FAO FISHERIES TECHNICAL PAPER 436
The use of ice on small fishing vessels
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Table of Contents
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© FAO 2003
Shawyer, M.; Medina Pizzali, A.F.
The use of ice on board smaller fishing vessels is increasing. One reason for this is the decrease in near-shore fish resources that is forcing the fishermen to make longer fishing trips and to conserve the catch on board during the trip. Another reason is the increasing demand for good quality fresh fish and the globalization of the markets for these products with increased quality control.
This publication describes the requirements for the use of ice (and chilled seawater) on board fishing vessels, from small insulated containers in dugout canoes, to refrigerated tanks on bigger vessels. It also gives an overview of the different types of ice plants and the ice produced in them.
Chapter 1 describes the physical changes in fish exposed to heat, and how chilling the product delays these processes.
Chapter 2 gives an overview of the different types of ice and chilled seawater and how they are produced.
Chapter 3 describes the installation requirements for shore-based ice plants and how the ice is stored and handled.
Chapter 4 describes the on-board handling of ice and fish, including the advantages and drawbacks of the different types of ice and chilling systems.
Chapters 5 and 6 give a description of the materials used for insulation and the design of insulated containers and fish holds.
Finally, in Chapter 7 some calculations are given that can be used to estimate the quantity of ice needed for a fishing trip, and the volume of the fish hold.
The publication is aimed both at fishermen who want more information about the different techniques used, and at boat owners and economic agents who want to invest in the use of ice to preserve the catches.
Preparation of this document
1.1 Chilling versus freezing of fish
1.2 The preservative effects of chilling fish
1.3 Factors affecting the rate of spoilage in fish
1.3.2 Physical damage
1.3.3 Intrinsic factors
1.4 Shelf-life of fish in ice
2. The manufacture of ice
2.1 Sea or freshwater
2.2 Types of ice and how they are made
2.2.1 Block ice
2.2.2 Rapid block ice
2.2.3 Flake ice
2.2.4 Compacted blocks of small ice
2.2.5 Slush ice
2.2.6 Chilled seawater
2.2.7 Refrigerated seawater
2.3 Refrigerants and their environmental impact
2.4 Safety observations
3. Planning considerations for ice plants
3.1 Planning the requirements
3.2 Storage of ice on shore
3.3 Handling of ice
4. The use of ice and chilled seawater on fishing vessels
4.1 Initial capture and immediate handling on board
4.2 Fish storage considering type of ice used
4.2.1 Block ice/crushed ice
4.2.2 Flake ice
4.2.3 Slush ice
4.2.4 Chilled seawater
4.3 Workability of ice over time
4.4 Quantities of ice required on board
4.4.1 Chilling the fish
4.4.2 Trip duration and estimated volume and composition of catch
4.4.3 Storage considerations
5. Thermal insulation materials, technical characteristics and selection criteria
5.1 Heat transmission modes and technical terms
5.1.1 Heat transmission modes
5.2 Why insulation is necessary
5.2.1 Insulating materials
5.3 Thermal insulation materials
5.3.1 Polyurethane foam
5.3.2 Expanded polystyrene
5.3.3 Expanded perlite
5.3.6 Comparison of the various insulants
5.4 Types of protective lining for fish holds and selection of insulation materials
6. Containers and fish holds
6.1 Design of insulated boxes and containers for canoes and small fishing vessels
6.2 Insulated fish containers
6.2.1 Design factors and construction aspects
6.2.2 Commercially manufactured insulated containers
6.2.3 Locally made insulated containers
6.2.4 Locally made non-insulated fish boxes
6.3 Fish hold design
6.3.1 Penboards, shelving or boxes: benefits and disadvantages
6.3.2 Insulation: design considerations
6.3.3 Free surface effect
6.3.4 Sanitation in fish holds
6.3.5 Insulation installation in older vessels
7. Calculations and examples for insulated containers and fish holds
7.1 calculating the specific ice melting rate for an insulated container or fish hold
7.2 Methodology for the calculation of ice requirements for cooling fresh fish
7.3 Calculating gross fish hold volume
7.3.1 Cubic number method
7.3.2 Trapezoidal rule
7.3.3 Multiplier factor for hold volume
7.4 Losses of fish hold volume on installing insulation
7.5 Fish hold volume losses with penboards, shelving and/or boxes
Annex: Form templates for monitoring hold temperatures and calibration of thermometers
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