https://vital.seals.ac.za/vital/access/manager/Index en-us 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:65772 Wed 19 Jul 2023 14:31:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5204 Wed 12 May 2021 23:59:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20011 Wed 12 May 2021 23:04:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5254 Wed 12 May 2021 23:02:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5184 Wed 12 May 2021 23:01:12 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5341 Wed 12 May 2021 22:32:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5231 37 cm TL was biased towards females. Length-at-50% sexual maturity was attained at 32.1 cm TL for females and 23.7 cm TL for males. The rate of natural mortality was estimated at 0.15 year⁻¹, while fishing mortality rates during the 1970s, 1980s and 1990s were estimated at 0.01 year⁻¹, 0.04 year⁻¹ and 0.14 year⁻¹, respectively. Gillnetting for monkfish (300 mm stretched mesh) was highly efficient with a moderate bycatch of around 20% during the two years of operation. The main bycatch species were red crab, spider crab, squalid sharks, rays and Cape and Deep-water hake. The mean length of the monkfish caught in gillnets (67 cm TL) was significantly larger than the monkfish landed by the trawlers (38 cm TL) and less than 1% of immature fish were landed. Gillnet catch-per-unit-effort for monkfish fluctuated between 0.03 and 0.67 kg.day⁻¹.50 m net panel⁻¹, with a soak time of between one and sixteen days. More than 50% (by weight) of monkfish landed by monkfish and sole trawlers, consisted of fish below 36 cm TL. There was a significant increase in catches of juvenile monkfish during 1997 and 1998 in comparison to the period 1994 to 1996. Various types of rigid sorting grids were tested to release juvenile monkfish below 32 cm TL. Five grid designs were tested. These included an “Ex-it” grid with horizontal bars spaced at 55 mm, single grids with vertical and horizontal bars spaced at 55 mm and grids with circular openings of 110 and 168 mm in diameter. The most efficient design was the grid with circular openings of 110 cm in diameter, which ensured the escape of 66% of monkfish smaller than 31 cm TL. However, studies need to be undertaken to quantify the survival of released fish and to test the feasibility of using grid sorters on commercial monkfish and sole trawling gear. The monkfish resource was assessed by means of length cohort analyses, the Thompson and Bell predictive model and by way of a deterministic age-structured production modelling approach. The length cohort analysis models were sensitive to the rate of natural mortality and insensitive to changes in the terminal fishing mortality rate. These biases may, however, not be serious provided that estimates of abundance are used to reflect relative changes. Fish ranging between 26 and 59 cm TL are the most heavily exploited. The Thompson and Bell model predicted that the monkfish resource is exploited above MSY -levels and a reduction of approximately 40% in fishing effort would provide a higher yield. Yield-per-recruit ranged between 10 000 and 14 000 tonnes. Results should, however, be treated with caution, as the condition of steady state was not satisfied. The age-structured production model was tuned using trends in catch-per-unit-effort data, estimated by Generalised Linear Modeling, as well as relative abundance indices calculated from hake biomass surveys. The model was found to be sensitive to both the ‘steepness’ parameter h and estimates of natural mortality. The ‘depletion’ level of the monkfish resource is currently estimated to be 49%. Estimated coefficients of variation were high (> 63%) due to the lack of a consistent trend within the abundance indices to tune the model. Overall productivity of the monkfish resource was estimated to be approximately 16%, similar to other southern African demersal resources. Results of the risk analyses suggest that catches in excess of 7 000 tonnes may be unsustainable and that catches of 5 000 or 6 000 tonnes would decrease the risk of stock collapse and possibly lead to a recovery in the stock. Monkfish management strategies were reviewed and these were considered in relation to the results of this study. The following management recommendations were made: to follow the precautionary approach and implement a total allowable catch for monkfish; to implement rigid sorting grids as these would be the most appropriate way in which to reduce catches of juvenile monkfish; to restrict soak time, depth of operation and implement means to reduce ‘ghost fishing’ by gillnetting and finally, to develop a management procedure for Namibian monkfish with the main objective being the sustainable exploitation of the resource.]]