Vlarine Fisheries Researcb, Management and Development Project BGD/80/025/CR 7
Marine Fisheries Resources Survey Demersal Trawling BGD/80/025/CR7
Survey Cruise Report No. 7 Jarwary 5-16, 1985
By T F White FAO Team Leader/Senior Fisheries Biologist
Chittagong Bangladesh July 1985
United Nations Development Programme, Food and Agriculture Organization of the United Nations ii
Information provided in this Cruise Report is the result of analysis of data obtained during the survey cruise. Any interpretation of these data represents the opinions of the authors alone and does not necessarily represent the opinion of the Food and Agriculture Organization.
Similarly. the designations employed and the presentation of the material and maps in this document do not imply the expression of any opinion vvhatsoever. on the part of the United Nations or the Food and Agriculture Organization of the United Nations concerning the legal or constitutional status of any country, territory or sea area. or concerning the delimitation of frontiers. iii
SUMMARY
Daylight trawling was conducted on 45 randomly selected stations, ranging in depth from 15 to 107 metres, with an average overall catch rate of 99 kg/30 minutes trawling. The density decreased considerably cetwern the shallcwer ar.d deeper water, the mern catch rate in waters less than 50 metres in depth being around 200-250 kg/30 minutes trawling, while in the deeper waters, it was less than 50 kg/30 minutes trawling.
The most abundant species in the overall catch were catfish (Family Ariidae), jewfish (Family Sciaenidae), hairtaiL Lepturacanthus savala, scads (Family Carangidae), threadfin bream, Nemipterus japonicus and lizard fish, Saurida spp., all in approximately equal amounts. Penaeid prawns were virtually absent.
Few of the fish landed during the survey were of commercial value, due to their abundance, type or size.
The overall demersal biomass calculated for the survey area was between 40,000 and 294,000 m.t., of which some 100 tonnes only were prawns.
Few pelagic fish were observed visually or using the sonar or fish finder, although around 20% of the catch consisted of "pelagic" species.
Eight to ten "Thai" trawlers were observed operating in shallow waters in the north cen tral section of the survey area.
Water conditions over the survey area were somewhat clearer than during previous cruises.
CRUISE DETAILS
Cruise No. : 8 Duration : 10 days from January 6-16, 1985 No. of trawl stations completed : 45 Cruise Leader Mr Md. Gulam Mustafa Biologists Mr S. A. Ouayum Mr Zubair Ahmed Chowdhury Mr Nasiruddin Sada IV
TABLE OF CONTENTS
Page 1. INTRODUCTION 1 2. MATERIALS AND METHODS 1 2.1 The Survey Area and Selection of Trawl Stations 1 2.2 The Vessel and Gear 1 2.3 Treatment of the catch 2 2.4 Data Analysis 2
3. RESULTS 3 3.1 General 3 3.2 Distribution and Abundance of the Major Species 3 3.2.1 Bathymetric distribution 6 3.2.1.1 10-20 metre depth zone 6 3.2.1.2 21-30 metre depth zone 6 3.2.1.3 31-50 metre depth zone 7 3.2.1.4 51-100 metre depth zone 7 3.2.1.5 101-200 metre depth zone 7 3.2.1.6 Summary - Bathymetric distribution 7 3.2.2 Geographical distribution 8
3.3 Distribution and Abundance of the Most Common Species in the Catch. 8 3.3.1 Family Ariidae (catfish) 9 3.3.2 Family Sciaenidae (jewfish) 9 3.3.3 Family Trichiuridae (Hairtail) 9 3.3.4 Family Nemipteridae (Threadfin bream) 10 3.3.5 Family Carangidae (scads) 10 3.3.6 Family Mullidae (goatfish) 10 3.3.7 Family Haemulidae (grunter) 11 3.3.8 Family Formionidae (Carangidae) (black pomfret) 11 3.3.9 Family Leiognathidae (pony fish) 11 3.3.10 Family Stromateidae (pomfret) 11 3.3.11 Family Scombridae (mackerels) 12 3.3.12 Family Synodontidae (lizard fish) 12 3.3.13 Family Priacanthidae (bulls eye) 12 3.3, 14 Penaeid -prawns 12 3.3.15 Other Species 13
4. STANDING STOCK ESTIMATION 13 5. PELAGIC FISH 15 6. OCEANOGRAPHY 15 7. OBSERVATIONS OF COMMERCIAL FISHING ACTIVITY IN THE SURVEY AREA 17 8. COMPARISION WITH OTHER CRUISE RESULTS 17 v
UST OF TABLES Page 1. Percentage Composition of the Catch by Family for each Depth Zone and for the Total Survey Area (Listed in order of occurrence in the total catch) 3 2. Average Catch Rates Obtained (All species combined) by Depth Strata 6 3. Total Density and Biomass 13 4. Density and Biomass of Penaeid prawns 14 5. Secchi Disc and Surface Water Temperature Measurements 16
LIST OF FIGURES 1. Survey area showing position of stations 20 2. Survey area showing the zones into which pooled length frequency samples were allocated 21 3. Catch rate (kg/30 minutes haul) versus depth of trawling (metres) for Total Catch -All species 22 4. jewfish, Family Sciaenidae 23 5. hairtaiJ, Lepturacanthus sava/a 24 6. catfish, Family Ariidae 25 7. threadfin bream, Nemipterus japonicus 26 8. goatfish, Upeneus sulphureus 27 9. pony fish, Leiognathus spp. 28 10. indian mackerel, Rastre/liger kanagurta 29 11. lizard fish, Saurida spp. 30 12. bulls eye, Priacanthus sp. 31 13. hard tail scad, Megalaspis cordy/a 32 14. blotched grunter, Pomadasys maculatus 33 15. silver lined grunter, Pomadasys hasta 34 16. white pomfret Pampus argenteus 35 17. Chinese pomfret Pam pus chinensis 36 18. black pomfret Parastromateus niger 37 19. round scad, Decapterus maruadsi 38 20. spanish mackerel, Scomberomorus guttatus 39 21. kuweh trevally, Atropus atropus 40 22. Penaeid prawns 41 23. Distribution of total fish stock over the survey area 42 24. jewfish, Family Sciaenidae 43 25. catfish, Family Ariidae 44 26. hairtail, Lepturacanthus savala 45 27. threadfin bream, Nemipterus japonicus 46 28. yellow lined goatfish, Upeneus sulphureus 47 29. pony fish, 4eiognathus sp. 48 30. indian mack~rel, Rastrelliger kanagurta 49 vr
Page 31. Distribution of lizard fish, Saurida spp. 50 32. bulls eye, Priacanthus sp. 51 33. silver lined grunter, Pomadasys hasta 52 34. white pomfret. Pampus argenteus 53 35. Chinese pomfret Pampus chinensis 54 36. round scad, Decapterus maruadsi 55 37. Spanish mackerel, Scomberomorus guttatus 56 38. penaeid prawns 57 39. Length frequency histogram for hairtail, Lepturacanthus sava/a 58 40. kuweh trevally, Atropus atropus 59 41. grunter, Pomadasys hasta 60 42. black pomfret, Parastromateus niger 61 43. white pomfret, Pampus argenteus 62 44. indian mackerel, Rastrelliger kanagurta 63 45. lizard fish, Saurida tumbil 64 46. brown shrimp, Metapenaeus monoceros Male 65 47. brown shrimp, Metapenaeus monoceros Female 66 48. tenpounder, E!ops machnata 67 49. Secchi disc measurements in the survey area 68 50. Observed fishing activity 69 51. Bathythermograph profiles 70
APPENDiX A RESEARCH VESSEL R/V "ANUSANDHAN("
APPENDIX B ENGEL HIGH OPENING BOTTOM TRAWL
APPENDIX C SURVEY LOG SHEETS 1. INTRODUCTION In order to understand more about the abundance and distribution of the living mar ine resources within the Bangladesh continental shelf, the Bangladesh Government with the assistance of FAO; commenced a comprehensive survey programme in Sep tember 1984.
