4 . FISHERIES RESEARCH BOARD OF CANADA Translation Series No. 1056 On a method of making more productive fishery of the Lavers (Porphyra). Engineering ways of improvement and construction By Takeo Kurakake Original title: Doboku Koho ni yoru Non i Gyojo no Kairyo Zosei. From: Suisan Zoyoshoku Sosho, No. 3. (Marine culture and propagation.) Published by: Nippon Suisan Shigen Hogo Kyokai (Japan Marine Resources Protection . Association). Tokyo, Japan. Booklet No. 3, pp. 1-52, 1964. Translated by the Translation Bureau (NO) Foreign Languages Division Department of the Secretary of State of Canada Fiseeries Research Board of Canada Brôlogical Station, Nanaimo, B. C. 1968 95 pages typescript _4 /! •/ DEniI■ RTMENT OF THE SECRETARY OF STATE SECRÉTARIAT D'ÉTAT BUREAU FOR TRANSLATIONS BUREAU DES TRADUCTIONS 'IN LANGUAGES DMSÎON DES LANGUES î OREGWVISION ÉTRANGÈRES • Wi fr:UY ES g ;3 (.1-1 C. A D 0 CA D NANAIMO, e. L. TRANSLATED FROM - TRADUCTION DE INTO - X japanese English SUBJECT - SUJET Seaweed Cultivation Engineering AUTHOR - AUTEUR Kurakake, Takeo TITLE IN ENOL101-1 - TITRE ANGLAIS On a Method of Making More Productive Fishery of the Lavers (Porphyre). Engineering Ways of Improvement and Construction. , TITLE IN FOREIGN LANGUAGE - TITRE LANGUE LTTRANCURE 110 Doboku Koho ni yoru Non i Gyojo no Kairyo Zosei REFERENCE - RdFÉRENCE (NAME OF BOOK OR RUCLICATION - NOM DU LIVRE OLL PUDLICATION) Fishery Propagation Series #3 PUBLISHER - LIDITEUR Marine Resources Protection Institution of Japan -- Corporation CITY - VILLE DATE PAGES .Tokyo March 18, 1964 52 REQUEST RECEIVED FROM OUR NUMBER REQUII PAR Martha Skulski NOTRE DOSSIER N 0 0433 DEPARTMEN TRANSLATOR Noriko Olive MINIST ERE' Fisheries Research Board of Canada TRADUCTEUR '' YOUF2 NUMBER DATE comPLETrzD May 769-18-14 1 1968• • ie r'IE DOSSIER N 0 REMPLI E L IZ DATE RECEIVED 1,2112.7.0 L FebruaW22, 1968. f DEIPARTMENT OF THE SECRETARY OF TA SECRÉTARIAT D'h- AT TRANSLATION BUREAU BUREAU DES TRADUCTIONS 01.h FOREIGN LANGUAGES DIVISION DIVISION DES LANGUES ÉTRANGÈRES YOUR NO. DEPARTMENT DIVISION/0RANC.1 CITY VOTRE N ° MINIST ERE. DIVISION/DIRECTION VILLE 769-18-14 Fisheries - OUR NO. LANGUAGE TRANSLATOR (IN' TIALS) DATE NOTRE N ° LANGUE TRADUCTEUR III:ITIALES; 0433 Japanese N.O. //,/: •--1."`-e-.--(1 On a Method of Making More Productive Fishery of the Lavers (Porphyra) Engineering Ways of Improvement and Construction KURAKE Takeo Introduction 2 1 Features of Shallow Sea Fishing Grounds 2 Wind and Waves and the Situation of Fishing Grounds- Depth -- Water Quality, Turbidity, Amount of Sunlight -- Currents 2 The Construction of Fishing Grounds 4 3 Methodswith Engineering Earthworks 5 The Method of Ground Levering . and Land Readjustment -- Producing Water Courses -- Tilling of Tidal Flats 4 The Construction of Fishing Grounds by Establishing Break Water Fences 22 Waves in Siellow Sea Fishing Grounds and Wave Breaking -- Establishment of Fences 9 Their Construction ,;;Z SOS-200-10.-31 , 2 and Their Effect -- Stones to be Used to Make Concealed Banks -- Piles to be Used in Pile Rows -- Putting the Construction Work into Operation -- Effect of Work 5 Offshore Culture Conserving Facilities 42 ,Locations in Aichi Prefecture Where Fishing Ground Improvement Construction Work Has Been Carried Out Bibliography 49 Introduction 2 The improvement and construction of fishing grounds ha d been • conducted since &Id-times by the methods of constructing shores, or fish nesting areas, tilling tide flats and cleaning the surface of rocks. After the war, from about 1951 - 1952, this work has been recommenced with Government aid. In Aichi Prefecture, since 1952, by construction work using large construction machines and by establishment of break water fences from 1957 as well as the work of moving stones and making fish nesting areas, the improvement and construction of fishing grounds has been conducted mainly for those fishing grounds with demarcated fishing rights such as laver fisheries, and common fishing grounds such as those for short-necked clams. When attempting this work, if such • fundamental factors as what constitutes good fishing grounds' 3 in shallow sea or a what conditions the fishing grounds should fulfil are not apparent, the methods of construction and improvement cannot be (71termined. Therefore, first of all, our understanding of these factors will be described. 