An account of the pearl fisheries of Ceylon /

Mode of access: Internet.

Bibliography on pearl oysters

The preparation of this preliminary list was undertaken to meet the needs of the present investigation of the Pearl Banks, Gulf of Mannar. The recent repopulation of the Pearl Banks has revived interest in Ceylon's pearls and pearl fisheries. Successful fisheries have been held recently and surveys of the Pearl Banks are carried out regularly. The bibliography deals with all aspects of the biology of the pearl oyster, as well as the pearl fisheries. But its scope is limited by the library facilities available at the Fisheries Research Station, the Colombo Museum Library, the University of Ceylon Library and the Library of the Ceylon Institute for Scientific and Industrial Research. Annotation is not possible at this stage, for all publications are not available for reference.

Ceylon journal of science.

Publication suspended 1939-1955.

Travels in the interior of Mexico, in 1825, 1826, 1827, & 1828 /

Bound in 3/4 contemporary leather.

Temporal tracking of mineralization and transcriptional developments of shell formation during the early life history of pearl oyster Pinctada maxima

Molluscan larval ontogeny is a highly conserved process comprising three principal developmental stages. A characteristic unique to each of these stages is shell design, termed prodissoconch I, prodissoconch II and dissoconch. These shells vary in morphology, mineralogy and microstructure. The discrete temporal transitions in shell biomineralization between these larval stages are utilized in this study to investigate transcriptional involvement in several distinct biomineralization events. Scanning electron microscopy and X-ray diffraction analysis of P. maxima larvae and juveniles collected throughout post-embryonic ontogenesis, document the mineralogy and microstructure of each shelled stage as well as establishing a timeline for transitions in biomineralization. P. maxima larval samples most representative of these biomineralization distinctions and transitions were analyzed for differential gene expression on the microarray platform PmaxArray 1.0. A number of transcripts are reported as differentially expressed in correlation to the mineralization events of P. maxima larval ontogeny. Some of those isolated are known shell matrix genes while others are novel; these are discussed in relation to potential shell formation roles. This interdisciplinary investigation has linked the shell developments of P. maxima larval ontogeny with corresponding gene expression profiles, furthering the elucidation of shell biomineralization.

Short-term survival of discarded pearl perch (Glaucosoma scapulare Ramsay, 1881) caught by hook-and-line in Queensland, Australia

Post-release survival of line-caught pearl perch (Glaucosoma scapulare) was assessed via field experiments where fish were angled using methods similar to those used by commercial, recreational and charter fishers. One hundred and eighty-three individuals were caught during four experiments, of which >91% survived up to three days post-capture. Hook location was found to be the best predictor of survival, with the survival of throat- or stomach-hooked pearl perch significantly (P < 0.05) lower than those hooked in either the mouth or lip. Post-release survival was similar for both legal (≥35 cm) and sub-legal (<35 cm) pearl perch, while those individuals showing no signs of barotrauma were more likely to survive in the short term. Examination of the swim bladders in the laboratory, combined with observations in the field, revealed that swim bladders rupture during ascent from depth allowing swim bladder gases to escape into the gut cavity. As angled fish approach the surface, the alimentary tract ruptures near the anus allowing swim bladder gases to escape the gut cavity. As a result, very few pearl perch exhibit barotrauma symptoms and no barotrauma mitigation strategies were recommended. The results of this study show that pearl perch are relatively resilient to catch-and-release suggesting that post-release mortality would not contribute significantly to total fishing mortality. We recommend the use of circle hooks, fished actively on tight lines, combined with minimal handling in order to maximise the post-release survival of pearl perch.

Short-term survival of discarded pearl perch (Glaucosoma scapulare Ramsay, 1881) caught by hook-and-line in Queensland, Australia

Post-release survival of line-caught pearl perch (Glaucosoma scapulare) was assessed via field experiments where fish were angled using methods similar to those used by commercial, recreational and charter fishers. One hundred and eighty-three individuals were caught during four experiments, of which >91 survived up to three days post-capture. Hook location was found to be the best predictor of survival, with the survival of throat- or stomach-hooked pearl perch significantly (P < 0.05) lower than those hooked in either the mouth or lip. Post-release survival was similar for both legal (≥35 cm) and sub-legal (<35 cm) pearl perch, while those individuals showing no signs of barotrauma were more likely to survive in the short term. Examination of the swim bladders in the laboratory, combined with observations in the field, revealed that swim bladders rupture during ascent from depth allowing swim bladder gases to escape into the gut cavity. As angled fish approach the surface, the alimentary tract ruptures near the anus allowing swim bladder gases to escape the gut cavity. As a result, very few pearl perch exhibit barotrauma symptoms and no barotrauma mitigation strategies were recommended. The results of this study show that pearl perch are relatively resilient to catch-and-release suggesting that post-release mortality would not contribute significantly to total fishing mortality. We recommend the use of circle hooks, fished actively on tight lines, combined with minimal handling in order to maximise the post-release survival of pearl perch.