Initially, the investigations concentrated on the demersal resources, which were sui-· veyed using a 32m: research vessel with a high opening, demersal fish/shrimp trawl. A series of cruises were planned to cover both the summer monsoon (April-September) and winter (October-March) periods. Due to the widespread influence of the monsoon discharge of the Ganges/Brahmaputra river system into the northern Bay of Bengal, it was important that the survey be conducted during both seasons. This report covers the Eighth of a series of cruises conducted over the winter period. (Note that cruise number seven was not a demersal survey cruise and no report has been prepared for this cruise.)
2. MATERIALS AND METHODS 2.1 THE SURVEY AREA AND SELECTION OF TRAWL STATIONS The survey area extended from the 10 metre depth contour in the north and east, to the 200 metre depth contour in the south. A line drawn at 45° from the southern tip of St. Martins Island was considered to approximate the Bangladesh/Burmese mar ine border in the south east. ln the west the survey area extended to the Bangladesh/ Indian marine border, but in practice no trawling was conducted west of the eastern edge of the "swatch of no ground". The survey area, tcgetJ-,er with the 10,20,30,50, 100, and 200 metre depth contours is outlined on all Figures used in this report.
Fifty trawl stations were selected prior to the cruise on a random basis covering the entire survey area. Stations ranged in depth from 15 to 107 metres. The survey area and selected stations are shown in Figure 1.
Previous trawl surveys conducted in these waters had found very low catch rates in waters deeper than about 80 metrns. In order to maximise the information obtained from this cruise, it was decided to exclude the 100-200 metre depth zone from this survey. Thus the survey area actually extended from the 10 to the 100 metre. not the 200 metre depth contours.
The most practical cruise track to cover these stations was selected by the captain of the research vessel in consultation with the cruise leader.
2.2 THE VESSEL AND GEAR The survey vessel, the R/V "Anusandhani" is a 32.4 metre "multipurpose" research vessel, although principally designed for stern trawling, constructed in Japan in 1979. Details of the vessel are provided in Appendix A.
The trawl net used was an Engel high opening fish/shrimp trawl with a cod-end mesh size of 32mm. Details of the fishing gear are provided in Appendix B. 2
A Furuno FUV-11 echo sounder was run continuously throughout the survey cruise. In addition, a Furuno FH-103 sonar was operated when steaming in water deeper than 50 metres. The sonar beam was set at an angle of 10° and swept a forward area between 30° to port and 30° to starboard at an average beam range of 800 metres.
A retrievable bathythermograph, manufactured by Ogawa Seiki Co. Ltd. Japan was used to take temperature profiles at selected stations. Secchi disc transparencies and surface water temperatures were taken at all stations using a standard 30 cm diameter white disc and 0-51°c thermometer and bucket respectively.
2.3 TREATMENT OF THE CATCH Stations were only trawled during daylight in order to avoid any possible bias in catch rates due to day/night variations in abundance. All hauls were of 30 minutes duration, the time commencing when the net reached the bottom, as d~termined by the net-sonde and terminating when hauling commenced. If trawls were discontinued within 15 minutes of shooting, they were considered invalid and the results discarded.
The catch was sorted into species and each weighed separately to the nearest 0.25 kg. In the event that the catch in a particular haul exceeded 500 kgs (approximately) then it was subjectively subdivided into two equal portions, one of which was sorted and the results then doubled. If the number of individuals of any species present in the catch was less than around 20 then the numbers of that species in the haul was counted in order to calculate the average weight of that species. If the number was greater than this, then a weighed sample was usually taken for length/frequency measurement and the average weight calculated in this manner.
In any event, samples of 50-200 fish were selected randomly for length measurement for most species in the catch, where the species were clearly identifiable. As the tax onomy of the catfish (Family Ariidae) and jevvfish (Family Sciaenidae) was confused, no length measurements were made for these two Families. Lengths were in cm, fork length. Samples of penaeid prawns were also taken for length frequency measurement. These were measured in cm from the tip of the rostrum to the posterior edge of the telson. Sexes were measured separately.
2.4 DATA ANALYSIS All data were recorded on proforma sheets which are shown in Appendix C.A. Hew lett Packard 868 microcomputer was used to store and analyse the catch, Length frequency and oceanographic data,· using programmes written specifically for the purpose. From these data, density and biomass estimates were calculated as described in Section 3.4.