> Wed 12 May 2021 21:02:06 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5249 Wed 12 May 2021 20:52:43 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5209 Wed 12 May 2021 20:48:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5375 Wed 12 May 2021 20:36:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5241 Wed 12 May 2021 20:14:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:38336 Wed 12 May 2021 20:11:48 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5217 Wed 12 May 2021 20:10:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5224 0.05). The length-frequency distribution analysis revealed that the three species had the same growth rate regardless of habitat type. However, females grew faster than males. An investigation of reproductive biology showed that the three species have low fecundity and they are asynchronous spawners, with a breeding peak during August and September period. Furthermore, the length-fecundity relationships for L. ''pinkhead'', and 0. argyrosoma "red" indicated that fecundity was more closely related to length in the south eastern side than in the south western side. Based on the above characteristics of L. ''pinkhead'', 0. argyrosoma "red" and C. cf virginalis, and the substrate types, it was strongly suggested that the existing sanctuary (lightly fished) in the south eastern side of the lake could immediately be enlarged to conserve the fish stocks, favourable substratum and aquatic animals that may be of tourists concern.]]> Wed 12 May 2021 20:03:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5221 Wed 12 May 2021 20:00:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5255 Wed 12 May 2021 19:51:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:38253 0.05) results when temperature was analysed by t-test between 2002 and 2015. There was also a weak correlation between length frequency and the total squid catch in a given year (F Statistic (df = 1; 13) is 3.686 and 5.394 for males and females respectively, R² is 0.221 for males and 0.293 for females), but too weak to interpret, given the lack of other supporting data and the short time series. The ML_TW relationship showed no significant trends between the years for either sex. There was also no correlation between the ML_TW and total squid catch or temperature. A white caecum occurred significantly more often in males than in females (dof = 1; p < 0.05) from General Linear Model (GLM), indicating that the presence of non-feeding males in the spawning grounds may be linked to the behaviour of spawning squid.]]> Wed 12 May 2021 19:49:49 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5219 Wed 12 May 2021 19:45:13 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5223 Wed 12 May 2021 19:29:46 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5193 Wed 12 May 2021 19:14:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:25532 Wed 12 May 2021 19:09:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5353 Wed 12 May 2021 19:04:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5226 Wed 12 May 2021 19:02:54 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5233 Wed 12 May 2021 18:40:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26570 Wed 12 May 2021 18:40:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5355 Wed 12 May 2021 18:19:13 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5235 Wed 12 May 2021 17:51:12 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5345 Wed 12 May 2021 17:41:39 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5262 Wed 12 May 2021 17:39:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5338 Wed 12 May 2021 17:38:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5191 Wed 12 May 2021 17:38:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5250 Wed 12 May 2021 17:37:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5248 Wed 12 May 2021 17:37:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5298 Wed 12 May 2021 17:24:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5220 100 mm SL) exposed animals relied on shell thickness and adhesion to combat predators, while small (> 45 mm SL) sub-boulder animals and medium sized (50 - 95 mm SL) animals relied on their cryptic microhabitats and the protective spine canopies of co-resident urchins (Parechinus angulosus) for daytime protection. Populations of H. midae were discontinuously distributed along the coast, occupying small isolated reefs which offered a suitable array of microhabitats and a good food supply. They mostly inhabited shallow intertidal and subtidal reefs, but were occasionally encountered on deeper subtidal reefs at 4 - 5 meters. Mean length- and width-at-age were determined from growth rings composed of alternate conchiolin (dark) and aragonite (white) bands in the internal nacreous shell layer. Growth was described by the Special Von Bertalanffy growth equation: Lt(mm) = 176.998918 (1 - e⁻°·²⁴²⁴¹⁹⁽t ⁺ °·⁴⁹⁵⁴⁹⁴⁾) Wt(mm) = 159.705689 (1 - e⁻°·¹⁹⁵⁴³⁹⁽t ⁺ °·²¹¹⁶⁾) The ageing technique used was validated for animals from Great Fish Point and Mgwalana using independent tag-return data. The same data provided evidence that growth rates varied between animals from Great Fish Point and Bird Island. The growth data also showed that H. midae exhibited a high degree of individual variation in growth rate. Males