Adult African sharptooth catfish, Clarias gariepinus, population dynamics in a small invaded warm-temperate impoundment
- Booth, Anthony J, Traasg, Graham L, Weyl, Olaf L F
- Authors: Booth, Anthony J , Traasg, Graham L , Weyl, Olaf L F
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446759 , vital:74558 , https://www.tandfonline.com/doi/abs/10.1080/15627020.2010.11657279
- Description: African sharptooth catfish, Clarias gariepinus, is a successful aquatic invader as it has a eurytopic physiology, is highly fecund, grows quickly and has an omnivorous diet. Despite possible threats that include predation of and competition with indigenous species, habitat degradation, and the spread of diseases and parasites, there is a lack of knowledge regarding its ecology and population dynamics within invaded systems. This study presents a mark–recapture experiment to investigate its population structure, natural mortality rate, population size and density within a population inhabiting a small, 76 ha invaded water supply reservoir in the temperate Eastern Cape region, South Africa.
- Full Text:
- Date Issued: 2010
- Authors: Booth, Anthony J , Traasg, Graham L , Weyl, Olaf L F
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446759 , vital:74558 , https://www.tandfonline.com/doi/abs/10.1080/15627020.2010.11657279
- Description: African sharptooth catfish, Clarias gariepinus, is a successful aquatic invader as it has a eurytopic physiology, is highly fecund, grows quickly and has an omnivorous diet. Despite possible threats that include predation of and competition with indigenous species, habitat degradation, and the spread of diseases and parasites, there is a lack of knowledge regarding its ecology and population dynamics within invaded systems. This study presents a mark–recapture experiment to investigate its population structure, natural mortality rate, population size and density within a population inhabiting a small, 76 ha invaded water supply reservoir in the temperate Eastern Cape region, South Africa.
- Full Text:
- Date Issued: 2010
Histological validation of gonadal macroscopic staging criteria for Labeo cylindricus (Pisces: Cyprinidae)
- Booth, Anthony J, Weyl, Olaf L F
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124593 , vital:35634 , https://doi.org/10.1080/15627020.2000.11657094
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
- Full Text:
- Date Issued: 2010
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124593 , vital:35634 , https://doi.org/10.1080/15627020.2000.11657094
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
- Full Text:
- Date Issued: 2010
Reproductive biology of a riverine cyprinid, Labeo umbratus (Teleostei: Cyprinidae), in small South African reservoirs
- Potts, Warren M, Booth, Anthony J, Hecht, Thomas, Andrew, Timothy G
- Authors: Potts, Warren M , Booth, Anthony J , Hecht, Thomas , Andrew, Timothy G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125854 , vital:35826 , https://doi.10.2989/16085910509503849
- Description: The reproductive and recruitment characteristics of moggel, Labeo umbratus, populations were examined in four small South African reservoirs. Reproduction, characterised by an extended spawning season, high fecundity, short incubation time and rapid larval development, appears to be ideally suited to the highly variable environment of small reservoirs. Evidence suggested that L. umbratus spawns in the reservoirs. In two reservoirs where samples were conducted monthly, GSI (gonado-somatic index) was positively correlated with both water temperature and day length, whilst the CPUE (catch per unit effort) of juveniles was not related to any environmental variable. The success of moggel spawning appeared to increase when there was early spring and consistent summer rainfall.
- Full Text:
- Date Issued: 2010
- Authors: Potts, Warren M , Booth, Anthony J , Hecht, Thomas , Andrew, Timothy G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125854 , vital:35826 , https://doi.10.2989/16085910509503849
- Description: The reproductive and recruitment characteristics of moggel, Labeo umbratus, populations were examined in four small South African reservoirs. Reproduction, characterised by an extended spawning season, high fecundity, short incubation time and rapid larval development, appears to be ideally suited to the highly variable environment of small reservoirs. Evidence suggested that L. umbratus spawns in the reservoirs. In two reservoirs where samples were conducted monthly, GSI (gonado-somatic index) was positively correlated with both water temperature and day length, whilst the CPUE (catch per unit effort) of juveniles was not related to any environmental variable. The success of moggel spawning appeared to increase when there was early spring and consistent summer rainfall.
