Content uploaded by Madalina Galatchi
Author content
All content in this area was uploaded by Madalina Galatchi on Mar 28, 2019
Content may be subject to copyright.
Academy of Romanian Scientists
Annals Series on Biological Sciences
Copyright ©2017 Academy of Romanian Scientist
Volume 6, No. 1, 2017, pp. 75 - 81
ISSN 2285 – 4177
Academy of Romanian Scientists Annals - Series on Biological Sciences, Vol. 6, No.1, (2017) 75
AGE DETERMINATION ASPECTS IN ANCHOVY
(Engraulis encrasicolus, LINNAEUS, 1758)
AT THE ROMANIAN BLACK SEA COAST
Mădălina GALAŢCHI1, 2,*, Magda NENCIU1, Mioara COSTACHE3,
Valodia MAXIMOV1, Dragomir COPREAN2,4
1National Institute for Marine Research and Development “Grigore Antipa”,
Constanta, Romania (corresponding author: madalina.galatchi@gmail.com)
2Ovidius University of Constanta, Romania
3Fish Culture Research and Development Station Nucet, Romania
4Academy of Romanian Scientists, Splaiul Independentei 54, 050094 Bucharest,
Romania.
Abstract
Age is a factor providing significant information on species evolution at population level.
Anchovy is a pelagic, gregarious, small-sized species and, until 20 years ago, it
represented an important share of Black Sea fish catches. The Black Sea anchovy stock
has suffered in the past decades from various causes, among which overexploitation,
penetration of alien species, pollution etc.
Age determination of Romanian Black Sea anchovies was made by otolith reading using
an inverted microscope. A decrease of the 2+ years share and an increase of the 1+ years
age classes share were reported.
Key words: anchovy, Black Sea, otoliths, age
Introduction
In recent years, marine fisheries along the Romanian Black Sea coast have
been limited to performing stationary fishing, in the coastal and shallow area
(forage and spawning grounds for many fish species), using fixed fishing gears.
As a follow-up of analyzing the samples collected during 2010-2014, it
was noticed that the biomass of commercial fish species recorded a continuous
drop (Table 1). This decrease may be the result of several factors: eutrophication
(sources from agriculture, municipal waste, industry etc.), harmful substances
(sources from agriculture, industry, municipal waste etc.), commercial fisheries,
alien species. The anchovy biomass and catches were largest during the 1980s.
The first signs of overfishing appeared after 1984, when anchovy shoals were
difficult to be found and the fishery enterprises incurred losses; it appears that the
Mădălina GALAŢCHI, Magda NENCIU,
Mioara COSTACHE, Valodia MAXIMOV, Dragomir COPREAN
76 Academy of Romanian Scientists Annals - Series on Biological Sciences, Vol. 6, No.1, (2017)
dramatic reduction of the Black Sea anchovy stock in the late 1980s was due to
the combined action of two factors: the excessive fishing and Mnemiopsis leidyi
outburst [1].
Table 1. Biomass (tons) of the main commercial fish species
of the Romanian Black Sea coasts (original, according to internal NIMRD Reports).
Species
2010
2011
2012
2013
2014
Engraulis encrasicolus
(anchovy)
50
41
57
44
30
Sprattus sprattus (sprat)
59634
60000
68887
56429
60000
Gobiidae sp. (gobies)
500
500
450
300
300
Psetta maeotica (turbot)
1149
1147
628
554
298
Squalus achantias
(dogfish)
13051
10000
1550
4483
1520
Merlangius merlangus
euxinus (whiting)
20948
21000
5650
19797
15550
As it arises from the table above, anchovy, species with high commercial
value and targeted by active fisheries before, has recorded massive biomass drops
in the past years. Thorough population studies of the species are needed, in order
to better understand the development of events such as biomass decrease.
Consequently, the accurate determination of fish age is one of the most important
aspects in population dynamics studies. Age is the background for calculation of
growth, mortality, recruitment and other fundamental parameters for population
studies [2].
Age determination in fish can me made by three methods:
skeletochronology (the concentric growth rings identified in a bone cross-section
are counted), scalimetry (estimation of the age of fish by examination of
concentric peaks on their scales) and otolithometry (identifying the annual growth
rings of otoliths in the internal ear). Otoliths, sometimes referred to as ear bones,
are of unique value for age determination of teleost fishes because across taxa
they are the only hard structures that continue growing even after somatic growth
has ceased [3], but also because they are easily collected and stored.
Age Determination Aspects in Anchovy (Engraulis encrasicolus, LINNAEUS, 1758)
at the Romanian Black Sea Coast
Academy of Romanian Scientists Annals - Series on Biological Sciences, Vol. 6, No.1, (2017) 77
The analysis of otoliths for age determination can be carried out in two
different ways: at macrostructural level, considering annual bands, and at
microstructural level, based on daily increments.
Materials and methods
Aiming at determining the age of anchovy, samples were collected from fixed
fishery points located along the Romanian Black Sea coast, during May-
September of the past years. Anchovy specimens were brought to the laboratory
and analyzed on length classes or individually, with the purpose of assessing the
general state of anchovy population at our coast (Fig. 1).
