachusetts, USA, Bahamas, Gulf,of Mexico, Antilles, southward to Trinidad and northern Brazil
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North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS)
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Habitat

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benthic
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North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS)
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Kennedy, Mary [email]