Spatial and seasonal distribution patterns of juvenile and adult raggedtooth sharks (Carcharias taurus) tagged off the east coast of South Africa

2007 ◽  
Vol 58 (1) ◽  
pp. 127 ◽  
Author(s):  
M. L. Dicken ◽  
A. J. Booth ◽  
M. J. Smale ◽  
G. Cliff
Keyword(s):  
South Africa ◽  
East Coast ◽  
Average Rate ◽  
Anthropogenic Activities ◽  
Average Distance ◽  
Movement Patterns ◽  
Release Site ◽  
Distribution Patterns ◽  
Juvenile Sharks ◽  
Carcharias Taurus

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 coast of South Africa. In total, 125 C. taurus juveniles and 178 C. taurus maturing subadults and adults were recaptured, representing recapture rates of 11.2% and 7.5% respectively. The average distance travelled by juvenile sharks was 18.7 km (95% CI = 10.8–26.6 km). Juvenile sharks displayed site fidelity to summer nursery areas. The average distance travelled by maturing and adult sharks was 342 km (95% CI = 275–409 km). One female shark, however, was recaptured 1897 km from its original release site. The average rate at which pregnant sharks moved south from their gestation to pupping grounds was 2.6 km day–1 (95% CI = 2.04–3.16 km day–1). This study highlights the differences in movement patterns between C. taurus juveniles and adults and suggests philopatric behaviour in both life-history stages.

scholarly journals Preliminary observations of tag shedding, tag reporting, tag wounds, and tag biofouling for raggedtooth sharks (Carcharias taurus) tagged off the east coast of South Africa

2006 ◽  
Vol 63 (9) ◽  
pp. 1640-1648 ◽  
Author(s):  
M.L. Dicken ◽  
A.J. Booth ◽  
M.J. Smale
Keyword(s):  
South Africa ◽  
East Coast ◽  
Telephone Survey ◽  
Total Length ◽  
Significant Difference ◽  
Juvenile Sharks ◽  
Carcharias Taurus ◽  
Tag Shedding

Abstract 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 biofouling for the raggedtooth shark (Carcharias taurus), tagged off the east coast of South Africa. Between 2002 and 2004, 84 juvenile (<1.8 m total length, TL), and 24 adult (>1.8 m TL) C. taurus were double-tagged. Of these, 11 juvenile and six adult double-tagged sharks were recaptured. Significantly, more tags were shed from adult than from juvenile sharks, and there was also a significant difference between the number of anterior and posterior tags shed. Rates of tag reporting were estimated from a survey of 477 randomly selected shore-anglers, and they varied both temporally and spatially from 27% to 100%. In all, 93 tag recaptures were reported in the survey, most (75.3%) with some biofouling. Tag-inflicted damage was reported in 35.5% of recaptured sharks, and the incidence of tag-inflicted damage was greater for disk (77.8%) than for dart tags (25.3%).

Estimates of juvenile and adult raggedtooth shark (Carcharias taurus) abundance along the east coast of South Africa

2008 ◽  
Vol 65 (4) ◽  
pp. 621-632 ◽  
Author(s):  
Matthew Laurence Dicken ◽  
Anthony John Booth ◽  
Malcolm John Smale
Keyword(s):  
South Africa ◽  
East Coast ◽  
Adult Survival ◽  
Juvenile Survival ◽  
Tag Loss ◽  
Oceanographic Research ◽  
The Mean ◽  
Juvenile Sharks ◽  
Carcharias Taurus ◽  
Probability Of Capture

A Cormack–Jolly–Seber model was developed to estimate abundance, survival, and probability of capture for juvenile (<1.8 m total length, TL) and adult (>1.8 m TL) raggedtooth sharks (Carcharias taurus) along the east coast of South Africa. Model estimates were adjusted to account for tag loss, nonreporting, and after release mortality. The model was constructed using mark–recapture data from the Oceanographic Research Institute and Port Elizabeth Museum cooperative tagging programs from 1984 to 2004. The adjusted estimate for juvenile survival was 0.56 and that for adult survival was 0.89. The adjusted estimate of probability of capture for juvenile sharks ranged from 0.06 to 0.17, while that for adult sharks was from 0.02 to 0.04. The mean annual abundance of juvenile sharks was 6800 (coefficient of variation, CV = 13%) and adult sharks 16 700 (CV = 9%). The accumulated effect of tag loss, nonreporting, and after release mortality were to reduce the overall estimate of juvenile and adult abundance by approximately 50%. The adjusted estimate of population size for both juvenile and adult sharks over the last decade appears to have remained constant (P > 0.05).

