39 research outputs found
Pathway to sustainability: the Marine Stewardship Council certification standard as an improvement framework for African fisheries
Fishery certification is increasingly employed as a multi-stakeholder, market-based mechanism to promote sustainability of fisheries. Preparing for, and achieving certification continues to deliver tangible improvements and benefits to fisheries, but the number of certified fisheries from Africa remains low. Some of the factors that constrain certification of fisheries in the region include limited data to assess and manage fisheries, the open access nature of many fisheries, overfishing, poor management, inadequate enforcement, and low demand for certified seafood. To overcome these constraints, several fisheries employ a âpathway to sustainabilityâ approach that involves using the MSC fisheries standard as a framework for gap analysis, action planning, progress tracking and improvement. Certification may not always be the goal. This allows fisheries to make ongoing improvements over prior performance, regardless of whether they immediately achieve certification or not. Progress towards the desired goal, sustainable management, can be tracked over time. Some of the reported benefits include clarity of objectives, consolidation and focus of stakeholder efforts, participatory engagement, ability to attract resources for improvements, benchmarking of performance and, ultimately, improved environmental performance through better fisheries management. This paper discusses the uptake of this approach in Africa, by presenting case study fisheries from the continent. It outlines mechanisms through which these fisheries embarked on a pathway to sustainability using the MSC fisheries standard, and the outcomes from these initiatives. It highlights the successes and challenges associated with implementation. The paper concludes that the MSC standard and the improvements that it incentivizes can make a positive contribution to regional efforts to improve environmental sustainability, fisheries governance and consequently the socio-economic viability and resilience of fisheries in Africa
Shore-based observations of seasonality, movements, and group behavior of southern right whales in a nonnursery area on the South African west coast
The southern right whale's (Eubalaena australis) demography, occurrence, habitat use, and behavior off South Africa are known predominantly from an ongoing aerial survey data set that started in 1971. The fixed timeframes of these surveys and their geographical bias towards south coast nursery areas have constrained our knowledge about the right whale's seasonal distribution elsewhere. We present shore-based observations and tracking of right whales at Saldanha Bay on the west coast (2001â2003) that reveal a near year-round presence and strongly nearshore distribution. With seasonal progression from winter to summer we observed a gradual increase in sighting rate, reduction in swimming speed, less directionality of movement, an increase in group size, and more surface active groups. The area appears to be important for feeding and socializing but not as a calving or nursery area. Individual transits between the south and west coasts, bidirectional alongshore movements, and extended seasonal presence may all be indicative of reoccupation of their former range along the west coast. This is important given the increasing ship traffic at Saldanha Bay, the rapid expansion of the region's oil and gas industry, and the known vulnerability of the closely related North Atlantic right whale (E. glacialis) to ship strikes.The National Research Foundation (NRF) of South Africa (Grant no. 2047517), the Earthwatch Institute, and PADI Project AWARE UK (Small Grant no. 095). JB was the grateful recipient of postgraduate bursaries from the University of Pretoria and NRF, a Grant-in-Aid from the Society for Marine Mammalogy, and the Charles Astley Maberly Memorial bursary from the Wildlife Society of South Africa.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1748-76922015-10-30hj201
Towards assessing impacts of alien plant infestations on river systems in the Southern Cape using cost-benefit analyses
Ecosystem resilience is key to the provision of dependable ecosystem goods and services, and it is generally accepted that ecosystem diversity helps to maintain sys-tem resilience. It is therefore reasonable to postulate that changes to the variables that drive species patterns will result in changes to ecosystem community structure and consequently negatively impact on system resilience. Alien vegetation in the riparian zone can impact on water temperatures, flow patterns, degree of shading, channel modification, and changes to natural sediment loads. Climate change is likely to exacerbate the problem both directly through its amplification of thermal extremes in aquatic systems, and indirectly through its impacts on dispersal patterns of alien invasive vegetation
Editorial: African ocean stewardship: navigating ocean conservation and sustainable marine and coastal resource management in Africa
Does temporal and spatial segregation explain the complex population structure of humpback whales on the coast of West Africa?
