Ovarian atresia in cephalopods

Ovarian atresia is described for the first time in cephalopods. Detailed histological examination of ovaries of Loligo vulgaris reynaudii in various stages of maturity revealed atresia in primary, previtellogenic and vitellogenicoocytes. These were analysed separately. Previtellogenic and vitellogenic oocytes could be subdivided into five clear stages, whereas primary atretic oocytes are given a general description. Follicular atresia lowers the number of maturing and mature eggs in the ovary, so previous fecundity estimates for cephalopods may have been too high. To correct potential fecundity estimates for losses arising from atresia, it is necessary to estimate the duration of each atresia stage in relation to the total spawning period

COMMERCIAL FISHING RIGHTS ALLOCATION IN POST-APARTHEID SOUTH AFRICA: RECONCILING EQUITY AND STABILITY

No Abstract.African Journal of Marine Science Vol.25(1) 2003: pp. 25-3

Early post-cleavage stages and abnormalities identified in the embryonic development of chokka squid eggs Loligo vulgaris reynaudii

Six early, post-cleavage embryonic stages for chokka squid Loligo vulgaris reynaudii eggs that were developed in an aquarium are identified and described, expanding the embryonic stages for this species from 14 to 20. The influence of water temperature on embryonic development is described. At temperatures 15&#176C, high percentages of morphological abnormalities were observed in embryonic development. Gross forms are described and illustrated.Keywords: abnormalities, aquarium, embryonic development, chokka squidAfrican Journal of Marine Science 2002, 24: 379–38

The biology of the skates raja wallacei and r.pullopunctata (batoidea: rajidae) on the Agulhas bank, South Africa

Aspects of the biology of Raja wallacei and R. pullopunctata were investigated using data collected in 1995 and 1996 from research and commercial trawls on the Agulhas Bank, South Africa. Age and growth parameters were investigated by examination of bands on the vertebral centrum. Estimates of Von Bertalanffy parameters for R. wallacei were L‡ = 405.40 mm disc width (DW), K = 0.27 and t0 = . 0.08 years for males and L‡ = 435.23 mm DW, K = 0.26 and t0 = .0.21 years for females. For R. pullopunctata, the estimates were L‡ = 770.50 mm DW, K = 0.10 and t0 = .2.37 years for males and L‡ = 1 326.75 mm DW, K = 0.05 andt0 = .2.20 years for females. Growth was significantly different between sexes for both species. The oldest aged R. wallacei and R. pullopunctata were 15 and 18 years respectively. The length at first maturity was approximately 350 mm DW or 7 years of age for R. wallacei and 600 mm DW or 9 years of age for R. pullopunctata. The length-at-50% maturity for R. wallacei was 395 mm DW for males and 400 mm DW for females. R. wallacei fed primarily on benthic teleosts and crustaceans. There were significant differences (p < 0.05) in the diet between research- and commercially caught fish, in terms of percentage frequency of occurrence and volume of prey

A survey of the South African shore-angling fishery

Roving creel surveys and aerial surveys of shore-angling were undertaken as part of a national investigation into linefishing in South Africa. Shore patrols utilized a random stratified sampling procedure to collect catchand-effort data, and a questionnaire provided information on fishing effort, angler demographics, economics and attitudes towards current regulations. A total of 1 677 patrols, covering 19 616 km, was conducted betweenApril 1994 and February 1996, during which period 9 523 anglers had their catches checked and 4 490 were interviewed. A further 16 497 km were covered by aerial surveys, when 22 609 anglers were counted. Fromthe aerial surveys, angler densities were highest on the KwaZulu-Natal coast (4.65 anglers.km–1), followed by the Southern Cape coast (2.29 anglers.km–1), the Eastern Cape coast (0.36 anglers.km–1) and the WestCoast (0.12 anglers.km–1). Catch rates varied from 1.5 kg.angler –1.day–1 on the Southern Cape coast to 0.45 kg.angler–1.day–1 on the KwaZulu-Natal coast. Total effort was estimated at 3.2×106 angler days.year–1 and the total catch was estimated at 4.5×106 fish.year–1 or 3 000 tons.year–1. Targeted species varied regionally, with elf Pomatomus saltatrix (29%) being the most sought after species on the KwaZulu-Natal coast, kob Argyrosomus japonicus (18%) on the Eastern Cape coast and galjoen Dichistius capensis on the Southern Cape coast (30%) and along the West Coast (50%). The catch composition by mass was dominated byP. saltatrix on the KwaZulu-Natal coast (29%), the Eastern Cape coast (26%), and on the Southern Cape coast (56%) and by white stumpnose Rhabdosargus globiceps (40%) on the West Coast. Although anglersgenerally supported the regulations currently governing the linefishery, the questionnaire results showed that knowledge and compliance of them was poor. A low level of law enforcement was found, except for inKwaZulu-Natal. Management of the linefishery is discussed in relation to the findings of this study

