Growth of Encrasicholina punctifer (Engraulididae) is estimated, based on samples obtained during five surveys on Sofala Bank (central Mozambique). The estimated values of the von Bertalanffy growth function, TL∞=12 cm and K=2.0 yearˉ¹ are compared with results of growth studies elsewhere in the Indo-Pacific region, based mainly on the index Φ=log(sub)10 K+2*log(sub)10L∞ assumed to be constant within species. This comparison is rendered difficult by the uncertain taxonomical status of stolephorid anchovies

De Paula e Silva, R.

Aquatic Commons

ABSTRACT 
Revista de Investiga9ao Pesqueira 
Maputo No. 21 (1992): 69 - 78 
Growth of the Buccaneer Anchovy 
Encrasicholina punctifer 
off Mozambique, Based on Samples 
Collected in Research Surveys 
by 
RIDDEPAULAESILVA 
Growth of Encrasicholina punctifer ( Engraulididae) is estimated, based on samples obtained during 
five surveys on Sofala Bank (central Mozambique). The estimated values of the von Bertalanffy 
growth function, TLOO = 12 em and K = 2.0 year-1 are compared with :results of growth studies 
elsewhe:re in the Indo-Pacific :region, based marnly on the index<!>'= log10 K + 2 * log10 Loo assumed 
to be constant within species. This comparison is :rende:red difficult by the unce:rtain taxonomical 
status of stolephorid anchovies. 
RESUMO 
Com base em amostras colhidas du:rante cinco cruzeiros de investiga9ao no Banco de Sofala, 
estimaram-se os parfu:netros de c:rescimento K e Loo da anchoveta pirata, Encrasicholina punctifer. 
Os valo:res adoptados, TLOO = 12 em e K = 2.0 po:r ano, sao compa:rados com outros :resultados obtidos 
na :regiao IndoPacffica, utilizando o indice <!>' = log10 K + 2 * log10 Loo, que se pode conside:rar 
constante para cada especie. A compara9ao to:rna-se dificil devido a posi9ao sistematica ince:rta das 
anchovetas. 
69 
70 
INTRODUCTION 
Anchovy was found to be the main fish resource of Mozambique, as far as total biomass is concerned, 
during the acoustic surveys by RN "DR. FRIDTJOF NANSEN" (Saetre & Paula e Silva, 1979). 
Further confirmation of high biomass levels, associated with wide fluctuations of abundance, was 
obtained by subsequent acoustic assessments by the same vessel (Brinca et al., 1981, 1983, 1984). 
In 1984, a project was launched, with the assistance of the Norwegian Government, to perform 
experimental fishing and associated technological studies to initiate the development of a fishery on 
this resource. The project vessel, MIS "A TL<j> Y VIKING" was also used for research surveys, aimed 
at developing an understanding of the Mozambican marine fish resources. These surveys provided 
the main source of material used for the present study. 
MATERIALS AND METHODS 
Catch per haul and length-frequency observations from five surveys performed by MIS "ATL<j>Y 
VIKING" and from one survey by the RN "Dr. FRIDTJOF NANSEN" were used (Table 1). 
The surveys covered Sofala Bank (central Mozambique), where the main fish resources are 
concentrated (see Fig. 1 ). 
Table 1. Basic infonnation on surveys of Mozambican waters used as sources of data on 
Encrasicholina punctifer. 
Survey# Vessel Period No. of samples 
1 F. Nansen May 
-
Jun 83 9 
2 A. Viking Oct - Nov 85 5 
3 A. Viking Nov85 5 
4 A. Viking Sep86 8 
5 A. Viking Feb - Mar87 14 
6 A Viking Jul - Aug87 6 
All catches were done with pelagic trawl, except for three samples from survey #1 and five from 
survey #3, which were taken from shrimp trawl hauls. The original data are summarized in the 
respective cruise reports (Brinca et al., 1984; Paula e Silva, 1985, 1986, 1987a, 1987b). 
(/) 
0 
G) 
~ 
::ll 
-
-c 
...J 
16 
~ . Anchovies 
~ Inshore sardines 
17 
Ill Scads and mackerel 
rniDB Lorge sardines .. 
and ponyfish .. 
.. 
18 
Mozambique 
Channel 
19 
20 
21 
35 36 37 38 39 40 
Longitude (0 E) 
Fig. 1. Illustrating the distribution of the main pelagic species of Sofala 
Bank, (adapted from Brinca et al., 1983), and Encrasicholina punctifer Fam. 
Engraulididae (adapted from Whitehead & Wongratana, 1984). 
71 
Some samples from the F. NANSEN survey consist of a mix of two closely allied species, 
