Aquaculture: farming aquatic animals and plants

The output from world aquaculture, a multi-billion dollar global industry, continues to rise at a very rapid rate and it is now acknowledged that it will take over from fisheries to become the main source of animal and plant products from aquatic environments in the future. Since the first edition of this excellent and successful book was published, the aquaculture industry has continued to expand at a massive rate globally and has seen huge advances across its many and diverse facets. This new edition of Aquaculture: Farming Aquatic Animals and Plants covers all major aspects of the culture of fish, shellfish and algae in freshwater and marine environments. Subject areas covered include principles, water quality, environmental impacts of aquaculture, desert aquaculture, reproduction, life cycles and growth, genetics and stock improvement, nutrition and feed production, diseases, vaccination, post-harvest technology, economics and marketing, and future developments of aquaculture. Separate chapters also cover the culture of algae, carps, salmonids, tilapias, channel catfish, marine and brackish fishes, soft-shelled turtles, marine shrimp, mitten crabs and other decapod crustaceans, bivalves, gastropods, and ornamentals. There is greater coverage of aquaculture in China in this new edition, reflecting China's importance in the world scene. For many, Aquaculture: Farming Aquatic Animals and Plants is now the book of choice, as a recommended text for students and as a concise reference for those working or entering into the industry. Providing core scientific and commercially useful information, and written by around 30 internationally-known and respected authors, this expanded and fully updated new edition of Aquaculture is a book that is essential reading for all students and professionals studying and working in aquaculture. Fish farmers, hatchery managers and all those supplying the aquaculture industry, including personnel within equipment and feed manufacturing companies, will find a great deal of commercially useful information within this important and now established book

The effects of stocking density and ration on survival and growth of winged pearl oyster (Pteria penguin) larvae fed commercially available micro-algae concentrates

AbstractCommercially available micro-algae concentrates have been successfully used as an alternative to live micro-algae as a food source during routine larval culture of the winged pearl oyster, Pteria penguin. This supports the development of simplified hatchery facilities and larval rearing protocols that are more appropriate to Pacific island nations. An optimal feeding regime based on these products that also accounts for larval stocking density is yet to be developed. Two experiments were conducted at a commercial pearl oyster hatchery facility in the Kingdom of Tonga to examine the combined effects of stocking density and ration on survival and growth of both D-stage (from 1 to 8 days post-fertilsation) and umbo-stage (from 8 to 17 days) P. penguin larvae. Both experiments used a factorial design combining three larval stocking densities (D-stage: 2, 6 & 10 larvaemL−1; umbo-stage: 1, 3 & 5 larvaemL−1) and three rations (D-stage: 5, 10 & 15 cellsmL−1; umbo-stage: 10, 15 & 20 cellsmL−1). Survival during D-stage was significantly improved in aquaria stocked below 10 larvaemL−1, whereby a density of 6mL−1 maximised larval production. An intermediate ration of 10×103 cellsmL−1 maximised both survival and growth during D-stage. Increasing the initial stocking density of umbo-stage larvae from 1 to 3mL−1 resulted in significant reductions in both survival and growth. Growth of umbo-stage larvae stocked at a density of 1mL−1 increased significantly when ration remained below 20×103 cellsmL−1. The results of this study provide a basis for optimised hatchery culture protocols for P. penguin that are more appropriate to Pacific island nations

Fish rejections in the marine aquarium trade: an initial case study raises concern for village-based fisheries

A major difficulty in managing wildlife trade is the reliance on trade data (rather than capture data) to monitor exploitation of wild populations. Collected organisms that die or are rejected before a point of sale often go unreported. For the global marine aquarium trade, identifying the loss of collected fish from rejection, prior to export, is a first step in assessing true collection levels. This study takes a detailed look at fish rejections by buyers before export using the Papua New Guinea marine aquarium fishery as a case study. Utilizing collection invoices detailing the species and quantity of fish (Actinopteri and Elasmobranchii) accepted or rejected by the exporting company it was determined that, over a six month period, 24.2% of the total fish catch reported (n = 13,886) was rejected. Of the ten most collected fish families, rejection frequency was highest for the Apogonidae (54.2%), Chaetodontidae (26.3%), and Acanthuridae (18.2%) and lowest for Labridae (6.6%) and Hemiscylliidae (0.7%). The most frequently cited reasons for rejection were fin damage (45.6% of cases), undersized fish (21.8%), and fish deemed too thin (11.1%). Despite fishers receiving feedback on invoices explaining rejections, there was no improvement in rejection frequencies over time (r = -0.33, P = 0.15) with weekly rejection frequencies being highly inconsistent (range: 2.8% to 79.4%; s = 16.3%). These findings suggest that export/import statistics can greatly underestimate collection for the marine aquarium trade as additional factors such as fisher discards, escapees, post-collection mortalities, and unregulated domestic trade would further contribute to this disparity