Possible maternal offloading of metals in the plasma, uterine and capsule fluid of pregnant ragged-tooth sharks (Carcharias taurus) on the east coast of South Africa

2017 ◽  
Vol 24 (20) ◽  
pp. 16798-16805 ◽  
Author(s):  
Kristina Naidoo ◽  
Anil Chuturgoon ◽  
Geremy Cliff ◽  
Sanil Singh ◽  
Megan Ellis ◽  
...  
Keyword(s):  
South Africa ◽  
East Coast ◽  
Carcharias Taurus

Occurrence of tuna and mackerel larvae (Family: Scombridae) off the east coast of South Africa

2000 ◽  
Vol 51 (8) ◽  
pp. 777 ◽  
Author(s):  
Lynnath E. Beckley ◽  
Jeff M. Leis
Keyword(s):  
South Africa ◽  
East Coast ◽  
Temporal Distribution ◽  
Western Indian Ocean ◽  
Distribution Patterns ◽  
Agulhas Current ◽  
The North ◽  
Scomberomorus Commerson ◽  
Euthynnus Affinis ◽  
King Mackerel

Spatial and temporal distribution patterns of scombrid larvae along the east coast of South Africa were investigated from ichthyoplankton collections made during May–June 1990 (winter), October 1990 (spring) and February 1991 (summer). Results were analysed in relation to oceanographic conditions and known spawning localities of tuna and mackerels in the western Indian Ocean. In total, eight species were represented in the samples, with highest diversity in February and lowest numbers in May–June. Larvae of the temperate chub mackerel Scomber japonicus were most abundant at shelf stations during October. Larvae of neritic tunas Auxis sp. and Euthynnus affinis occurred in shelf stations off KwaZulu–Natal in February and extended southward in a plume along the shelf edge. Larvae of skipjack tunaKatsuwonus pelamis were most abundant in the Agulhas Current during February. Only a few larvae of oceanic tunas Thunnus spp., wahoo Acanthocybium solandri and king mackerel Scomberomorus commerson were collected in the Agulhas Current in the north of the study area during February when there was an intrusion of warm Tropical Surface Water. This indicates that spawning of these species probably does not occur off the east coast of South Africa.

Movement patterns of juvenile sand tigers (Carcharias taurus) along the east coast of the USA

2014 ◽  
Vol 161 (5) ◽  
pp. 1149-1163 ◽  
Author(s):  
Jeff Kneebone ◽  
John Chisholm ◽  
Gregory Skomal
Keyword(s):  
East Coast ◽  
Movement Patterns ◽  
The Usa ◽  
Carcharias Taurus

Predicting future distribution patterns of Jatropha gossypiifolia L. in South Africa in response to climate change

2022 ◽  
Vol 146 ◽  
pp. 417-425
Author(s):  
Moleseng Claude Moshobane ◽  
Bester Tawona Mudereri ◽  
Mukundi Mukundamago ◽  
Tavengwa Chitata
Keyword(s):  
Climate Change ◽  
South Africa ◽  
Distribution Patterns ◽  
Jatropha Gossypiifolia

scholarly journals Population irruption of the clam Meretrix morphina in Lake St Lucia, South Africa

2017 ◽  
Vol 113 (7/8) ◽  
Author(s):  
Nelson A. F. Miranda ◽  
Nasreen Peer ◽  
Renzo Perissinotto ◽  
Nicola K. Carrasco ◽  
Salome Jones ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
East Coast ◽  
Severe Drought ◽  
Freshwater Input ◽  
Large Populations ◽  
Ocean Region ◽  
West Indian Ocean ◽  
First Time ◽  
Eastern Seaboard

The thick-shelled clam Meretrix morphina, previously referred to as Meretrix meretrix, now occurs in the west Indian Ocean region, along the eastern seaboard of Africa, from the Red Sea to the Mlalazi Estuary, close to the Tugela River. Its presence in South Africa is only of recent recording. Meretrix morphina was detected for the first time in Lake St Lucia in 2000. The population declined and was not detected from 2005 until 2011, most likely as a result of a severe drought that resulted in widespread desiccation and hypersalinity in the lake. The system then experienced increased freshwater input resulting in lower salinities from 2011 until 2014, during which time M. morphina reappeared and their population gradually increased. In 2015, M. morphina became abundant in St Lucia, attaining unprecedented densities of 447 ind./m2. Biomass, expressed as a fresh weight, varied in the different basins of St Lucia, ranging from 195 g/m2 at Lister’s Point to 1909.8 g/m2 at Catalina Bay. However, in 2016, when drought conditions returned, M. morphina disappeared. This species appears to thrive under brackish salinities and high temperatures. It is able to establish large populations with high biomass and can become dominant. However, M. morphina is sensitive to desiccation and hypersaline conditions. This clam has substantial commercial value and is exploited along the African east coast, particularly in Mozambique. In future, it may feature more prominently in South African estuaries. However, the ecology of M. morphina is still largely unknown.

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