Humpback whales (Megaptera novaeangliae)
in the Southeastern Atlantic Ocean (International Whaling
Commission âBreeding Stock BââBSB) are distributed
from the Gulf of Guinea to Western South Africa. Genetic
data suggest that this stock may be sub-structured, but it
remains unknown if this is due to reproductive segregation.
This paper evaluates the spatial and temporal population
structure of BSB humpback whales using a combination of
maternally and bi-parentally inherited markers. The genetic
differentiation that we identify in this study could be due to
a combination of (1) spatial and/or temporal segregation on breeding grounds in the greater Gulf of Guinea, (2) the possibility
of maternally inherited site fidelity to specific feeding
grounds and (3) the use of two generalized but exclusive
migratory routes (coastal and offshore) between feeding and
breeding areas. Further, photo-identification and genetic
sampling efforts in other areas of the Sub-Saharan Western
Africa winter range and targeted deployment of satellite tags
would help to clarify some of the apparent complexity in the
population structure of animals biopsied in this region.National Research Foundation (South Africa) under Grant Number 2053539. I. Carvalho
was supported by a PhD scholarship (SFRH/BD/18049/2004), from
the Portuguese Foundation for Science and Technology (Fundação para a CiĂŞncia e TecnologiaâFCT).http://link.springer.com/journal/227hb201
Transit station or destination? Attendance patterns, movements, and abundance estimate of humpback whales off west South Africa from photographic and genotypic matching
Humpback whales found off west South Africa (WSA) are known to display an atypical migration that may include
temporary residency and feeding during spring and summer. At a regional scale there is uncertainty about how
these whales relate to the greater West African Breeding Stock B as a whole, with evidence both for and against
its division into two sub-stocks. A database containing sighting information of humpback whales intercepted by
boat in the WSA region from 1983 to 2008 was compiled. It included a total of 1,820 identification images of
ventral tail flukes and lateral views of dorsal fins. After systematic within- and between-year matching of images of
usable quality, it yielded 154 different individuals identified by tail flukes (TF), 230 by left dorsal fins (LDF), and
237 by right dorsal fins (RDF). Microsatellite (MS) matching of 216 skin biopsies yielded 156 individuals. By
linking all possible sightings of the same individuals using all available identification features, the periodicity and
seasonality of 281 individual whales were examined. Sixty whales were resighted on different days of which 44
were between different calendar years. The most resightings for one individual was 11 times, seen in six different
years, while the longest interval between first and last sightings was about 18 years. A resighting rate of 15.6% of
whales at intervals of a year or more indicates long-term fidelity to the region. Shorter intervals of 1 â 6 months
between sequential sightings in the same year may suggest temporary residency. The TF image collection from
WSA was compared to TF collections from four other regions, namely Gabon, Cabinda (Angola), Namibia and the
Antarctic Humpback Whale Catalogue (AHWC). Three matches were detected were between WSA (in late spring
or summer) and Gabon (in winter), confirming direct movement between these regions. The capture-recapture
data of four different identification features (TF, RDF, LDF and MS) from six successive subsets of data from
periods with the highest collection effort (2001 â 2007), were used to calculate the number of whales that utilise
the region, using both closed and open-population models. Since dorsal fins have never been used to estimate
abundance for humpback whales, the different identification features were evaluated for potential biases. This
revealed 9 â 14% incidence of missed matches (false negatives) when using dorsal fins that will result in an
overestimate, while variation in individual fluke-up behaviour may lower estimates due to heterogeneity of
individual capture probability, by as much as 57-69%. Taking into consideration the small dataset and low number
of recaptures, the most consistent and precise results were obtained from a fully time-dependent version of the
Jolly-Seber open-population model, with annual survival fixed at 0.96, using the MS dataset. This suggests that
the WSA feeding assemblage during the months of spring and summer of the study period numbered about 500.
