Matt Dicken

Matt Dicken

About

28
Publications
8,823
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617
Citations
Citations since 2016
8 Research Items
349 Citations
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060
Introduction
Skills and Expertise

Publications

Publications (28)
Article
Full-text available
Risk-induced fear effects exerted by top predators are pervasive in terrestrial and marine systems, with lasting impacts on ecosystem structure and function. The loss of top predators can disrupt ecosystems and trigger trophic cascades, but the introduction of novel apex predators into ecosystems is not well understood. We documented the emigration...
Article
The common smooth-hound shark, Mustelus mustelus, is a widely distributed demersal shark under heavy exploitation from various fisheries throughout its distribution range. To assist in the development of appropriate management strategies, the authors evaluate stock structure, site fidelity and movement patterns along the species’ distribution in so...
Article
Full-text available
The common smoothhound, Mustelus mustelus, is an epibenthic species targeted by fisheries around the world driven by the increasing demand for shark products. Given the wide-spread occurrence of this species and corresponding lack of molecular data in many areas of said distribution, baseline molecular assessments of this commercially important sha...
Article
Full-text available
Genomic data can be a useful tool in the management and conservation of biodiversity. Here, we report the development of genomic resources for the spotted ragged-tooth shark Carcharias taurus using genome-wide DNA data from Illumina next-generation sequencing. We explored two commonly used genetic marker types: microsatellites and mitochondrial DNA...
Article
Full-text available
White sharks, Carcharodon carcharias, are often described as elusive, with little information available due to the logistical difficulties of studying large marine predators that make long-distance migrations across ocean basins. Increased understanding of aggregation patterns, combined with recent advances in technology have, however, facilitated...
Article
Full-text available
The current study provides long-term catch-rate, biological and feeding data for smooth hammerhead sharks, Sphyrna zygaena, caught in South Africa’s KwaZulu-Natal bather protection programme. In total, 2 512 S. zygaena were caught in net installations between 1978 and 2014, and 72 S. zygaena were caught on drumlines between 2007 and 2014. There was...
Article
Full-text available
Andreotti et al. (2016; Mar Ecol Prog Ser 552:241-253) estimate an abundance (N) of 438 white sharks Carcharodon carcharias and a contemporary effective population size (CNe) of 333 individuals along the South African coast. N was estimated by using a mark-recapture analysis of photographic identification records from a single aggregation site (Gan...
Article
Full-text available
The current study provides long-term catch rate and biological data for tiger sharks Galeocerdo cuvier caught in the KwaZulu-Natal bather protection programme. Between 1978 and 2014, 1 760 G. cuvier were caught in nets and between 2007 and 2014, 108 G. cuvier were caught on drumlines. Standardised catch rates increased significantly over time (p <...
Article
Spotted raggedtooth sharks Carcharias taurus occur along the southern and eastern coasts of South Africa. We report on movements of juveniles and adults within a known nursery area on the Eastern Cape coast using acoustic telemetry. The focus area of the study was Algoa Bay, where six VEMCO VR2 ultrasonic receivers were placed at known shark aggreg...
Article
Full-text available
Direct observations of sharks attacking mysticetes are rare. The present study provides the first direct observation of dusky sharks (Carcharhinus obscurus) attacking a humpback whale (Megaptera novaeangliae) calf. The event was witnessed on 16 July 2014 within the Pondoland Marine Protected Area, South Africa, during the annual sardine run. The ev...
Article
Full-text available
This paper presents the first quantitative study on the seasonal occurrence and body location of white shark (Carcharodon carcharias)-inflicted injuries on Cape fur seals (Arctocephalus pusillus pusillus) at Black Rocks, in Algoa Bay. Between January 2010 and October 2011, 22 boat trips were made to Black Rocks to chum for white sharks. On 19 of th...
Article
This paper presents the first quantitative study on the seasonal occurrence and body location of white shark (Carcharodon carcharias)-inflicted injuries on Cape fur seals (Arctocephalus pusillus pusillus) at Black Rocks, in Algoa Bay. Between January 2010 and October 2011, 22 boat trips were made to Black Rocks to chum for white sharks. On 19 of th...
Article
We present the first quantitative study of the occurrence, size and sex of white sharks Carcharodon carcharias at Bird Island, Algoa Bay. Twenty-two boat trips were made to Bird Island between November 2009 and October 2011 to chum for sharks. A total of 53 sharks was observed over the study period, ranging in size from 1.5 to 4.5 m total length (T...
Article
The present study provides information on the existence of a possible inshore nursery area for white sharks (Carcharodon carcharias) in Algoa Bay, South Africa. In total, 43 flights were conducted, using a Robinson R22 helicopter, between October 2010 and March 2012. A total of 50 white sharks was sighted, with a maximum sighting rate of seven shar...
Article
Using on‐site survey data collected via the administration of a questionnaire to 197 respondents during the period stretching from January 2007 to December 2007 from the Aliwal Shoal Marine Protected Area, this study estimates and compares an ordinary least squares and two Poisson count data models of recreational tiger shark diving demand. The Poi...
Article
Catches from Angling Week competitions between 1999 and 2010 were analysed to examine changes in catch and effort. Over the course of the study period there was a marked drop in the number of competing anglers and a significant reduction in the total number of fish caught (p = 0.026). There was also a significant (p < 0.01) shift in the areas fishe...
Article
Identifying nearshore waters that serve as important habitats for neonate and juvenile sharks is crucial for effective fisheries management. This study examined the abundance of neonate and juvenile dusky sharks Carcharhinus obscurus within the Port of Ngqura, on the south-east coast of South Africa, between September 2006 and August 2007 using a c...
Article
Biofouling of external tags can damage both the animal and the tag. It is an inherent problem to many fish-tagging studies; however, it has received little attention. Between 2005 and 2007, we investigated the taxonomic group and wet weight of sessile multicellular eukaryonts growing on 33 B-type dart tags recaptured from raggedtooth sharks (Carcha...
Article
This study provides one of the first quantitative assessments of a fish community within a pre-operational deep-water port system. Between September 2006 and September 2007 a total of 4 559 fish, representing 47 species and 27 different families, were caught within the Port of Ngqura, Africa's deepest port, in 1 713 h of shore-angling (2.3 fish ang...
Article
Understanding recreational aspects of the tourism industry developing around the KwaZulu-Natal sardine run is important for the protection and sustainability of the Pondoland Marine Protected Area (MPA), on the south-east coast of South Africa. Between June and July 2007, a total of 128 people visited this area to experience the sardine run using b...
Article
Understanding differences in the recapture rate between different tags (A-, B- and C-types), capture methods (rock-and-surf anglers, scientific divers and Natal Sharks Board protection nets) and life-history stages (juvenile and adult) is critical in evaluating the results obtained from cooperative tagging programmes (CTPs). A generalised linear mo...
Article
Understanding socio-economic aspects of the tiger shark Galeocerdo cuvier diving industry, including information on participant expectations, experiences and expenditure, is necessary for the effective management of the Aliwal Shoal Marine Protected Area on the east coast of South Africa. Between January and December 2007, a total of 2 133 tiger sh...
Article
Observations of great white sharks (Carcharodon carcharias) scavenging from cetacean carcasses are rare and have only been reported in the scientific literature for large (>3.5 m total length (TL)) individuals. Between 13 October and 25 November 2006, young of the year and juvenile great white sharks were observed scavenging from the carcass of a h...
Article
Full-text available
Understanding the movement patterns of raggedtooth sharks (Carcharias taurus) is crucial in defining habitat use and evaluating the effects of exploitation and anthropogenic activities. Between 1984 and 2004, 1107 C. taurus juveniles (<1.8-m TL) and 2369 C. taurus maturing subadults and adults (>1.8-m TL) were tagged and released along the east coa...
Article
A double-tagging experiment and integrated on-site questionnaire and telephone survey were used to investigate aspects of tag shedding, tag reporting, tag wounds, and tag biofoul- ing for the raggedtooth shark (Carcharias taurus), tagged off the east coast of South Africa. Between 2002 and 2004, 84 juvenile (1.8 m TL) C. taurus were double-tagged....
Article
Full-text available
An integrated telephone and on-site questionnaire survey was used to estimate total shark fishing effort and specific catch of the ragged-tooth shark Carcharias taurus by coastal club-affiliated shore-anglers, primarily along the east coast of South Africa. Mean total shark fishing effort was estimated to be 37 820 fisher-days year−1 (95% CI = 28 2...
Article
Catches from competitive shore-anglers, inshore boat-based anglers and sightings by spearfishers and divers were used to infer the spatial and seasonal movement patterns of young-of-the-year (2.4m TL) ragged-tooth sharks Carcharias taurus along the coast of South Africa. Adult sharks inhabited the entire coast between Maputaland in the east and St...