For the analysis of the length frequency data, the survey area was subdivided into eight zones, as shown on Figure 2. For each species. samples taken from within the s2me zone were pooled and a single histogram produced for that zone. The histograms were then plotted onto the maps of the survey area on the position where the samples were taken. 3 RESULTS 3.1 General Forty five of the fifty rand_omly selected stations were trawled successfully. The five other stations were found to be untrawlable due to the presence of large numbers of gill and/or stake net operators in the near vicinity. Most of the aborted stations were in depths less than 30 metres. The following is a summary of the stations successfully trawled by depth zone. The positions of these stations are shown on Figure 1. Depth zone No. of successful hauls 10-20 metres 7 21-30 3 31-50 4 51-100 27 100+ 4 Total: 45 Bathythermograph profiles were taken at six stations, and secchi disc and surface water temperature readings were taken at all stations. 3.2 DISTRIBUTION AND ABUNDANCE OF THE MAJOR SPECIES Table 1 below lists all families or species groups caught during the survey cruise in order of their contribution to the combined total catch of the 45 stations. Their per centage contribution to the total catch of each depth zone is also illustrated on this Table. It may be seen that while some families may have contributed relatively little to the overall catch they may have made up a significant proportion of the catch of a particular depth zone. "Trash" here is defined as small fishes, which because of their size and variety could not be identified/sorted with reasonable accuracy, together with sponges, molluscs, small crustaceans etc. TABLE 1 Percentage composition of the catch by family for each depth zone and for the total survey area. These are listed in order of occurrence in the total catch.
DEPTH ZONE (METRES) FAMILY TOTAL 10-20 21-30 I 31-50 j 51-100!101-200 % ARI I DAE 5.79 14.57 16.06 10.43 10.73 (Catfish) SCIAENIDAE 19.49 3.21 2.77 6.04 1.45 8.38 (Jewfish) TRiCHIURIDAE 1.03 24.19 9.90 3.63 2.91 7.14 (Hairtail) CARANGIDAE (Jacks, Scads, 3.90 3.67 12.81 6.78 25.45 7.09 Trevallies etc) NEMIPTERIDAE .21 .18 1.11 16.58 18.55 7.04 (Threadfin bream) 4
DEPTH ZONE (METRES) I FAMILY TOTAL 10-20 21-30 I 31-50 I 51-1 oo 1101-2001 %
SYNODONTIDAE 5.92 3.48 4.08 9.50 27.64 7.00 (Lizard fish) MULLIDAE 1.45 8.06 13.57 5.11 6.13 (Goat fish) Trash Fish 2.79 1.83 7.89 7.86 1.45 5.57
SCOMBRIDAE 1.14 3.21 5.88 8.13 5.03 (Marckerels and tunas) LEIOGNATHIDAE 11.58 3.02 4.57 .73 4.58 (Ponyfish) PRIACANTHIDAE .73 9.43 21.09 4.17 (Bulls Eyes) HAEMULIDAE 13.39 1.37 .21 3.73 (Grunts, Sweetlips) SPHYRAENIDAE 5.69 .55 1.18 2.27 .29 2.65 (Barracudas) FORMIONIDAE .10 15.67 .69 2.57 (Black Pomfrets) STROMATEJDAE 2.43 1.83 7.28 .41 2.45 (Pomfrets) CEPHALAPODA (Squid, Cuttlefish 4.76 .82 .76 2.23 .73 2.37 Octopus) SKATES AND RAYS 6.20 ,83· .28 1.87
TR!ACANTHODIDAE 4.60 .18 1.21 CHIROCENTRIDAE 2.02 .37 2.01 .96 (Wolf Herring) Sicklefishes 2.95 .82 .88
LACTARllDAE .16 5.31 .14 .84 (False Trevallies) CLUPEIDAE (Herrings, Sardines, .52 1.42 1.59 .03 .66 Shads etc,) APOGONIDAE 1.56 1.07 .29 64 (Cardinal fish) LUTJANIDAE 1.00 .39 (Snappers) CRUSTACEANS .50 .03 .81 .39 (Prawns) 5
DEPTH ZONE (METRES) FAMILY TOTAL % 10-20 l 21-30 l 31-50 / 51-1ooj101-200
PSETTODIOAE .72 .39 .34 (Indian Halibuts) ARIOMMATIDAE .35 .58 .29
CYNOGLOSSI DAE 78 .02 .21 (Tongue Soles) CARCHARHINIDAE 1.10 .14 .21 (Sharks) SPAR I DAE .57 .14 .20 (Sea breams) SERRANIDAE .48 .19 (Groupers) ELOPIDAE .10 .92 .17 .19 (Tarpon) TERA PON I DAE .16 .82 .16 (Terapon Perches) EPHIPPIDAE .57 .15 (Spade fish) FISTULARll DAE (Flutemouths, Cornet .04 .34 .14 fishes) POLYNEMI DAE .05 .55 .09 (Th readfi ns) RACHYCENTRI DAE .55 .08 (Cobia) CRUSTACEANS 13 .09 .08 .15 .08 (Others) TETRAODONTI DAE .21 .05 (Puffer fish) SIGANIDAE .07 .01 (Rabbit fish) GERREIDAE .05 .01 (Mojarras)
100% 100% 100% 100% 100% 100% 6
3.2.1 Bathymetric distribution The average catch rates obtained during the survey are shown on Table 2. The "range" is 2 Standard Errors of the mean. The species composition of the catches in each depth zone are shown on Table 1,
TABLE 2
Depth zone Average catch rate Range No. of hauls (metre) ( Kg/30 minutes hau I) ..., 10-20 209 948 I 21-30 225 491 3 31-50 261 1028 4 51-100 51 43 27 100+ 17 8 4 Average 99 75 Total : 45
3.2.1.1 10-20 metre depth zone The average catch rate in this depth zone was 209 kg/30 minutes trawling. Nearly 20% of the catch consisted of jewfish (Family Sciaenidae). Surprisingly, the next most im portant species were the grunters, Pomadasys hasta and P. maculatus (ratio 3: 1) which represented 13% of the catch from this depth zone. Although always prEsent, grunters had never represented such a large percentage of the catch in any of the previous survey cruises. Pony fish, Leiogathus spp. were the third most abundant Family, re presenting nearly 12% of the catch. These three families together accounted for nearly half of the total catch from the 10-20 metre depth zone.
Other species which were relatively well represented were the rays, catfish (Family Ariidae) and lizard fish (Saurida sp.) each contributing some 6% of the catch.
3.2.1.2 21-30 metre depth zone Only three hauls were carried out in this depth zone for an average catch rate of 225 kg/30 minutes trawling. 24% of the catch consisted of hairtail, Lepturacanthus savala and a further 15% of each of black pomfret, Parastromateus niger and catfish. In this depth zone also over 50% of the catch was made up of just three families. It is noticable that with the exception of the catfish, none of the other two species were particularly well represented in the shallowest depth zone.