The relationship of these whales to those (perhaps strictly migratory) that may occur here in other seasons of the
year, and their links to possible migratory routes and other feeding or breeding areas remain uncertain.National Research Foundation
(NRF), South Africa, under Grant Number 2047517. Earthwatch
Institute (funding), The Mazda Wildlife Fund (through the provision of a field vehicle), SASOL (through the
donation of two four-stroke engines), PADI Project AWARE (UK) (funding), the South African Navy (access to the
shore-based look-out), the Military Academy, University of Stellenbosch (accommodation) and Iziko South African
Museum (office space and support). JB gratefully received financial support in the form of bursaries from the
NRF, the Society for Marine Mammalogy, University of Pretoria, and the Wildlife Society of South Africa (Charles
Astley Maberley Memorial bursary). The Namibian Dolphin Project is supported by NACOMA (Namibian Coastal
Conservation and Management Project), the Nedbank Go Green Fund, Mohammed bin Zayed Species
Conservation Fund, the British Ecological Society, the Rufford Small Grants Foundation and the Namibia Nature
Foundation. JB and TJQC received funding from the International Whaling Commission (IWC) to conduct
between-region matching.http://www.tandfonline.com/loi/tams20nf201
Mother knows best: occurrence and associations of resighted humpback whales suggest maternally derived fidelity to a southern hemisphere coastal feeding ground
Site fidelity is common among migratory cetaceans, including humpback whales (Megaptera novaeangliae). In the Northern Hemisphere it has been found that fidelity to humpback whale feeding grounds is transferred maternally but this has never been shown for the species in the Southern Hemisphere. We examined this in a unique feeding area off west South Africa using resighting data of 68 individually identified humpback whales by means of photographic (tail flukes and dorsal fins) and/or molecular methods (microsatellite genotyping) over an 18 year span. We found short-term association patterns and recurrent visits typical of other feeding grounds. Males and females had different seasonality of attendance. Significant female-dominated presence corresponded to timing of an expected influx of females on their southward migration from the breeding ground: firstly non-nursing (possibly pregnant) females in mid-spring, and mothers and calves in mid-to late summer. The potential benefit of this mid-latitude feeding area for females is illustrated by a record of a cow with known age of at least 23 years that produced calves in three consecutive years, each of which survived to at least six months of age: the first record of successful post-partum ovulation for this species in the Southern Hemisphere. We recorded association of a weaned calf with its mother, and a recurring association between a non-lactating female and male over more than two years. Moreover, three animals first identified as calves returned to the same area in subsequent years, sometimes on the same day as their mothers. This, together with numerous Parent-Offspring relations detected genetically among and between resighted and non-resighted whales is strongly suggestive of maternally derived site fidelity at a small spatial scale by a small sub-population of humpback whales.National Research Foundation (NRF), South Africa [2047517]; PADI Project AWARE (UK) [095]; Earthwatch Institute (project title "Whales of South Africa"
Population Structure of Humpback Whales from Their Breeding Grounds in the South Atlantic and Indian Oceans
Although humpback whales are among the best-studied of the large whales, population boundaries in the Southern Hemisphere (SH) have remained largely untested. We assess population structure of SH humpback whales using 1,527 samples collected from whales at fourteen sampling sites within the Southwestern and Southeastern Atlantic, the Southwestern Indian Ocean, and Northern Indian Ocean (Breeding Stocks A, B, C and X, respectively). Evaluation of mtDNA population structure and migration rates was carried out under different statistical frameworks. Using all genetic evidence, the results suggest significant degrees of population structure between all ocean basins, with the Southwestern and Northern Indian Ocean most differentiated from each other. Effective migration rates were highest between the Southeastern Atlantic and the Southwestern Indian Ocean, followed by rates within the Southeastern Atlantic, and the lowest between the Southwestern and Northern Indian Ocean. At finer scales, very low gene flow was detected between the two neighbouring sub-regions in the Southeastern Atlantic, compared to high gene flow for whales within the Southwestern Indian Ocean. Our genetic results support the current management designations proposed by the International Whaling Commission of Breeding Stocks A, B, C, and X as four strongly structured populations. The population structure patterns found in this study are likely to have been influenced by a combination of long-term maternally directed fidelity of migratory destinations, along with other ecological and oceanographic features in the region