- Full Text:
- Date Issued: 2010
Retrospective stock assessment of the Emperor red snapper (Lutjanus sebae) on the Seychelles Bank between 1977 and 2006
- Grandcourt, E M, Hecht, Thomas, Booth, Anthony J, Robinson, J
- Authors: Grandcourt, E M , Hecht, Thomas , Booth, Anthony J , Robinson, J
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125887 , vital:35829 , https://doi.10.1093/icesjms/fsn064
- Description: The Emperor red snapper, Lutjanus sebae, known as “Bourzwa” in the Seychelles, is distributed throughout the Indo-West Pacific from the southern Red Sea and East Africa to New Caledonia, north to Japan and south to Australia. It occurs near coral or rocky reefs and also over adjacent sand flats and gravel patches between 5 and 180 m deep (Allen, 1985; Anderson, 1986). Juveniles are frequently commensal with sea urchins (Kuiter and Tonozuka, 2001), and are found in nearshore, turbid waters (Williams and Russ, 1992), mangrove areas (Allen, 1985), and around coastal and offshore reefs (Williams and Russ, 1992). Larger L. sebae are generally found deeper, although they are also known to move into shallower water during winter (McPherson et al., 1988; Williams and Russ, 1992). Prey items include fish, crabs, other benthic crustaceans, and cephalopods. Lutjanus sebae is a large, long-lived species, attaining a maximum size of 116 cm fork length (McPherson and Squire, 1992) and maximum age of 34 years (Newman and Dunk, 2002). Despite an absence of data on its population structure, mixing, and identity, the population on the Seychelles Bank has been considered to be a unit stock for assessment purposes because of its remote location (e.g. Lablache and Carrara, 1988; Mees, 1992).
- Full Text:
- Date Issued: 2008
- Authors: Grandcourt, E M , Hecht, Thomas , Booth, Anthony J , Robinson, J
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125887 , vital:35829 , https://doi.10.1093/icesjms/fsn064
- Description: The Emperor red snapper, Lutjanus sebae, known as “Bourzwa” in the Seychelles, is distributed throughout the Indo-West Pacific from the southern Red Sea and East Africa to New Caledonia, north to Japan and south to Australia. It occurs near coral or rocky reefs and also over adjacent sand flats and gravel patches between 5 and 180 m deep (Allen, 1985; Anderson, 1986). Juveniles are frequently commensal with sea urchins (Kuiter and Tonozuka, 2001), and are found in nearshore, turbid waters (Williams and Russ, 1992), mangrove areas (Allen, 1985), and around coastal and offshore reefs (Williams and Russ, 1992). Larger L. sebae are generally found deeper, although they are also known to move into shallower water during winter (McPherson et al., 1988; Williams and Russ, 1992). Prey items include fish, crabs, other benthic crustaceans, and cephalopods. Lutjanus sebae is a large, long-lived species, attaining a maximum size of 116 cm fork length (McPherson and Squire, 1992) and maximum age of 34 years (Newman and Dunk, 2002). Despite an absence of data on its population structure, mixing, and identity, the population on the Seychelles Bank has been considered to be a unit stock for assessment purposes because of its remote location (e.g. Lablache and Carrara, 1988; Mees, 1992).
- Full Text:
- Date Issued: 2008
Reproductive biology of ningu, Labeo victorianus (pisces: cyprinidae), in the kagera and Sio rivers, Uganda
- Rutaisire, Justus, Booth, Anthony J
- Authors: Rutaisire, Justus , Booth, Anthony J
- Date: 2005
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125864 , vital:35827 , https://doi.10.1007/s10641-004-5564-8
- Description: We investigated aspects of the reproductive biology of the cyprinid fish, Labeo victorianus, locally known as ningu, in the Kagera and Sio Rivers, Uganda. These rivers represent the last remaining refuges for this species within Uganda. L. victorianus is a highly fecund, potamodrometic fish that migrates upstream to spawn. Spawning is generally synchronised with the bimodal water level maxima observed within the rivers. There were, however, some deviations from this pattern. We caught sexually mature fish throughout the year in the Sio River, and noticed that spawing started before the second rainfall peak. Fish from the Kagera matured at significantly larger sizes than fish from the Sio River. Male and female fish, from both rivers, fed intensively during the non-breeding months accumulating significant fat reserves; a probable energy storage mechanism prior to their spawning migrations. The differences between the populations is probably a phenotypic response to differing abiotic factors such as river size, flow velocity and food availability.
