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Fisheries and Aquaculture Management Lecture 3: Haplochromis of Lake Victoria Introduction In the last two decades interest in the phylogeny of the African Cichlidae has greatly increased Amongst the East African cichlids, the haplochromines of Lake Victoria have become a focus of attention because their ecosystem has been irreversibly changed by the introduction of the Nile perch (Lates niloticus) Among the three great African Lakes, Lake Victoria, the source of the Nile, was the last to be discovered by Europeans. Not until thirty years after its discovery by John Harming Speke in 1858, were the first fish specimens from Lake Victoria brought to Europe by G.A. Fisher. Introduction F. Hilgendorf (director of the Berlin Museum) was the first zoologist to examine and describe this collection. Among the 19 specimens, probably collected at the shores of the southern (= "German") part of the lake, were eight specimens belonging to the Cichlidae (then known as Chromidae). Hilgendorf (1888) (erroneously) described two specimens as Chromis niloticus Linnaeus, 1758 (= Oreochromis niloticus) and placed the remaining six specimens in five new species. Introduction For the generic placement of the new species Hilgendorf followed Günther (1862) and Bleeker (1868). In the second part of his revision of the Cichlidae, in which the number of African genera was raised to 19 (due to the examination of the Moore collection from Lake Tanganyika), Boulenger (1899) considered Haplochromis and Ctenochromis to be synonyms of Tilapia The classification of the very numerous African members of this family presents the greatest difficulties, and the division into genera is unsatisfactory and open to criticism. Introduction The species descriptions of Greenwood, the first ichthyologist involved in field-work on Lake Victoria, were quite different from preceding ones. They were characterized not only b y the fact that the descriptions of the external morphology, gill rakers, oral and pharyngeal teeth and preserved coloration were much more detailed, but they also contained information on the ecology, e.g. habitat, breeding and food, and often, on live coloration. All new species of haplochromine cichlids from lake Victoria described by Greenwood et al. (1957-1978) were placed in the genus Haplochromis. Characters used in the definition of haplochromine genera External characters mentioned in the earliest descriptions of haplochromine genera were: body shape (compressed, elongate, oblong); number of dorsal and anal spines; scale type (cycloid or ctenoid); scale size (small, moderate, large); squamation of cheek and gill cover. Dental characters which were used were: tooth shape (canine, monocuspid, bicuspid, or tricuspid); tooth size; number of tooth rows. Gill raker shape and size (short, medium sized, moderately long) was used as well. Later on the number of vertebrae and the exposure of the maxilla were added. Boulenger (1902) mentioned tooth curvature and the movability of the teeth. Taxonomy of Lake Victoria haplochromine cichlids in general Size range of adults 5-25 cm standard length. One nostril on each side of the snout. The dorsal fin, comprising a spinous and a soft rayed part, is continuous. The lateral line is interrupted. From tilapiine cichlids, which share the foregoing characters, haplochromine cichlids are distinguished by the following features. The scales on the flank and caudal peduncle are ctenoid (feel rough to the touch). Adult males have brightly coloured egg dummies on the anal fin. The "tilapia mark" at the base of the dorsal fin, which characterizes the juveniles (up to 10 cm) of the tilapiine cichlid species in Lake Victoria, is absent Until Greenwood's revisions, apart from the monotypic genera, the only generic name which was introduced especially for Lake Victoria cichlids was Haplochromis. Originally proposed by Hilgendorf (1888) as a subgenus of Chromis in the description of Chromis (Haplochromis) obliquidens, it was raised to the generic level by Boulenger (1906) to accommodate cichlid species from Lake Victoria with teeth intermediate between those of Paratilapia (outer rows with conical teeth) and Tilapia (outer rows with bicuspid teeth). Genera in haplochromine taxonomy In a discussion on the generic or specific value of morphological characters, only dental characters and the number of anal fin spines were considered of being valuable for the generic classification. The unravelling of the phylogenetic relationships with in Haplochromis became a major research subject. Later research based on cladistic principles indicated that the haplochromine species of Lakes Victoria, Edward, George, and Kivu had to be considered