Assessment of resource availability and sustainability for subsistence fishers in South Africa, with a review of resource management procedures

The availability of resources and their suitability for subsistence and small-scale commercial fishers in South Africa were assessed and appropriate options for the management of resources recommended. Assessment of current resource utilization and recommendations for future subsistence and/or small-scale commercial use were based on information gathered during a nationwide survey of 144 subsistence fishing communities in South Africa and a review of relevant published and unpublished literature. Current patterns of resource use in three regions of the coast (West, South and East coasts) revealed that most true subsistence fisheries occur in the eastern half of the country. These fisheries are primarily focused on invertebrate species found on intertidal rocky shores and sandy beaches, or in estuaries. Fish are harvested by rod or handline, netting or traditional fishing methods (fishtraps, spearing, baited baskets). No “new” or previously underutilized resources were identified as suitable for subsistence fishing in any of the three regions. The potential for several new small-scale commercial fisheries was identified, but the need to retain certain resources for subsistence fisheries (rather than converting them to small-scale commercial fisheries) was evident in certain areas. Resources with high commercial value were not considered suitable for subsistence fishing, but rather for the introduction of small-scale commercial fisheries. The overall management strategy for the subsistence sector, which is currently in the process of being developed, must ensure sufficient flexibility to be able to take into account regional and site-specific requirements. It will also need to develop co-management structures, protect traditional fishing practices, avoid user conflict and provide for no-take areas, all within the framework of sustainable resource utilization.Keywords: estuarine resources, fisheries management, intertidal resources, subsistence fisheries, subtidal resourcesAfrican Journal of Marine Science 2002, 24: 489–50

An economic valuation of the South African linefishery

Economic data collected during 1995 and 1996 in a national survey of shore-anglers and skiboat fishermen is used to provide an economic assessment of aspects of recreational, subsistence and commercial linefishing on the South African coastline. Results show that more than 90% of shore-anglers have incomes which lie in the highest two quintiles of the distribution of incomes, and tha

Spatial patterns in the biology of the chokka squid, Loligo reynaudii on the Agulhas Bank, South Africa

Although migration patterns for various life history stages of the chokka squid (Loligo reynaudii) have been previously presented, there has been limited comparison of spatial variation in biological parameters. Based on data from research surveys; size ranges of juveniles, subadults and adults on the Agulhas Bank were estimated and presented spatially. The bulk of the results appear to largely support the current acceptance of the life cycle with an annual pattern of squid hatching in the east, migrating westwards to offshore feeding grounds on the Central and Western Agulhas Bank and the west coast and subsequent return migration to the eastern inshore areas to spawn. The number of adult animals in deeper water, particularly in autumn in the central study area probably represents squid spawning in deeper waters and over a greater area than is currently targeted by the fishery. The distribution of life history stages and different feeding areas does not rule out the possibility that discrete populations of L. reynaudii with different biological characteristics inhabit the western and eastern regions of the Agulhas Bank. In this hypothesis, some mixing of the populations does occur but generally squid from the western Agulhas Bank may occur in smaller numbers, grow more slowly and mature at a larger size. Spawning occurs on the western portion of the Agulhas Bank, and juveniles grow and mature on the west coast and the central Agulhas Bank. Future research requirements include the elucidation of the age structure of chokka squid both spatially and temporally, and a comparison of the statolith chemistry and genetic characterization between adults from different spawning areas across the Agulhas Bank