Encrasicholina punctifer and E. heteroloba. Since the size composition of the samples from these 
two species are very similar, the samples were used as is, such as to obtain an extra sample 
representing the periods between February-March and July-August. 
Total catch in weight was estimated (rather than measured) during the surveys, and the number of 
anchovies caught was then obtained through a raising fac'"-:>r computed from the weight of 
subsamples. These numbers were then raised to the respective catch. 
All processing was performed using the Compleat ELEF AN software package (Pauly, this vol. ). The 
catch-at-length data were grouped for each survey, then pooled into an artificial year using weights 
corresponding to the square root of sample size. Table 2lists the six resulting "monthly samples" used 
for growth analysis. 
72 
Table 2. "Artificial year" composed of the combined samples of anchovy raised to the catch. 
Mean length 
(FL-cm) Feb Juna Aug Sep Oct Nov 
2.75 7 
3.25 59 107 
3.75 180 59 108 
4.25 21724 164 235 73032 
4.75 58170 7 B891 242433 5 32 
5.25 87029 38 124503 64187 5 0 
5.75 23380 1442 46131 2683 5 808 
6.25 6448 8672 23540 6074 0 13792 
6.75 31152 33954 15084 1719 210 251311 
7.25 63207 106099 15191 6134 4326 573181 
7.75 97344 267452 6170 8611 6299 242642 
8.25 67499 265862 2585 48289 12497 79980 
8.75 4017 212039 4627 14647 26828 4777 
9.25 194 7397 8555 5149 3265 177 
9.75 1 64 1224 363 2 
10.25 7 1 4 
Sum 460352 903315 281747 473173 53803 1166706 
alncludes a mix of E. punctifer and E. heterolobus; sample numbers divided by ten, for compatibility with the other 
samples. 
As described in Pauly & David (1981), the estimation of growth parameters using the ELEFAN I 
program is performed by identifying the von Bertalanffy curve that gives the best fit to the length-
frequency data, as restructured by running averages. Different sets of values of Loo and K can be 
entered or made to vary, as well as for the parameters which express seasonality in growth. These 
are "C" or amplitude of the seasonal oscillation, and "WP", or winter point expressing the period of 
the year when minimum growth occurs. 
In order to compare the estimates obtained with other results in the literature, the index $' = log10 
K + 2log10 L= was used, as described in Pauly & Munro (1984); to obtain more comparable values 
for comparisons, some published data were reprocessed, using the method ofGulland & Holt (1959). 
RESULTS AND DISCUSSION 
Growth Patterns 
Fig. 2 shows two growth curves with the selected parameters superimposed on the "artificial year" 
obtained by pooling the available length-frequency samples. 
10 
-
8 ..... 
E ..... 
u ..... 
6 ,.,. , 
" .r:: ,.,. 
-0 4 
c: 
41) 
...! 2 
0 
J F M A M J J A s 0 N 0 
Month 
Fig. 2. Growth pattern ofEncrasicholina punctifer, shown by two c~UVes linking the main 
components of the samples. The growth parameters of the two curves are: TLoo = 12 em; 
K = 2.0 year ; C = 0.6; WP = 0.8 
73 
As might be seen, the two main modes of the length distributions are "hit" by the curves, of which 
each represents a recruitment event. Similar results were obtained when placing the different samples 
at their original distances in time (plot not shown). 
Table 3 compares different values ofL00, K, and$' available in the literature with those resulting from 
the present study. 
Length-frequency data collected in discrete surveys can be suspected not to be optimal to study the 
biology of anchovies. These small fishes have short life cycles and thus several surveys per year 
would be necessary to track the rapid changes in their overall abundance and/or size composition. 
Furthermore fixed stations from a research survey are bound to be affected by random phenomena 
linked to the schooling and the patchy distribution of the fish. 
Taxonomical Status of Stolephorid Anchovies 
The uncertain taxonomical status of the small Indo-Pacific anchovies has been responsible for 
frequent changes in scientific nomenclature, hampering the progress of the group's knowledge. 
Although recent revisions exist (Whitehead et al., 1988), field ideiAtification of the different genera 
and species continues to be difficult. 