together The following definition of Haplochromis may be used: Lacustrine, maternal mouthbrooding Cichlidae naturally occurring in the Lake Victoria basin, with a Haplochromis type of pharyngeal apophysis, i.e. with the basioccipital contributing to the articulation facet for the upper pharyngeal bones as well as to the support of that cranial facet (Greenwood, 1978). The teeth of the outer row of the oral jaws are unicuspid, bicuspid or tricuspid. In many species a mixture of these types is found. When tricuspids are present they are usually most numerous in the caudal part of the jaws. Definition of Haplochromis (Contd’) Teeth of the 1-11 inner rows are unicuspid and/or tricuspid, exceptionally bicuspid, usually of a smaller size than the outer row teeth. The pharyngeal jaws may vary from thin and slender to massive and strong. Pharyngeal teeth vary from slender to molariform and from pronounced to bevelled or hooked (Barel et al., 1977). Usually there is a distinct sexual dimorphism in coloration; the males being the more colourful sex. On the anal fin of males 1-9 distinct egg dummies are present. The anal f in with 3 spines. Proposal to stabilize nomenclature Until now morphological investigations have failed to give us a clear picture of the phylogenetic relationships among the Lake Victoria haplochromines. However, there are at least indications from both morphological (scale and squamation) characters (Lippitsch, 1993) and molecular data (Sage et al., 1984; Meyer et al., 1990) that the Lake Victoria (super) flock is a monophyletic group. Reproduction Brood care All species show some form of parental care for both eggs and larvae, often nurturing free-swimming young until they are weeks or months old. Parental care falls into one of four categories: 1. Open (Substrate) brooding Open or substrate brooding cichlids lay their eggs in the open, on rocks, leaves, or logs. Male and female parents usually engage in differing brooding roles. Most commonly, the male patrols the pair's territory and repels intruders, while females fan water over the eggs, removing the infertile and leading the fry while foraging. However, both sexes are able to perform the full range of parenting behaviours. Reproduction Contd’ 2. 3. 4. Cave brooding Secretive cave spawning cichlids lay their eggs in caves, crevices, holes, or discarded mollusc shells, frequently attaching the eggs to the roof of the chamber. Free-swimming fry and parents communicate in captivity and in the wild. Frequently this communication is based on body movements, such as shaking and pelvic fin flicking. In addition, open and cave brooding parents assist in finding food resources for their fry. Ovophile mouthbrooding Ovophile mouthbrooders incubate their eggs in their mouths as soon as they are laid, and frequently mouthbrood freeswimming fry for several weeks. Larvophile mouthbrooding Larvophile mouthbrooders lay eggs in the open or in a cave and take the hatched larvae into the mouth. Mouthbrooders, whether of eggs or larvae, are predominantly females. Mating Cichlids mate either monogamously or polygamously. The mating system of a given cichlid species is not consistently associated with its brooding system. For example, although most monogamous cichlids are not mouthbrooders, Chromidotilapia, Gymnogeophagus, e.t.c. are all monogamous mouthbrooders. In contrast, numerous open or cave spawning cichlids are polygamous; examples include Apistogramma, Lamprologus e.t.c. Population status In 2010, the International Union for Conservation of Nature classified 184 species as vulnerable, 52 as endangered, and 106 as critically endangered. At present, the IUCN only lists Yssichromis sp. Nov. “argens” as extinct in the wild, and six species are listed as entirely extinct, but it is acknowledged that many more possibly belong in these categories (for example, Haplochromis aelocephalus, H. apoogonoides, H. dentex, H. dichrourus and numerous other members of the genus Haplochromis have not been seen since the 1980s, but are maintained as Critically Endangered in the small chance that tiny but currently unknown populations survive). Population status (Contd’) Because of the introduced Nile perch (Lates niloticus) and water hyacinth, deforestation that led to water siltation, and overfishing, many Lake Victoria species have been wiped out or drastically reduced. By around 1980, lake fisheries yielded only 1 percent cichlids, a drastic decline from 80 percent in earlier years. About two-thirds of endemic cichlids (approximately 300 species), especially bottom feeders, became endangered or extinct. Some survivors have adapted by becoming smaller or hybridizing with other species. Haplochromis latifasciatus is critically endangered