44 research outputs found
Portrait of Allen J. Ellender of Louisiana
No full textInscribed: To Senator James O. Eastland/from his friend/Best wishes,/Allen J. Ellender/U.S.S. La/5-12-45https://egrove.olemiss.edu/joephoto_b/1099/thumbnail.jp
Portrait of Senator Allen J. Ellender.
No full textHandwritten inscription: \u27To Felton M. Johnson, affectionately known to all of us as \u27Skeeter,\u27 a most [gifted] secretary from his friend Allen Ellender - U.S.S. LA 3/4/48\u27https://egrove.olemiss.edu/fmjohnston/1266/thumbnail.jp
Portrait of Senator Allen Ellender.
No full textHandwritten inscription: For Senator Ellender.https://egrove.olemiss.edu/joephoto_c/1130/thumbnail.jp
Ecological consequences of non-native fish invasion in Eastern Cape headwater streams
No full textThe introduction, spread and concomitant impacts of non-native species are a global problem. Fish are among the most widely introduced vertebrate groups, with their impacts affecting multiple levels of organisation- from individuals, populations and communities, to entire ecosystems. In South Africa, the largest perceived threat to range-restricted endemic headwater stream fishes is said to be invasion by non-native fishes, however, as is the case elsewhere, invasive impacts are often a case of risk perception rather than actual risk analysis. Two range-restricted headwater species, the Eastern Cape redfin Pseudobarbus afer and the Border barb Barbus trevelyani are redlisted by the International Union for the Conservation of Nature (IUCN) as ‘Endangered’, primarily due to invasion by non-native fishes. To investigate invasions in South Africa, and provide a quantitative estimate of the impact of non-native fishes on the two imperilled endemics, P. afer and B. trevelyani, the overall aims of this thesis were to: (A) Provide a literature review on non-native fish invasions in South Africa; (B) Using two case studies on the headwaters of the perennial Keiskamma and episodic Swartkops River systems, investigate the naturalisation-invasion continuum to provide a holistic view of the invasion process in these variable environments. The specific thesis objectives were: (1) Reviewing current knowledge of invasive impacts of non-native fishes in South Africa; (2) Investigating invasibility of headwater stream environments by non-native fishes; (3) Determining the establishment success of non-native fishes, (4) Assessing the spatial and temporal impacts of invasion; (5) Understanding mechanisms responsible for non-native fish impacts; (6) Investigating the threat of non-native fish invasion on the genetic diversity of two the two headwater fishes, P. afer and B. trevelyani. Results from the literature review of fish invasions (Chapter 1) showed that South Africa has a long history of non-native fish introductions, spanning two and a half centuries. Currently, 55 species have been introduced or translocated. Many of these introduced species have become fully invasive (36%). Their impacts also span multiple levels of biological organisation. There was a general paucity of studies on fish invasions (38 studies), however, of those conducted, reviewed studies placed emphases on invasive impacts (25 studies) and the transport, introduction, establishment and spread stages of the invasion process were largely ignored. The two study systems, the Swartkops and Keiskamma Rivers, were heavily invaded and numbers of introduced species surpassed that of natives (Chapter 2, 3 and 5). Headwater streams had varying invasibility and a number of non-native species were successfully established (Chapter 2, 3, 5 and 6). The remainder of the invasions were casual incursions into headwater streams from source populations in mainstream and impoundment environments which were invasion hotspots. Irrespective of establishment, four predatory invaders (largemouth bass Micropterus salmoides, smallmouth bass M. dolomieu, brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss) impacted heavily on native fish communities (Chapter 3, 4 and 5). Two broad types of invasion were documented, top down invasion by non-native O. mykiss and S. trutta and upstream invasion by M. salmoides and M. dolomieu (Chapter 3 and 5). Their impacts included changes in community structure, extirpation from invaded stream reaches resulting in contracted distribution, and isolation and fragmentation of native fish populations. The impacts of non-native predatory fishes were particularly acute for P. afer and B. trevelyani. Where non-native predatory fish occurred, P. afer and B. trevelyani had been extirpated (Chapter 3 and 5). As a result both native species exhibited contracted distributions (>20% habitat loss due to invasion). Upstream invasion by centrarchids isolated and fragmented P. afer populations into headwater refugia, while top down invasion by salmonids excluded B. trevelyani from invaded, more pristine stream reaches, by forcing the species into degraded unsuitable lower stream reaches. Predation also disrupted population processes such as adult dispersal for P. afer, and centrarchid-invaded zones acted as demographic sinks, where adults dispersing through invaded reaches were rapidly depleted. While the Mandela lineage of P. afer exhibited little within or between drainage genetic structuring, B. trevelyani was >4% divergent between drainages, and up to 2% divergent between streams within the Keiskamma River system (Chapter 7). The distribution of genetic diversity for B. trevelyani also indicated that the loss of diversity was imminent without immediate conservation interventions. This thesis has provided conclusive evidence that native fishes are vulnerable to invasion and that non-native predatory fishes have significant impacts on native fishes in Eastern Cape headwater streams. If management and conservation measures are implemented, the unwanted introduction and spread of non-native fishes may be restricted, allowing native fishes opportunities for recovery
The impact of angling on smallmouth and largemouth yellowfish, labeobarbus aeneus and labeobarbus kimberleyensis, in Lake Gariep, South Africa
No full textA large sportfishery that targets both smallmouth (Labeobarbus aeneus) and largemouth
(Labeobarbus kimberleyensis) yellowfish exists in South Africa. Both species have high
conservation priority, and no assessments documenting the effect of angling on L. aeneus and
L. kimberleyensis have been undertaken. The overall aim of this study was to provide an
assessment of the impact of angling on L. aeneus and L. kimberleyensis. The specific
objectives of this study were to characterise the sectors utilising Lake Gariep, document catch,
effort and total catch for the fishery as well as the locality specific biology of L. aeneus and L.