Recommendations for the management of subsistence fisheries in South Africa

This paper summarizes recommendations for the management of previously marginalized and neglected subsistence fisheries in South Africa. The recommendations stem from the activities and analyses of a task group appointed by Government and mandated to provide advice about management of the new fishing sector. The following focus areas were identified for attention: planning for implementation; definitions of subsistence fishers and other sectors; assessment and categorization of resources; determination of types of fishing activities; zonation; management systems; training; communication mechanisms; application and allocation procedures; compliance processes; research and monitoring; development of institutional capacity. Subsistence fishers were defined as poor people who personally harvest marine resources as a source of food or to sell them to meet basic needs of food security; they operate on or near to the shore or in estuaries, live in close proximity to the resource, consume or sell the resources locally, use low-technology gear (often as part of a long-standing community-based or cultural practice), and the resources they harvest generate only sufficient returns to meet basic needs of food security. A second group of informal fishers was identified that fishes for profit but cannot be equated to large industrial fisheries, and a new sector was proposed to accommodate these artisanal “small-scale commercial” fishers. Resources were classified for use by these different sectors based on accessibility, fishing methods, cash value and sustainability. In all, 12 different categories of subsistence and small-scale commercial fisheries were identified, and a preliminary list of resource species suitable for different fishing sectors is presented. A multi-tiered institutional management structure is recommended, with the national agency (MCM) controlling issues of national concern, and supporting and coordinating the activities of provincial and local structures. The management agents required for effective implementation were identified and include a dedicated national Subsistence Fisheries Management Unit, provincial management agencies that have the capacity to be delegated authority, Regional Fieldworkers, an independent Advisory Group for Subsistence Fisheries Management, local comanagement structures, and community monitors responsible for observing and recording fishing activities and catches. Co-management, involving both authorities and users in joint management, is advocated in preference to previous top-down approaches, because of its potential to improve communication and compliance.Keywords: coastal zonation, fisheries management, fisheries rights, subsistence fisheriesAfrican Journal of Marine Science 2002, 24: 503–52

The process of developing a management system for subsistence fisheries in South Africa: recognizing and formalizing a marginalized fishing sector in South Africa

Subsistence fishers were first recognized as a formal fishing sector in South Africa when new fishing legislation, aimed at redressing past inequalities, was enacted in 1998. Little information was available about these fishers, their activities, and the resources upon which they rely. Recognizing the imperative to gain an understanding of the fishers and to consult broadly, the national agency responsible for the management of marine living resources, Marine and Coastal Management (MCM) of the Department of Environmental Affairs and Tourism, appointed a Subsistence Fisheries Task Group (SFTG) in December 1998 to provide advice on the implementation of appropriate management systems for subsistence fisheries. This paper describes the process followed to formulate recommendations that were presented by the SFTG to MCM in February 2000. The activities of the SFTG fell into two categories: research aimed at identifying subsistence fishers and gaining an understanding of their activities and socio-economic profiles; and consultation aimed at ensuring that the needs and aspirations of fishers and the experience of local managers were incorporated. Research included both field-based studies and synthesis of information about comparative fisheries elsewhere. Consultation took the form of local interviews and focusgroup discussions, meetings with fishers and a national workshop. A pivotal activity was the development of a clear definition and qualifying criteria for subsistence fishers. A significant outcome was the identification of a separate small-scale commercial sector, previously erroneously lumped with subsistence fishers. Needs of fishers and problems identified during the process provided the basis for recommendations in the following areas: definitions, assessment and categorization of resources, management systems, communication mechanisms, application and allocation procedures, capacity building, compliance, research and monitoring, and funding and staff required for the management of this new sector. An evaluation is made of the opportunities presented by the SFTG process, constraints experienced and lessons learnt, giving important insights that are applicable to other similar processes, yet seldom documented in formal literature. Keywords: management of fisheries, subsistence fisheriesAfrican Journal of Marine Science 2002, 24: 405–42