The chokka squid, Loligo vulgaris reynaudii, is a commercially important species supporting a large, high-value export fishery for South Africa. This study reviewed its population dynamics and reproductive biology. Biological information collected on biannual research cruises from September 1986 to April 1999 on the Agulhas Bank as well as information from commercial vessels operating in the inshore environment collected between April 1988 and July 1989 and again between June 1999 and May 2000 were analysed. Size ranges of juveniles, subadults and adults were calculated and used to determine seasonal distribution and abundance patterns. Based on Gonadosomatic Indices (GSI) and percentages of mature squid in each month, two peak reproductive seasons in summer and winter were identified although mature squid were present all year round. Seasonal peaks in sex ratio were also apparent with males outnumbering females by up to 4:1 in the peak-breeding season. The size at which squid matured, demonstrated both spatial and temporal patterns. Squid caught in spring matured at a smaller size than squid caught in autumn and at successively smaller sizes from west to east across the Agulhas Bank. Size at maturity was highly variable especially in males where “sneaker males” were evident in both seasons. Length-to-weight linear regression revealed significant differences between maturity stages and between sexes. Females demonstrated steeper length-to-weight regression slopes than males in the peak-breeding seasons. Aspects of squid biology pertinent to fishery management were highlighted as well as potential areas where research should be directed in order to develop future stock assessment models.

The objective of this thesis is to analyse the management and redistribution policies implemented in the South African squid industry. This is done within the broader context of fisheries policies that have been implemented within the South African fishing industry as the squid industry has developed. The study therefore has an institutional basis, which reviews the development of institutional mechanisms as they have evolved to deal fisheries management problems. These mechanisms (which can either be formal or informal) consist of committees, laws and constitutions that have developed as society has progressed. Probably the most prominent of these, in terms of current fisheries policy, is the Marine Living Resources Act (MLRA) of 1998. The broad policy prescription of the MLRA basically advocates the sustainable utilisation of marine resources while outlining the need to restructure the fishing industry to address historical imbalances and to achieve equity. It is this broad objective that this thesis applies to the squid fishery. The primary means of achieving the above objective, within the squid industry, has been through the reallocation of permit rights. These rights also provide the primary means by which effort is managed. A disruption in the rights allocation process therefore has implications for resource management as well. Permits rights can be described as a form of use right or propertY right. These rights are structured according to their operational-level characteristics, or rules. Changing these rules can thus affect the efficiency or flexibility of a rights based system. This is important because initial reallocation of rights, by the Department of Environmental Affairs and Tourism (DEAT), was based on an incomplete set of rights. This partly led to the failure of early redistribution attempts resulting in a "paper permit" market. Nevertheless, this thesis argues that redistribution attempts were based on ill-defined criteria that contributed to the failure described above. In addition to this the method through which redistribution was attempted is also questionable. This can be described as a weak redistribution strategy that did not account for all equity criteria (i.e. factors like capital ownership, employment or relative income levels). This thesis thus recommends, among other things, that an incentive based rights system be adopted and that the design of this system correctly caters of the operational-level rules mentioned above. In addition to this a strong redistribution, based on fishing capital, ownership, income and the transfer of skills, should be implemented. / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in

It was previously thought that the South African chokka squid Loligo reynaudi is exclusively an inshore, shallow water spawner. Although spawning mostly within shallow bays (<60 m) the presence of squid eggs in trawls at depths up to 130 m indicates this species frequently makes use of deeper spawning areas on the mid-shelf. The extent of mid-shelf spawning (referred to as deep spawning) and the contribution to recruitment has yet to be assessed. Studies have shown mid-shelf bottom temperature to vary considerably from those inshore, suggesting chokka squid spawn in two very different oceanographic environments. Considering these apparent environmental differences, what leads to the mid-shelf environment becoming a suitable spawning habitat? Does a suitable benthic habitat, required for the attachment of egg pods, occur on the mid-shelf? These questions are not only important for determining the extent of deep spawning, but also to the understanding of factors “driving” deep spawning. The fate of deep spawned hatchlings is another unknown. It has been proposed that the main chokka squid inshore spawning grounds are positioned to exploit the net westward currents on the Eastern Agulhas Bank, i.e. paralarvae would be transported west from the hatching site to the cold ridge, an area of high primary and secondary productivity on the Central Agulhas Bank. This concept has come to be known as the Western Transport Hypothesis. Lagrangian ROMS-IBMs (regional ocean model system – individual-based model) predict the net westward transport of paralarvae from both the inshore and deep spawning grounds, to the cold ridge. These