An overview of sea cucumber fishery management in the Fiji Islands

The Fijian sea cucumber fishery began in the early 1800's in response to demand from Asian markets for bêche-de-mer. The fishery has shown classic 'boom and bust' production cycles for much of its life. From 1984-2012 a total of 8,620 t of bêche-de-mer were exported from Fiji. Particularly large volumes were exported in 1987 (>600 t), 1988 (>700 t) and 1996 (>600 t) and declines in export volumes are notable following these peaks. Subsequent export peaks of around 400 t in 2005 and 2011, are considerably lower than those in the 1980s and 1990s and after 2005, annual exports averaged 243 t. Between 2003 and 2012 export volumes of high value species declined from 14-8%, while that of medium value species increased from 50-59%. Sandfish (Holothuria scabra) appeared on export manifests in 2003 and 2004 despite an export moratorium for this species. Despite numerous recommendations to improved sustainability of the Fijian sea cucumber fishery, management measures consist primarily of an export size limit of 7.62 cm for bêche-de-mer. Over-exploitation of the resource and declining sea cucumber stocks have resulted. A historic overview of the Fijian sea cucumber fishery was provided within the context of the various fishery management approached adopted by other South Pacific Island nations. It includes data gathered by interviews with sea cucumber fishermen, bêche-de-mer processors and other stakeholders and makes recommendations for an effective management plan for a fishery that is an important livelihood activity for coastal communities in Fiji

Assessing Pearl Quality Using Reflectance UV-Vis Spectroscopy: Does the Same Donor Produce Consistent Pearl Quality?

Two groups of commercial quality (“acceptable”) pearls produced using two donors, and a group of “acceptable” pearls from other donors were analyzed using reflectance UV-Vis spectrophotometry. Three pearls with different colors produced by the same donor showed different absorption spectra. Cream and gold colored pearls showed a wide absorption from 320 to about 460 nm, while there was just slight reflectance around 400 nm by the white pearl with a pink overtone. Cream and gold pearls reached a reflectance peak at 560 to 590 nm, while the white pearl with pink overtone showed slightly wider absorption in this region. Both cream and gold pearls showed an absorption peak after the reflectance peak, at about 700 nm for the cream pearl and 750 nm for the gold pearl. Two other pearls produced by the same donor (white with cream overtone and cream with various overtones) showed similar spectra, which differed in their intensity. One of these pearls had very high lustre and its spectrum showed a much higher percentage reflectance than the second pearl with inferior lustre. This result may indicate that reflectance is a useful quantitative indicator of pearl lustre. The spectra of two white pearls resulting from different donors with the same color nacre (silver) showed a reflectance at 260 nm, followed by absorption at 280 nm and another reflectance peak at 340 nm. After this peak the spectra for these pearls remained flat until a slight absorption peak around 700 nm. Throughout the visible region, all white pearls used in this study showed similar reflectance spectra although there were differences in reflectance intensity. Unlike the spectral results from white pearls, the results from yellow and gold pearls varied according to color saturation of the pearl. The results of this study show that similarities between absorption and reflectance spectra of cultured pearls resulting from the same saibo donor are negligible and could not be detected with UV-Vis spectrophotometry. Nevertheless, this technique could have a role to play in developing less subjective methods of assessing pearl quality and in further studies of the relationships between pearl quality and that of the donor and recipient oysters

