Background and purpose: Small pelagic fish species round sardinella (Sardinella aurita) has expanded its habitat during the last few decades towards colder parts of the Mediterranean Sea. In the ...Adriatic Sea, this investigation is the first attempt to study its gonad development histologically.Materials and methods: S. aurita specimens were sampled monthly from commercial landings of purse seine catches from the eastern part of the Adriatic Sea from November 2007 to January 2009. After biometric parameters were determined, gonads were removed from the fish and weighed. Sex and gonad development were determined macroscopically by the shape and the structure of gonads and afterwards gonads were analysed histologically.Results: The phases of gonadal development of both sexes of S. aurita were: immature, developing, spawning capable, regressing, and regenerating. An annual reproduction cycle based on gamete development revealed five stages of oocyte development: chromatin nucleolar stage, perinucleolar stage, yolk vesicle (cortical alveoli) formation, vitellogenic (yolk) stage, and ripe (mature) stage. Spermatogenesis was described through three stages: spermatocytogenesis (formation of primary spermatocytes from spermatogonia), meiosis (formation of secondary spermatocytes and spermatids) and spermiogenesis.Conclusions: Gonadal histology analyses of both sex of S. aurita indicated summer spawning manner of this species, with a peak in June-August period.
Background and purpose: Small pelagic fish species round sardinella (Sardinella aurita) has expanded its habitat during the last few decades towards colder parts of the Mediterranean Sea. In the ...Adriatic Sea, this investigation is the first attempt to study its gonad development histologically.Materials and methods: S. aurita specimens were sampled monthly from commercial landings of purse seine catches from the eastern part of the Adriatic Sea from November 2007 to January 2009. After biometric parameters were determined, gonads were removed from the fish and weighed. Sex and gonad development were determined macroscopically by the shape and the structure of gonads and afterwards gonads were analysed histologically.Results: The phases of gonadal development of both sexes of S. aurita were: immature, developing, spawning capable, regressing, and regenerating. An annual reproduction cycle based on gamete development revealed five stages of oocyte development: chromatin nucleolar stage, perinucleolar stage, yolk vesicle (cortical alveoli) formation, vitellogenic (yolk) stage, and ripe (mature) stage. Spermatogenesis was described through three stages: spermatocytogenesis (formation of primary spermatocytes from spermatogonia), meiosis (formation of secondary spermatocytes and spermatids) and spermiogenesis.Conclusions: Gonadal histology analyses of both sex of S. aurita indicated summer spawning manner of this species, with a peak in June-August period.
A total of 1125 specimens of sardine,
Sardina pilchardus, ranging in total length from 4.9 to 12.5
cm (mean 8.31
±
1.41
cm) and in weights between 1.02
g and 11.18
g (mean 4.40
±
1.87
g) were ...randomly sampled using a beach seine from the Krka River estuary. Samples were collected monthly according to their occurrence in this area from October to February during 2002/03, 2003/04 and 2004/05, which is during the spawning period of this species. Monthly fluctuations in the length frequency distributions of sardine were observed during that time. The length–weight relationship of all sardine specimens was described by the equation:
W
=
0.007
L
2.9587
(
r
2
=
0.9626); and the isometric nature of relative growth was established (
t
=
−5.1495;
p
<
0.05). According to the allometric condition factor
K
a, sardine specimens were in better somatic condition at the beginning of their appearance (spawning period) in the Krka River estuary. The length at which 50% of sardines were mature (
L
50) was calculated to be 7.9
cm.
