Interactions of Fishes with Particular Reference to Coelacanths in the Canyons at Sodwana Bay and the St Lucia Marine Protected Area of South Africa
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View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by South East Academic Libraries System (SEALS) Coelacanth Research South African Journal of Science 102, September/October 2006 461 Interactions of fishes with particular reference to coelacanths in the canyons at Sodwana Bay and the St Lucia Marine Protected Area of South Africa Phillip C. Heemstraa*, Hans Frickeb, Karen Hissmannb, Jürgen Schauerb, Malcolm Smalec and Kerry Sinkd would also discourage a hungry coelacanth. And a newborn Latimeria is too large to be consumed by a sawshark. The narkid The deep demersal fish fauna at depths of 100–400 m in canyons off electric ray is a small species, but its electric shocking ability the St Lucia Marine Protected Area along the north coast of would be an effective deterrent to a coelacanth, with their KwaZulu-Natal is compared with similar fish communities at the supposed electro-receptive susceptibility. Juvenile pineapple Comoro Islands and in the Indo-Pacific region. Fifty-four fish fish occur on coral reefs, where they are not likely to encounter species were seen or photographed from the submersible Jago or coelacanths; and the adults, which are common in the coela- by the discovery team of scuba divers in the coelacanth, Latimeria canth caves, are equipped with an armour of hard spiny scales chalumnae, habitat of the canyons off Sodwana Bay. An additional and formidable locking fin spines that make them very difficult 94 fish species known from depths of 100–200 m along the coast of for a fish to swallow. northern KwaZulu-Natal are likely to occur in the canyon habitat. The fish fauna of the Sodwana canyons shares at least 18 species Prey with the deep demersal fish community off tropical coral reefs of the Indo-Pacific region. Thirty-seven of the Sodwana canyon fishes are Prey species for Latimeria (indicated with the letters f or F in also known from the coelacanth habitat in the Comoros. Table 1) are those fish of similar size, lifestyle and behaviour to the species found in the stomach contents of Latimeria.3 Table 1 lists 124 species as food or potential prey for the coelacanths. Another 4 species are considered dubious food items. With its Introduction formidable fin spines and thick prickly scales, even small The deep demersal fish fauna of the canyons along the north Myripristis chryseres may be rejected as prey. The distasteful coast of KwaZulu-Natal, South Africa is poorly known, difficult mucus of Aulacocephalus temmincki is known to deter piscivorous to sample and not easy to study. Table 1 lists 54 fish species that fishes, and the puffers (Arothron inconditus and Canthigaster were seen and photographed from the submersible Jago or by rivulata) may also be distasteful to predators. the discovery team of scuba divers in the coelacanth habitat of the canyons off Sodwana Bay. An additional 94 fish species that Competitors are known in depths of 100 to 359 m along the coast of northern Fish of moderate (40 cm ) to large (2 m) size that are known KwaZulu-Natal1 and are likely to occur in the canyons are also piscivores are considered competitors of Latimeria (designated included in the fish fauna of the canyons off the coast of with the letter C in the first column of Table 1). In the Sodwana KwaZulu-Natal. canyon habitat, 65 (44%) of the 148 species listed as occurring in The 54 species identified from video images from 47 Jago dives the canyons are considered competitors of Latimeria. In the and visual observations by P.C. Heemstra on one dive in South Comoran coelacanth habitat, 31% (27 species) of the fishes are Island Rock Canyon to 198 m are probably less than a third of the thought to be competitors. fish fauna in the deep demersal ecosystem of the canyon heads along this coast. With such limited information, our picture of Predators this fish fauna is obviously incomplete. We can, however, make The only predators of adult Latimeria would be large sharks some heuristic comparisons with the fish fauna of the Latimeria (Hexanchus griseus, Carcharhinus altimus, and C. obscurus). habitat at Grand Comoro (Ngazidja) Island2 and the shallow Although the tiger shark, Galeocerdo cuvier, is generally found in coral-reef fish community at Sodwana Bay in the Greater St shallow water (5–50 m), it is known to feed occasionally on deep Lucia Marine Protected Area of KwaZulu-Natal. demersal sharks such as sawsharks (Pristiophoridae) and Fish interactions angelsharks (Squatinidae). It thus seems plausible that a tiger shark might also attack an adult coelacanth. But the occurrence The fishes that occur in the canyons may interact directly with of tiger sharks below 100 m is so rare that it is not considered a Latimeria as prey, predator or competitor (for food), or (for a member of this deep demersal fish fauna. few species) they may have no direct interaction with Latimeria. Juvenile Latimeria would be