kimberleyensis. The study was undertaken on Lake Gariep, South Africa's largest
impoundment, situated on the Orange River system in central South Africa.
Subsistence fishers were the dominant user group, constituting 60 % of the fishery, the
remainder constituted recreational anglers. Angler catches were dominated by carp (Cyprinus
carpio; 74 %), followed by mudfish (Labeo capensis; 13 %) and smallmouth yellowfish (8
%). Catches of largemouth yellowfish contributed < 0.5 % to the total catch. The relative
abundance of species by weight differed by area (χ² test of independence: χ² = 182, df = 4, p ≤
0.05). On any sampling day time fished was the best predictor for differences in probability of
capture (PC) (Wald X²(1) = 7.169, p = 0.007). The probability of capturing L. aeneus differed
significantly between month (Wald X²(5) = 20.690, p = 0.000) and region (Wald X²(3) =
46.755, p = 0.000). The single best predictor of differences in log abundance and non-zero
CPUE was region (Factorial ANOVA p ≤ 0.05).
Mean CPUE ranged from 0.21 ± 0.06 kg. man⁻¹.hr⁻¹ to 0.82 ± 0.11 kg. man⁻¹.hr⁻¹ in the OV
region and 0.42 ± 0.10 kg. man⁻¹.hr⁻¹ to 1.17 ± 0.24 kg. man⁻¹.hr⁻¹ in the GD region. Angler
effort was higher in OV than in GD and ranged from 17 ± 3 anglers/day to 45 ± 9 anglers/day
and 6 ± 1 anglers/day to 41 ± 8 anglers/day, respectively. Total catch was higher in the GD
46.0 [95 % CI = 15:102.6] t. period⁻¹ than the OV region 40.0 [95 % CI = 13.9:89.6] t. period⁻¹. The total catch from the Lake Gariep fishery between March and December 2007 was
estimated to be 86.0 [95 % CI = 40.4:154.8] t. period⁻¹.
Age and growth was determined using whole otoliths. The growth of L. aeneus was best
described by the von Bertalanffy growth model as Lt = 481.80 (1- e⁻°·²²⁽t⁺°·⁶¹⁾). Gonadal development for L. aeneus was seasonal, with the gonadosomatic index peaking in January,
revealing a distinct spawning season. The length at 50 % maturity for female L. aeneus was
attained at a fork length of 354.7 mm. Natural mortality (M) was estimated at 0.55 year⁻¹. The
growth of L. kimberleyensis was described by the von Bertalanffy growth model as Lt = 763.22 (1- e⁻°·¹¹⁽t⁺°·⁶³⁾). Only 6 mature female and 15 mature male L. kimberleyensis were
recorded during the study period. The smallest mature female was a 390 mm FL stage four
female and the earliest recorded mature male was a 337 mm FL, ripe running male. Natural
mortality (M) was estimated at 0.08 year⁻¹ for L. kimberleyensis.
Per recruit analysis indicated that current fishing mortality reduces the L. aeneus spawner
biomass by 7 %, which is considered negligible. Labeobarbus kimberleyensis forms an
insignificant proportion of anglers catches and stock status is currently considered pristine
Insights into the impacts of rural honey hunting in Zambia
No full textThis is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordData Availability Statement: The data that support the findings of this study are available from the corresponding author upon reasonable request
Pith-helmeted experts and greenhorns : approaches to conducting research with indigenous communities
No full textThis thesis was scanned from the print manuscript for digital preservation and is copyright the author.