The otolith (sagitta) measurements of five pelagic fish species - Engraulis encrasicolus (Linnaeus, 1758); Sardina pilchardus (Walbaum, 1792); Scomber scombrus Linnaeus, 1758; Scomber japonicus ...Houttuyn, 1780 and Belone belone (Linnaeus, 1761) - were obtained by image analysis of catch samples retrieved from the Croatian part of the Adriatic Sea. Three dimensionless shape descriptors of form factor (FF), roundness (RD) and aspect ratio (AR) were analysed and revealed statistically significant differences between the otoliths of the stated pelagic fish species. Maximum otolith length (LO) and otolith weight (WO) were linearly correlated to total fish length (TL) for each studied fish species; they were increasing proportionally during fish growth.Original Abstract: U radu se iznose rezultati morfometrijske analize otolita brgljuna Engraulis encrasicolus (Linnaeus, 1758), srdele Sardina pilchardus (Walbaum, 1792), skuse Scomber scombrus Linnaeus, 1758, lokarde Scomber japonicus Houttuyn, 1780 i iglice Belone belone (Linnaeus, 1761). Za svaku je istrazivanu vrstu analizirano po 30 jedinki koje potjecu iz lovina ostvarenih na podrucju istocnog dijela Jadrana tijekom razdoblja sijecanj - prosinac 2005. godine. Na temelju analize triju faktora oblika otolita (FF, RD, AR) je uoceno da postoji statisticki znacajna razlika izmedju otolita promatranih pelagicnih vrsta riba. Znacajna linearna korelacija je utvrdjena izmedju najvece duzine otolita (LO) i ukupne duzine tijela ribe (LT) kao i mase otolita (WO) i ukupne duzine tijela ribe (LT) - s porastom ukupne duzine tijela analizirane pelagicne vrste se proporcionalno povecavala najveca duzina otolita i masa otolita.
Painted comber, Serranus scriba (Linnaeus, 1758), is a subtropical species which is found in the Eastern Atlantic, Mediterranean and Black Sea. The aim of this study was to report the data on the ...painted comber morphometric and meristic characteristics in the Adriatic Sea, as until now they have not been systematically studied. Samples of 253 painted comber individuals were monthly caught as by-catch species of the small coastal trawl between June 2001 and May 2002 in the Trogir Bay area (eastern mid-Adriatic). In order to analyzed biometry of the species, fifteen morphometric and eight meristic characters were measured. Total length of painted comber specimens ranged between 7.1 and 20.0 cm, the mean value was 11.0 plus or minus 1.70 cm. Comparison of the obtained morphometric and meristic characteristics with the same ones that were published earlier did not show differences between painted comber populations inhabiting the Adriatic, different parts of the Mediterranean areas (including the Black Sea) and the eastern Atlantic.
This paper presents some biological features of juvenile and adult specimens of Atlantic bonito, Sarda sarda (Bloch, 1793), in the eastern middle Adriatic Sea. A total of 194 specimens were analysed, ...of which 93 were juveniles and 101 were adults. Juvenile individuals ranged from 5.7 to 8.4 cm while adults ranged from 39.3 to 56.7 cm. In order to analyse biometry, nine morphometric characters were analysed. Length-length equations for overall converted body lengths of fish were linear. Comparison of length-length relationships between juvenile and adult specimens showed statistically significant differences in almost all morphometric characteristics, except for the fork length-second dorsal fin base. Females insignificantly prevailed in adults. Overall gonads were in post-spawning state. Juveniles were unsexed. Length-weight relationships of juveniles and adults were W = 0.0033LF super(3.424) and W = 0.0149LF super(2.984), respectively.Original Abstract: U radu su analizirani juvenilni i adultni primjerci palamide, Sarda sarda (Bloch, 1793), prikupljeni na podrucju istocnog dijela srednjeg Jadranskog mora. Ukupno je obradjeno 194 primjerka, od cega je 93 juvenilnih i 101 adultni. Analizom biometrijskih svojstava zabiljezene su promjene morfometrijskih odnosa s porastom vilicne duzine (LF), te je utvrdjeno da postoji statisticki znacajna razlika izmedju morfometrijskih odnosa juvenilnih i adultnih primjeraka palamide, osim kod odnosa LF-LD2. Spol je bilo moguce odrediti samo kod adultnih primjeraka, gdje su brojcano neznatno dominirale zenke. Analizom stanja gonada utvrdjeno je da su se svi adultni primjerci izmrijestili. Kod juvenilnih primjeraka duzinsko-masenim odnosom je utvrdjena pozitivna alometrija (b = 3.424), dok je kod adultnih primjeraka utvrdjena izometrija (b = 2.984).
