aquaculture

Alfred J. Römer has published a report about the pearl cultivation in New Zealand – specifically on the pearls and abalone (Paua – Haliotis iris) cultured by Rainbow Abalone Ltd©, New Plymouth, New Zealand.

From the report:

This sea snail, which grows up to 18 cm in length and 13 cm wide, is the New Zealand representative of some hundred Abalone species found world-wide. Its underwater habitat is from a depth close to the surface to approximately 30 meters, where the water is not only clear and rich on oxygen, but where seaweed grows in larger amounts.

There are about 100 abalone species in the world. The FAO have prepared a training course on the artificial breeding of the Ezzo Abalone (Haliotis discus hannai).

From the introduction:

Abalones have been long considered as a valuable fishery product. From as far back as 1880 until 1952, studies were mainly focussed on its habitat, taxonomy, spawning season, breeding, feeding habits, and growth. Throughout this period studies were also concentrated on artificial propagation and rearing methods suitable for selected areas, as well as on transplanting and releasing adult abalones to potential on-growing sites.

In the 1960’s, on the basis of successful seed rearing experiments, studies were conducted with the view to produce seeds on an industrial scale. These studies, eventually succeeded in the establishment of a seed production system.

Maritime countries have given priority to aquaculture development with the objective of preserving and increasing their natural resources. It is in line with this aim that the Democratic People’s Republic of Korea (DPRKorea) has embarked on an intensified development of numerous aquatic resources. The suggested method of abalone culture is to release hatchery-bred juveniles into natural waters and allow them to grow mainly on natural feed organisms. This method fully considers the fact that it takes 3 to 4 years for abalones to attain the desired marketable size. However, due to the increasing demand of the high valued gastropod, a number of land-based intensive farming techniques have been developed.

The Korean-US Aquaculture note that Halotic discus hannai is one of the most common species cultured in Korea. The species, sized 120~180mm in shell length, spawn in June to July. It is this foot which is the edible part of the animal and is considered a great delicacy by a number of Asian cultures. High prices are paid for abalone meat, which constitutes between 28 to 46% of the abalone’s live weight (depending on season and location).

Research on estimates of genetic parameters for growth traits of the sea urchin, Strongylocentrotus intermedius is available for free download.

There is no published information about heritabilities or genetic correlations for any trait in the sea urchin. This study investigates heritability and genetic correlations for growth traits in sea urchin at 8, 10, and 12 months after metamorphism, a continuation of studies on heritability of growth at juvenile stages of sea urchins Strongylocentrotus intermedius.

The authors, Xiao-lin Liua, Ya-qing Chang, Jian-hai Xiang, and Xue-bin Cao, introduce the report with:

Genetic improvement of breeding stocks becomes more and more important in aquaculture. Even slight improvement in body weight and size would be a major advance since body size at a certain age is a common performance trait in breeding programs. Heritability and genetic correlation are two important parameters, which measure the relative magnitude of additive genetic variation for a trait and covariation between traits. Henderson’s (1973) pioneering work provided a technique that enabled separation of genetic and environmental effects when predicting cattle breeding values. The technique now dominates analysis of data from livestock improvement schemes, both in prediction of breeding values and estimation of genetic parameters.

A joint study on bay ecosystem modelling with oysters has been undertaken in Korea by Korean and USA universities. Pacific oysters (Crassostrea gigas) or Cham-Gull as they’re locally known, have been the focus of this study.

The study was undertaken in Kamakman Bay – a semi-closed bay, famous for its oyster culture. In 1995, a total of 191,156 metric tons of oysters were produced in Korea using aquaculture. Some 20% of the total oyster yields were from Kamakman Bay. The Kamakman Bay area is also certified as “clean sea” by the USA FDA and is therefore suitable for oyster productions. Oysters produced in this bay are exported to the USA.

The oysters are cultured using hanging rope lines and rifters (buoys). The local government lease (license) the oyster grounds to the growers. Each grower may get one to two hectare of the sea surface as a oyster farm. The growers also form unions to assist each other with the oyster husbandry. There are two oyster grower unions in the area.

Trochus, Trochus niloticus, have long been exploited for both subsistence and export in the South Pacific. On the coral reefs where they are found, most can be collected by hand or free diving. The shells are used to make jewellery and as inlay in carvings, but their primary use is in the production of mother-of-pearl clothing buttons. Such clothing buttons are in high demand in the fashion industry.

The wharf price in the Australian market is somewhere in the region of $A 2 million. There is some research being undertaken to culture Trochus by James Cook University, Townsville, Far North Queensland, Australia.