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TUVALU BAITFISH SURVEY AND DEVELOPMENT PROJECT
R.D. Gillett
Tuna and Billfish Assessment Programme Technical Report No.14
South Pacific Commission Noumea, New Caledonia
April 1985
© Copyright South Pacific Commission, 1985.
All rights reserved. No part of this publication may be reproduced in any form or by any process, whether for sale, profit, material gain, or free distribution
without written permission. Inquiries should be directed to the publisher.
Original text: English
Prepared for publication at South Pacific Commission headquarters, Noumea, New Caledonia
and printed at System Press Pty Ltd, Sydney, 1985
Ill
PREFACE
The Tuna and Billfish Assessment Programme is an externally funded part of the work programme of the South Pacific Commission and is the successor of the Skipjack Survey and Assessment Programme. Current responsibilities of the Tuna Programme include compilation and maintenance of a fisheries statistics data base for the commercial fisheries in the region, and biological research on fish stocks which support this fishery. The work of the Programme is presently funded by donations from the governments of Australia, France, New Zealand, and the United States of America. The beneficiaries of this work are the island states of the South Pacific Commission who use the research results in the development and management of fisheries in their Exclusive Economic Zones.
The Technical Report series published by the Tuna Programme report on research results obtained by Programme staff. These reports cover a wide variety of topics and range in content from highly technical material of interest primarily to specialists, to material of much wider interest. The basis for these reports is the ongoing research of the Programme and includes information obtained by Programme staff during the pursuit of their current activities, data contained in the regional fisheries data base, and data obtained during the Skipjack Programme.
6
<i
V
TABLE OF CONTENTS
Page
LIST OF TABLES vi
LIST OF FIGURES vi
1.0 INTRODUCTION 1 1.1 Background 1 1.2 Terms of Reference 1 1.3 Itinerary 2
2.0 ACTIVITIES 2 2.1 Phase 1 - Sprat Monitoring Programme 2
2.1.1 General description 2 2.1.2 Preliminary results 4 2.1.3 Future monitoring 4
2.2 Phase 2 - Development of Baitfishing Techniques 6 2.2.1 The baitfish 6 2.2.2 Liftnet baitfishing 6
2.2.2.1 Daytime liftnet fishing techniques 10 2.2.2.2 Night-time liftnet fishing techniques 10
2.2.3 Results of liftnet fishing 12 2.2.4 Other areas 12 2.2.5 Fusiliers and cardinalfish as baitfish 15 2.2.6 Notes on cardinalfish behaviour 15 2.2.7 The baitfishing crew 18
2.2.7.1 Performance of the crew 18 2.2.7.2 Future baitfishing 18
2.2.8 Other considerations 18 2.2.8.1 Gear 18 2.2.8.2 Future liftnet fishing requirements 19 2.2.8.3 Safety 19
2.3 Phase 3 - Small-scale, Live-bait Tuna Fishing Trials 19 2.3.1 Gear and modifications 19 2.3.2 Fishing techniques 20 2.3.3 Results 20
3.0 CONCLUSIONS 21 3.1 Blue Sprat Monitoring Programme 21 3.2 Development of Baitfishing Techniques 21 3.3 Small-scale Fishing Trials 22
REFERENCES 23
APPENDICES A. English, scientific and Tuvalu baitfish names 25 B. Gear specifications 27 C. Sun and moon data for blue sprat monitoring 29 D. Blue sprat data sheet 31 E. Instructions for blue sprat data sheet 33 F. Instructions for blue sprat monitoring 35 G. Participants in the project 37 H. Baitfish size frequency data 39 I. 1. Movements of fusiliers and cardinalfish away from
a coral boulder at sunset 41
vi
o 2. Movements of fusiliers and cardinalfish towards a
coral boulder at dawn 42 J. Notes of fusilier behaviour A3 K. How to change a bouki-ami net into a liftnet 45
•
VI1
LIST OF TABLES
Table Page
1 Sampling locations 4
LIST OF FIGURES
Figure Page
1 Sprat monitoring locations in Funafuti lagoon 3
2 Preliminary sprat monitoring results 5
3 Funafuti lagoon 7
4 Cardinalfish 8
5 Diver about to enter water with corner of net and longline float 8
6 Transporting the bait by slinging the liftnet between
two skiffs 9
7 The five stages of a night-time liftnet set 11
8 Liftnet fishing catches 13
9 Liftnet fishing results 14
10 Nukufetau lagoon 16
11 Live-bait tuna fishing on the Tui Puga 19
12 Small-scale tuna fishing results 20
TUVALU BAITFISH SURVEY AND DEVELOPMENT PROJECT
1.0 INTRODUCTION
1.1 Background
The development of a pole-and-line fishery for surface tuna is highly dependent on a supply of live baitfish. In Tuvalu exploratory fishing to gauge the magnitude of the baitfish resource has been carried out by Van Camp Seafood Company in 1972, the South Pacific Commission (SPC) in 1978 and 1980, the Ika Corporation of Fiji in 1980, and the Tuvalu-owned, 173-tonne pole-and-line vessel, Te Tautai. from 1982 to 1984. All of these fishing operations used lights at night to attract baitfish, which were caught by nets set from the tuna fishing vessels. Catches comprised almost exclusively the blue sprat, Spratelloides delicatulus. The amount of bait caught was generally not great, although there was a considerable amount of variability.
In October 1983 as a joint SPC/Food and Agriculture Organization of the United Nations (FAO) project, Mr Robert Gillett visited Tuvalu for a one week period to determine the possibility of catching baitfish by methods other than those previously used. On the basis of a brief survey of Funafuti Lagoon, it was concluded that a baitfishing project would be worthwhile. Plans for such a project were formulated in discussions between the SPC Tuna Programme, Tuvalu Fisheries Division and FAO.
1.2 Terms of Reference
Mr Gillett was assigned to the project from 4 April to 7 June 1984 with the following terms of reference:
(i) Determine if the supply of baitfish for tuna fishing can be increased through a survey of Funafuti Lagoon and developing techniques for capturing species not presently being utilised (primarily fusiliers) with coral head liftnets;
(ii) Set up a monitoring system to determine variability/seasonality of blue sprats using light attraction;
(iii) Train local crew in bait survey and capture techniques, net construction/modification/repair and baitfish transport/storage/ handling;
(iv) Prepare a final report detailing all activities, areas surveyed, baitfish species sighted and approximate quantities, baitfish species captured/quantities, evaluation of effectiveness of various capture techniques, evaluation of local crew's ability to continue survey in other lagoons, and a rough estimate of the overall baitfish resource likely to be available in Funafuti Lagoon for tuna fishing operations;
(v) Conduct trials in small scale pole-and-line fishing if time permits.
2
1.3 Itinerary
The following travel was undertaken during the project:
04 April 04 April 06 April 06 April 15 May 15 May 17 May 18 May 04 June 04 June 06 June
Depart Arrive Depart Arrive Depart Arrive Depart Arrive Depart Arrive Depart
Noumea Suva Suva Funafuti Funafuti Nukufetau Nukufetau Funafuti Funafuti Suva Suva
2.0 ACTIVITIES
Operationally, the project was divided into three phases:
Phase 1 - Implementation of the blue sprat monitoring programme.