- Full Text:
- Date Issued: 2005
- Authors: Rutaisire, Justus , Booth, Anthony J
- Date: 2005
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125864 , vital:35827 , https://doi.10.1007/s10641-004-5564-8
- Description: We investigated aspects of the reproductive biology of the cyprinid fish, Labeo victorianus, locally known as ningu, in the Kagera and Sio Rivers, Uganda. These rivers represent the last remaining refuges for this species within Uganda. L. victorianus is a highly fecund, potamodrometic fish that migrates upstream to spawn. Spawning is generally synchronised with the bimodal water level maxima observed within the rivers. There were, however, some deviations from this pattern. We caught sexually mature fish throughout the year in the Sio River, and noticed that spawing started before the second rainfall peak. Fish from the Kagera matured at significantly larger sizes than fish from the Sio River. Male and female fish, from both rivers, fed intensively during the non-breeding months accumulating significant fat reserves; a probable energy storage mechanism prior to their spawning migrations. The differences between the populations is probably a phenotypic response to differing abiotic factors such as river size, flow velocity and food availability.
- Full Text:
- Date Issued: 2005
Spatial aspects of the reproductive and feeding biology of the striped robber, Brycinus lateralis (Pisces: Characidae), in the Okavango Delta, Botswana
- Booth, Anthony J, McKinlay, Bruce W
- Authors: Booth, Anthony J , McKinlay, Bruce W
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446838 , vital:74564 , https://doi.org/10.1080/15627020.2001.11657111
- Description: The Okavango Delta is a vast inland wetland system situated in northern Botswana. High rainfall is received in early summer in the southern Angolan highlands and throughout the Delta with the flood waters reaching the upper riverine floodplain between March and May where it percolates through to the lower drainage rivers between July and September. Aspects of the reproductive and feeding biology of two allopatric populations of the striped robber, Brycinus lateralis, a small characin species inhabiting the northern riverine floodplain and southern drainage rivers, were investigated. Both populations were similar in the biological aspects studied, with the flood cycle having little influence on the timing of reproduction, sexual maturity and dietary composition. Female fish from both populations matured sexually at 57 mm SL, breeding over a protracted period during the warm, summer months. In both populations, the sex ratio was female-dominated at 4.8:1 (riverine floodplain) and 2.2:1 (drainage rivers). The striped robber is an opportunistic micro-carnivore with immature fish feeding predominantly on Daphnia spp. and adults being largely insectivorous.
- Full Text:
- Date Issued: 2001
- Authors: Booth, Anthony J , McKinlay, Bruce W
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446838 , vital:74564 , https://doi.org/10.1080/15627020.2001.11657111
- Description: The Okavango Delta is a vast inland wetland system situated in northern Botswana. High rainfall is received in early summer in the southern Angolan highlands and throughout the Delta with the flood waters reaching the upper riverine floodplain between March and May where it percolates through to the lower drainage rivers between July and September. Aspects of the reproductive and feeding biology of two allopatric populations of the striped robber, Brycinus lateralis, a small characin species inhabiting the northern riverine floodplain and southern drainage rivers, were investigated. Both populations were similar in the biological aspects studied, with the flood cycle having little influence on the timing of reproduction, sexual maturity and dietary composition. Female fish from both populations matured sexually at 57 mm SL, breeding over a protracted period during the warm, summer months. In both populations, the sex ratio was female-dominated at 4.8:1 (riverine floodplain) and 2.2:1 (drainage rivers). The striped robber is an opportunistic micro-carnivore with immature fish feeding predominantly on Daphnia spp. and adults being largely insectivorous.
- Full Text:
- Date Issued: 2001
Incorporating the spatial component of fisheries data into stock assessment models
- Authors: Booth, Anthony J
- Date: 2000
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124800 , vital:35698 , https://doi.10.1006/jmsc.2000.0816
- Description: Fisheries-dependent and independent data have a strong spatial component. These data are also multi-dimensional, making them difficult to visualize and analyze, prompting the use of spatial analysis to facilitate an understanding of their relationships. One aspect of fisheries data that is often ignored is the distribution and abundance of a particular resource and the fishing patterns of its harvesting fisheries. In order to improve management advice, stock assessors need to incorporate the spatial component of these data into an existing assessment framework. This paper presents a three-dimensional visualization of the age-structure and fishery dependent and independent data associated with the sparid fish Pterogymnus laniarius on the Agulhas Bank, South Africa. A spatially-referenced spawner biomass per-recruit model is developed to illustrate the applicability of incorporating spatially referenced information in providing management advice. The model provided evidence that, even on a spatial scale, fishing mortality is significantly correlated to fishing effort. Areas of high levels of spawner biomass are noted, all of which corresponded to those geographic areas with a combination of low fishing effort and high adult biomass.