Moreover, the schooling behavior of these fishes is odd, in the sense that different species and size 
composition appear in survey catches from neighboring stations (Brinca et al., 1984), as well as in 
landings from nearby areas (Tiews et al., 1970). 
74 
Table 3. Comparison of growth parameters available in the literature for E. punctifer and E. heterolobus. 
Species and source Area sampled (year) 
Encrasicholina punctiferb 
Ingles & Pauly (1984) Manila Bay (1957) 
" (1958) 
" (1961) 
Tiews et al. (1970) 
This study Sofala 1983-1987 
Encrasicholina heterolobac 
Tierney (1979) Papua New-Guinead 
Dalzell et al. (1980) (1976-1979)e 
Dalzell et al. (1980) (1976-79)d 
Dalzell et al. (1980) (1976-79/ 
Ingles & Pauly (1984) Manila Bay, 1958 
Ingles & Pauly (1984) Manila bay, 1961 
~' = log10 K + 2log1o L00• 
b= Stolephorus punctifer, S. buccaneeri and S. zollingerii. 
c= Stolephorus heterolobus. 
dotolith readings, our estimates (Gulland & Holt plot). 
eModal progression analysis, authors' results. 
fModal progression analysis, our estimates. 
10.10 
10.60 
9.20 
12.00 
8.95 
9.60 
9.58 
8.31 
12.10 
11.40 
K 
(em, TL) 
1.10 
1.85 
1.15 
2.00 
3.65 
4.09 
4.02 
3.65 
1.60 
0.95 
2.05 
2.32 
1.99 
2.46 
2.47 
2.58 
2.57 
2.40 
2.37 
2.09 
Until1983 the anchovy resource off Mozambique was considered, based on Whitehead (1974), to 
consist of only one species, Stolephorus buccaneeri (Saetre & Paula e Silva, 1979; Brincaet al., 1981, 
1983). Thereafter more attention was given to this group and up to four species were identified in 
survey catches (Brinca et al., 1984); using Whitehead & Wongratana (1984) the main species was 
thenidentifiedasS.punctifer,ajuniorsynonymofEncrasicholinapunctifer(Whiteheadetal.,1988). 
Size Composition of the Resource 
As previously shown by Brinca et al. (1984 ), positive hauls usually consist of fish of uniform size, 
probably representing a single cohort. However quite different mean lengths have been found in the 
same survey. In the data analyzed here it was generally possible to discriminate up to three 
components. 
This suggests that several cohorts are produced every year, the most likely number of these being 
two. However, identification of spawning/recruitment periods was difficult as similar curves drawn 
75 
with slightly different, but also acceptable values of L_ and K suggested very different spawning/ 
recruitment periods. This is probably due to the limited quality of the data analyzed here. 
Growth Parameters 
TL_ was fixed at 12 em, just above the biggest fish measured, although this is a higher value than 
found in the literature, except for Tiews et al. (1970). Nevertheless it produced reasonable values of 
Rn forK ::::: 2.0 year-1. 
This value of the growth constant seems acceptable, both in terms of a short-lived species, as this is 
believed to be, and also considering the <I>' value obtained, which is well within the range of the values 
computed from the literature. 
Seasonality in Growth 
The "best fitting" growth curves were obtained considering seasonal oscillation of growth. Such 
seasonal oscillations are plausible, in view of the subtropical conditions and shallow depths which 
characterize the biotope of E. punctijer. 
Nevertheless the amplitude of the seasonal oscillation of growth was not very high (C = 0.5) for the 
"best fit". On the other hand the position in time of the winter point (WP = 0. 8, corresponding to mid-
September) is compatible with ·..:1e notion that the "aquatic winter" occurs 1.5 to 2 months after the 
lowest temperatures occur ashore. Furthermore, August-September is a season of strong winds, 
which can significantly decrease the water temperature. Thus, growth parameter estimates appear 
to be reasonable, although they might eventually be revised as better data become available. 
REFERENCES 
BRINCA, L., F. FREY, C. SILVAANDR. SAETRE (1981)- A survey on themarinefishresources 
of Mozambique. Reports on surveys with the RN "DR. FRIDTJOF NAN SEN". Instituto de 
Desenvolvimento Pesqueiro, Maputo/Institute of Marine Research, Bergen. 
76 
BRINCA, L., A. JORGE DASILVA, L. SOUSA, M.I. SOUSA AND R. SAETRE (1983)- A survey 