Phase 2 - Development of baitfishing techniques.
Phase 3 - Small-scale, live-bait tuna fishing trials.
2.1 Phase 1 - Sprat Monitoring Programme
One of the objectives of the blue spratl monitoring programme is to gain a better understanding of the factors responsible for the large variation in abundance of this baitfish. If particular environmental factors can be isolated, prediction of future baitfish catches could be made more accurately than at present.
A more immediate objective is that, by having the ability to determine the relative abundance of blue sprats in several areas, the Fisheries Division personnel could give valuable information to the fishing master of the local pole-and-line vessel (which often fishes in Fiji) on when to fish in Tuvalu and which areas are likely to be most productive.
2.1.1 General description
Blue sprats, unlike many tropical baitfish, congregate very close to the surface when attracted by fishing lights. It is therefore possible to judge the relative abundance of blue sprats by visual inspection during the night lighting period without actually having to catch the bait with nets. This simplifies a monitoring programme, as the only baitfishing equipment actually required is the lighting gear.
A system was set up using a 10.3-metre catamaran, an electrical generator, an above-water light, and an underwater light (see Appendix B
1. English, scientific, and Tuvalu baitfish names are given in Appendix A.
3
for gear specifications). The lights were switched on for equal periods of time in several locations in Funafuti Lagoon each month and the relative quantities of sprats attracted were noted along with simple environmental data.
The phase of the moon and cloud cover have a large effect on the ability of the fishing lights to attract bait. The effect of these two factors can be eliminated by sampling only during total darkness (i.e. periods at night without moonlight). Taking this into consideration, and other factors such as sprat behaviour and manpower requirements for the monitoring, it was decided that sprat monitoring should take place only when there is at least two hours of darkness at the beginning of a night. More specifically, only those nights in which moonrise occurs more than two hours after civil twilight are to be selected. Appendix C gives sun and moon data for April and May 1984. From this it can be seen that the nights suitable for monitoring occurred from the third night after full moon and continued for about two weeks.
Areas to be sampled were selected taking into consideration protection from prevailing winds, previous baitfishing success, distance from the fisheries jetty, and the desire to have as wide as possible coverage of Funafuti Lagoon. Figure 1 shows the areas selected and Table 1 gives some details of these four areas. Three sites were sampled once a month, while one was sampled twice.
FIGURE 1. SPRAT MONITORING LOCATIONS IN FUNAFUTI LAGOON
fr
FAGAFALE
••.•P.'?'* - #
4
TABLE 1. SAMPLING LOCATIONS
Spot
A
B
C
D
Position
08°30.5'S 179°11.5'E
08°29.5'S 179°12.0'E
08°26.5'S 179°11.0'E
08°36.0'S 179°06.5'E
Description
100 metres north of coral patch directly west of fisheries jetty
100 metres north of the coral patch offshore of the Van Camp wreck
400 metres south of the Marine Training School jetty
200 metres southwest of the tree line on Mateika Island
Depth
20 m
28 m
23 m
31 m
Sampling per
month
1
2
1
1
Information to be collected on each sampling night included data on wind, water temperature, rainfall, the presence of predatory fish, and the quantities of blue sprats observed. The amount of blue sprats was judged on a relative scale, zero being absolutely nothing and nine being vast quantities. Care was taken to standardise the quantity estimation procedure. The information was recorded on the Blue Sprat Data Sheets (Appendix D) according to the accompanying instruction sheet (Appendix E). Simplified instructions for the operation of the sprat monitoring programme by the Fisheries Division staff were prepared (Appendix F).
2.1.2 Preliminary results
Sprat monitoring was carried out on ten nights at four locations in April and May. Three Fisheries Division staff participated in the activities. On the five sampling nights in April, details of the gear and methodology were explained to the staff. During May the local staff was encouraged to take on as much responsibility as possible, and as a result, two sampling sessions were conducted satisfactorily using only local Fisheries Division personnel.
Data collected on the ten sampling nights appears in Appendix D. The relative quantities of sprats observed at the four sampling sites are shown in Figure 2.
On 7 May, the pole-and-line vessel, T_e. Tautai. arrived in Funafuti Lagoon after fishing for several months in Fiji. On the basis of the preliminary results of the sprat monitoring programme, the fishing master was advised that the most productive baitfishing area would probably be at sampling site "B". All of the T_e_ Tautai baitfishing activities for the month of May were at or near this location.
2.1.3 Future monitoring
It appears that the Fisheries Division staff can satisfactorily continue the sprat monitoring programme without additional outside input. Assistance may, however, be required for the analysis of data collected.
FIGURE 2. PRELIMINARY SPRAT MONITORING RESULTS
O i_ a
if)
a> 2 CD 4 -O
</)
+-> C D D
o >
a)
9-j
8-
7-
5-
4-
3 -
2 -
1 -
U l
O i—i—i—i—i—i—i—i—t—i—i—i—i—i—i—r
18 28
T — i — i — i — i — i — i — i — i — i — i — ( — i — i — i — i — i — i — i — i — i — i — i — r
8 18 28
APRIL MAY
6
In its present form, the sampling programme makes a significant demand on Fisheries Division manpower and vessel resources. If this proves to be an unacceptable hardship, the first step in scaling down the programme would be the elimination of sample site "D", the location furthest from the fisheries jetty.
To maximise the benefits, the blue sprat monitoring programme should continue for two years and, if possible, be extended to Nukufetau Atoll on an opportunistic basis.
2.2 Phase 2 - Development of Baitfishing Techniques
A short survey of Funafuti Lagoon in October 1983 revealed the presence of baitfish species which have not been previously utilised in Tuvalu. Indications were encouraging enough to warrant a major effort aimed at their capture. In February 1984, the gear listed in Appendix B was ordered and shipped to Funafuti. On 9 April, a crew of nine local men (Appendix G) was selected on the basis of swimming and diving ability, previous work experience, eagerness, and willingness to dive at night.
2.2.1 The baitfish
A close inspection by free diving of the lagoon area between the fisheries jetty and the south end of the airstrip (Figure 3) revealed that two types of baitfish - fusiliers and cardinalfish - were quite plentiful. This area is characterised by water 2 to 15 metres deep over a sandy bottom interspersed with coral boulders of various sizes usually spaced 50 to 100 metres apart. Virtually every coral boulder, as large as an automobile with crevices and protrusions in water at least 2.5 metres deep, had fusiliers. Quantities varied from 1 to 30 kg per coral structure, usually in proportion to the size of the boulder.
Cardinalfish (Appendix A and Figure 4) were associated with about 30 of the coral boulders in this area. It was not obvious why certain boulders had cardinalfish while others did not. Unlike fusiliers, the presence of this baitfish did not require crevices and protrusions on the coral; almost flat coral patches occasionally had large quantities. Amounts of cardinalfish varied from 1 to 90 kg per boulder, although amounts visible by superficial visual inspection usually appeared much lower.