1 Features of Shallow Sea Fishing Grounds 1) Wind and Waves and the Situation of Fishing Grounds When the mixing of water and regeneration of quality .of water in a fishing ground are considered, the more violent the wind and waves are, the better it should be, providing there is no disadvantage such ns the destruction of cultivating facilities by wind and waves. Considering the growth of levers, in a calm water mass the water around the thallus tends to become isolated from other water and this adversely affects the living conditions of the laver. Violent water currents or wind and waves prevent this because they are effective in dispersing the water around the laver. In this regard, the aspect directions of shallow sea fishing grounds are deter- mined naturally. In the case of laver , fishing grounds facing west, north-west and north, which get the winter seasonal wind, are good. 2) Depth Firstly, as to the sea depth, only the coastal slopes of the continental shelf •rd shallower depths are considered, giving 4 regard to the range in which earthworking can be done construc- tively. As the sea depth is dependent upon the height of the ground of the sea bed,when cultivating facilities are to be made, and if the species to be cultivated are ones which live in the intertidal zone such as laver, short-necked clams, oysters etc., the height of ground where these will grow in the sea bed is determined naturally. Regarding this, the height of these grounds in shallow sea is determined by tides. In other words, the standards vary from place to place with 5. the local tidel- c/-1,treen*. These are shown in the following table of figures based on Mikawa Bay and standards of the Tide Tables published by the Incorporated Foundation of the Weather Forcasting Association. 0 t G) Nagoya. CD Period of observation: 1949 to. • 0 e JUJ ILU 1 9 1961, 13 years. 5.81 0 ,C) Monthly mean tide level. 1959. 9. 26. 2113356 e Month. eei 0 Last 5 years. 1 1.896m 4. 790 G) Year. (2) Maximum tide level. • 2 1.912 4.264 >t Snherical buoy. C) Weather marker, (a Men level of Aigh water springs.. 3.231 01';131i-if.]•ieli,.liLk CD Mean tide level in last 5 years. CD/lean tide level in Tokyo Bay. Mean level of low water springs. 0 • Tide level table 2. 070 D.L. 7 2.166 (FD Minimum tide level. 0 Hours. L989 -11-U.i,[1 1:3Y Minutes. 10 2. 178 0. 677 11 2. 114 0. 648 D. L. n aom 0. 040 e 1951. 12. 30. 1?,520::.:• • e aom e 0. 000 L 'D. 5 3) Water Quality, Turbidity, Amount of Sunlight The more fertile with nutrient salts the water is, the better its quality. The tolerance levels for chlorine are wide. Unless organic matter is lower than B.O.D. 3.0 p.p.m, it is difficult to say whether the fishing ground will be stable. The turbidity of the water is questionable. Concerning laver, if a gill net suspended vertically from stakes so that it floats in the water, is used for laver culture, laver will not grow on that part of the gill net which is a little lower than the water surface; This depth below the water sur- face varies according to the location (waves, tide), season, and the turbidity in the fishing ground. Concerning differences in the times cf year, before and after the winter solstice it is best to put laver on the water surface because at that time, the amount of sunlight is the least. Moreover, as the • laver are thought to undergo nutritive propagation until this time of year, the superiority or inferiority of the usual horizontally fixed cultivating grounds alne decided by the turbidity of the water. 4) Currents The current inside shallow sea bays is mainly tidal ont, accompanied by bay and river currents and current due to the weather. Since the tidal current is the main one, this bay current flows with both the ebb tide and the high tide. If the topography of a fishing ground is a wide tidal flat without any obstruction and the sea bed is flat, the 6 current repeats such movements as flowing towards the offing at the time of the ebb tide, and being compressed towards the shore at the time of high tide, as a whole water mass. Therefore, as is shown in Figure 1, especially when the tide movement is small such as the time of a neap tide, each 2 supposed constituent part of the water mass repeats such move- ments as going out towards the off-shore and compressing towards the coast, whilst they maintain their own relative positions. In other words, in such shallow seas, outwardly the current seems to be flowing considerably, but as they are maintaining the situation of horizontal order, the rate at which the water layers mix together is very low. The degree of stability in this sense -- the horizontal stability e2xJ:DY___ of the water -- varies according to the magnitude of the spring or neap tides as well as the shape of the shallow sea bed, and the type of geographical features. Therefore, it is thought that shallow seas can be divided into the following three classifications. (1) The area where both the high tidal current and ebb tidal current Ï 1 ii., „;;J. • flow in the same direction or only Figure 1.