and females exhibited similar growth rates. Exposed large animals showed a preference for red seaweeds, in particular Plocamium corallorhiza and Hypnea spicifera, while small sub-boulder cryptic animals included larger proportions of brown (Ralfsia expansa) and green (VIva spp.) algae in their diets. Exposed individuals also exhibited a higher degree of selectivity towards prey items, but in general, stomach contents reflected the most abundant seaweed types. Both drift and attached algal species were utilized by H. midae which was a nocturnal feeder. Pigments from red algae were incorporated into the shell layers giving the shells a pink or brick red colour. Haliotis midae is a dioecious broadcast spawner. Gonad Bulk Indices in combination with detailed histological examination of gonads showed that individuals were iteroparous, asynchronous spawners and that the breeding season extended from March through to October, although the peak spawning activity was between April and June. Males and females can spawn partially, totally or not at all, with atresia of residual gametes occurring after spawning. There is no resting stage, and gametogenesis is initiated directly after spawning. The structure of the ovary and testis and the process of gametogenesis is typical of haliotid species. AI: 1 sex ratio was observed from all populations studied. Sexual maturity was first attained in the 40 - 59 mm SL size class, although evidence for the smallest size at first spawning was recorded at 54.6 mm SL for females and 69 mm SL for males. Sizes at 50% sexual maturity were 72.5 mm SL (52.8 mm SW) at Great Fish Point, 72.5 mm SL (57.4 mm SW) at Mgwalana, 73.7 mm SL (51.2 mm SW) at Cape Recife, and 73.5 mm SL (53.8 mm SW) at Kelly's Beach. Haliotis midae was typically highly fecund, although a high degree of variation resulting in poor relationships between fecundity/shell length and gonad weight/shell length. The relationship between fecundity and gonad weight was linear. In the Eastern Cape, H. midae possessed a faster growth rate, smaller size at sexual maturity, smaller maximum size and lower longevity when compared to con specifics in Western Cape waters. A smaller minimum legal size of 93 mm SW is proposed for Eastern Cape animals and it is suggested that the closed season be moved to the peak spawning period between April and June. The benefit of a closed season during the spawning period is questioned, and the feasibility of closed areas as a management option for H. midae in the Eastern Cape is discussed.]]> Wed 12 May 2021 16:44:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5181 Wed 12 May 2021 16:42:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:24014 Wed 12 May 2021 16:35:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5236 Wed 12 May 2021 16:33:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5246 Wed 12 May 2021 16:23:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5229 0.05) amount of variability (63%) was explained by a predictive model incorporating these variables as investigations were constrained by small sample sizes and aggregated catch information. Scientific survey data provided multi-species information and highlighted the high proportion of non-native fish species in Eastern Cape impoundments. Gillnet catches were influenced primarily by species composition and were less subject to fluctuations induced by environmental factors. Overall standardised gillnet CPUE was influenced by surface area, conductivity and age of impoundment. Although the model fit was not significant at the p<0.05 level, 23% of the variability in the data was explained by a predictive model incorporating these variables. The presence of species which could be effectively targeted by gillnets was hypothesised to represent the most important factor influencing catch rates. Investigation of factors influencing CPUE in impoundments dominated by Clarias gariepinus and native cyprinids indicated that warmer, younger impoundments and smaller, colder impoundments produced higher catches of C. gariepinus and native cyprinids respectively. A predictive model for C. gariepinus abundance explained a significant amount of variability (77%) in CPUE although the small sample size of impoundments suggests that predictions from this model may not be robust. CPUE of native cyprinids was influenced primarily by the presence of Labeo umbratus and constrained by small sample size of impoundments and the model did not adequately explain the variability in the data (r² = 0.31, p>0.05). These results indicate that angling catch- and scientific survey data can be useful in providing predictions of fish abundance that are biologically realistic. However, more data over a greater spatial scale would allow for more robust predictions of catch rates. This could be achieved through increased monitoring of existing resource users, the creation of a centralised database for catch records from angling competitions, and increased scientific surveys of South African impoundments conducted by a dedicated governmental function.]]