2.2.2 Liftnet baitfishing
Two small bouki-ami n e t s from F i j i were r igged as l i f t n e t s . This en t a i l ed a t t a c h i n g one of e i g h t 1 5 - m e t r e l i n e s to each c o r n e r and mid-section of a side of these r e c t a n g u l a r n e t s . At each of the e igh t points of attachment, a weight of 2 kg was t i e d to the net (F igure 5 ) . Each of the eight l ines was threaded through the eye of a l ong l ine b a l l (one bal l per l i n e ) . The finished product was a f l a t , rectangular net with a w e i g h t / l i n e / f l o a t arrangement a t t ached to e igh t po in t s around t h e perimeter of the net (see Appendix B for d e t a i l s ) .
To famil iar ise the newly recruited bai t f ishing crew with these ne t s , a ser ies of pract ice se ts was made on a f l a t sandy bottom in about 3 metres of water. The crew learned to s tack the net i n to the p r o j e c t ' s sk i f f , co-ordinate the i r a c t i v i t i e s to get the net into the wa te r , spread i t out on the surface, sink the net to the bottom, and s t re tch the net out on the bottom to achieve maximum coverage. Because i t was a n t i c i p a t e d t ha t some
FIGURE 3. FUNAFUTI LAGOON
M:
FAGAFALE.vf-
..ti*
FAGAFALE.=H<
.-*#-
* •*•' ;*' &J
•.•.•.r,v;'V.
AREA SURVEYED
CARDlNALFiSH
FIGURE 4 . CARDINALFISH
FIGURE 5 . DIVER ABOUT TO ENTER WATER WITH CORNER OF NET AND LONGLINE FLOAT
9
•» work would be done in fairly deep water, four members of the team were trained in SCUBA diving techniques. As no one in the team had previously worked with baitfish, time was devoted to teaching handling and
* transportation techniques.
2.2.2.1 Daytime liftnet fishing techniques
As the fusiliers appeared a promising resource, all initial baitfishing effort was directed at their capture. The basic technique consists of partially covering fusilier-associated coral boulders with the net, using a finely chopped bait to attract the fusiliers over the liftnet, and quickly raising the net to capture the fish. The liftnet is raised from the bottom by eight divers at the surface pulling on the eight lines attached to the perimeter of the net. The raising is greatly facilitated by having each line pass through the eye of a longline ball at the surface. Pulling on the ends of the lines results in the net being brought to the surface by 116 kg of force (14.5 kg of buoyancy per ball, eight balls total). When the edges of the net are at the surface, three or four crew members in the skiff restack the net assisted by others in the water. Care is taken to eliminate folds in the net, which could trap and injure baitfish. After most of the net has been dried up, the bait is either placed into a receiver (Appendix B), transferred directly to a small tuna fishing vessel, or transported to a larger pole-and-line vessel further offshore. In the later case, the net is suspended to another skiff and slowly motored (Figure 6).
0 The main problems with catching these fusiliers are: (1) encouraging the fusiliers, which are normally located over the coral boulder, to move closer to the bottom in the area of the net; (2) pulling the net fast enough so that the fish in this vulnerable area do not escape over the edge of the net.
FIGURE 6. TRANSPORTING THE BAIT BY SLINGING THE LIFTNET BETWEEN TWO SKIFFS
, •+• -\ ^ B ~ * ^ »
10
Previous work in Fiji in 1982 showed that when there is a significant amount of current, fusiliers are found close to the sandy bottom on the upcurrent side of coral boulders and thus are relatively easy to capture. Unfortunately, in the areas of Funafuti Lagoon where fusiliers are abundant, the current is very weak, and manoeuvring these fish into a vulnerable position proved extremely difficult. The use of certain types of finely chopped bait helped to a small degree. In order of increasing effectiveness, bait experimented with were: land crab (as used in the Maldive Islands), oilfish, rainbow runner, fusiliers, cabin biscuits, canned mackerel, yellowfin tuna and skipjack. Other attempts at manoeuvring fusiliers included varying the net soak time, portion of the boulder covered, placement of the net relative to the boulder and current, type of coral selected, water depth, and water clarity. The use of chopped skipjack as bait proved to be the most effective variation, however, only a portion of the fusiliers on each boulder could be enticed close to the net.
Initially, the fish that were manoeuvred to within 2 metres of the bottom in the area of the net panicked and escaped when the net was first being pulled upwards. The water resistance of a 4 mm mesh net is such that it is difficult to raise the edges rapidly. This problem was overcome by attaching a section of tuna purse-seine (10 cm mesh) to the perimeter of the flat liftnet, so that when the surface lines are pulled the net becomes a box shape with the sides extending upwards about 2 metres. This seine creates little water resistance and can be rapidly pulled towards the surface. Although the fusiliers could easily pass through the mesh, its presence was enough of a psychological barrier to scare the fish back into the centre of the net.
2.2.2.2 Night-time liftnet fishing techniques
During daytime fishing trials for fusiliers, it was noted that cardinal fish were associated with many of the coral boulders. Attempts to attract these fish into the liftnet using chopped bait were not successful, although a few kilograms could occasionally be scared into the net area and captured.
As it was known that cardinalfish leave the coral at night, a plan was made to set the liftnet at night over a cardinalfish associated coral boulder, and haul it during the day when these fish return. The procedure is basically the same as that described for daytime fusilier fishing, however, the coral boulder is completely covered by the net and this setting is done in total darkness. When the net is being pulled, the baitfish panic, but as the coral boulder is completely covered by the net, the fish have no refuge other than the centre of the net. Figure 7 depicts this technique. The first time the net was set in darkness, 27 kg of bait were captured and the staff of project TUV/79/003 quickly became interested in night-time liftnet fishing.
Subsequent refinements to the night-time liftnet technique included the development of procedures (1) to ensure that when the net was sunk from the surface at night, the coral boulder was completely covered; (2) to encourage cardinalfish slightly outside the net area to move towards the centre; and (3) to detect holes in the net as it is being raised to the surface so that they can be patched before becoming critical. As the project had access to two liftnets, two sets were possible each night. This setting could be done in about one and a half hours at night and the two nets could be hauled the following day in about one hour. About half an hour was devoted to net maintenance every fishing day.
11
FIGURE 7 . THE FIVE STAGES OF A NIGHT-TIME LIFTNET SET
TOP VIEW \ SIDE VIEW
NIGHT
©
. - • a
NIGHT
© NIGHT UNTIL DAY
DAY
DAY
12
2.2.3 Results of l i f t ne t fishing
Resu l t s of t h e day and n i g h t - t i m e l i f t n e t f i s h i n g a r e shown graphically in Figure 8. Species information and r e l a t i ve catches by each technique are given in Figure 9. Size frequency data for the b a i t f i s h appear in Appendix H.
The l i f t n e t s were set during the day for f u s i l i e r s on 42 o c c a s i o n s . Quantit ies of bai t captured ranged from zero to 13 kg per s e t , averaging 3.6 kg per s e t . Two spec ies of f u s i l i e r s made up 90 per cent of t h e catches by numbers. On fishing days , the net was set from one to e igh t times with the maximum da i ly catch being 24 kg. These r e s u l t s do not demonstrate that daytime l i f t n e t fishing is a viable a l te rna t ive method for catching bait in Funafuti Lagoon. I t may prove to be useful , however, when there i s an exceptional need for bai t such as for research purposes.
