https://vital.seals.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:62730 Wed 22 Mar 2023 11:29:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62728 Wed 22 Mar 2023 11:22:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62727 Wed 22 Mar 2023 11:15:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62725 Wed 22 Mar 2023 11:08:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30521 Wed 12 Oct 2022 12:48:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20335 Wed 12 Oct 2022 12:11:07 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2999 Wed 12 Oct 2022 10:14:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:8073 Wed 12 May 2021 23:41:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:13665 Wed 12 May 2021 23:39:08 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2650 Wed 12 May 2021 23:18:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2802 Wed 12 May 2021 22:45:43 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:627 Wed 12 May 2021 22:41:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20237 Wed 12 May 2021 22:39:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:13219 Wed 12 May 2021 22:29:39 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20053 Wed 12 May 2021 22:26:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:8072 Wed 12 May 2021 22:21:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26158 Wed 12 May 2021 20:19:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2233 Wed 12 May 2021 19:15:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:37207 Wed 12 May 2021 19:14:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4826 Wed 12 May 2021 19:12:49 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34296 Wed 12 May 2021 18:57:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5174 Wed 12 May 2021 18:52:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2811 Wed 12 May 2021 18:29:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20257 Wed 12 May 2021 18:28:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5264 Wed 12 May 2021 18:15:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:21066 Wed 12 May 2021 18:02:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4660 Wed 12 May 2021 17:50:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4339 Wed 12 May 2021 17:44:25 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34349 Wed 12 May 2021 17:38:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4379 Wed 12 May 2021 17:27:55 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4351 Wed 12 May 2021 17:26:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4342 Wed 12 May 2021 17:11:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1799 Wed 12 May 2021 16:49:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:33425 Wed 12 May 2021 16:42:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2430 Wed 12 May 2021 16:35:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26162 Wed 12 May 2021 16:24:03 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:6446 Wed 12 May 2021 16:21:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3059 Wed 12 May 2021 16:05:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5001 Wed 12 May 2021 15:55:07 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:42698 Wed 12 May 2021 14:34:43 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5307 Wed 07 Jul 2021 11:21:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:63328 Tue 11 Apr 2023 09:23:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:63323 Tue 11 Apr 2023 09:02:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:63322 Tue 11 Apr 2023 08:55:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:63320 Tue 11 Apr 2023 08:41:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:63316 Tue 11 Apr 2023 08:41:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:63317 Tue 11 Apr 2023 08:34:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:57085 Thu 29 Sep 2022 22:33:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:44264 Thu 26 Aug 2021 14:23:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:6864 Thu 15 Jul 2021 21:02:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:37180 Thu 13 May 2021 16:44:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26155 Thu 13 May 2021 13:48:03 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2240 Thu 13 May 2021 08:54:47 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2636 Thu 13 May 2021 08:24:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:13425 Thu 13 May 2021 08:23:56 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2790 Thu 13 May 2021 08:23:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:13424 Thu 13 May 2021 08:04:06 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34285 Thu 13 May 2021 07:38:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20299 Thu 13 May 2021 07:03:25 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5323 1100 mm TL (7 years) and all females >1200 mm TL (8 years) were mature. Females grew faster than males, but in both sexes growth slowed dramatically after maturity. Maximum age recorded was 42 years, but fish older than 27 years were rare. Adult A. japonicus were predominantly found in the nearshore marine environment, but also occurred in estuaries and in the surf zone. Spawning takes place in the nearshore environment, from August to November in Natal, and from October to January in the Southern and South-Eastern Cape regions. A large proportion of the adult population migrate to Natal to spawn, although spawning may continue once they return to the Cape. Early juveniles of 20-30 mm TL recruit into turbid estuaries along the entire east coast, possibly aided by olfactory cues. They appear to remain in the upper reaches of the estuaries where they find suitable food and refuge from predators until they grow to about 150 mm TL. Juveniles larger than this size were found in the middle and lower reaches of estuaries and also in the surf zone. Juvenile A. japonicus (<1000 mm TL) generally did not migrate long distances, but remained as separate sub-stocks until they reached maturity. A. inodorus grows more slowly than A. japonicus, and attains a lower maximum age (25 years) and a smaller maximum size (34 vs 75 kg). There was no significant difference between the growth rates of male and female A. inodorus. Those in the South-Westem Cape initially grew faster than those on the east coast, but growth slowed sooner in the former region with the result that these fish attained a smaller maximum size. Although ripe A. inodorus were sampled throughout the year, there was a distinct spawning season from August to December, with a peak in spring (Sept-Nov). Spawning occurred throughout the study area for this species, in <50 m depth. Size at sexual maturity for A. inodorus was smaller in the South-Eastern Cape than in the Southern Cape. Median size at maturity for females was attained at 310 mm TL (1.3 years) in the former and at 375 mm TL (2.4 years) in the latter region, and the length at which all females were mature was 400 mm (3.5 years) and 550 mm (4.7 years) respectively. For