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Project (1)
Project
Sharks are heavily exploited directly (e.g. shark fin soup) and indirectly (e.g. bycatch) all over the world (Baum et al. 2003; Clarke et al. 2006). Most sharks are vulnerable to overexploitation due to their late age at maturity and long reproductive cycle (Simpfendorfer et al. 2002, Romine et al. 2009). Compounding this issue is the lack of scientific knowledge on the impacts of reproductive behaviour on their spatial genetic structure. Most shark species invariably return to the same natal areas for mating and gestating, a concept known as reproductive philopatry (Heuter et al. 2005). They may also return to their natal region, although not necessarily to the exact pupping locality within this region, which is termed regional philopatry (Feldheim et al. 2013). Shark populations may be characterised by regional genetic structure at scales of 100s of km due to reproductive philopatry (Tillet et al. 2012). Identification of philopatric grounds for mating, gestating and pupping could play a pivotal role in mitigating biodiversity impacts arising from overfishing, bather protection nets and unintended destruction of philopatric areas due to anthropogenic effects (Heuter et al. 2005, Heupel et al. 2007). The impacts of shark fishing and the bather protection nets along the KwaZulu-Natal coast have the potential to significantly reduce genetic diversity in sharks characterised by reproductive philopatry. The evolutionary significant units associated with natal philopatric grounds represent reproductively isolated discrete females deserving special efforts for conservation and management. Currently, there is a lack of fundamental scientific knowledge on the impacts of reproductive philopatry in sharks distributed along the southern African coastline. The knowledge on how such reproductive behaviour could shape population genetic structure is crucial for sustainable species` conservation. Most shark species are highly mobile and may disperse at transoceanic scales. As a result, it is generally accepted that highly mobile sharks would be characterised by high genetic connectivity at both global (amongst continents) and regional (along continental coastlines) scales. Reproductive philopatry challenges the null hypothesis that sharks are characterised by genetic homogeneity across their distributional ranges. Genetic evidence of female philopatry has been suggested at a small regional scale along the northern Australian coastline in the pig-eye shark (Tillet et al. 2011). This project will use the raggedtooth shark, Carcharias taurus, as a model species to investigate the effects of a life-history trait (reproductive philopatry) on its genetic structure at a small regional scale (~1000 km) along the South African coastline. The study will apply mitochondrial DNA sequences and nuclear microsatellite markers to investigate genetic evidence of reproductive philopatry in raggedtooth sharks caught along the southern and eastern coasts of South Africa.