Results from night-time fishing were much more encouraging. The ne t s were set 17 times and captured from 12 to 88 kg per se t , averaging 34.3 kg per se t . Three species of cardinalf ish made up 65 per cent of the c a t c h . Two species of fu s i l i e r s contributed a t o t a l of 25 per cen t . The maximum catch per night , made p o s s i b l e by the use of two n e t s , was 126 kg. In general, the amount of cardinalf ish that can be captured on a p a r t i c u l a r coral boulder during night-time l i f t n e t fishing s ignif icant ly exceeds what i s v i s ib l e on the same boulder during the day.
Bait captured by the project was o r i g i n a l l y used for taxonomic and morphometric purposes. Afterwards, on four occasions bai t was t r a n s f e r r e d to the Te. Tautai . This ba i t , averaging 71 kg per t r a n s f e r , enabled the crew of the vessel to car ry out more tuna f i sh ing than would have been possible had the crew r e l i e d e n t i r e l y on b a i t t h a t they had c a p t u r e d themselves by conventional techniques at night . Ba i t f i sh captured by the project were also used on eight occas ions for s m a l l - s c a l e p o l e - a n d - l i n e fishing (see Section 3 .0 ) .
2.2.4 Other areas
The most favourable location for fishing with respect to the abundance of fusiliers and cardinalfish, protection from prevailing winds, and distance from the fisheries jetty is the area between the fisheries complex and the south end of the airstrip. All of the baitfishing carried out by the project in Funafuti Lagoon was done in this area, although most other shallow areas of the lagoon were surveyed for species that could be used as baitfish (Figure 1). This prospecting was done by visual observation while free diving or while being towed behind a vessel.
Although fusiliers were seen in many parts of the lagoon, in no area were they as abundant as in the fishing area. Very clear water and the absence of boulder-type coral structures may have been responsible for the scarcity of these baitfish.
Cardinalfish were also more abundant in the fished area than in other locations in Funafuti. Prospecting in many of the shallow areas of the lagoon revealed very few of these fish. However, relatively deep SCUBA diving in water up to 28 metres deep in the centre of the lagoon and in areas adjacent to the fished area revealed significant quantities of cardinalfish. It is suspected that daytime light intensity is a factor for the distribution of these fish; i.e. they are found on shallow coral boulders where the water is somewhat turbid.
13
FIGURE 8. LIFTNET FISHING CATCHES
U)
OH
u D. I
o o t <
100
80
60-
40
20-
NIGHT FISHING
0 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r
0 5 10 15 SET NUMBER
U)
a: D.
i o $ o t <
i i i i i i i i i i i i i i i i
20 25 30 35 SET NUMBER
i i i
40
14
FIGURE 9. LIFTNET FISHING RESULTS
Caeslo caerulaureus 15X_JH,
Archamla fucata 5% / Chromls sp. 5%
DAY FISHING
AVERAGE CATCH PER HAUL - 3.6 KG
/•*- Pterocaeslo sp. 7SJ5
NIGHT FISHING
AVERAGE CATCH PER HAUL - 34.3 KG
Archamla fucata 50X
Caeslo caerulaureus
2 0 *
\ Chellodlpterus qulnquellneata
and Apogon exost lgma
15X
other 10JS Pterocaeslo SD. 3X
NOTE: (1) SIZE OF CIRCLE PROPORTIONAL TO AVERAGE CATCH (2) SEE APPENDIX A FOR ENGUSH AND TUVALU RSH NAMES
15
Nukufetau Atoll, 50 nautical miles to the northwest of Funafuti Atoll, was surveyed for fusiliers and cardinalfish in mid-May. Figure 10 shows that approximately 75 per cent of the perimeter of the lagoon was prospected. Very few baitfish were seen in the northwest, northeast, and southwest areas. The five nautical mile southeast side of the lagoon, however, had favourable concentrations of fusiliers and cardinalfish over most of the coral boulders. These coral structures were spaced 100 to 200 metres apart on a sandy bottom in slightly turbid water.
An experimental set of the net was made at night on one of these Nukufetau coral boulders. Using an inexperienced crew, unsuitable net skiff, and no SCUBA gear, 35 kg of bait (70% cardinalfish) were captured.
2.2.5 Fusiliers and cardinalfish as baitfish
In the opinion of the project staff, both fusiliers and cardinalfish are excellent baitfish. These fish, unlike many tropical bait species, survive quite well in bait tanks. In addition, when thrown as chum, they have an excellent action in the water.
This view of fusiliers and cardinalfish is supported by Lewis, Smith and Ellway (1983), who state that these baitfish are robust and highly regarded as bait. Baldwin (1977) compares over 150 species of baitfish and concludes that the various species of fusiliers and cardinalfish are good or excellent as tuna bait. Smith (1977) reports that the handling characteristics of these two baitfish are excellent and are quite satisfactory as chum. It is stated by Wilson (1977) that some Okinawan fishermen believe that cardinalfish are a better bait than anchovy as they return to the boat faster and remain longer. It was also stated that fusiliers are strong when confined and make extremely good bait for skipjack.
A combination of different baitfish species sometimes is more effective for tuna fishing than a single species. Fusiliers and cardinalfish have different body colouration, shape, size, swimming patterns, and speed of return to vessel after chumming. It is believed that the combination of baitfish caught in night-time liftnet fishing (6 5% cardinalfish, 25% fusiliers) is an excellent bait.
An important aspect of cardinalfish which contributes to their value as bait is that they are not used by the people of Tuvalu as a food fish. The capture of cardinalfish would not involve direct competition with small-scale fishermen as would, for example, the capture of hardyheads, goatfish, or scads, as has been suggested by previous consultants.
2.2.6 Notes on cardinalfish behaviour
During daylight hours cardinalfish form a cloud around certain coral boulders. These fish are concentrated from the coral surface outwards about 50 cm and in daylight hours rarely stray more than a metre from the coral. The smallest Archamia individuals are located furthest from the coral, while the larger of the species are to be found very close to the coral surface. The characteristically larger Apogon and Cheilodipterus are most often found in crevices and holes. At night, there is a total absence of cardinalfish on the coral structures, although individual Apogon can be seen close to the bottom on adjacent sandy areas. Even during full moon periods, when underwater illumination is quite bright, no cardinalfish are found on the coral at night.
FIGURE 1 0 . NUKUFETAU LAGOON
. • : • ; / .
SAVEVE
AREA SURVEYED
SAVEVE
CARDINALFISH
17
As a knowledge of the diurnal movement patterns of cardinalfish is important for their capture, a study was made of their activities on a coral boulder at dawn and sunset. Appendices II and 12 show the results of the study. It can be seen that all activity takes place during the hour after sunset and during the hour before sunrise. The observations suggested, and were later confirmed by fishing, that the liftnet could be set an hour before sunrise and successfully hauled at sunrise.
Sometimes a liftnet can be set at night over a coral structure in such a manner that the net does not touch the sandy area on all sides (the coral is not "sealed"). This may be due to improper placement of the net at the surface before sinking, disregard of the current, or the net being too small for the size of the coral. In this situation, the Cheilodipterus and Apogon, and some of the fusiliers, will find their way into the coral, while the Archamia will position themselves over the net and will be almost the only baitfish captured.
