Warren Mason Potts

Warren Mason Potts
Rhodes University | RU · Department of Ichthyology and Fisheries Science

PhD

About

126
Publications
28,731
Reads
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Introduction
My research includes examining and predicting the response of coastal fishes climate change and understanding the synergistic impacts between exploitation and climate change. These findings are primarily contextualised in recreational fisheries, where I use this information to promote the strengthening of their governance (from policy to voluntary institutions) and employ a range of techniques to improve the environmental behaviour of anglers.
Additional affiliations
January 2016 - January 2016
Rhodes University
Position
  • Professor (Associate)
January 2016 - January 2016
Rhodes University
Position
  • Professor (Associate)

Publications

Publications (126)
Article
Non-compliance with recreational fishery regulations is considered to be one of the biggest threats to the sustainability of fisheries. Dedicated non-compliance studies are seldom carried out at the national level which makes it difficult to discern the behavioural compliance norms within a population. The instrumental approach for compliance is th...
Article
Argyrosomus japonicus is arguably South Africa’s most important estuarine recreational and small-scale fishery species. Although juvenile A. japonicus predominate in estuarine environments, where catch-and-release angling is common, limited C&R studies have taken place. The aim of this study was to use angler-behaviour to robustly examine the physi...
Article
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The role dentition plays in shaping feeding patterns has significant consequences for understanding the evolution of shark feeding. Despite this, research has generally failed to compare tooth morphology and feeding ecology in elasmobranchs. For this reason, the diet and dentition of 120 Triakis megalopterus were examined from three study sites in...
Article
Fishing guides are respected as opinion leaders of the recreational angling community, but little is known of their influence on angler behaviour. Given their social-standing, fishing guides may be perceived as role models by fishing clients – thereby potentially shaping the practices of many through their extensive networks of fishing clients. Thi...
Article
Inland recreational fisheries provide numerous socio-economic benefits to fishers, families and communities. Recreationally harvested fish are also frequently consumed and may provide affordable and sustainable but undervalued contributions to human nutrition. Quantifying the degree to which recreationally harvested fish contribute to food security...
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Changes in behaviour and physiology are the primary responses of fishes to anthropogenic impacts such as climate change and over-fishing. Behavioural changes (such as a shift in distribution or changes in phenology) can ensure that a species remains in an environment suited for its optimal physiological performance. However, if fishes are unable to...
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While the economic activity associated with recreational fishing is well assessed in the developed world, substantially less is known in developing countries. South Africa is a unique microcosm for applying economic evaluation frameworks through its dualist economy, which shares characteristics of both the developed and developing world. Understand...
Article
South Africa has a long history of engagement in citizen science (CS), particularly marine CS. This review examines the contributions made by marine CS, from the 1930s through to the current era, where websites, social media and mobile apps provide a wide range of opportunities. Largescale marine CS projects, such as the Oceanographic Research Inst...
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Climate change not only drives increases in global mean ocean temperatures, but also in the intensity and duration of marine heatwaves (MHWs), with potentially deleterious effects on local fishes. A first step to assess the vulnerability of fishes to MHWs is to quantify their upper thermal thresholds and contrast these limits against current and fu...
Article
Online evidence suggests that there has been an increase in interest of using unmanned aerial vehicles or drones during land-based marine recreational fishing. In the absence of reliable monitoring programs, this study used unconventional publicly available online monitoring methodologies to estimate the growing interest, global extent, catch compo...
Article
Recent investigations suggest that global warming is likely to alter temperature regimes along the southeastern coastline of South Africa through the increased frequency of upwelling events. Identifying thermal thresholds is fundamental in predicting the response of marine ectotherms to rapidly changing ocean temperatures. The aim of this study was...
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Inland recreational fisheries have social, economic, and ecological importance worldwide but these fisheries are increasingly challenged by the diverse effects of climate change. Coupled with other anthropogenic stressors, climate change has contributed to declines in freshwater biodiversity of greater severity than those observed across marine or...
