Investigating the LongLine Nursery System for Giant Clam

Investigating the Long-Line Nursery System for Giant Clam

Project / Seminar Material
Reference ID: PS-2020-TM

DEDICATION

This research material titled “Investigating the Long-Line Nursery System for Giant Clam” is dedicated to God for his enabling grace, and to all computer enthusiasts who contributed to make life a pleasant experience during my research documentation.

ACKNOWLEDGEMENT

I extend my sincere gratitude to all those who contributed to the completion of this project. Special thanks to my Supervisor (Name of your Supervisor), the Head of Department (Name of your HOD), the Lecturers in the department of Fishery and Aquaculture, Book Authors and Profound Scholars of existing or related project material on “Investigating the Long-Line Nursery System for Giant Clam” for their invaluable guidance, support, and expertise throughout the journey.

I am also grateful to your study area (mention any funding organizations, if applicable) for their financial assistance. This research would not have been possible without the encouragement and assistance of some stakeholders (mention any mentors, teachers, or colleagues). Additionally, I would like to acknowledge the understanding and patience of my family and friends during this endeavor. Your unwavering support has been a constant source of motivation. Thank you all for being part of this meaningful endeavor.


Investigating the Long-Line Nursery System for Giant Clam

CHAPTER ONE

1.0 Introduction

1.1 Background To The Study

Long-line nursery systems are versatile enough to handle a wide range of nursery systems for clams (Braley, 1999). Nursery rearing as well as grow-out can be accomplished on long-lines. Trays, tube modules and bags or cages can be hung in deep water for nursery rearing of clams. According to Braley (1999), seeded lines or socks (with adequate predator protection provided by modified lantern nets surrounding them) are commonly suspended from long-lines. Commonly used, highly productive and efficient, long-line nursery systems are flexible enough to handle a variety of shellfish species including clams and various grow-out and harvest methods. These systems are preferred in high exposure areas. Layout of a long-line nursery system depends very much on site characteristics. The most significant feature from the point of view of security and stability is the availability of shore that can be utilized for anchoring one end of the long-line. In some locations both ends can be fixed to the shore avoiding the need for anchoring in deep water. Anchoring long-lines securely in deep water at both ends is also commonly done in sites where shore anchoring is not possible or desirable (Adams, 2003). Length of the line depends entirely on the site itself.

With a large site, lines can be over 100m long which permits working along the lines with fewer time-consuming transitions from one line to the next. For most long-line systems, the horizontal long-line (or “backbone”) consists of a 1/2? to 1? poly rope. To this the floats and tubes or trays are attached. If this is not done carefully, the result will be lost floats, lost stock or both (Lucas, 2001). Long-line nursery systems are usually constructed either in a surface or subsurface array. Subsurface long-lines nursery system can be built so that the entire system (floats and horizontal long-line) is below the surface (sunken). This is commonly done in clam farming to prevent surface agitation from affecting the nets or cages and to place nursed clams in deep water where temperature and salinity are relatively stable. Subsurface long-lines are also constructed so that the flotation is on the surface but the horizontal long-line is 0.5m or more below the surface (Lucas, 2001). Long-lines nursery systems for clams are fixed to shore by means of galvanized shore pins which must be forced into holes drilled into shoreline rock. In most cases it will not be possible to attach both ends of a long-line to shore pins. Usually one- to two-ton concrete blocks, with anchor eye to attach the line, are used to secure the deep water end(s) of the line (Shang, 1998). Steel anchors similar to boat anchors (e.g. a plow type anchor) are also used to secure the line and the type will vary according to the bottom conditions on the site.

Depending on the length of line and the layout, more than one line can be attached to each anchor. To prevent excessive slack in the long-lines concrete weights, boom chain or bucket of rocks is usually attached to the anchor line. If site geography permits, it may be possible to construct a floating breakwater to protect the site from rough water and storm conditions (Adams, 2003). With this protection, the lines are almost always accessible to the crew on the skiff to transport the trays to and from the line. A piece of styrofoam is wedged into the inside of the tire and the tires are strapped together in staggered rows to form a breakwater which, in this case is shore anchored on one end and deep water anchored on the other. In giant clam nursery system, aeration is important for its mixing properties rather than for the provision of oxygen, except perhaps in the embryonic and early larval stages when both good mixing and oxygen are needed. For mixing, it is wiser to use a diffuser with larger, coarser bubbles rather than one with very fine bubbles, which could cause gas supersaturation (total gases, especially nitrogen) which is lethal in the case of giant clams. Although bivalve molluscs can handle lower levels of oxygen than most other aquaculture animals it is not wise to attempt supersaturation (Braley, 1999).

There are two main methods of aeration which are gravity aerators and submerged aerators. The gravity aerators are cheaper and in most cases supply the oxygen needs for both hatchery and land nursery tanks, but they do not provide mixing. An automatic mixing paddle fitted to each tank is required in combination with a gravity aerator system. Submerged aerators are probably more cost effective. This method of aeration may use air compressors or air blowers. Few hatcheries now use air compressors because there is a danger of oil leaking through rings and seals and getting into the air. Also, high pressure air is not usually needed and can cause problems such as supersaturation. Rootes type air blowers are the air blower of choice. Heslinga et al. (1990) recommend Sweetwater blowers for their reliability, corrosion resistance and quietness. Air blowers give low pressure and high volumes of air; perfect for shallow nursery or hatchery tanks.


1.2 Statement Of The Problem

Giant clams have long represented a valuable resource to the people in most part of the world in the form of a readily available and nutritious food source. However, in today’s cash driven economies, giant clams have also come to represent a source of export income in many countries that involve in its farming. Current uses for farm-produced giant clams include; stock enhancement, aquarium pets, biological specimens, food and shellcraft. Several methods have been used for its hatching and nursery but this system is focused on investigations on the long-line nursery system for giant clams.


1.3 Aim and Objectives Of The Study

The aim of the study is to investigate the Long-Line Nursery System for Giant Clam. In achieving this aim, the following specific objectives were laid out as follows:

  1. To examine the approaches to giant clams nursery.
  2. To investigate the long-line nursery system for giant clams.
  3. To identify the advantages and limitations in the long-line nursery system for giant clams.

1.4 Research Questions

The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:

  • What are the approaches to giant clams nursery?
  • What are the procedures and processes involved in the long-line nursery system for giant clams?
  • What are the advantages and limitations in the long-line nursery system for giant clams?

1.5 Significance Of The Study

The following are the significance of this study:

  1. Outcome of this study will educate on the easier method for the nursery of giant clams for improved method of production and better yield.
  2. This research will be a contribution to the body of literature in the area of the effect of personality trait on student’s academic performance, thereby constituting the empirical literature for future research in the subject area

1.6 Scope Of The Study

This study will cover the various approaches and systems of giant clam nursery with special focus and experiment on the long-line nursery systems for giant clams.


1.7 Limitation Of Study

During the course of this study, there were some problems encountered which stood as limitations to the research work. Some of the limitations include:

  1. Time Constraint:

    The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.

  2. Financial Constraint:

    Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).

CHAPTER TWO

2.0 Literature Review

2.1 Introduction

This chapter focuses on the review of related literature. A literature review includes the current knowledge as well as theoretical and methodological contributions to a particular topic. It documents the state of the art with respect to the topic you are writing. It surveys the literature in the topic selected. In this research work the literature review includes the …

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