Cardinalfish that are located furthest from the coral can be driven a short distance towards a net by a diver. This technique, however, does not work well for more than about one and a half to two metres as the fish then begin to take refuge in crevices where they cannot be dislodged.
An attempt was made to determine the rate at which a coral boulder that has been harvested becomes re-populated with fusiliers and cardinalfish. On the night of 30 April, a relatively small coral boulder was set on and the following day the liftnet was hauled capturing 3 5 kg of baitfish (60% cardinalfish, 30% fusiliers). An inspection dive immediately after the haul revealed that virtually 100 per cent of the baitfish had been captured and no fusiliers or cardinalfish remained on the coral boulder. Several inspection dives were made during the following month to observe the population level. It was estimated that ten days after the set, the amount of fusiliers and cardinalfish was about two-thirds that of the pre-harvest state. Thirty days after fishing, the population had returned to its original level. Whether this re-colonisation came from neighbouring coral boulders or from some other area is unknown.
Tests were made to determine the length of time that a liftnet that has been set at night can remain on the bottom without decreasing the catch of fusiliers and cardinalfish. On eight occasions liftnets were set at night and not hauled until 1500 hours the following afternoon. The amount of baitfish hovering over the nets did not noticeably decrease in the nine hours of daylight. Three times the nets were set and remained on the bottom in excess of two days. During one of these occasions, the amount of fusiliers decreased from about 25 kg to 3 kg. It was not possible to determine whether this was due to predation or to the baitfish seeking a more secure refuge.
To complement the knowledge of cardinalfish gained by experimental fishing, two experienced masterfishermen from Funafuti were questioned on the subject. These men confirmed the suspicion that cardinalfish in Funafuti are found in relatively murky water. In addition, they stated that there was no large seasonal fluctuation, but concentrations of fusiliers and cardinalfish seemed to be somewhat greater from June to September. They also believe that cardinalfish are more abundant in Nukufetau than Funafuti. To their knowledge cardinalfish have never been used as a food fish by the Tuvalu people.
As certain aspects of the behaviour of fusiliers were documented in previous reports, a summary appears in Appendix J.
18
2.2.7 The baitfishing crew
2.2.7.1 Performance of the crew
The baitfishing crew performed extremely well. As they were enthusiastic learners, they soon mastered the procedures for setting and hauling the liftnets. In the chaotic situation of setting a large net underwater in darkness, the crew managed to organise themselves quickly. With practice, several members of the crew became skilled at scouting coral boulders to determine the potential yield of a set. There was little apprehension among any of the crew for diving at night. The square mesh used in the liftnets is simple to patch and virtually no instruction was necessary. Figure 6 shows the technique used for baitfish transportation, which the crew learned rapidly and later improved. Appendix K of this report was written entirely by two baitfish team members and testifies to the fact that they are able to modify a bouki-ami net into a liftnet. Gear pilferage was almost, if not absolutely, zero. Before the project was half finished, the local crew were doing the routine baitfishing unassisted. In short, the performance of the local baiting crew left little to be desired.
2.2.7.2 Future baitfishing
The project has demonstrated that nine carefully selected Tuvalu men can successfully carry out night-time liftnet fishing. It is believed that as few as four of the original crew could train new members and be operational in a few days. This crew would need general supervision from the Fisheries Division for daily planning, encouragement, evaluation of performance, weekly inventory of gear and condition of nets, and general shore support, such as the procurement of fuel and SCUBA tanks. It is suggested that to maintain the high productivity of the crew, wages be structured on an incentive basis.
A typical fishing day would consist of setting two nets in the evening or before dawn, hauling them in daylight, patching any holes, and scouting for locations for the following day's set. This could be accomplished in five working hours. Assuming catch rates obtained by the project, the crew could conceivably catch 343 kg of bait per week using 225 man hours of labour.
2.2.8 Other considerations
2.2.8.1 Gear
One appealing aspect of liftnet fishing is the simplicity of gear requirements. Much of the equipment needed (Appendix B) is available at little or no cost. In several South Pacific countries there are many used bouki-ami nets which have been retired from service and are idle in storage. These nets can be modified fairly easily into liftnets (Appendix K). Longline cord and balls are in abundance in most Island countries. Weights can be fashioned out of scrap iron. The bait receiver is made almost entirely from cheap materials available locally.
SCUBA gear requires special mention. It was the most expensive equipment (over US$450 for one tank and one regulator) used with the liftnet. An important point to be made is that having one SCUBA diver is not absolutely essential, but very helpful. The liftnet can be set at night by a skilled crew in water up to nine metres deep, entirely by free diving. However, the procedure takes much longer, can be a real hardship on the crew, and coverage of the coral boulder could be less than 100 per cent, resulting in a reduced baitfish catch. In Funafuti Lagoon, at least
19
hal f of the s u i t a b l e cora l boulders a re in water deeper t h a n n i n e m e t r e s . F ishable l o c a t i o n s in Nukufetau are perhaps s l i g h t l y sha l lower .
2 . 2 . 8 . 2 Future l i f t n e t f i s h i n g requirements
At the reques t of the f i s h i n g m a s t e r of t h e Te. T a u t a i and w i t h t h e endorsement of the Tuvalu F i s h e r i e s Adviser , the b a i t f i s h team removed t h e t w o - y e a r - o l d b o u k i - a m i n e t from t h e T_e T a u t a i and m o d i f i e d i t i n t o a l i f t n e t . This net (Appendix B) , t o g e t h e r w i t h one of t h e l i f t n e t s from F i j i and a l l p ro j ec t gea r , was se rv iced and p l a c e d i n a l o c k e d F i s h e r i e s Divis ion s toreroom. The only a d d i t i o n a l equipment n e c e s s a r y f o r l i f t n e t f i s h i n g i s a diving k n i f e , net-mending n e e d l e s , n e t t w i n e , and b a t t e r i e s for the underwater t o r c h e s .
2 . 2 . 8 . 3 Safety
N i g h t - t i m e d i v i n g a r o u n d a l a r g e n e t can be d a n g e r o u s . The p o s s i b i l i t y t h a t an unwary d i v e r cou ld be t r a p p e d u n d e r t h e n e t was cons t an t l y s t r e s s e d to the crew. A po l icy was a d o p t e d t h a t a f r e e d i v e r should never go under the net and a SCUBA diver should always carry a kni fe wi th which he could cut himself f r e e of t h e n e t i f he became e n t a n g l e d . One diver on the sur face was charged wi th t h e r e s p o n s i b i l i t y of w a t c h i n g the SCUBA d ive r below and render ing a s s i s t a n c e i f needed. I t i s s t r o n g l y recommended t h a t these p o l i c i e s be cont inued .
2 .3 Phase 3 - S m a l l - s c a l e . L i v e - b a i t Tuna Fishing T r i a l s
2 . 3 . 1 Gear and mod i f i ca t ions
After a month of experimental b a i t f i s h i n g , i t became evident t h a t t h e n igh t - t ime l i f t n e t f i s h i n g would be s u c c e s s f u l in c a t c h i n g s i g n i f i c a n t amounts of b a i t . At t h a t point t h e 1 0 . 3 - m e t r e c a t a m a r a n , Tui Puga . was f i t t e d out for l i v e - b a i t f i s h i n g . A 6 0 7 - l i t r e aluminium tank was f a s t e n e d c e n t r a l l y on the ca tamaran and b a i t t a n k pumps and a s p r a y sys tem were i n s t a l l e d . S ix f i b r e g l a s s p o l e s were r i g g e d w i t h s t a n d a r d J a p a n e s e b a r b l e s s hooks. This gear i s shown in Figure 11 and the s p e c i f i c a t i o n s a re l i s t e d in Appendix B.