Article
Anthropogenic induced climate change is predicted to increase the thermal variability in coastal waters, which can have strong physiological effects on individuals and populations of marine ectotherms. The magnitude and direction of these thermal effects varies depending on species, life stage, biogeography, habitat and season. This study aimed to...
Article
The literature on global trends in recreational fishing, the determinants of participation in recreational fishing, and the social embedding of recreational fishing in the public eye are reviewed across the world. Data support a conceptual life-cycle model of fisheries according to which interest in recreational fishing rises rapidly with economic...
Article
Sagittal otolith pairs were extracted from two-hundred-and-twenty-six giant African threadfin Polydactylus quadrifilis collected from the Kwanza Estuary in Angola between 2016 and 2018 ranging in size from 160 to 1360 mm fork-length (FL) and from one to 23 years of age (26 juvenile, 170 male, nine intersex and 27 female). An additional 85 otolith p...
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Ocean acidification is predicted to have widespread impacts on marine species. The early life stages of fishes, being particularly sensitive to environmental deviations, represent a critical bottleneck to recruitment. We investigated the effects of ocean acidification (∆pH = −0.4) on the oxygen consumption and morphometry during the early ontogeny...
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The distributions of ectothermic marine organisms are limited to temperature ranges and oxygen conditions that support aerobic respiration, quantified within the metabolic index (ϕ) as the ratio of oxygen supply to metabolic oxygen demand. However, the utility of ϕ at local scales and across heterogenous environments is unknown; yet, these scales a...
Article
Linefish' is a uniquely South African term used to describe marine fishes that are captured using hook and line. The South African linefishery is a complex socio-ecological system that has a considerable impact on the coastal marine environment while generating social and economic benefits for commercial, small-scale and recreational fishers. Like...
Article
Catch and release (C&R) angling is a popular pastime the world over; however, studies have found that fish can experience considerable stress during a C&R event. To determine the effect of a C&R event on angled fishes, the physiological stress response (PSR) is often assessed. However, the peak PSR only occurs after a delay and is species-specific....
Article
Best-practice guidelines to improve recreational fishers’ handling during catch-and-release (C&R) events are critical to improve the conservation and management of fish stocks worldwide. While best-practice research is growing, there are knowledge gaps, with the effects of sand exposure on fish mucous membranes understudied. This study aimed to det...
Preprint
The red steenbras Petrus rupestris is endemic to South Africa, occurring from False Bay in the Western Cape Province to St Lucia in the province of KwaZulu-Natal. This species, the largest member of the family Sparidae, has undergone a substantial stock decline as a result of overfishing and is considered to be collapsed. Various aspects of its lif...
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Foreign fishing tourism (FFT) is becoming increasingly popular in the developing world, where it often coexists alongside other important sectors involving domestic recreational anglers and dependant artisanal and subsistence fishing communities. Therefore, it is important that FFT operations use effective catch‐and‐release (C&R) angling to minimis...
Article
Millions of individuals worldwide rely on recreational fishing activities for leisure, food, and employment. Recreational fishing is the dominant freshwater fisheries sector in much of the highly developed world and plays a growing role in the marine realm, but in developing countries recreational fisheries occur within a different set of contextua...
Article
Catch-and-release (C&R) angling has increased in popularity through its mandatory and voluntary use in fisheries conservation and management. However, research has shown that fish can experience considerable stress during a C&R event. The physiological response of fishes is typically assessed by measuring the concentrations of blood-plasma cortisol...
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It has been suggested that tourism fisheries can raise the value of landed catch, provide alternative livelihoods for local artisanal fishers and, because recreationally caught fishes are often released, simultaneously conserve stocks. However, for fishing tourism to meet ecotourism standards, sustainable, local economic benefit is imperative. This...
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Quantifying how the heart rate of ectothermic organisms responds to environmental conditions (e.g. water temperature) is important information to quantify their sensitivity to environmental change. Heart rate studies have typically been conducted in lab environments where fish are confined. However, commercially available implantable heart rate bio...