- Full Text:
- Date Issued: 2000
- Authors: Booth, Anthony J
- Date: 2000
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124800 , vital:35698 , https://doi.10.1006/jmsc.2000.0816
- Description: Fisheries-dependent and independent data have a strong spatial component. These data are also multi-dimensional, making them difficult to visualize and analyze, prompting the use of spatial analysis to facilitate an understanding of their relationships. One aspect of fisheries data that is often ignored is the distribution and abundance of a particular resource and the fishing patterns of its harvesting fisheries. In order to improve management advice, stock assessors need to incorporate the spatial component of these data into an existing assessment framework. This paper presents a three-dimensional visualization of the age-structure and fishery dependent and independent data associated with the sparid fish Pterogymnus laniarius on the Agulhas Bank, South Africa. A spatially-referenced spawner biomass per-recruit model is developed to illustrate the applicability of incorporating spatially referenced information in providing management advice. The model provided evidence that, even on a spatial scale, fishing mortality is significantly correlated to fishing effort. Areas of high levels of spawner biomass are noted, all of which corresponded to those geographic areas with a combination of low fishing effort and high adult biomass.
- Full Text:
- Date Issued: 2000
Reproductive and feeding biology of the Natal mountain catfish, Amphilius natalensis (Siluriformes: Amphiliidae)
- Marriott, Michael S, Booth, Anthony J, Skelton, Paul H
- Authors: Marriott, Michael S , Booth, Anthony J , Skelton, Paul H
- Date: 1997
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125837 , vital:35823 , https://doi.10.1023/A:1007361511052
- Description: The family Amphiliidae comprises nine genera and about 60 species. Only five species are found in southern Africa, three of which belong to the genus Amphilius (Skelton 1993). These soft-bodied catlets inhabit clear, fast flowing mountain streams where they live amongst cobbles, feeding predominantly on benthic invertebrates (Crass 1964, Skelton 1993). The Natal mountain catfish, A. natalensis Boulenger, 1917, is a small, nocturnal species with a restricted distribution along the eastern seaboard of southern Africa. It occurs in mountain streams from the Umkomaas River north to the Limpopo system in South Africa. It is also present in the Marozi River, a tributary of the Zambezi River in Zimbabwe and in the Ruo River, Malawi (Skelton 1984, 1993). Skelton (1993) suggested that predation by introduced trout species has led to scarcity of A. natalensis in many streams. In spite of this, no studies on the biology of this catfish species have been published. This study presents the first quantitative information on the biology of an amphiliid catfish, A. natalensis including gametogenesis, spawning seasonality, size-at-maturity, adult sex ratio and diet.
- Full Text:
- Date Issued: 1997
- Authors: Marriott, Michael S , Booth, Anthony J , Skelton, Paul H
- Date: 1997
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125837 , vital:35823 , https://doi.10.1023/A:1007361511052
- Description: The family Amphiliidae comprises nine genera and about 60 species. Only five species are found in southern Africa, three of which belong to the genus Amphilius (Skelton 1993). These soft-bodied catlets inhabit clear, fast flowing mountain streams where they live amongst cobbles, feeding predominantly on benthic invertebrates (Crass 1964, Skelton 1993). The Natal mountain catfish, A. natalensis Boulenger, 1917, is a small, nocturnal species with a restricted distribution along the eastern seaboard of southern Africa. It occurs in mountain streams from the Umkomaas River north to the Limpopo system in South Africa. It is also present in the Marozi River, a tributary of the Zambezi River in Zimbabwe and in the Ruo River, Malawi (Skelton 1984, 1993). Skelton (1993) suggested that predation by introduced trout species has led to scarcity of A. natalensis in many streams. In spite of this, no studies on the biology of this catfish species have been published. This study presents the first quantitative information on the biology of an amphiliid catfish, A. natalensis including gametogenesis, spawning seasonality, size-at-maturity, adult sex ratio and diet.
- Full Text:
- Date Issued: 1997
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