vulnerable to any piscivore known Examples of fish that are unlikely to interact directly with coela- from their habitat that is large enough to swallow them or canths are the saw shark, Pliotrema warreni, the narkid electric equipped with the dentition to bite them into pieces. These ray, Heteronarce garmani, and the pineapple fish, Monocentris supposed predators (see Table 1) would include sharks, conger japonicus. Saw sharks are too large at birth to be easily swallowed eels (Conger sp.) the pike conger (Muraenesox spp.), large by Latimeria, and the sharp rostral teeth of juvenile sawsharks rockcods (Epinephelus spp), Scombrops, and oilfish, Ruvettus aSouth African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa. pretiosus. bMax-Planck-Institut für Verhaltensphysiologie, D-82319 Seewiesen, Germany. c Port Elizabeth Museum, P.O. Box 13147, Humewood 6013, South Africa. Species comments dAfrican Coelacanth Ecosystem Programme, South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140. The bigeye sixgill shark, Hexanchus nakamurai Teng, 1962 (Hexanchus *Author for correspondence. E-mail: [email protected] vitulus Springer & Waller, 1969 is a synonym), is known from 462 South African Journal of Science 102, September/October 2006 Coelacanth Research KwaZulu-Natal, southern Mozambique, Table 1. Preliminary list of fishes seen or photographed in canyons† near Sodwana Bay and known from depths of Madagascar, Aldabra, Kenya, Taiwan, 100–200 m along the north coast of KwaZulu-Natal. Philippines and both sides of the Atlantic Ocean.4 Family: Species (interaction) Status/number Comments/depth range Carcharhinus sp.: a shark with black tips on the dorsal and pectoral fins and lower Hexanchidae: Heptranchias perlo (f, P, C) Transient?/Nil Known in area; 10–1000 m Hexanchidae: Hexanchus griseus (P, C) Resident?/Nil Known in area; size 5+ m; 0–1875 m caudal fin lobe was seen near the bottom Hexanchidae: Hexanchus nakamurai (f, P, C) Resident/Nil Known in area; size 1.8 m; 90–600 m at the head of Jesser and Wright canyons. This could be either the spinner shark, C. Squalidae: *Centrophorus granulosus (P, C) Resident/Nil Known in area; size 1.5 m; 274–457 m brevipinna, or the blacktip shark, C. lim- Squalidae: *Cirrhigaleus asper (C) Resident/Nil Known in area; 214–600 m batus. Neither species is common below Squalidae: Squalus megalops (C) Resident/Nil Known in area; 50–732 m 75 m. Squalidae: Squalus mitsukurii (C) Resident/Nil Known in area; 50–740 m Although Odontaspis ferox was occa- Dalatiidae: Dalatias licha (f, P, C) Resident?/Nil Known in area; 37–1800 m sionally encountered in the coelacanth Carcharhinidae: Carcharhinus albimarginatus (P, C) Transient?/3 Filmed by scuba divers; 5–120 m habit at Ngazidja,2 it was not seen in the Carcharhinidae: Carcharhinus altimus (P, C) Transient/Nil Known in area; 25–430 m Sodwana canyons. Unlike its shallow- Carcharhinidae: Carcharhinus sp (P, C) Transient/0–1 Jesser Canyon water relative, Carcharias taurus, which is Carcharhinidae: Carcharhinus obscurus (P, C) Transient/Nil Known in area; 0–400 m seasonally common on the coral reefs at Sodwana, O. ferox prefers depths of Odontaspididae: *Odontaspis ferox (P, C) Resident/Nil Known in area; 13–420 m 2 150–420 m. This shark attains 4.1 m and Scyliorhinidae: *Cephaloscyllium sufflans (F, C) T/R/Nil Known in area; 40–440 m is a likely predator of juvenile Latimeria. Pristiophoridae: Pliotrema warreni (X) Resident/Nil Known in area; 60–430 m A 48 cm juvenile swell shark, Cephaloscyllium sufflans, was found in the Squatinidae: Squatina africana (f, P, C) Resident/Nil Known in area; 50–400 m stomach of a Latimeria caught at Grand Rhinobatidae: Rhinobatos annulatus (f) Resident/0–1 South Island Rock, 118 m Comoro.3 The species is also known from Kenya and the central coast of KwaZulu- Narkidae: Heteronarce garmani (X) Resident/Nil Known in area; 73–329 m Natal. Dasyatidae: Dasyatis thetidis (P, C) Resident/Nil Known in area; 2–366 m Three other sharks may also interact as Latimeriidae: *Latimeria chalumnae Resident/0–7 Jesser & Wright;110–130 m prey, predator or competitor of Latimeria: they are Heptranchias perlo, Dalatias licha Muraenesocidae: *Muraenesox bagio (f, P, C) Resident/Nil Known in area; size 180 cm ; 2–100 m and Squatina africana. Ophichthidae: Xyrias revulsus (f, C) Resident/Nil Known in area; size 88 cm ; 146–209 m The pike conger, Muraenesox bagio, at- tains 180 cm. Small pike conger might be Synaphobranchidae: Ilyophis brunneus (F, C) Resident/Nil Stomach contents; 1,500 m prey of Latimeria, and large Muraenesox Chlorophthalmidae: Chlorophthalmus punctatus? (f) Resident 0–1 Wright Canyon; 130–439 m could be predators of small Latimeria. Large monks (Lophius spp.) might be Paralepidae: species not determined (f) Resident/Nil Known in area; 50–1000 m predators of small Latimeria; small monks Synodontidae: Saurida undosquamis (f, C) Transient/Nil Known in area; 2–200 m (including the genera Lophiodes and Synodontidae: Synodus indicus (f) Transient/Nil Known in area; 20–100 m Lophiomus) might be prey of Latimeria.