Other species included the goatfish, Upeneus su!phureus and the false trevally Lactarius !actarius 7
3.2.1.3 31 ~50 metre depth zone The average catch rate in this depth zone was 261 kg/30 minutes trawling. Catfish were well represented in the hauls with 16% of the total catch. Goatfish and the Carangids, represented by several species, but particularly the hard tail scad, Mega!aspis, cordy!a, round scad, Decapterus maraudsi and big eye scad, Selar boops, both contri buted a further 13% to the total catch. Hairtail contributed 10% and white pomfret Pampus argenteus, anchovies (mainly Setipinna taty) and Indian mackerel Rastre!!iger kanagurta a further 7%, 6%, and 6% respectively,
3.2.1.4 51-100 metre depth zone More than half the total number of hauls carried out during this survey took place in this depth zone. The average catch rate was only 51 kg/30 minutes trawling, con siderably less than in the shallower waters. The composition of the catch was also quite similar to that of the shallower waters. Japanese threadfin bream, Nemipter ;aponicus, which had been entirely absent from the shallower catches, reprEsented 17% of the catch in this zone, Catfish were again well represented, with 10% of the catch, but the next most abundant species, lizard fish (9.5%) and bulls eye, Priacanthus spp. (9%) had not been represented in any noticable quantities in the shallower waters.
Other species present in significant quantities were round scad (7%), jewfish (6%) go&tfish (5%) and anchovies ( 4.5%).
3.2.1 .5 101-200 metre depth zone Four hauls were conducted in this depth zone, the deepest of which was in 107 metres, for an average catch rate of only 17 kg/30 minutes trawling,
Lizard fish, round scad, bulls eye and Japanese threadfin bream together accounted for around 90% of the total catch in approximately equal amounts.
3.2.1.6 Summary - Bathymetric distribution The overall average survey catch rate was 99 kg/30 minutes trawling, however, this value gives no indication of the bathymetric distribution Gf 1he catch. Catch rates in waters shallower than about 50 metres averaged between 200 and 250 kg/30 minutes trawling. This rate dropped to 51 kg/30 minutes trawling in the 51-100 metre zone and further again to 17.5 kg/30 minutes trawling in 'lhe waters deeper than 100 metres.
As well as the considerable reduction in the catch rate after discending beyond the 50 metre contour, there was also some change in the species composition of the catch. While the shallower water catches were dominated by hairtail, catfish, goatflsh jewfish and black pomfret, the deeper catches were based more upon the lizard fish japanese threadfin bream and bulls eye.
Few species, with the exception of some of the scads, hairtail and catfish traversed all depth zones. 8
The relationship between the depth of trawling and catch rates for all species com bined an:l for sp::;cific Families or species are illustrated on the following designated Figures:
Figures Total catch (all species combined) 3 Jewfish (Family Sciaenidae) 4 Hairtail (Lepturacanthus spp,) 5 Catfish (Family Ariidae) 6 Japanese threadfin bream (Nemipterus japonicus) 7 Yellow lined goatfish (Upeneus su/phureus) 8 Pony fish (Leiognathus spp.) 9 Indian mackerel (Rastre!liger kanagurta) 10 Lizard fish (Saurida spp.) 11 Bulls eye, (Priacanthus spp.) 12 Hard tail scad (Mega!aspis cordy!a) 13 Blotched grunter (Pomadasys maculata) 14 Silver lined grunter (Pomadasys hasta) 15 White pomfret (Pampus argenteus) 16 Chinese pomfret (Pampus chinensis) 17 Black pomfret (Parastromateus niger) 18 Round scad (Decapterus maruadsi) 19 Spanish mackerel (Scomberomorus guttatus) 20 Carangid (Atropus atropus) 21 Penaeid prawns 22 3.2.2 Geographical distribution Catch rates obtained at the 45 survey stations are shown on Figure 23 plotted according to the locations of the respective stations. Catch rates have been arbitrarily sul:divided into fJ'Jr c:ite;:prie.s, viz. u11der 10, 11-50, 51-100 and greaterthen 100 kg/30 minutes trawling. This Figure provides a general overview of the distribution of the demersal stock over the survey area.
As discussed above, the highest catch rates were found in the shallower waters. From Figure 23, its apparent that the catch in these shallow waters were more or less similar in the eastern, central and western sectors of the survey area, although perhaps more consistent along the eastern side below Cox's Bazar,
As discussed below, many of these differences in catch rates between the eastern and western side of the survey area are due to catches of one or two particular species.
3.3 DISTRIBUTION AND ABUNDANCE OF THE MOST COMMON SPECIES IN THE CATCH The following species/Families were most common in the survey catch. Not all are considered to be commercially important, although determination of which species have commercial importance and which do not, must be subjective, influenced by the fish marketing situation in Bangladesh and the acceptability of these species on export m;irkets. Tha siza and type of the fish are both important factors to be considered. 9
On this basis. the Families/species below were considered of more or less economic importance. This does not imply that other species not mentioned would not have some retail value, or at least be suitable for reduction to fish meal. However because of their size. abundance, or type it is considered that most trawler operators would consider them uneconomic to ~ort and handle and would discard them as "trash". The amount of fish considered as "'Trash" by this definition would be considerably higher than that categorised as "Trash" on Table 1 on the basis of sorting during our survey activities. 3.3.1 Family Ariidae (catfish) Local markets in Bangladesh do not discriminate between the various species of this Family. Price is determined essentially by size (and condition), generally being some what higher for the larger (30 cm and above) fish. Catfish were present in practically all hauls made in depths less than 80 metres, but none of the deeper hauls (Figure 6). Overall, they represented 10% of the total survey catch. They were distributed throughout the shallower areas of the rntire survey area (Figure 25). The average catch rate was 9.4 kg/30 minutes trawling, although this reached 64 kg/30 minutes trawling in the 31-50 metre depth zone. !\l.ost of the catfish were "large" in excess of 300 gms and would be readily market able in Bangladesh 3.3.2 Family Sciaenidae (jewfish) At least four separate "types" of jewfish are recognized on the Bangladesh markets (although these do not represent four species). In general, size is the main criterion for price in the local markets, not species. No attempt was made to differentiate between species in the survey catches. Practically all jewfish caught during the cruise resulted frcm just two hauls, one in 15 metres depth which yielded 180 kg and the other in 75 metres which yielded 80 kg. The locations of these two hauls are illustrated on Figure 24. Jewfish were present in few other hauls and these were all in waters less than 50 metres depth. As a result of these two "exceptional" catches, jewfish represented 8% of the total survey catch. The overall average catch rate however was only 3.6 kg/30 minutes trawling. More than half of the jewfish caught were less than 15 ems in length and many were less than 10 ems. Thus, despite their relative abundance, few were sufficiently large to attract high marked prices (although all sizes are saleable in Bangladesh).