Researchers can access this thesis by asking their local university, institution or public library to
make a request on their behalf. Monash staff and postgraduate students can use the link in the References field
Resilience of imperilled headwater stream fish to an unpredictable high-magnitude flood
No full textHeadwater stream fish communities are increasingly becoming isolated in headwater refugia that are often cut off from other metapopulations within a river network as a result of nonnative fish invasions, pollution, water abstraction and habitat degradation downstream. This range restriction and isolation therefore makes them vulnerable to extinction. Understanding threats to isolated fish populations is consequently important for their conservation. Following a base-flow survey, a high-magnitude flood (peak flow of 1245 m-3s-1) provided an opportunity to investigate the response of endangered Eastern Cape redfin Pseudobarbus afer populations to a natural disturbance in the Waterkloof and Fernkloof streams, two relatively pristine headwater tributaries of the Swartkops River system within the Groendal Wilderness Area, Eastern Cape Province, South Africa. Pseudobarbus afer had limited distributions, occupying 3 km in both the Fernkloof and Waterkloof streams. Fish population assessments before and after the flood event indicated that there were no longitudinal trends in P. afer abundance before or after the flood, but overall abundance post-flooding in the Fernkloof stream was higher. There were no noticeable changes in P. afer size structure pre- and post-flood. Pseudobarbus afer showed resilience to a major flooding event most likely related to evolution in river systems characterised by environmental stochasticity.
Conservation implications: This research provides insight into the population level responses of native headwater stream fishes to unpredictable natural disturbance. Of particular relevance is information on their ability to withstand natural disturbances, which provides novel information essential for their conservation and management especially as these fishes are already impacted by multiple anthropogenic stressors
Quantifying the annual fish harvest from South Africa’s largest freshwater reservoir
No full textSouth African inland fisheries are poorly developed and their contribution to near-shore communities is poorly understood. This study is the first comprehensive assessment of recreational and subsistence angling undertaken in an inland fishery in South Africa. The study was conducted on the 360 km2 Lake Gariep, South Africa’s largest freshwater reservoir. A total of 508 anglers were interviewed between February 2007 and January 2008. Of those interviewed, 67% were subsistence anglers and 33% recreational anglers. Catch per unit effort (CPUE) did not differ significantly between sectors. CPUE fluctuated seasonally, ranging between 0.37 (95% CI= 0.26 to 0.51) kg·angler-1·h-1 in winter and 0.88 (0.67 to 1.17) kg·angler- 1·h-1 in summer. The duration of a fishing day ranged from 5.99 (5.24 to 6.74) h in mid-winter to 7.26 (6.88 to 7.63) h in early summer. Expected end-of-day catch (CPUE × fishing-trip duration) ranged from 2.2 to 6.4 kg·angler-1·d-1 depending on the season. The number of anglers ranged from 22 (8 to 53) anglers·d-1 in June/July to 74 (25 to 176) anglers·d-1 in April. Total annual catch from the roving creel survey was estimated at 71.4 (57.4 to 91.4) t·yr-1. Another 7.5 t∙yr-1 were landed during recreational angling competitions. The resultant total catch divided by the lakeshore population equated to a per capita fish supply of 11.1 kg·yr-1. More than 70% of the catch was the alien invasive carp Cyprinus carpio and there was no evidence of overfishing. The fish resource of Lake Gariep is of significant recreational and subsistence value. As a result of the low fish price (ZAR5.72 ± 2.60·kg-1) subsistence fishing was considered a low-revenue activity that mainly augmented food security in lakeshore communities. The relatively high CPUE indicated that the fishery may be an important safety-net during periods when alternate sources of livelihoods are limited. Consequently, we recommend that the importance of angling to local communities needs to be taken into account when planning fisheries development and developing an inland fisheries polic
A review of current knowledge, risk and ecological impacts associated with non-native freshwater fish introductions in South Africa
No full textThe introduction and spread of non-native species is one of the least reversible human-induced global changes. In South Africa, non-native
fish introductions have occurred over the last two and a half centuries. Resultant invasions have been cited as a primary threat to imperilled
South African fishes and other aquatic fauna. Addressing a problem of this magnitude requires an organised approach. The aim of this paper
is to summarise the current knowledge, risk and ecological impacts associated with non-native freshwater fish introductions in South Africa.
A total of 55 fishes have been introduced into novel environments in South Africa. Of these, 27 were alien and 28 were extralimital
introductions. Only 11 introduced species failed to establish and of the 44 species that have established, 37% are considered fully invasive.
Introductions for angling were responsible for the highest proportion (55%) of fully invasive species with the remainder linked to inter-basin
water transfers (15%), bio-control (15%), ornamental fish trade (10%) and aquaculture (5%). There was a general paucity of published
literature on the introduction, establishment and spread of non-native fishes, and recent research has largely focused on impacts on native
biota. While documented impacts spanned multiple levels of biological organisation, most papers focused on individual and population level
impacts. Large taxonomic biases were also observed, and invasive impacts were estimated for less than 50% of fully invasive fishes. There is
also an extensive knowledge gap on the impacts of associated parasites and diseases introduced with non-native fishes. These knowledge
gaps constrain effective management of non-native fishes in South Africa and research at all invasion stages (introduction, establishment,
spread and impact) is necessary to guide conservation practitioners and managers with information to manage current invasions and curb
future introductions