FIGURE 1 1 . LIVE-BAIT TUNA FISHING ON THE TUI PUGA
t
20
2 .3 .2 Fishing techniques
Immediately after the liftnet was hauled, the captured baitfish were carefully bucketed from the net directly to the bait tank on the catamaran. The average catch per night-time haul, 34.3 kg, is a convenient amount as it is about the maximum quantity of baitfish that can be carried in the bait tank. After bait loading, the catamaran proceeded directly to the tuna fishing grounds. Fishing took place to the southeast, south and west of Funafuti Atoll, and to the southwest of Nukufetau Atoll.
The fishing strategy followed was basically the same as that of much larger Japanese-style pole-and-line vessels. After a school began biting, however, the catamaran was kept moving slightly ahead and all poling was done from the stern. The 4.3-metre stern could accommodate a maximum of five fishermen. An occasional thrust of forward motion was used to flush bait out from the hull, and was frequently successful in re-stimulating fish to bite.
2 . 3 . 3 Resu l t s
A t o t a l of 194 kg of b a i t was t r a n s f e r r e d t o t h e Tui Puga on e i g h t o c c a s i o n s . A major r e s t r i c t i o n p l a c e d on s m a l l - s c a l e , l i v e - b a i t t u n a f i s h i n g i s t h a t on a small v e s s e l , the s i z e of the b a i t tanks and t h e more r a p i d , j e r k y v e s s e l m o t i o n r e s u l t i n a v e r y h i g h m o r t a l i t y of t h e r e l a t i v e l y f r a g i l e b a i t f i s h spec ies u s u a l l y caught by convent iona l g e a r a t n i g h t . A l t e r n a t i v e l y , more robust cu l t u r ed b a i t has proven too e x p e n s i v e . I t was p l eas ing to record t h a t t h e m o r t a l i t y of t h e b a i t f i s h caugh t by n i g h t - t i m e l i f t n e t f i s h i n g averaged l e s s than 5 per cen t pe r f i s h i n g t r i p aboard the Tui Puga.
On e igh t f i s h i n g days a t o t a l of 117 t u n a were c a u g h t . F i g u r e 12 d e p i c t s t h e d a i l y r e s u l t s . S e v e r a l f a c t o r s were r e s p o n s i b l e f o r t h e r e l a t i v e l y low catch r a t e . Tuna s c h o o l s were s c a r c e d u r i n g most of t h e f i s h i n g per iod and most of t h e s c h o o l s l o c a t e d and f i s h e d c o n s i s t e d of mackerel tuna and rainbow runner , which do no t b i t e as w e l l as s k i p j a c k .
FIGURE 12. SMALL-SCALE TUNA FISHING RESULTS
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FISHING DAY
21
The five men fishing on the stern had no previous poling experience and therefore conditions were at times chaotic; some fish were poled completely over the bow, many were dislodged from the hook in the water, and line tangles were common. In addition, mechanical problems of the catamaran interfered with the fishing operation on a few occasions. It is believed that none of the above problems are insurmountable, and with additional experience the catch rate would undoubtedly improve. The Tuvalu Fisheries Division has estimated an average catch of 33 three-kilogram skipjack per day would be necessary for the fishing operation to reach the break-even level for expenses relating to baitfishing, vessel use, and crew costs. The project managed to exceed this catch on only one day, but the outlook for the future is promising.
In several Pacific Island countries, industrial-scale pole-and-line fishing operations are encountering difficulty due to the present low market price for tuna. On the domestic market, however, the prices paid for the quality and quantity of fish which could be caught by a small pole-and-line operation have suffered no such drop. Therefore, the major factor presently detracting from the success of the large pole-and-line fleets would not necessarily affect a small vessel.
3.0 CONCLUSIONS
3.1 Blue Sprat Monitoring Programme
Due to behavioural characteristics of the blue sprat, it was possible to set up a fairly simple system to monitor their relative abundance in Funafuti Lagoon. Such a monitoring programme, if carried out regularly for two years, would give valuable insight into the population dynamics of the only baitfish in Tuvalu which can be caught by conventional gear. A less ambitious monitoring programme, conducted only intermittently, would produce information useful for directing the movements of the Te. Tautai. If the project is assigned a fairly high priority in the Fisheries Division work programme, local staff should be able to carry out the work.
3.2 Development of Baitfishing Techniques
The results of the project demonstrate that it is possible through a technique not previously used in Tuvalu to catch significant quantities of baitfish. In the opinion of several baitfish authorities, the species captured - fusiliers and cardinalfish - are very good baitfish. The best fishing area for the bait is conveniently located near the Funafuti urban centre. Baitfish mortality would not be a major concern as survival in bait tanks is excellent. Furthermore, competition with small-scale fishermen would not be a problem. The value of fu-feiliers and cardinalfish as a supplementary bait for an industrial-scale fishing operation has been satisfactorily demonstrated and the possibilities for a small-scale operation are promising.
The resource does, however, have limitations. During the survey it was revealed that in the area near the urban centre there are approximately 30 coral boulders for setting the net at night. Considering that an average haul yields 34.3 kg of bait, approximately one tonne of bait could be caught by setting the net once on each coral boulder.
The value of this baitfish resource to Tuvalu is highly dependent on two factors: (1) the speed and mechanism by which a harvested coral boulder
22
becomes re -popula ted with c a r d i n a l f i s h , and (2) the degree of n a t u r a l f luctuations in the cardinalf ish popu l a t i on . Studies on a s ing le cora l boulder showed r e l a t i v e l y rap id r e - p o p u l a t i o n , and deep diving in the centre of the lagoon showed a d d i t i o n a l q u a n t i t i e s of c a r d i n a l f i s h . Idea l ly , the popula t ion s i ze of c a r d i n a l f i s h i s h a b i t a t - l i m i t e d , and re-population of coral boulders i s from a large reserve population in deep water. However, if the re-population is from neighbouring cora l boulders the res i l i ence to fishing pressure would be much l e s s .
During a short survey, i t was not possible to determine the degree of natural population f luc tua t ions . Interviews with masterfishermen i n d i c a t e no great seasonality is to be expected. Baldwin (1977) , however, s t a t e s that many cardinalf ish species in other areas of the c e n t r a l and western Pacific are seasonal.
Continuation of night-time l i f t n e t fishing on an i n t e n s i v e bas i s and closely moni tor ing the catch appear to be the most p r a c t i c a l means of acquiring information on re-population and seasonali ty. I t i s recommended that th is addit ional work be ca r r i ed out when e i t h e r the Tui Puga or Te Tautai can make use of the bait catch.
The a p p l i c a b i l i t y of n i g h t - t i m e l i f t n e t f i sh ing to o ther P a c i f i c Island countries should not be overlooked.