Recovery rates for eight commercial sea cucumber species from the Fiji Islands

Determination of the original weight and length of sea cucumbers processed and dried to become bêche-de-mer (BDM), is an important tool in sea cucumber fishery management. The only management mechanism for the sea cucumber fishery in the Fiji Islands is a minimum length prescribed for BDM for export. However, different commercial species have different shrinkage rates during processing and previous studies have suggested modification of fisheries management for sea cucumbers to include species-specific minimum harvest size limits This study determined weight-based and length-based recovery rates (i.e. the length/weight of BDM recovered after processing from the initial length/weight of fresh sea cucumber), for eight commercial sea cucumber species following processing to BDM; White Teatfish (Holothuria fuscogilva), Black Teatfish (Holothuria whitmaei), Tigerfish (Bohadschia argus), Surf Redfish (Actinopyga mauritiana), Hairy Blackfish (Actinopyga miliaris), Stonefish (Actinopyga lecanora), Prickly Redfish (Thelenota ananas) and Sandfish (Holothuria scabra). Length and weight recovery rates varied between species and ranged from the highest recovery values of 54.9% for length and 11% for weight in Black Teatfish, to the lowest recovery values of 32.6% for length and 3.0% for weight in Sandfish and Tigerfish, respectively. Length-based and weight-based relationships were generated for each species through the various stages of processing from fresh to dried (BDM) allowing estimation of initial fresh weight/length from partially or fully processed BDM and vice versa. Information generated in this study provides a basis for developing more species-specific harvest size restrictions for sea cucumbers in the Fiji Islands, and has application in stock assessment studies, estimation of harvest data, monitoring of harvest size limits and standardizing catch data

Influence of Moult Cycles on Digestive Enzyme Activities during Early Larval Stages of Panulirus ornatus

The tropical spiny lobster, Panulirus ornatus, has a complex life cycle characterised by a series of moults that occur throughout pelagic larval stages. Significant morphological, physiological, and biochemical changes commonly coincide with moulting and can have dietary implications when culturing this species. Digestive enzyme activities respond to nutritional requirements and have provided useful insight into nutrient use dynamics associated with first-feeding in P. ornatus. Beyond first-feeding, however, information on digestive enzyme activities in P. ornatus is scarce. Greater knowledge of fluctuations in digestive enzyme activities during moult cycles should facilitate better formulation of feeds and more efficient feeding regimens. As an initial step towards this goal, the present study evaluated the influence of moult cycles on digestive enzyme activities during early larval stages of P. ornatus. The investigation focused exclusively on early larval stages (stages I-III) when delivery of appropriate feeds and nutrition can dramatically affect subsequent growth and survival

Trace metal content in sediment cores and seagrass biomass from a tropical southwest Pacific Island

A unique feature of seagrass among other ecosystem services is to have high phytoremediation potential that is a cost-effective plant-based approach and environmentally friendly solution for metal contamination in coastal areas. The goal of this study was to assess the phytoremediation prospective of seagrass for Cu, Fe, Mn and Zn in Fiji Islands. Heavy metal content was measured in sediments and tissues of the seagrasses Halophila ovalis, Halodule pinifolia and Halodule uninervis to test for local-scale differences. The local study shows that metal concentration in sediment and seagrass tissue was significantly variable, regardless of species and sediment type. Sedimentary concentration of Cu, Fe, Mn and Zn obtained in the present study seemed to be lower than that of previous studies. The results support that H. ovalis is a good bioindicator species since it accumulated up to 5-fold more of these metals compared to the Halodule species

Mitochondrial and nuclear genetic analyses of the tropical black-lip rock oyster (Saccostrea echinata) reveals population subdivision and informs sustainable aquaculture development

The black-lip rock oyster (Saccostrea echinata) has considerable potential for aquaculture throughout the tropics. Previous attempts to farm S. echinata failed due to an insufficient supply of wild spat; however, the prospect of hatchery-based aquaculture has stimulated renewed interest, and small-scale farming is underway across northern Australia and in New Caledonia. The absence of knowledge surrounding the population genetic structure of this species has raised concerns about the genetic impacts of this emerging aquaculture industry. This study is the first to examine population genetics of S. echinata and employs both mitochondrial cytochrome c oxidase subunit I gene (COI) and single nucleotide polymorphism (SNP) markers