Patterns in the distribution and abundance of terrestrial arthropods on sub-Antartic Marion Island
Quantitative studies of complete soil arthropod communities are considered essential if a thorough understanding of the structure and dynamics of soil faunas, and their likely response to anthropogenic environmental change, is to be gained. In practice, however, high species richness and poor taxonomic knowledge for most systems often hampers the acquisition of such information. In consequence, many studies resort to the use of higher taxa or more qualitative data. Sub-Antarctic terrestrial systems which are moderately diverse with well-known faunas allow us to bridge some of these problems. Two major terrestrial habitat types (or biotopes) are distinguished on sub-Antarctic islands, namely the epilithic and vegetated biotopes. These two habitat types differ in terms of current extent of vegetational cover and age relative to previous glacial events. The epilithic biotope includes the older habitats such as rocky shores and fellfields that have escaped glaciation, have little vascular plant cover, and is cryptogamÂŹdominated. Quantitative data on the soil fauna of a fellfield habitat on sub-Antarctic Marion Island is used to illustrate the pitfalls associated with the qualitative approach. Fellfield is an important vegetation complex in the broad Antarctic region, and on Marion Island consists of both bare rocky areas and cushion plants. Soil arthropod communities in these two distinct habitat components were quantified over one year. Species richness was relatively high (42 spp.) and consisted almost exclusively of indigenous species, although abundances were lower compared with less extreme vegetation types in the sub-Antarctic. In general, arthropods either showed no pronounced seasonal peak in abundance, or a summer peak, although these patterns differed between habitat components within species, and between species. Quantitative analyses highlighted prominent differences between the two habitat components in arthropod community structure, despite the fact that most species were common to both of them. Qualitative analyses, in contrast, obscured these differences, while the use of higher taxa for analyses of seasonality resulted in abundant species generally masking the phenologies of less abundant ones. It is concluded that quantitative analyses of soil arthropod communities are essential if natural and anthropogenic changes in their structure are to be detected, monitored and understood. Studies on sub-Antarctic insects have suggested that species inhabiting the epilithic habitats exhibit higher habitat preference or specificity and also a higher incidence of biotic interactions, such as competition, than those in vegetated habitats. The Acari, a more speciose but less well studied group than the insects, is used to independently test the aspect of habitat specificity. Seventeen different habitats or zones belonging to both the epilithic and vegetated biotopes were quantitatively sampled for mites over a one year period. These included a rocky shore, mire and non-mire lowland vegetation, and a mid-altitude fellfield. Species richness across all habitats was 39 spp., while rocky shore habitats showed higher abundances, but lower species richness, and a distinct fauna, to strictly terrestrial habitats. Multivariate analyses indicated that mite assemblage structure differed significantly between all different habitat types. However, most species in the terrestrial habitats (both epilithic and vegetated) were shared, suggesting that the epilithic fellfield, and especially its vegetated component (Azorella selago cushion plants) would have been suitable refugia during glaciation. The shoreline, due to its distinct fauna, seems a less likely refuge from which recolonisation of vegetated habitats could have taken place. Most species could be considered habitat generalists, although the epilithic habitats (shore and fellfield) had more habitat specific species than the lowland vegetated habitats. Bothrometopus elongatus is one of four Ectemnorhinus-group species restricted to the epilithic biotope on the Prince Edward Islands. The biology of this species was examined over a full year at Kerguelen Rise, a mid-altitude fellfield site on Marion Island. B. elongatus adults eclose from April onwards, reaching maximum densities (c. 17 individuals.m-2) in September. Females mature approximately three eggs at