3.3 Small-scale Fishing Tr ia ls
The a b i l i t y to catch b a i t f i s h t h a t can s u r v i v e t h e s t r e n u o u s conditions found on a small vessel creates new p o s s i b i l i t i e s for small- and medium-scale f i s h e r i e s development. The p r o j e c t d e m o n s t r a t e d t h a t l ive-ba i t f i sh ing techniques could be adapted to a small v e s s e l using locally caught b a i t . Although catches were not great , success would almost cer ta inly increase with experience.
23
REFERENCES
BALDWIN, W.J. (1977) . A review of the use of l i v e b a i t f i s h e s t o c a p t u r e sk ip jack t u n a , Katsuwonus pe lamis . in the t r o p i c a l P a c i f i c Ocean w i t h e m p h a s i s on t h e i r b e h a v i o u r , s u r v i v a l and a v a i l a b i l i t y , i n . Shomura, R . S . ( e d . ) , C o l l e c t i o n of t u n a b a i t f i s h p a p e r s , NOAA Technical Repor t . NMFS C i r c u l a r 408.
LEWIS, A.D. , B.R. SMITH and C.P. ELLWAY (1983) . A guide to the common tuna b a i t f i s h e s of t h e South P a c i f i c Commission a r e a . Handbook N o . 2 3 , South P a c i f i c Commission, Noumea, New Caledonia .
SMITH, B.R. (1977) . Appra isa l of t h e l i v e - b a i t p o t e n t i a l and h a n d l i n g c h a r a c t e r i s t i c s of the common tuna b a i t spec ies i n Papua New G u i n e a , in Shomura, R.S. ( e d . ) , C o l l e c t i o n of t u n a b a i t f i s h p a p e r s , NOAA Technical Repor t , NMFS Ci rcu la r 408.
WILSON, P.T. (1977) . O b s e r v a t i o n s of t h e t u n a b a i t s p e c i e s and t h e i r h a b i t a t s in the Palau I s l a n d s , in . Shomura, R.S . ( e d . ) , C o l l e c t i o n of tuna b a i t f i s h pape r s , NOAA Technical Report . NMFS Ci rcu la r 408.
25
APPENDIX A. ENGLISH, SCIENTIFIC AND TUVALU BAITFISH NAMES
English Name Scientific Name Tuvalu Name
Bronze-streaked cardinalfish
Five-lined cardinalfish
One-lined cardinalfish
(Fusilier)
Gold-banded fusilier
Damselfish
Goatfish
Scad
Hardyheads, Silversides
Blue sprat
Archamia fucata Matapa
Cheilodipterus quinquelineata Kalisi
Apogon exostigma
Pterocaesio sp.
Caesio caerulaureus
Chromis sp.
Family Mullidae
Selar sp.
Family Atherinidae
Spratel loides del icatulus
Palumaliau
Ulia
Ulia
Moimoi
Afulu, Kalo
Salala
Sa l i i
Kavaliki
Note: Pterocaesio sp. samples were forwarded to taxonomic a u t h o r i t i e s . The species in question appears to be previously undescribed (Carpenter, pers . comm.).
Cheilodipterus quinquelineata
Archamia fucata
Apogon exost igma
Drawings from Lewis, Smith, and Ellway (1983)
27
APPENDIX B. GEAR SPECIFICATIONS
PHASE ONE
Electrical generator
Voltage transformer
Above-water light
Underwater light
Yamaha EF 2800 220 volt 2.2 kw rated output 2.6 kw maximum output 4 cycle petrol engine
220 volt to 110 volt
100 volt 500 watt
100 volt 1500 watt
PHASE TWO
Liftnet No.l (from Fiji)
Liftnet No.2 (from Fiji)
Liftnet No.3 (constructed by project crew)
Skiff
12 m x 12 m flat net 15 cm of selvage around perimeter 4 mm square mesh 15 m lengths of 12 mm polypropylene
line attached to each corner and and middle of a side, 8 lines total
One longline ball attached to each of the above lines - 30 cm diameter, 14.5 kg buoyancy per ball, 8 balls total
One 2 kg lead weight attached to each line next to the net, 8 weights total
11 m x 13.5 m flat net 15 cm selvage around the perimeter 4 mm square mesh 15 m lengths of longline cord (7 mm)
attached to each corner and middle middle of a side, 8 lines total
One longline ball attached to each line, 8 balls total
One 2 kg weight attached to each line next to the net, 8 weights total
14 m x 14 m flat net 4 mm square mesh (attachments are as described for No.l liftnet)
5.5 m length 1.6m beam 5 hp Yamaha outboard engine
28
Bait receivers (2 total)
Bait scoops (2 total)
Torches (6 total)
Buckets (5 total)
SCUBA gear
Misc.
200-litre used oil drums (1) 33 cm x 69 cm hole cut in side of one (2) 36 cm x 72 cm hole cut in side of other
Wooden handle Stainless steel frame (1) 30 cm diameter (2) 40 cm diameter
4 mm square mesh
Toshiba underwater flashlight 4-battery model
Blue plastic 15-litre
1 Sherwood 2000 regulator 5 80 cu. ft. air tanks 5 spare "o" rings 1 weight belt - 9 lb. weights 1 back pack
14 diving masks 1 diver's knife with holster 5% boric acid/isopropyl alcohol ear solution (prevents ear infections when used after diving)
PHASE THREE
Fishing vessel
Bait tank
Bait tank pumps (2 total)
Spray system
Fishing gear
Tui Puga Launched 1981 10.3 m x 4.3 m catamaran 5 gross tonnes displacement
90 cm x 90 cm x 75 cm 0.607 cu. metre volume 6 total 2 cm drain holes 9 mm plywood cover
Jabsco Water Puppy 6660-2103 12 volt d.c. 12.4 litres per minute per pump 8 amp draw per pump
Yamaha YP20G portable water pump 480 litres per minute 2 cycle petrol engine 2 1/2 inch intake hose 2 inch discharge hose
3.5-metre fibreglass poles, 6 total No. 2.5 barbless polefishing lures
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51 3
APPENDIX D. BLUE SPRAT DATA SHEET
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BLUE SPRAT DATA SHEET
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33
APPENDIX E. INSTRUCTIONS FOR THE BLUE SPRAT DATA SHEET
SPACE ITEM EXAMPLE
1-2 3-4 5-6 7 8
9 10-14 15 16-21 22 23-24
25 26
27 28-31
32 33-35
36 37
38 39
40 41-43
44 45-47
48 49-80
YEAR MONTH DAY BLANK LETTER CODE FOR LOCATION BLANK LATITUDE TO 1/10 MIN BLANK LONGITUDE TO 1/10 MIN BLANK PERSON WHO RECORDED THIS DATA BLANK QUANTITIES OF BAIT
BLANK WIND SPEED AND DIRECTION BLANK WATER TEMPERATURE IN DEGREES CENTIGRADE TO 1/10 DEGREE BLANK SIZE OF SPRATS OBSERVED
BLANK PRESENCE OF PREDATORS
BLANK RAINFALL IN MM DURING PREVIOUS 24 HRS BLANK RAINFALL IN MM DURING PREVIOUS WEEK BLANK ADDITIONAL FACTORS OR COMMENTS IN WORDS
1984=84 APRIL=04 9TH=09
SEE TABLE ONE
7 DEG 41 MIN SOUTH = 07410
178 DEG 1.2 MIN EAST = 178012
BOB GILLETT = BG
SCALE FROM ZERO TO NINE 0 = ABSOLUTELY NOTHING 9 - VAST QUANTITIES
5 KNOTS NORTHWEST WIND = NW05 CALM= 0000
28.5 DEG CENTIGRADE= 285
S= LESS THAN 30 MM M= BETWEEN 30 AND 50 MM L= GREATER THAN 50 MM
0= NO PREDATORS S= SOME PREDATORS M= MANY PREDATORS
12 MM RAIN= 012
0 MM RAIN= 000
35
APPENDIX F. INSTRUCTIONS FOR BLUE SPRAT MONITORING
Sampling nights occur 3 days after the full moon and continue for 2 weeks.