simulations were used to investigate the transport of hatchlings to the cold ridge feeding grounds before the exhaustion of yolk reserves. The fate of paralarvae on reaching the feeding grounds has not yet been investigated. This work has contributed new knowledge to our understanding of deep spawning and its role in recruitment. Specific aims of this study were to (1) determine the extent, range and importance of the deep spawning grounds relative to those inshore; (2) investigate the deep spawning ground habitat (Agulhas Bank mid-shelf) morphology and oceanographic environment; (3) determine the transport and survival of deep spawned hatchlings; and (4) investigate the origin and distribution of chokka squid paralarvae on the Agulhas Bank. The extent, depth range and importance of the deep spawning grounds, relative to those inshore was assessed using 23 years of demersal trawl survey data. Data for both the west and south coasts of South Africa were examined for egg capsules. No spawning was found on the west coast. Data showed that chokka squid preferred the Eastern Agulhas Bank for spawning. Spawning occurred not only inshore but also on the mid-shelf extending to depths of 270 m near the shelf edge. The majority of deep spawned eggs however, were found in the depth range 71-130 m. Squid egg density markedly decreased beyond 70 m, suggesting delineation between the inshore and deep spawning grounds. Total egg biomass calculations for depths shallower and deeper than 70 m indicated the coastal area to be strongly favoured, i.e. 82 vs. 18%. These results contest the commonly accepted notion that chokka squid is an inshore spawner and redefine the spawning grounds to extend across the shelf. Apart from an initial study investigating bottom temperature on the mid-shelf, very little is known about the deep spawning habitat. St Francis Bay, a commonly used spawning location, was chosen as a demonstration area for further study. The deep spawning grounds (71-130 m) were mapped and benthic habitat described from underwater video footage. A study investigating cross-shelf bottom conditions was undertaken off Thys Bay. CTD data were used to compare seasonal bottom temperature and oxygen on the St Francis Bay inshore and deep spawning grounds. Squid movement between the two spawning habitats was assessed using filament tagging. Predation and fishing pressure across the spawning grounds was reviewed. The mid-shelf benthic habitat was found to be similar to that inshore and available for spawning. Despite the generally colder bottom temperatures on the mid-shelf, this study showed that bottom temperature in deeper waters can at times be warmer than inshore. Although mid-shelf warming events lasted from a few hours to a number of days, they resulted in similar conditions to those on the inshore spawning grounds. It is likely these events act to expand or shift spawning habitat. The movement of squid between the two spawning habitats makes it possible for them to seek patches of warm bottom water with appropiate substrate. This suggests they are spawning habitat opportunists. Predation and fishing pressure appear to be higher on the inshore spawning grounds. It is feasible that this also forces spawners to seek out more favourable habitat offshore. An individual-based model was used to predict the fate of mid-shelf and inshore hatched paralarvae. Within the model, both the highly productive cold ridge and inshore spawning grounds were considered feeding or nursery areas. Paralarvae were released from six inshore and six deep spawning sites, spanning the coast between Port Alfred and Knysna. All paralarvae not reaching the feeding areas before the exhaustion of yolk-reserves (≤5 days), not retained within the feeding grounds (≥14 days), and not retained on the Agulhas Bank after exiting the feeding grounds were considered lost. This work illustrated the dependence of paralarval transport success on both spawning location and time of hatching, as established in earlier studies. The current IBM has expanded on initial work, emphasizing the importance of the cold ridge and inshore spawning grounds as nursery areas for deep and inshore spawned paralarvae, respectively. This work has highlighted the complex interactions between processes influencing recruitment variability for chokka squid. Possible relationships between periods of highest recruitment success and spawning peaks were identified for both spawning habitats. Based on the likely autumn increase in deep spawning off Tsitsikamma, and the beneficial currents during this period, it can be concluded deep spawning may at times contribute significantly to recruitment. This is particularly true for years where the cold ridge persists into winter. Data on chokka squid paralarval distribution are scarce. Paralarval distribution and abundance, in relation to Agulhas Bank oceanography, was investigated using bongo caught paralarvae and corresponding oceanographic data. Individual-based models (IBMs) were used to predict the origin or spawning site of the wild caught paralarvae, with reference to inshore versus deep spawning. Although failing to predict realistic points of origin, this study provided evidence to support a number of scenarios previously assumed to influence chokka squid recruitment. First is the possible influence of coastal upwelling on the retention, and hence spatial distribution, of paralarvae on the inshore spawning grounds. The second factor thought to impact recruitment is the loss of paralarvae from the Agulhas Bank ecosystem. This study confirmed the removal of paralarvae from the Eastern Agulhas Bank due to Agulhas Current boundary phenomena and resultant offshelf leakage. In addition, data suggested that the formation of the cold ridge could enhance retention on the Central Agulhas Bank, and so prevent offshelf leakage from the Central and Western Agulhas Bank. A synthesis of the main conclusions is presented. Implications of the findings and directions for future research are discussed.