3.3.3 Family Trichiuridae (hairtail) As with the jewfish (Section 3.3.2), almost half of the hairtail, Lepturacanthus savala caught during the survey cruise were landed in one haul in about 25 metres of water. The location of this haul is illustrated on Figure 26. Nevertheless, practically all of the remaining hauls in all depths contained some hairtail (Figure 5).
The overall average catch rate was 18.2 kg/30 minutes trawling, although this rose to 191 kg/30 minutes in the 21-30 metre depth zone (this is hardly surprising in view of the large haul mentioned above). 10
The fish ranged in length from approximately 30 ems to 80 ems, although fish caught in any particular area tended to be unimodal with a more restricted size range, as indicated on Figure 39. Hairtail are traditionally sold as a dried product in Bangladesh.
3.3.4 Family Nemipteridae (Japanese threadfin bream) Japanese threadfi.n bream, Nemipterus japonicus were present in most hauls throughout the survey area, but particularly those in waters deeper than about 75 metres (Figure 7). The overall average survey catch rate was 4.3 kg/30 minutes trawling, although some individual hauls in the deeper waters yielded 40-50 kg. All higher catches were made in the eastern sector of the survey area (Figure 27).
Practically all of these fish were less than 20 ems in length and about half were less than 15 ems. Thus although relatively common in the deeper catches, they are of limited economic importance due to their small size.
3.3.5 Family Carangidae (scads) Carangids were represented in partically all hauls throughout the survey area. Overall, they represented 7% of the total survey catch, although- this rose to 25% in the hauls in the 101-200 metre depth zone. The overall average catch rate was 6 kg/30 minutes trawling, Four main species were represented, the hard tail scad. Megalaspis cordy!a, round scad, Dacapterus mJraud:>i, big eye scad, Se!ar boops and Atropus atropus. All are commercially important in most countries, although less so in Bangladesh. Practically all of the hard tail scad caught during the survey resulted from one haul in 30 metres of water, although they were present in most hauls in depths less than about 45 metres (Figure 13). Atropus atropus, were similarly restricted to the shallow waters less than 45 metres depth, although catch rates were relatively low compared with the other species of this Family (Figure 31). The average length of these fish was around 16 ems (Figure 40).
Round scad on the other hend were more widespread in their distribution, occuring in all depths (Figure 19) and throughout the entire survey area (Figure 36). Big eye scad were only caught in two hauls in 40-50 metres of water.
3.3.6 Family Mullidae (goatfish) Goatfish, principally Upeneus su!phureus represented 6% of the overall survey catch. The overall average catch rate was 6.4 kg/30 minute trawling. Although a few goatfish were caught in the deeper hauls, the majority were caught in hauls made in depths less than 60 metres (Figure 8). The highest density was found in the 31-50 metre depth zone, where the average catch rate reached 56 kg/30 minutes trawling. The highest concentrations of goatfish were located in the eastern side of the survey area (Figure 28 ). 11
Although goatfish are popular in some European markets, the average length of the fish landed during this survey cruise was only around 10 ems and at this size would be unlikely to attract much interest.
3.3.7 Family Haemulidao l_giunters)
Two species of grunter~ were encountered in the survey hauls, the silver lined grunter, Pomadasys hasta and the blotched grunter, Pomadasys macu/ata. The former are a valuable fish, particularly on export markets, although few are seen on Bangladesh markets as they are rarely caught by the "traditional" gears. The latter species has no value and is usually discarded as trash. Both species were most abundant in the shallowest waters (Figures 14 and 15). The average catch rate of the silver lined grunter was 11 kg/30 minutes trawling in the 10-20 metre depth zone. They were never present in hauls made in waters deeper than 30 metres. Although they were encountered in most shallow water hauls, the highest den· sity of this species was found in the Elephant Point area along the east coast south of Cox's Bazar (Figure 33). Two size groups of silver lined grunter were present (Figure 41 ), a smaller group with a mean length of around 30 ems and a larger group around 40 ems. Approximately equal number of fish were represented in each size group.
3.3.8 Family Formionidae (Carangidae) (black pomfret) Black pomfret, Parastromateus niger are a valuable fish in Bangladesh and on export markets, albeit less valuable than the white and Chinese pomfret. One haul in 30 metres of water yielded 85 kg of black pomfret (Figure 18), although they were only occasionally present in the other hauls during this survey cruise. This may reflect the schooling behaviour of these fish. The mean length of the fish was approximately 25 cm.
3.3.9 Family Stromateidae (white and Chinese pomfret) White and Chinese pomfrets, Pam pus ·argenteus and P. chinensis respectively were both present in most hauls made in depths less than 30 metres, although white pomfret were occasionally present in catches in depths up to 65 metres (Figures 16 and 17) Of the two, white pomfret were the most abundant. Catch rates of this species reached 13 kg/30 minutes trawling in the 31-50 metre depth zone. Both species were widespread throughout the survey area (Figure 34 and 35). The white pomfret were unimodal in length with a mean size around 22 ems (Figure 43). 3.3.10 Family Leiognathidae (pony fish) Pony fish, Leiognathus spp. were present in most hauls made in depths less than about 40 metres (Figure 9). Their average catch rate in the 10-20 metre depth zone was 16 kg/30 minutes trawling. They are schooling fish and consequently successive catches are often quite variable i.e. some relatively high catches are sometimes made in an area where other hauls yield very few of these fish. Practically all were caught in the eastern side of the survey area adjacent to Elephant Point south Cox's Bazar (Figure 29). Pony fish are generally discarded as trash by trawlers, but they are retained by the set bag net operators and sold as a dried product in Bangladesh. 12
3.3.11 Family Scombridae (mackerels) Scombrids, which represented 5% of the total survey catch were represented by two species, the Spanish or spotted mackerel, Scomberomorus guttatus and the Indian mackeral, Rastrel/iger kanagurta. Both are normally regarded as pelagic species. Indian mackerel occurred in all hauls made between 35 and 65 metres, but never in the shallower hauls and only once in a deeper haul in 93 metres (Figure 10). All were caught in the eastern side of the survey area (Figure 30). The average catch rate in the 31-50 metre depth zone was 12.5 kg/30 minutes trawling. Although too few were measured (34 fish) for a reliable representation of their length distribution, it would appear (Figure 44) that they were unimodal with a mean length of 20 ems. Spanish mackerel were generally restricted to the shallower waters Jess than 40 metres in depth (Figure 20). Catches were more widespread over the survey area than those of the Indian mackerel. The highest catch was made in the north west of the survey area (Figure 37). The average catch rate in the 21-30 metre depth zone was 6.8 kg/ 30 minutes trawling.