On a sampling night, generator operation should begin at civil twilight, which in Tuvalu is about 20 to 22 minutes after the sun touches the horizon. The operation terminates 2 hours later.
The following are the sampling locations:
(a) 100 metres north of the coral patch directly west of the Fisheries jetty;
(b) 100 metres north of the coral patch off the Van Camp wreck;
(c) 400 metres south of the Marine Training School jetty;
(d) 200 metres southwest of the tree line at north end of Mateika Island.
Location "B" is to be sampled first and then again after the other locations have been sampled once.
Fuel the generator with straight (unmixed with oil) petrol and check the crankcase oil level.
Depart from the Fisheries jetty in time to arrive at the sampling location at least 10 minutes before civil twilight.
Start the generator without the voltage converter connected. Plug in the voltage converter and then plug in the above-water light into the voltage converter. Lower the underwater light 1.5 metres into the water and plug it into the voltage converter. NEVER turn on the underwater light unless it is submerged.
Every 5 or 10 minutes observe the quantities of sprats that have gathered around the light. Also note the presence of any predatory fish in the water and anything unusual (e.g. generator stopped for 30 seconds at 0745 hrs). The water temperature 30 cm below the surface is to be recorded. Note the maximum amount of sprats present during the second hour of observation. Record this information on the Blue Sprat Data Sheet.
Turn the generator off after the two-hour period has been completed. Cover the generator with the tarpaulin and store the lights below. At the completion of the month's sampling, spray gear with oil and store it ashore.
3
9
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37
APPENDIX G. PARTICIPANTS IN THE PROJECT
Baitfishing team: Iakopo Vakafaa Enesi Tiale s,t Taoa Vaiaua s Eliapo Sualo s,t Norman Iese t Teauoki Auina s Kilisone Tui Teisio Faiaki Tavo Motumua
s = Trained in shallow water SCUBA diving techniques
t = Graduate of Tuvalu Maritime School
Fisheries Division staff: Michael Batty Fatulolo Vave Ioapo Tapu Semesi Founuku Meneva Teagai Lota Bakai
Te Tautai crew: Apelamo Vaiguna Kutimeni Taulialia Atafia Tauvalie Esekia Haleti Filioma Teafiula Keipasi Tuisaga Faimalana Teokila Taula Kaio Tausavali Litogi Pauna Pauna
Nukufetau Atoll residents: Simona Aleke Fanini Maleko Fafe Nelesonia Fakafounga Papa Maniotai Noa
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41
APPENDIX II. MOVEMENTS OF FUSILIERS AND CARDINALFISH AWAY FROM A CORAL BOULDER AT SUNSET. Observations made on a cloudless day with sunset at 1745 hrs.
Cheilodipterus Time Archamia and Apogon Pterocaesio Caesio
1700 about 1 metre very close to rock above rock above rock from rock and in crevices
1710
1720
1730
1740
1750 start to move away from rock
1800 " a few moving away from rock
1810 many have moved " some leave most have away from rock rock left rock
1820 most have moved many have moved most have away from rock away from rock rock
1830 all have left only a few remain " only a few rock on rock remain
1840 darkness darkness darkness darkness
Note: Archamia, Cheilodipterus, and Apogon are cardinalfish. Pterocaesio and Caesio are fusiliers.
42
APPENDIX 12. MOVEMENTS OF FUSILIERS AND CARDINALFISH TOWARDS A CORAL BOULDER AT DAWN. Observat ions made on a c loud l e s s day w i t h sun r i s e a t 0609 h r s .
Che i lod ip t e rus Time Archamia and Apogon P te rocaes io Caesio
0500
0510
0520
0530
0540
0550
0600
0610
none visible
it
ii
some have returned to rock
II
continue to return
many have returned
n
none visible
II
II
some have returned to rock
II
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many have returned
II
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II
II
some have returned to rock
many have returned
II
II
it
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II
II
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II
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it
0620
43
APPENDIX J. NOTES ON FUSILIER BEHAVIOUR
Caesio and Pterocaesio are located on the up-current side of coral boulders, scare easily towards coral protection, but soon gain composure.
These fish are attracted by any sort of detritus being stirred up.
They are strongly attracted by finely chopped skipjack.
It is difficult to lead fusiliers down-current.
These fish are not attracted by lights set near coral at night.
At night they are usually not found around the coral where they are found during the day.
They are hesitant to enter confined areas (traps).
Fusiliers exhibit little learned response to avoid a net.
These fish are usually associated with Chromis; however, fusiliers are much more daring and venture further from coral protection.
Fusiliers do not appear to become quickly saturated with food.
When the fish notice the net being raised, they charge towards the coral.
If the edge of the net is more than two metres off the bottom when the charge of fish reaches the edge, the fish will probably not go over the top, but will turn back towards the centre.
45
APPENDIX K. HOW TO CHANGE A BOUKI-AMI NET INTO A LIFTNET by Enesi Tiale and Iakopo Vakafaa, baitfish team members
1. Before you start changing a bouki-ami net to a liftnet, make sure to get all the tools nearby for the job. Needles, pairs of scissors, knives, and net twine a little bit larger than bouki-ami repair twine are needed.
2. Carry the bouki-ami net to a flat area that you know is large enough to stretch the net out fully. After the net is stretched out, measure it.
3. Now you know how long and wide it is. Our net was about 30 x 30 metres.
4. Now you cut the net. Decide on what size liftnet you want. We found that a 12.5 x 12.5 metres net was a little small during our work.
5. If you want a finished net to be 14 x 14 metres then you cut the net 15 x 15 to give it some "belly".
6. Use a pair of scissors for cutting it. Cut very straight along the square mesh.
7. When you finish cutting the entire net out, fold over the whole length of each side about 5 cm (2 inches) and sew this so the edge is now very strong. Use a net twine that is stronger than regular bouki-ami twine.
8. Cut the selvage from the old bouki-ami and sew it all around the new liftnet. The selvage helps to distribute the strain of pulling on a net to a larger area. When sewing the selvage to the net use strong twine and tie an extra strong knot about every 12 cm (5 inches) in addition to the regular stitches.
9. Attach a 15-metre length of longline cord to each corner and to the middle of each side. At the same position tie a 2 kg weight. Thread the line through the eye of a longline ball.
10. Good luck!