on the fish resources at Sofala Bank:, Mozambique, September, 1982. Reports on surveys with 
the RN "DR. FRIDTJOF NANSEN". Instituto de Investiga~ao Pesqueira, Maputo/Institute 
of Marine Research, Bergen. 
BRINCA, L., V. MASCARENHAS, B. PALHA DE SOUSA, L. PALHA DE SOUSA, M.I. 
SOUSA, R. SAETREAND I. TIMOCHIN (1984)- A survey on the fish resources at Sofala 
Bank: Mozambique, May-June 1983. Reports on surveys with the RN "DR. FRIDTJOF 
NANSEN". Instituto de Investiga9ao Pesqueira, Maputo/Institute of Marine Research, 
Bergen. 
DALZELL, P.J. AND J.W.J. WANKOWSKY (1980)- The biology, population dynamics and 
fisheries dynamics of exploited stocks of three baitfish species, Stolephorus heterolobus, S. 
devisi and Spratelloides gracilis in Ysabel Pasage, New Ireland Province, Papua New 
Guinea. Research Bulletin no. 22. Department of Primary Industry, Port Moresby. 
GULLAND,J.A.ANDS.J.HOLT(1959)-Estimationofgrowthparametersfordataatunequaltime 
intervals. J. Cons. ClEM 25(1): 47-49. 
INGLES,J.ANDD.PAULY(l984)-Anatlasofthegrowth,mortalityandrecruitmentofPhilippine 
fishes. ICLARM Technical Reports 13: 127 pp. 
PAULA E SILVA, R.; (1985)- Relat6rio do cruzeiro realizado como MIS "ATL<j) Y VIKING" para 
avalia9ao acustica dos pequenos peixes pehigicos no Banco de Sofala, Novembro de 1985. 
Instituto de Investiga~ao Pesqueira, Maputo. (Manuscript) 
PAULA E SILVA, R.; (1986)- Relat6rio do cruzeirorealizadocomo MIS "ATL<j)YVIKING"para 
avalia~ao acustica dos pequenos peixes peh1gicos no Banco de Sofala, Setembro de 1986. 
Instituto de Investiga~ao Pesqueira, Maputo. (Manuscript) 
PAULA E SILVA, R.; (1987a)- Relat6rio do cruzeirorealizado como MIS "ATL<j) YVIKING"para 
avalia9ao acusrica dos pequenos peixes pehigicos no Banco de Sofala, FevMar/1987. 
Instituto de Investiga~ao Pesqueira, Maputo. (Manuscript) 
77 
PAULAESIL VA, R.; (1987b) -Relat6riodocruzeirorealizadocomoM/S "ATLcpYVIKING"para 
avalia9ao acustica dos pequenos peixes pehigicos no Banco de Sofala, J ulAgo/1987. Instituto 
de Investiga9ao Pesqueira, Maputo. (Manuscript) 
PAULY, D. AND N. DAVID (1981)- ELEFAN I, a BASIC program for the objective extraction 
of growth parameters from length-frequency data. Meeresforsch./Rep. Mar. Res. 28( 4): 205-
211. 
PAULY, D. AND J.L. MUNRO (1984)- Once more on growth comparisons in fisheries and aquatic 
invertebrates. Fishbyte 2(1): 21. 
SAETRE, R. AND R. PAULA E. SILVA (1979)- The marine fish resources of Mozambique. 
Reports on surveys with the RN"DR. FRIDTJOF NAN SEN''. Instituto de Desenvolvimento 
Pesqueiro, Maputo/Institute of Marine Research, Bergen. 
TIEWS, K., I.A. RONQUILLO AND L.M. SANTOS (1970) - On the biology of anchovies 
(Stolephorus Lacepede) in Philippine waters. Proc. IPFC 13(2): 20-48. 
TIERNEY, D.P.; (1979)- The life history andfisherydynamicsof Stolephorus heterolobus,S. devisi 
and Spratelloides gracilis, three important species used as bait in the Papua New Guinea pole 
and line skipjack fishery. Fisheries Division, Department of Primary Industry, Port Moresby. 
(Manuscript.) 
WHITEHEAD,P.J.P.;(1974)-FamilyEngraulidae./nW.FischerandP.J.P.Whitehead(eds.)FAO 
species identification sheets for fishery purposes. Eastern Indian Ocean (fishing area 57) and 
Western Central Pacific (fishing area 71). Vol. II. FAO, Rome. 
WIDTEHEAD, P.J.P. AND T. WONGRATANA (1984) - Engraulidae. In W. Fischer and G. 
Bianchi (eds.) FAO species identification sheets for fishery purposes. Western Indian Ocean 
(Fishing Area 51). Prepared and printed with the support of the Danish International 
Development Agency (DANIDA). Rome, FAO, Vol. II: pag. var. 
78 
WHITEHEAD, P.J.P., G. NELSON AND T. WONGRATANA (1988)- FAO species catalogue. 
Vol. 7. Clupeoid fishes of the World. Part 2. Engraulididae. FAO Fish. Synop. (125). Vol. 
7, Pt. 2. 


Growth of the buccaneer anchovy Encrasicholina punctifer off Mozambique, based on samples collected in research surveys

http://aquaticcommons.org/17010/1/RIP21_069.pdf

Growth of the buccaneer anchovy Encrasicholina punctifer off Mozambique, based on samples collected in research surveys

Abstract

Similar works

Full text

Available Versions

Aquatic Commons