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Two geographically non‐overlapping species are currently described within the sparid genus Spondyliosoma: Spondyliosoma cantharus (Black Seabream) occurring across Mediterranean and eastern Atlantic waters from NW Europe to Angola; and S. emarginatum (Steentjie) considered endemic to southern Africa. To address prominent knowledge gaps this study i...
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Recreational fisheries hold immense ecological, social, and economic value. The management of these fisheries is increasingly important as we move forward in the Anthropocene. Recreational fisheries managers face several challenges as fisheries often involve diverse social and ecological systems comprised of complex feedback and stakeholder motivat...
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Two sister species of horse mackerel (Trachurus trachurus and T. capensis) are described and intensively harvested in East Atlantic waters. To address long‐standing uncertainties as to their respective geographical ranges, overlap, and intraspecific population structure this study combined genetic (mtDNA and microsatellite) analysis and targeted sa...
Article
As marine environments are influenced by global warming there is a need to thoroughly understand the relationship between physiological limits and temperature in fish. One quick screening method of a physiological thermal tipping point is the temperature at which maximum heart rate (ƒHmax) can no longer scale predictably with warming and is referre...
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Resilience thinking has generated much interest among scientific communities, yet most resilience concepts have not materialized into management applications. We believe that using resilience concepts to characterize systems and the social and ecological processes affecting them is a way to integrate resilience into better management decisions. Thi...
Book
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The Southern African Marine Linefish Symposium is an event where scientists come together and present any contemporary research relating to linefisheries in the region. The symposium occurs every 4 - 7 years depending on circumstances and the research presented at each event is summarized and published in the form of a proceedings document. The lat...
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The Frenchman seabream Polysteganus baissaci is an important commercial fish species found on the slopes of the fishing banks of the exclusive economic zone of Mauritius. Exploitation of this species started in 2007, and it is targeted using hydraulic reels with baited hooks. The introduction of suitable management measures is important for this fi...
Article
The population of Cape fur seal Arctocephalus pusillus pusillus at Ilha dos Tigres off the coast of southern Angola is expanding. Until now the only available biological information on the population has been its demographic parameters, and this insufficiency has hindered our understanding of the population’s ecology. The current study aimed to des...
Article
The effectiveness of recreational fisheries governance has been mixed, with some countries boasting good governance practices that sustain productive recreational fisheries, while others lack any policies and governance structures specific to recreational fisheries. Here, we identify what constitutes effective governance of recreational fisheries b...
Article
Although marine recreational fisheries are socially and economically important, there is often limited funding for their monitoring and assessment. With South African anglers reporting catch declines for almost all targeted species and little long-term monitoring data available, novel methods need to be explored to provide managers with additional...
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The El Niño–Southern Oscillation (ENSO) phase state is reported to drive interannual variability in sea temperatures along South Africa’s south coast through its influence on wind-induced upwelling processes. Whether ENSO drives the intensity of localised, abrupt, intermittent upwelling is less well known. To explore this relationship, we used an i...
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While otoliths are considered the most reliable structure to accurately age fish, a variety of otolith preparation techniques are available, which have consequences on the otolith's optical properties and therefore interpretation of growth bands. Recently, numerous studies from a variety of authors have criticised the use of whole otoliths in agein...
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Physiological rates and processes underpin the relationships between ectothermic organisms, such as fish, and their environment. The response and persistence of fish populations in an increasingly variable ocean is dependent on the distribution and diversity of physiological phenotypes. Growing evidence suggests that fisheries exploitation can sele...
Article
Estuarine-dependent marine fish species rely on shallow, sheltered and food rich habitats for protection from predators, growth and ultimately recruitment to adult populations. Hence, habitats within estuaries function as critical nursery areas for a variety of fish species. Results from stomach content analysis and dietary diatom composition of a...
Article
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For most rare marine species abundance trends are poorly estimated. This uncertainty often translates into disagreement on managment regulations, impeding conservation efforts when they are most urgently required. The world’s largest sea bream, the red steenbras (Petrus rupestris), has been subject to a substantial and widely acknowledged decline d...