a time and these commence hatching in July. Larval eclosion reaches a peak in November, during which time larval densities are also highest (c. 153 individuals.m-2). The larvae develop through six instars, which is within the range found for other Ectemnorhinus-group species. The high densities of B. elongatus in fellfield habitats, and its single, virtually discrete annual generation, make this species unusual among insects indigenous to the sub-Antarctic. The latter generally have low densities compared to other micro-arthropods, prolonged life cycles, and flexible life histories. It is suggested that the diversity of life histories found amongst the indigenous insects at Marion Island presents considerable potential for testing environmental effects on insect life histories. An overview of sub-Antarctic insect life history data suggests that the indigenous species, with generally prolonged life cycles, are at a disadvantage relative to introduced ones that have more rapid cycles and often complete several generations per year. This is reason for concern given rapid climate change at these islands.Dissertation (MSc (Zoology))--University of Pretoria, 2006.Zoology and Entomologyunrestricte
Local movements, migrations and habitat use of humpback whales off the west coast of South Africa, including observations of southern right whales
The migration of Southern Hemisphere humpback whales Megaptera novaeangliae between their
feeding and breeding areas is considered a highly predictable and seasonal event. The west coast of
Africa is host to Breeding Stock (BS) B, which has been divided into sub-stocks B1 and B2 based on
different catch histories observed between Gabon in the north, and other stations to the south â a
notion supported by recent regional genetic analysis, some samples of which were collected during
this project. It has thus been assumed that the west coast of South Africa (WSA) functions as a
migratory corridor for BS B2 whales. While catch data from Saldanha Bay in 1911-12 supported the
existence of two migration peaks, a pilot study in the spring of 1993 (the first dedicated study in over
80 years) suggested a more atypical pattern, with some whales apparently abandoning or suspending
their migration, possibly to feed. This has been complicated further by the detection of direct transits of
10 individual humpbacks through microsatellite matches between Gabon and WSA, and has raised
questions about the exact function and relationship of WSA to BS B humpback whales.
This thesis presents the results from a study based at Saldanha Bay that included shore-based
observations of whale groups during two field seasons (July â December 2001, May 2002 - February
2003), and photographic and genetic data collected during boat intercepts from 1983 to 2008. The
observed relative abundance of humpback whales again did not support a classical migration pattern,
with the highest sighting rates from mid-spring through summer. Movement patterns of humpback
groups tracked by theodolite showed mid-spring to be a turning point in their behaviour, after which
they swam significantly slower, showed an increase in ânon-directionalâ movement, and were found
farther from shore. Data on group composition and sex showed a significantly female-biased sex ratio
during mid-spring, unlike most low-latitude areas where males predominate. The individual
identification of humpback whales by means of photographs of ventral tail flukes, left and right dorsal
fins, and through microsatellites, yielded numerous resightings at intervals of a year or more,
indicating a high level of fidelity to the region and temporary residency by some individuals. Population
estimates were calculated using open and closed capture-recapture models and suggest that about
500 animals are present in the area during the spring/summer season.
Direct observation of humpback whales feeding on crustacean prey, short-term association patterns,
and the resighting of individuals participating in feeding aggregations in multiple years confirmed this
area to be a feeding ground for humpback whales during spring and summer months. Concurrent
shore-based observations on southern right whales Eubalaena australis showed that this species was
present virtually throughout the study period, also utilising feeding opportunities during summer. The
potential benefit of this mid-latitude feeding area for humpback females is illustrated by a record of a
cow that produced calves in three consecutive years, each of which survived to at least six months of
age - the first observation of post-partum ovulation for this species in the Southern Hemisphere. The
return of three known calves to the same area is strongly suggestive of maternally derived site fidelity.Thesis (PhD)--University of Pretoria, 2012.Zoology and EntomologyPhDUnrestricte