> Wed 12 May 2021 16:19:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5234 0.05) between slopes of the control and 0.11 ± 0.02 mg/l Cu, and between 0.29 ± 0.02 and 47 ± 0.04 mg/l Cu before and after introducing food in the tanks. The slopes of both the control and 0.11 ± 0.02 mg/l Cu were significantly different from those of 0.29 ± 0.02 and 0.47 ± 0.04 mg/l Cu (p < 0.05). There were significant differences in the mean opercular movements per minute between treatments (p < 0.05). There was hyperventilation at 0.11 ± 0.02 mg/l Cu i.e. 87 ± 18 opercular movements per minute (mean ± standard deviation) and hypoventilation at 0.29 ± 0.02 and 0.47 ± 0.04 mg/l Cu i.e. 37 ± 34 and 13 ± 6 opercular movements per minute compared to the control. Hypo- and hyperventilation were related to the lesser and greater gill damage, respectively. In conclusion Cu accumulation and effects on histology of the liver, gills and were related to the concentration of Cu in the water and duration of exposure showing a gradual increase in incidence and intensity with larger duration of exposure time and increasing Cu concentration. The fish were initially able to homeostatically regulate and detoxify Cu. However, as the exposure continued, the homeostatic mechanism appears to have failed to cope with the increasing metal burden causing advanced histological changes.]]> Wed 12 May 2021 15:54:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5179 Wed 12 May 2021 15:49:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5252 Wed 12 May 2021 15:44:24 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:41462 Wed 12 May 2021 15:10:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:41506 Wed 12 May 2021 14:11:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:41357 Wed 12 May 2021 14:00:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:45147 Wed 11 May 2022 12:11:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:42814 0.05; df = 2). However, mortalities were high and growth rates low, indicating that the rearing conditions were sub-optimal, possibly masking genetic differences. No significant differences were observed in oxygen consumption rates (ANOVA, P = 0.18; df = 2), and CTM (t-Test, P = 0.31; df = 3) between the two populations. The CTM for both populations was between 29 - 30℃. The farm trial yielded no significant differences in growth rate during the Nursery phase (t-Test, P = 0.25; df = 2), however significant differences in growth rate were observed during the grow out phase with the Central region abalone offspring growing faster than the Eastern edge population (t-Test, P = 0.04; df = 4) indicating the possibility of a genetic difference between the two populations. Further experiments will be required to determine whether the differences observed in the growth trial were genetically or environmentally induced.]]> Tue 18 May 2021 14:45:49 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:45054 0.05), with the overall population growth curve being best described as L(t) = 697.15(1-e-0.06(t-6.30)). Males matured at a slightly larger size than females, however, no significant differences were observed (LRT, p > 0.05). The length- and age- at-50% maturity was 330 mm (FL) and 5.73 years for the full population, respectively. Histological analyses showed that Oplegnathus conwayi are asynchronous spawners with a gonochoristic reproductive style. Macroscopic staging and gonadosomatic index results indicated a protracted spawning season for Oplegnathus conwayi, with a peak in spring. A survey was designed and disseminated to collect FEK on the biology and population status of Oplegnathus conwayi and human dimension information on South Africa’s spearfishery. A total of 103 survey responses were received, of which 94 were regarded as specialised (spearfishers who had greater experience, skill and avidity, and maintained spearfishing as an important component of their lifestyle) spearfishers. Based on the responses of the specialist spearfishers, the top four main species caught by spearfishers from this survey were Seriola lalandi (13.9%), Pachymetopon grande (11.7%), Oplegnathus conwayi (11.4%) and Sparodon durbanensis (11%), and the majority of respondents indicated that there had been no changes in abundance, size and catches of these species in the years that they had been spearfishing. Respondents indicated that Oplegnathus conwayi are most commonly targeted in the Eastern Cape and are found at depths of up to 40 m. Respondents also indicated that there may be a seasonal onshore (Summer/Winter) and offshore (Summer/Winter) migration with year-round spawning and a peak in November, December and January. The incorporation of spearfishers into the data collection, both through the collection of specimens and their FEK, was beneficial to this study. Besides providing samples from a broader geographical range than the primary collection area, the collaboration with spearfishers has promoted the inclusion of this group into the management system. The findings