Article
Recreational fisheries (RF) are complex social-ecological systems that play an important role in aquatic environments while generating significant social and economic benefits around the world. The nature of RF is diverse and rapidly evolving, including the participants, their priorities and behaviors, and the related ecological impacts and social...
Article
Area management in the form of no-take marine protected areas (MPAs) has been criticised as a fisheries management tool because of its limited capacity to provide short-term benefits to local fisheries. This study used data from a long-term fish monitoring and tagging project to assess whether catch-and-release (C&R) shore angling could be compatib...
Article
Fisheries managers are increasingly promoting catch-and-release (C&R) to manage recreationally angled fish stocks. Despite this, there is a scarcity of information on the effects of C&R on estuarine-dependent species. Cape stumpnose Rhabdosargus holubi dominates the recreational fisheries catch and provides an important source of food for subsisten...
Article
Climate change is altering many environmental parameters of coastal waters and open oceans, leading to substantial present-day and projected changes in the distribution, abundance and phenology of marine species. Attempts to assess how each species might respond to climate change can be data-, resource- and time-intensive. Moreover, in many regions...
Article
Catch-and-release (C&R) is increasingly popular in recreational fisheries as it is thought to protect target species while still allowing anglers to continue recreational fishing activities. Several studies have highlighted high rates of mortality and many sub-lethal effects which ultimately have a negative impact on fish population viability. With...
Article
Full-text available
Catch-and-release (C&R) is increasingly popular in recreational fisheries as it is thought to protect target species while still allowing anglers to continue recreational fishing activities. Several studies have highlighted high rates of mortality and many sub-lethal effects which ultimately have a negative impact on fish population viability. With...
Article
The hottentot seabream Pachymetopon blochii is a small-sized (maximum 2.67 kg) sparid endemic to southern Africa. It is an important target in South Africa's Western Cape traditional linefishery, particularly in the absence of more valuable pelagic species (such as Thyrsites atun and Seriola lalandi). In 2000, South Africa's linefishery was declare...
Article
ABSTRACT While acoustic telemetry (AT) has become the dominant technique for understanding patterns of fish migration, catch rate (CR) and conventional tagging (CT) techniques still play a major role, particularly in developing countries. Understanding the potential biases of each technique is important for fish migration research. We compared thes...
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The genus Diplodus presents multiple cases of taxonomic conjecture. Among these the D. cervinus complex was previously described as comprising three subspecies that are now regarded as separate species: Diplodus cervinus, Diplodus hottentotus and Diplodus omanensis. Diplodus hottentotus exhibits a clear break in its distribution around the Benguela...
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A total of 141 Polydactylus quadrifilis were sampled from the Kwanza Estuary in Angola ranging in size from 436 to 1360 mm fork-length (FL). Of these, 124 were male, six intersex and 11 female. Female fish were significantly longer (mm, FL) and heavier (kg) than males and had significantly higher gonadosomatic indices (GSI’s) than those of males an...
Article
The West Coast dusky kob Argyrosomus coronus is a commercially exploited fish with a distribution confined to the Angola–Benguela Frontal Zone (ABFZ) of the southeastern Atlantic Ocean. A previous study revealed that during a recent period of local warming the species extended its distribution into Namibian waters, where it hybridised with the resi...
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Accurate species identification and biogeographic characterisation are fundamental for appropriate management of expanding cephalopod fisheries. This study addresses this topic within the common cuttlefish Sepia officinalis species complex (S. officinalis, S. hierredda and S. vermiculata), with an emphasis on occurrence in African waters. Tissue sa...
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This study aimed to assess the suitability of the Berkowitz' (2005) social norms approach (SNA) for improving compliance behaviour amongst recreational fishers. A total of 138 recreational shore anglers were interviewed in Eastern Cape, South Africa and asked about their compliance, attitudes towards compliance, perceptions of compliance and the at...
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There is a growing need to incorporate biotic interactions, particularly those between predators and their prey, when predicting climate-driven shifts in marine fishes. Predators dependent on a narrow range of prey species should respond rapidly to shifts in the distribution of their prey, whereas those with broad trophic adaptability may respond t...