Fig. 1. Anchovy specimens analyzed in the laboratory (original).
A batch of approximately 200 individuals is analyzed for each sampling
station; specimens are weighed, measured and, after separation on length or
weight classes, sex, maturation degree and parasitization extent (where the case)
are determined, and subsequently otoliths are extracted for age determination;
growth rings are identified with an inverted microscope (Fig. 2).
Fig. 2. Identification, extraction and analysis of otoliths (original)
Mădălina GALAŢCHI, Magda NENCIU,
Mioara COSTACHE, Valodia MAXIMOV, Dragomir COPREAN
78 Academy of Romanian Scientists Annals - Series on Biological Sciences, Vol. 6, No.1, (2017)
Otoliths were collected by performing a section on the fish head, extracted
and subsequently cleaned of the protection membranes with an alcohol-based
solution. They were then stored in dry spaces until inverted microscope analysis
was performed.
Age determination was made by identifying the growth rings on the
surface of otoliths (Fig. 3).
Fig. 3. Anchovy otoliths, age 1 : 1+ (original).
For an accurate age estimation, after identifying and counting annual growth
rings, other aspects are also considered, such as likely hatching date, time of
fishing etc. [4].
Results and discussions
During the analyzed period, the dominant age classes were between 1 : 1+ and
2 : 2+ years, while the 3 : 3+ age class had a smaller share; individuals belonging
to the 4: 4+ years age class were identified only in an isolated manner (Fig. 4).
Age Determination Aspects in Anchovy (Engraulis encrasicolus, LINNAEUS, 1758)
at the Romanian Black Sea Coast
Academy of Romanian Scientists Annals - Series on Biological Sciences, Vol. 6, No.1, (2017) 79
Fig. 4. Percentage of age classes in anchovy 2010-2014 (original)
Compared to previous years, it was noted that the share of individuals aged 1 :
1+ and 2 : 2+ years is dominant, with a slight increase of 3 : 3 + years individuals
[5]. As such, it can be concluded that a slight rejuvenation of anchovy population
of the Romanian Black Sea coast is documented.
Fig. 5. Percentage of age classes in anchovy 2000-2008
Mădălina GALAŢCHI, Magda NENCIU,
Mioara COSTACHE, Valodia MAXIMOV, Dragomir COPREAN
80 Academy of Romanian Scientists Annals - Series on Biological Sciences, Vol. 6, No.1, (2017)
(modified after Maximov et al., 2010).
Representation of several age classes in the population of one species in an
ecosystem is an indicator of a good general state.
Conclusions
Age determination in fish can me made by three methods:
skeletochronology (the concentric growth rings identified in a bone cross-section
are counted), scalimetry (estimation of the age of fish by examination of
concentric peaks on their scales) and otolithometry (identifying the annual growth
rings of otoliths in the internal ear). In this case, age determination of anchovy of
the Romanian Black Sea coast was made by otolith analysis.
The results pointed out that, during the analyzed period, the dominant age
classes were between 1 : 1+ and 2 : 2+ years, while the 3 : 3+ age class had a
smaller share, while anchovy individuals belonging to the 4: 4+ years age class
were identified only as isolated specimens.
Compared to previous years, it was noted that the share of individuals
aged 1 : 1+ and 2 : 2+ years is dominant, with a slight increase of 3 : 3 + years
individuals [5], thus indicating a rejuvenation of anchovy population of the
Romanian Black Sea coast.
Identification of several age classes in the anchovy sampled from the
Romanian coastal waters show a reproductive success of the species, as well as a
good state of the environment it lives in.
Acknowledgements
This research was completed within the PhD research program of the Doctoral
School of Applied Sciences, “Ovidius” University of Constanta, Romania, and
with the full support of colleagues from NIMRD “Grigore Antipa” Constanta.
References
[1] G. Radu et al., State of the Main Black Sea Commercial Fish Species
Correlated with the Ecological Conditions and Fishing Effort, J. Environ. Prot.
Ecol. 12 (2), 1730 (2012).
[2] S. Vander Kooy and K. Guindon-Tisdel, A practical handbook for
determining the ages of Gulf of Mexico fishes, Ocean Springs, MS, 111 (2003).
Age Determination Aspects in Anchovy (Engraulis encrasicolus, LINNAEUS, 1758)
at the Romanian Black Sea Coast
Academy of Romanian Scientists Annals - Series on Biological Sciences, Vol. 6, No.1, (2017) 81
[3] M. E. Matta and D. K. Kimura, Age determination manual of the Alaska
Fisheries Science Center Age and Growth Program, NOAA Professional Paper
NMFS 13 (2012).
[4] ICES, Workshop on micro increment daily growth in European Anchovy
and Sardine (WKMIAS), ICES CM 51 (2014).
[5] V. Maximov et al., Analysis of the Evolution of Fishing and Biological
Characteristics of the Main Fish from the Romanian Pontic Basin, between 2000
and 2008, Cercetari Marine, 39 (2010).