3.3.12 Family Synodontidae (lizard fish)
At least two main species of lizard fish were present in the survey catches, Saurida elongata and S. tumbil. They were present throughout the entire survey area (Figure 31) in all depths (Figure 11) and represented 7Yo of the total survey catches. The average overall catch rate was 6 kg/30 minutes trawling. Two size (length) groups were present in the shallower catches (at least in Saurida tumbil), a smaller group with a mean length of around 20 ems an9 a larger group vvith a mean length of around 30 ems (Figure 45). In the deeper waters, the smafler group was absent.
3.3.13 Family Pricanthidae (bulls eye) 20% of the fish landed in the 101-200 metres "depth zone were bulls eye Priacanthus sp. (principally P. hamrur). They were represented in most all hauls made in waters deeper than about 40 metres and all those deeper than 80 metres (Figure 12). They were present throughout the entire survey area (Figure 32). Bulls eye have little or no commercial value in Bangladesh or elsewhere.
3.3.14 Penaeid prawns Panaeid prawns are the most valuable marine resource in the Bay of Bengal and are the basis for the present Bangladesh marine trawl fishery. The demersal trawl used during this survey was not designed specifically for prawns and thus the catch rates obtained are not considered indicative of potential commercial catch rates. Also catch rates of penaeid prawns are usually higher at night than during daylight and as our trawling was restricted to daylight, lower catch rates could be expected on average than these of commercial trawlers which fish 24 hours per day. The catch rates do however illustrate the relative abundance and distribution of penaeid prawns throughout the survey area. The major species captured were Metapenaeus spp. Penaeus monodon, P. semisulcatus and Parapenaeopsis sculptt!is. 13
Catches of penaeid prawns during this cruise were very poor, in fact the average catch rate was only 0.18 kg/30 minutes trawling. They were caught in all depths between 25 and 95 metres (Figure 22) and generally throughout the entire survey area, although the highest catch (6.5 kg/30 minutes trawling) was made in the north western sector (Figure 38). The most abundant species was the brown shrimp, Metapenaeus monoceros. Only one size (age) group was represented in the catches and these were all adult shrimp (Figures 46 and 47). No recent recruitment had apparently taken place. 3.3.15 Other species The above list includes only those species which were prominent in the catches for one reason or another. Other species of greater commercial value may have been caught also, but if not listed, then it is because the catch rates were too low to warrant any special attention. Length frequency measurements were also taken for tarpon, Elops machnata and these are shown on Figure 48.
4 STANDING STOCK ESTIMATION An estimate of the standing stock present in each of the above depth strata and for the total survey area was made using the "swept area" method. The results are presented on Table 3 below. In order to reduce the variance. geometric. rather than arithmetic means were used for these analyses (described by Pauly in the report prepared from the FAO Marine Fisheries Resources Survey and Exploratory Fishing Project in Burma Fl/DP/BUR/77/003. Field Document 6). An escapement factor ot 50% was used for the calculation of biomass. i. e, it was assumed that 50% of the fish in the path of the net avoided CCJpture by escaping through or around the net. Trawls were generally conducted against the current whenever possible at the same engine revolutions and propeller pitch. The average trawling speed was calculated to be 3.0 knots. As the majority of the catch consisted of "true" demersal species and genually small fish, the "herding" effect of the warps was considered negligible. Thus, the average distance between the trawl wing tips, rather than the distance between the otter boards was used for the biomass calculation. This distance was 18,0 metres on average Using these values. the area swept by the net during a 30 minutes trawl was cal 2 culated to be 0.111 km • TABLE 3 Total Density and Biomass Depth zone Area Density Density Biomass Range No. of 2 2 (Metres) (Km ) (Kg/Km ) Range · (M.T.) Biomass Hauls 10-20 6,861 B.340 37,897 57,220 260.012 7 21-30 3,369 8,984 19,624 30,263 66.113 3 31-50 3.400 10.434 41.108 35.477 139.767 4 51-100 17,710 2,040 1,699 36,133 30,095 27 101-200 10,880 702 318 7,642 3.465 4 Total/Average 42.220 3,949 2.999 166,736 126,630 45 14
Note the large variances associated with the calculations for the separate strata. This is of course expected when so few hauls are used for these determinations. In spite of this shortcoming, it would appear from Table 3 above that the overall stock density was similar over the entire shallow water zone between 10 and 50 metres. The density decreased sharply in the 50-100 metre zone to around 20-25% of that in the shallower waters. The average density of demersal fish in the waters deeper than 100 metres was much less again, being around 30% of the level in the 51-100 metre depths zone. The rigid stratification of the temperature and oxygen profiles in the survey area at this time of the year (see Section 6) may have been the cause of this dramatic decrease in fish abundance in the deeper waters.
As a result of the differences in surface areas of the different depth strata, the greatest biomass occurred in the 10.,.20 metre depth zone (about 30% of the total) and the least (4% of the total) in the 101-200 metre depth zone. The overall stratified biomass estimate was 167,000 m. t. ± 127,000 m. t., i.e. between 40,000 m. t. and 294,000 m. t. In view of this range, the estimate is of little practical value.
As discussed above, the bulk of this biomass consists of either very small or otherwise non- important species. If one subjectively adds the proportions of "useful" fish from Table 1, then the biomass of "commercial" species is around 65% of the total i.e between 26,000 m. t. and 190,000 m. t. This estimate will vary considerably, depending upon one's definition of "commercial", but the above estimate is probably generous under any criteria.
Prawns demand special attention, as they are of considerable economic importance to Bangladesh- However as discussed in Section 3.3.14 above, the catch of penaeid prawns during this cruise was very poor. The average catch rate was only 0.18 kg/30 minutes trawling and the highest rate, which was in the 21-30 metre depth zone was still only 0.79 kg/30 minutes trawling. The biomass Estimate in set out below in Table 4.