of this study also suggest that FEK data can be more reliable if the concept of recreational specialisation is incorporated into data collection. While the FEK suggested that the population was stable, a stock assessment is necessary to fully understand the population status and implement management strategies. Nevertheless, the key life history characteristics (slow growth and late maturation) observed in this study are characteristic of species that is vulnerable to overexploitation, and thus the precautionary approach should be applied. The reproductive information collected in this study has provided information for the implementation of an appropriate size limit regulation for Oplegnathus conwayi. Here, a minimum size limit of 400 mm TL, which corresponds approximately with the length-at-50% maturity of 330 mm FL, would be appropriate to allow fish to mature and spawn, and reduce the likelihood of recruitment overfishing. Reduction in the bag limit from five to two fish per person per day may also be appropriate as a precautionary measure until a stock assessment has been completed. Finally, the incorporation of stakeholder into biological collection and the use of FEK may be a useful approach for other data deficient species and in countries with limited resources for ecological research.]]> Thu 29 Sep 2022 14:29:54 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30599 Thu 29 Sep 2022 14:23:25 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5389 Thu 29 Sep 2022 14:19:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:42759 10 m depth) and inshore sites (intertidal surf zones). Many sites in the bay, especially the atypical site at Cape Recife, exhibit higher than the average pH levels (>8.04), suggesting that pH variability may be biologically driven. This is further evidenced by high diurnal variability in pH (~0.55 pH units). Although the specific drivers of the high pH variability in Algoa Bay could not be identified, baseline carbonate chemistry conditions were identified, which is necessary information to design and interpret biological experiments. Long-term, continuous monitoring is required to improve understanding of the drivers of pH variability in understudied coastal regions, like Algoa Bay. A local fisheries species, D. capensis, was selected as a model species to assess the impacts of future OA scenarios in Algoa Bay. It was hypothesized that this temperate, coastally distributed species would be adapted to naturally variable pH conditions and thus show some tolerance to low pH, considering that they are exposed to minimum pH levels of 7.77 and fluctuations of up to 0.55 pH units. Laboratory perturbation experiments were used to expose early postflexion stage of D. capensis to a range of pH treatments that were selected based on the measured local variability (~8.0–7.7 pH), as well as future projected OA scenarios (7.6–7.2 pH). Physiological responses were estimated using intermittent flow respirometry by quantifying routine and active metabolic rates as well as relative aerobic scope at each pH treatment. The behavioural responses of the larvae were also assessed at each pH treatment, as activity levels, by measuring swimming distance and speed in video-recording experiments, as well as feeding rates. D. capensis had sufficient physiological capacity to maintain metabolic performance at pH levels as low as 7.27, as evidenced by no changes in any of the measured metabolic rates (routine metabolic rate, active metabolic rate, and relative aerobic scope) after exposure to the range of pH treatments (8.02–7.27). Feeding rates of D. capensis were similarly unaffected by pH treatment. However, it appears that subtle increases in activity level (measured by swimming distance and swimming speed experiments) occur with a decrease in pH. These changes in activity level were a consequence of a change in behaviour rather than metabolic constraints. This study concludes, however, that based on the parameters measured, there is no evidence for survival or fitness related consequences of near future OA on D. capensis. OA research is still in its infancy in South Africa, and the potential impacts of OA to local marine resources has not yet been considered in local policy and resource management strategies. Integrating field monitoring and laboratory perturbation experiments is emerging as best practice in OA research. This is the first known study on the temperate south coast of South Africa to quantify local pH variability and to use this information to evaluate the biological response of a local species using relevant local OA scenarios as treatment levels for current and near future conditions. Research on local conditions in situ and the potential impacts of future OA scenarios on socio-economically valuable species, following the model developed in this study, is necessary to provide national policy makers with relevant scientific data to inform climate change management policies for local resources.]]