Stimulating investment in pearl farming in Solomon Islands: Final report

The overall objective of the project is the reduction of poverty in rural areas of Solomon Islands through creation of livelihoods based on sustainable aquaculture. This fits within the over-arching goals of the WorldFish Center in the Pacific to reduce poverty and hunger in rural communities, and with the Ministry of Fisheries and Marine Resources (MFMR) to stimulate rural development and to develop aquaculture. It has been recognised that the nature of the pearl farming industry means that a high chance of success requires a long term investment from an established pearl farming organisation. This project has been specifically designed to compile the elements of a pre-feasibility study to provide offshore pearl companies with sufficient information to investigate the potential for long-term investment in pearl farming in Solomon Islands. This report also includes the following 6 appendices: Appendix I) Past research and development on black-lip pearl oysters in Solomon Islands; Appendix II) Suitability of habitats in the Solomon Islands and other regions of the Pacific for growth of black-lip and silver-lip pearl oysters; Appendix III) Water temperature and cyclone frequency in the Solomon Islands and other key regions of the Pacific: implications for pearl farming; Appendix IV) Abundance, size structure and quality of silver-lip pearl oysters in Solomon Islands; Appendix V) Solomon Islands: the investment climate for pearl farming; Appendix VI) Pearl farming policy and management guidelines.

Fisheries of the Farasan Islands (Red Sea)

The fisheries of the Farasan Islands (Saudi Arabia, Red Sea) are described. The fishery resources are exploited by artisanal, investor and industrial sectors. The artisanal fishery consists mostly of line fishing around coral reefs and about half the fishing effort occurs within the proposed marine protected area (MPA). Activities by investor and industrial fisheries sector include line fishing, gill netting, fish trapping and demersal fish trawling. The relevant resource management issues that need to be addressed as part of a planning study for the establishment of a MPA are also presented. The major issues are: (1) the decline in the catch of the artisanal fishery; (2) by catch and habitat degradation; (3) sustainability in the collection of giant clams and pearl shells; and (4) the lack of information such as the importance of MPA to fisheries, stock assessment and catch and effort data. A significant role in the future management of the fisheries has been identified for the traditional representatives of the artisanal sector.

Influence of nutrient source on specific dynamic action of Pearl Spot, Etroplus suratensis (Bloch)

The magnitude of apparent specific dynamic action (SDA), the maximum rate of oxygen consumption and the length of time that the rate of oxygen uptake remained elevated above the prefeeding level were measured in the Pearl Spot, Etroplus suratensis, fed isonitrous test diets (D 1 - D 4 ) with varying nutrient sources. Irrespective of the diets, the metabolic rate increased immediately after feeding and reached the maximum within 3 to 4 hours. The source of nutrients in the diet significantly altered the magnitude of SDA. It was maximum (91.76% and 129.56%) for those fed on diets D 2 and D 3 and minimum 46.47% and 50.30% for those fed on diets D 1 and D 4 , respectively.

History of the Atlantic Pearl-Oyster, Pinctata imbricata, Industry in Venezuela and Colombia, with Biological and Ecological Observations

In the 1500’s, the waters of Venezuela and to a lesser extent Colombia produced more natural pearls than any place ever produced in the world in any succeeding century. Atlantic pearl-oysters, Pinctata imbricata Röding 1798, were harvested almost entirely by divers. The pearls from them were exported to Spain and other European countries. By the end of the 1500’s, the pearl oysters had become much scarcer, and little harvesting took place during the 1600’s and 1700’s. Harvesting began to accelerate slowly in the mid 1800’s and has since continued but at a much lower rate than in the 1500’s. The harvesting methods have been hand collecting by divers until the early 1960’s, dredging from the 1500’s to the present, and hardhat diving from 1912 to the early 1960’s. Since the mid 1900’s, Japan and other countries of the western Pacific rim have inundated world markets with cultured pearls that are of better quality and are cheaper than natural pearls, and the marketing of natural pearls has nearly ended. The pearl oyster fishery in Colombia ended in the 1940’s, but it has continued in Venezuela with the fishermen selling the meats to support themselves; previously most meats had been discarded. A small quantity of pearls is now taken, and the fishery, which comprised about 3,000 fishermen in 1947, comprised about 300 in 2002.

A History of the Pearl Oyster Fishery in the Archipielago de las Perlas, Panama

The pearl oyster, Pinctada margaritifera mazatlanica, was once found around the Archipielago de las Perlas in Panama in abundance and it supported a substantial fishery by hard hat divers. The products were pearls, shells used for making buttons, and meats used locally for food. After the mid 1920’s, the fishery declined due to overfishing, and by the 1940’s it was nearly gone. The oysters began to repopulate the grounds during the 1970’s, but the oysters remain relatively scarce. Fishing has since resumed on a small scale by skin divers using face masks.

Pearl oyster survey, Gulf of Mannar, 1964

This note reports the results of the 1964 Pearl Bank Survey. These surveys are conducted annually by the Fisheries Department to assess the possibility of a fishery; for detailed accounts of past surveys see Sivalingam (1955, 1958) who has also provided (1962) a complete list of all literature on the Ceylon Pearl Banks. The 1964 survey was carried out with the Department's m. v. "North Star" (42') and m. v. "Seer" (45') and a 25' mechanised fishing boat as tender, between the 17th and 29th of April.

The 1958 pearl oyster fishery, Gulf of Mannar

The continental shelf between the three and twelve fathom lines, off the Ceylon coast in the Gulf of Mannar is popularly known as the Pearl Banks. Though the area of this plateau is extensive the pearl oysters are concentrated on restricted areas known as "paars". The more productive of these are the Cheval Group of paars and the Moderagam Paar. The Peria Paar and Twynam's Paar though covering larger areas are not dependable as oyster beds. The True Vankalai, Peria Paar Karai and Muthuvarathu Paars are small in extent, but have yielded oysters on a commercial scale. Although the Ceylon Pearl Banks has been commercially fished for centuries, the first scientific investigation of its pearl oysters on an intensive scale was started by Herdman in 1902 (1902-06) and later continued by Hornell (1905-41), Shipley (1904-06), Pearson (1911-33), Jameson (1912-13), Southwell (1910-14) and Malpas (1922-39).