TABLE 4 Density and Biomass - Penaeid Prawns
Depth zone Area Density Density Biomass Range No. of 2 (Metres) (Km ) (Kg/km') Range (M.T.) Biomass Hauls 10-20 6,861 0 0 0 0 7 21-30 3,369 14 15 48 52 3 31-50 3,400 1 4 4 51-100 17,710 5 1 85 17 27 101-200 10,880 0 0 0 0 4 Tota I/Average 42,220 3 1 137 30 45 15
The density and biomass calculations reflect the poor catches. The overall biomass estimate of penaeid prawns was between 107 and 167 m. t. This estimate is considerably lower than that obtained during previous cruises (see BGD/80/025/CR. 1-5) and is most prot>ably due to a reduction in th3 c:itchability of the prawns or in other words are flection of their ''activity", rather than any real reduction in abundance in the survey area. This reduction in catchability could be due to the lower water temperatures or other environ mental parametres.
Discussion about the potential yield of fish and shrimp that could be extracted on a sustained basis from these stocks will be postponed until all cruises in the winter series are completed and a more comprehensive set of data are available upon which to base such a calculation. The above estimations of density, biomass etc should be used with caution, in view of the relatively small number of hauls involved.
5 PELAGIC FISH
The sonar was operated occasionally while cruising between stations in water deeper than 50 metres. In shallower waters, bottom reflections make interpretation of the echo difficult. In addition, the fish finder/echo sounder was run continously throughout the entire cruise.
No surface school were observed, and only one large subsurface school was observed on the echo sounder in 30-35 metres of water in the north central section of the survey area. The species comprising this school could not be determined. No schools were observed on the sonar.
Approximately 20% of the total survey catch consisted of "pelagic" fish, which include the Families Scombridae (mackerels), Carangidae (scad), Clupidae (herings, shad), EngrauLidae (anchovies), Leiognathidae (pony fish) and Gerridae (mojarras).
6 OCEANOGRAPHY
Oce·anqgraphy per se was not intended to be a major research act1v1ty of the survey programme. Nevertheless, as the distribution and abundance of fish in the survey area were likely to be influenced by the seasonable monsoonal discharge of the river systems in particular, it was considered useful to measure certain parameters.
Turbidity, as determined using a standard secchi disc was measured at nearly all stations. The results are plotted on Figure 46 and shown on Table 5.
Waters over the entire survey area were considerably clearer during this cruise than during the pre'Vious cruise (Cruise No. 6) in December. Secchi disc visibility was generally in excess of 15 metres and often greater than 25 metres. The only evidence of any turbid, presumably lower salinity water was a "band" of more turbid water alor.g the eastern coast which extended out to the 30 metre contour (Figure 49). 16
Surface water temperatures were also quite uniform over the survey area, ranging from 23°C to 26°C .. with most being around 24°C.
Six bathythermograph profiles were taken in the deeper waters. These are shown on Figure 50. All profiles illustrate the surface cooling effect due presumably to the cooler air temperature. This cooling effect extended to a depth of 10-25 metres. Below this depth, temperature either declined are remained steady after an initial increase.
TABLE 5 Secchi disc and surface water temperature measurements (see also Figure 56)
Date Latitude Longitude Surface temp. Secchi Deg. Min. Deg. Min. (Deg C) depth (M.)
070185 21 5 91 22 23.0 17.0 070185 21 10 91 14 24.0 10.5 070185 20 51 91 10 23.0 17.0 070185 20 47 91 11 24.0 080185 20 48 90 50 24.0 27.0 080185 20 57 90 50 23,0 25.0 080185 21 6 90 38 25.0 15.0 080185 21 7 90 35 24.0 16.0 080185 21 2 90 11 25.0 080185 21 6 90 11 24.0 090185 21 17 90 12 23.0 9.0 090185 21 18 90 6 24.0 15.0 090185 21 17 90 4 24.0 14.0 090185 21 21 89 51 24.0 15.0 090185 21 18 89 47 24.0 21.0 090185 21 10 89 43 24.0 100185 20 54 89 36 24.8 29.0 100185 20 53 89 41 25.0 zoo 1OU185 20 57 89 52 25.6 300 100185 20 34 90 17 24.6 110185 20 33 90 37 24.6 28.0 110185 20 26 90 43 24.6 27.0 110185 20 23 90 51 24.8 27.0 110185 20 29 91 7 25.2 28.0 110185 20 30 91 4 25.8 32.0 17
TABLE 5 (CONTD) Date Latitude Longitude Surface temp, Secchi Deg. Min Deg. Min (Deg C) Depth (M) 110185 20 32 91 6 25.0 120185 20 31 91 12 24.2 29.0 120185 2.0 25 91 17 24.4 29.0 120185 20 23 91 23 24.0 29.0 120185 20 16 91 26 24.2 29.0 120185 20 14 91 29 24.6 25.0 120185 20 12 91 30 24,6 25.0 120185 20 14 91 17 25.4 100185 20 58 89 26 24.0 29.0 130185 20 38 91 20 24.0 25.0 130185 20 39 91 25 24.0 25.0 130185 20 30 91 32 24.6 24.0 130185 20 41 91 53 24.6 12.0 140185 20 44 92 8 26.0 2.5 140185 20 58 92 2 26.0 2.5 140185 21 7 91 59 25.4 2.0 140185 20 55 91 49 23.4 8.0 140185 20 52 91 49 23.6 150185 20 55 91 41 23.0 9.0 150185 20 56 91 31 23.6 12.0
7. OBSERVATIONS OF COMMERCIAL FISHING ACTIVITY IN THE SURVEY AREA. Two groups, each of 4 or 5 so-called "Thai" trawlers were observed operating in the north central sector of the survey area during the time of the survey (Figure 51) It is not known whether they were targeting on prawns or fish. The water depth in these areas was approximately 15-20 metres.
Many gill net vessels were operating inside the 15 metre contour in the Cox's Bazar area and in the north western sector of the survey area (Figure 51)
8. COMPARISON WITH OTHER CRUISE RESULTS. The results obtained during the survey cruise were similar to those obtained during the previous cruise, No. 6 which took place between December 13 and 21st 1984. The overall catch rate had decreased, but when considering the variance associated with these values, the results are more or less similar. The dramatic reduction in density noted between the shallower and deeper water at the 50 metre depth contour was 1B
even more pronounced during this cruise. This disparity in density between the shallow and deep catches had been in evidence in practically all of the previous six cruisEs, but never as pronounced as during this most recent cruise.