> Thu 29 Sep 2022 12:42:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28707 Thu 13 May 2021 16:40:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5253 Thu 13 May 2021 10:49:07 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5232 Thu 13 May 2021 10:47:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5349 Thu 13 May 2021 09:16:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:25445 Thu 13 May 2021 08:50:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5201 Thu 13 May 2021 07:12:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5348 Thu 13 May 2021 06:58:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5227 Thu 13 May 2021 06:47:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5366 Thu 13 May 2021 06:43:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5261 4 ‰). In addition, it was determined that river flow rate during the month prior to sampling also had a profound effect on species composition in all three regions. Based on the available evidence it is suggested that for most species this is related to conductivity levels rather than flow per se.]]> Thu 13 May 2021 06:39:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5222 Thu 13 May 2021 06:30:12 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5365 Thu 13 May 2021 06:25:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:29391 Thu 13 May 2021 06:19:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20023 Thu 13 May 2021 06:09:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:21103 Thu 13 May 2021 05:59:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5306 Thu 13 May 2021 05:34:12 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5242 Thu 13 May 2021 05:30:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5190 Thu 13 May 2021 05:18:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5372 Thu 13 May 2021 05:05:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:38102 Thu 13 May 2021 04:58:25 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5225 Thu 13 May 2021 04:31:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5230 Thu 13 May 2021 04:24:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5378 Thu 13 May 2021 04:05:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5216 Thu 13 May 2021 03:59:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5356 Thu 13 May 2021 03:55:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5342 Thu 13 May 2021 03:31:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5376 Thu 13 May 2021 03:14:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5245 Thu 13 May 2021 03:09:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5340 Thu 13 May 2021 02:40:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28154 Thu 13 May 2021 02:39:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5291 0.05). Protein (p<0.0001) and energy (p<0.0.1) levels of suspended solids were significantly greater in raceways dedicated to feeding Abfeed. The infestation level (number of tubes/centimetre on the grwoing edge) was significantly higher (p<0.001) in Abfeed-fed abalone. The morphometrics of the sabellids indicated that sabellids from Abfeed-fed abalone were larger in various body measurements: length (p<0.00001); neck width (p<0.001); base width (p<0.001); and surface area (p<0.001). This study suggests that abalone diet has an important influence on the infestation level and size of sabellids and that this is likely to be due to the fragmentation and leaching of nutrients from the artificially enriched commercial abalone diet.]]> Thu 13 May 2021 02:34:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:38658 Thu 13 May 2021 02:30:12 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5187 Thu 13 May 2021 02:04:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5385 Thu 13 May 2021 01:52:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5194 Thu 13 May 2021 01:39:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5208 Thu 13 May 2021 01:36:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5215 Thu 13 May 2021 01:34:54 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5347 Thu 13 May 2021 01:31:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5259 Thu 13 May 2021 01:01:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5214 5 years) based on the F₀·₁ harvesting strategy. It is, therefore, recommended that the age-at-capture should be increased from 2.67 to 5 years to optimise yield.]]> Thu 13 May 2021 00:58:55 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5218 Thu 13 May 2021 00:48:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:71930 Thu 04 Apr 2024 18:57:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:71929 Thu 04 Apr 2024 18:50:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:71928 Thu 04 Apr 2024 17:34:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:72146 Sat 20 Apr 2024 16:17:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28660 Mon 24 Apr 2023 08:33:54 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:45340 Mon 22 Nov 2021 15:55:03 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:50004 Mon 10 Oct 2022 08:02:20 SAST ]]>