males the estimates of Lso and total maturity were 200 mm (1 year) and 400 mm (2.8 years) for the SouthEastern Cape and 250 mm (1.5 years) and 450 mm (3.4 years) in the Southern Cape. East of Cape Agulhas, A. inodorus was found from just beyond the surf zone to depths of 120 m. Adults occurred predominantly on reef (>20 m) while juveniles were found mainly over soft substrata of sand/mud (5-120 m depth). Early juveniles do not enter estuaries, but apparently recruit to nursery areas immediately beyond the backline of breakers (5-10 m depth), and then move seawards with growth. No juveniles were obtained from the area west of Cape Agulhas as substrates <200 m depth were unsuitable for trawling. Due to lower water temperatures, the adults in this area were found from within the surf zone to depths of only 20 m. East and west of Cape Agulhas there was evidence of offshore dispersal in winter, in response to oceanographic changes. Based upon otolith morphology, juvenile and adult distribution patterns, sizes at sexual maturity and on tagging data, A. inodorus between Cape Point and the Kei River apparently exist as three separate stocks, one in the South-Eastern Cape, one in the Southern Cape and one in the South-Western Cape, with limited exchange. The life-histories of A. japonicus and A. inodorus are discussed in terms of their management. The large size at maturity of A. japonicus together with evidence for considerable human impact on the early juvenile, juvenile, and the adult phases of the life-cycle indicate that estuarine nursery habitats need to be conserved, that the minimum size limit should be increased, and that current bag limits for this species should be reviewed. Although the current minimum size limit provides protection for A. illodorus until maturity, evidence is presented which indicates that at least one and possibly all of the stocks of this species are currently over-exploited. Stock assessment of the South African A. japonicus and A. inodorus resources, and the implementation of effective management strategies, are therefore a matter of urgency.]]> Thu 13 May 2021 07:01:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26157 Thu 13 May 2021 06:57:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2968 Thu 13 May 2021 06:43:56 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20249 Thu 13 May 2021 06:30:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5753 0.05) within species. I conclude therefore that in these three species spermatogenesis is aseasonal. No conclusions about seasonality of spermatogenesis could be made for S. coeruleoalba owing to the small sample size. Large Graafian follicles occurred in the ovaries of all four species in most months of the year. However, the presence of Graafian follicles can not be taken as an indication of timing of reproduction since they may be remnants of follicles that have not yet degenerated. In D. delphis, T. aduncus and S. coeruleoalba luteal bodies (corpora albicans or corpora lutea) occurred in most months of the year. Active corpora lutea will be present in all months, in some members of the population, since gestation is approximately 12 months. The sperm structure of D. delphis was examined by scanning electron microscopy. The sperm of D. delphis is essentially similar to that described for two other species of Cetacea (Physeter catodon and Tursiops aduncus), having an ellipsoidally shaped head and a short mid-piece with nine mitochondria. The sperm dimensions for D. delphis were head length, 4.4pm; head width, 2.0pm and mid-piece length, 2.4pm. An analysis of foetal age in D. delphis showed that the majority of the foetuses were conceived in January with birth occurring the following summer (December), suggesting that reproduction is seasonal. Neonates of T. aduncus were found throughout the year suggesting aseasonal reproduction. Foetal material was not available for S. coeruleoalba and S. chinensis. Seasonality of reproduction in the four species of dolphins studied has been discussed in relation to feeding, migration and worldwide distribution of the species.]]> Thu 13 May 2021 06:13:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1752 Thu 13 May 2021 05:04:07 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26163 Thu 13 May 2021 05:01:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3434 Thu 13 May 2021 04:36:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5258 Thu 13 May 2021 04:06:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:8130 Thu 13 May 2021 03:42:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2097 Thu 13 May 2021 03:37:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:33857 Thu 13 May 2021 03:27:06 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26161 Thu 13 May 2021 03:15:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1807 Thu 13 May 2021 02:55:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2225 Thu 13 May 2021 02:51:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4960 Thu 13 May 2021 02:33:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4962 Thu 13 May 2021 02:16:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2781 Thu 13 May 2021 01:57:18 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5290 Thu 13 May 2021 01:39:46 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62920 Mon 27 Mar 2023 11:43:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62921 Mon 27 Mar 2023 11:36:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62919 Mon 27 Mar 2023 11:36:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62918 Mon 27 Mar 2023 11:29:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62878 Mon 27 Mar 2023 09:37:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62871 Mon 27 Mar 2023 09:17:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62861 Mon 27 Mar 2023 09:03:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62864 Mon 27 Mar 2023 09:02:49 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62860 Mon 27 Mar 2023 09:02:46 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62863 Mon 27 Mar 2023 09:02:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62862 Mon 27 Mar 2023 09:02:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62858 Mon 27 Mar 2023 08:55:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62855 Mon 27 Mar 2023 08:55:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62857 Mon 27 Mar 2023 08:55:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62853 Mon 27 Mar 2023 08:34:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62852 Mon 27 Mar 2023 08:27:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62851 Mon 27 Mar 2023 08:27:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:63164 Mon 03 Apr 2023 11:08:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:63163 Mon 03 Apr 2023 10:54:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62819 Fri 24 Mar 2023 14:58:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62818 Fri 24 Mar 2023 14:52:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62814 Fri 24 Mar 2023 14:31:09 SAST ]]>