Overall, the species composition of the catch was similar to that of the last cruise: The dominant species (Families) were the jewfish, catfish, hairtail, Japanese threadfin bream and the scads. Within any particular depth zone, there were some differences in the relative abundances of certain species, but this is to be expected when relatively few hauls are involved and many of the species involved are schooling types of fish. For instance, anchovies represented 23% of the catch in the 10-20 metres zone during cruise No. 6, but only 0.6% on this cruise. Overall however, they represented 4:7% of the total catch of cruise No. 6 and 3.1 % of the catch of this cruise. Conversely, hairtail represented 24% of th? catch of the 21-30 metre zone during this cruise, but only 2% of the catch from that zone during cruise No. 6. Overall however, hairtail represrntEd around 7% of the total catches of both cruises.
A notable difference however was in the abundance of penaeid prawns. Although not part1cu1ar1y abundant during the previous cruise, they were virtually absent in the catches during this cruise. This result was not altogether unexpected. as the estimate of prawn abundance had shown a progressive decline over the last few survey cruises.
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': "O \". : Qiir ·~,,····· ~ :I .;;to •... : ..0 '10----=-- / :/o ---._ / 0 __ ...... -.... ~~ ----==------~ ------.... _...... ,/ - 70 Bothythermogroph Profiles JANUARY 1985 Lat. 20 Deg 14 Min Lat. 20 0Gg 34 Min Lat. 20 Deg 32 Min Lon. 91 Deg 17 Min Lon. 90 0Gg 17 Min Lon. 91 Deg 6 Min T9mp CdQg D TQmp (deg C) Temp (dQg C) 15 17 19 21 23 25 27 29 15 17 19 21 23 25 27 29 15 17 19 21 23 25 27 29 --- trott.om------ Lat. 20 Deg 47 Min Lat. 21 Deg 6 Min Lat. 21 Deg 10 Min Lon. 91 Deg 11 Min Lon. 90 Deg 11 Min Lon. 89 Deg 43 Min Temp (deg C) Temp (deg C) Temp (deg C) 15 17 19 21 23 25 27 29 15 17 19 21 23 25 27 29 15 17 19 21 23 25 27 29 --- trott.om------SOttom------70 Bothyth8rmogroph Profil8s JANUARY 1985 Lat. 20 Deg 14 Min Lat. 20 Deg 34 Min Lot. 20 Deg 32 Min Lon. 91 Deg 17 Min Lon. 90 Deg 17 Min Lon. 91 Deg 6 Min Temp (dg9 C) Temp (dg9 C) Temp (deg C) 17 19 21 23 25 27 29 15 17 19 21 23 25 27 29 15 17 19 21 23 25 27 29 0 ID -0 :::r('f' ,.... ,.... 31...... 31.._, 3.._, Lat. 20 Deg 47 Min Lat. 21 Deg 6 Min Lat. 21 Deg 10 Min Lon. 91 Deg 11 Min Lon. 90 Deg 11 Min Lon. 89 Deg 43 Min TGmp (deg D Temp (deg C) Temp (deg C) 15 17 19 21 23 25 27 29 15 17 19 21 23 25 27 29 15 17 19 21 23 25 27 29 I J -- ---sot"to'"m------SOt~om ------APPENDIX A RESEARCH VESSEL R/V 11ANUSANDHANI" «· Principal Dimension Caoacity~ -- -- ~ Fish Hold 73.67 M2 Length Overall 32.40M Fuel Oil 88.22 M2 Length B.P. 28.00M Fresh water 34.53 M2 Breadth Mid 7.50M Freezing Room 11.17 M 2 G_omplements Depth Mid 3.30M Officer Gross Tonnage 221.16 G. T. Crew Main Engine 900 PS Scientists -=== Max Trial SP 12.44km Total 22 APPENDIX B ENGEL HIGH OPENING BOTTOM TRAWL GENERAL ARRANGEMENT FOR ENGEL 486 MESH HIGH OPENING BOTTOM TRAWL 1. Headline 57.50 metres P. P. Combination 2. Footrope 66.30 mtrs. P. P. Combination wire rope 12mm dia with steel core wire rope 14mm dia with steel core RUBBER disc Ground rope 5 x 13, 10 mtrs. APPENDIX C SURVEY LOG SHEETS MARINE FISHERIES RESEARCH, MANAGEMENT AND DEVELOPMENT PROJECT (BGD/80/025) FISHING LOG DAY MONiH YEA.A VESS.EL NAME GEAR TYPE LOCAL TIME LATITUDE AND LONGITUDE BOTTOM FISHING POSITION OF SHOOTING POSITION OF HAULING DISTANCE TIME SHOT TIME HAULED DIRECTION DEPTH (m) DEPTH (m) TRAVELLIED N.M. 0 H I I s H 0 0 0 0 s IN I I E l 'J E DECCA Readings Shooting DECCA Readings Hauling R G p R G p SAMPLE BASKETS HAUL VALIDITY TOTAL FOR VALID HAUL ENTER 1 BASRETS COMPOSITION OF TOTAL CATCH FOR NON-VALID HAUL ENTER 0 SPEC I E·S CODE NUMBER WEIGHT (kg) SPECIES CODE NUMBER WEIGHT REMARl<:S: (DETAILS OF GEAR DAMAGE ETC.) SCIENTIST l/C ...... MARINE FISHERIES RESEARCH, MANAGEMENT AND DEVELOPMENT PROJECT (BGD/80/025) LENGTH FREQUENCY SHEET DAY MON YEAR VfSSEL STATION DATE NUMBER NAME ] SPECIES SPECIES TOTAL SPEClf:.S CM TICK CODE CM TICK CODE TOTAL 0 0 1 2 2 4 3 6 4 8 5 0 6 2 7 4 8 6 9 s 0 0 1 2 2 4 3 6 4 8 5 0 6 2 7 4 8 s 9 8 0 0 1 2 2 4 3 6 4 8 5 0 6 2 7 4 8 6 9 8 0 0 1 2 2 4 3 6 4 8 5 0 6 2 7 4 8 6 9 8 0 0 : I [IN SAME UNITS I '"i~~~:r AS TOTAL CATCH) I MARINE FISHERIES RESEARCH. MANAGEMENT AND DEVELOPMENT PROJECT (BGD/80/025) BIOLOGICAL SAMPLING SHEET sheet of · ------··------·--· ------·M AY MONTH YEAR ~f-P•EC-le5•~1_:_.,.-..,__...... ,....,..,.....__,l.._~_~_J_~..._...... , ...... ,..--..m CRUISE I I STATION UL [ NUMBER NUMBER MBER ~-----.ii FISH· WEIGHT SEX REMARKS LENGTH MA.TUll:llY AGE No. (mm) (g) M.orF 1 2 3 4 5 6 7 a 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 ... 24 25 26 27 28 29 30 SCIENTIST l/C ·····································-···························