The present study was undertaken not only to register the new recently noticed maximum age and total length of Serranus scriba (Linnaeus, 1758), contributing to the knowledge of this species in the ...Mediterranean and Adriatic Sea inclusively. A painted comber specimen of 323 mm of total length and age 16 years was caught during August 2008 in the Lavdra Channel (middle-eastern Adriatic Sea).Original Abstract: Jedinka pirke Serranus scriba (Linnaeus, 1758) je ulovljena uz sjeverozapadnu obalu otoka Mala Lavadra (istocni dio srednjeg Jadrana). Totalna duzina tijela kao i starost ulovljene pirke je najveca zabiljezena do sada na podrucju njenog rasprostranjenja i iznosila je 323 mm odnosno 16 godina.
This paper presents the results of population structure, mortality and exploitation of gilt sardine Sardinella aurita, Valenciennes 1847, from the catches of inshore (Virsko more) and offshore waters ...(Dugi otok) in the Zadar area between November 2007 and January 2009. A total of 2033 specimens (983 male, 1021 female, 29 undetermined) showed the sex ratio m/f=0.96; females predominated. The total length (TL) of all observed specimens varied from 10.0 to 32.5 cm (mean±SD=22.0 ± 3.65 cm). The age of gilt sardine varied from 0+ to 5+. The values of natural (M), fishing (F), total mortality (Z) and survival rate (S) coefficients were M=0.46, F=0.23, Z=0.69 and S=0.60, respectively.Even though the catches of gilt sardine have not been recorded yet for the Croatian part of the Adriatic Sea, as far as the world’s seas and oceans are concerned, the total catches were ca. 500 000 t in the last decade.
This paper presents inter-annual fluctuations in the population structure, condition, lengthweight relationship and abundance of sardine, Sardina pilchardus (Walb., 1792), the most important fish ...species in the Adriatic Sea. The random samples were obtained from the nursery ground (Zrmanja River estuary, n=2 893) and spawning ground (off Dugi Otok, n =1 628) of the sardine. Representative samples of catches obtained by purse seine fishing were collected during the 2002-2006 period. Total lengths ranged from 5.0 to 19.5 cm (mean lengths between 7.35 plus or minus 1.005 and 13.87 plus or minus 1.102 cm; Zrmanja River estuary) and 11.5 to 19.5 (mean lengths between 15.22 plus or minus 1.826 and 16.19 plus or minus 0.854, off Dugi Otok). The length-weight relationships of sardine from the Zrmanja River estuary and off Dugi Otok point to positive and negative allometry, respectively. A comparison of the allometric condition factor (K sub(a)) of sardine specimens, which ranged from 13.0 to 16.0 cm, showed higher values in the area off Dugi Otok (K sub(a) =0.467) than in the area of the Zrmanja River estuary (K sub(a)=0.331), especially during 2003 (K sub(a) =2.653). In terms of the fish abundance index, seasonal fluctuations were noticed. The highest values were observed in the area off Dugi Otok during autumn and in the Zrmanja River estuary during spring.Original Abstract: U radu su prikazani rezultati izucavanja visegodisnjih fluktuacija strukture populacije, kondicije, abundancije i duzinsko-masenog odnosa srdele Sardina pilchardus (Walb., 1792), iz obalnog (obitavaliste, hraniliste) i otvorenog mora (mrijestiliste) istocnog dijela Jadrana. Tijekom razdoblja 2002.-2006. je ukupno analizirano 4 521 jedinki ove, za hrvatsko gospodarstvo jedne od najznacajnijih ribljih vrsta u Jadranskom moru. Totalne duzine su kolebale izmedju 4,5 to 19,5 cm, s prosjecnim duzinama izmedju 7,35 plus or minus 1,005 i 13,87 plus or minus 1,102 cm u estuariju rijeke Zrmanje, te 11,5 i 19,5 s prosjecnim duzinama izmedju 15,22 plus or minus 1,826 i 16,19 plus or minus 0,854 cm u podrucju Dugog otoka. Srdela iz podrucja Dugog otoka je imala negativnu alometriju, a iz podrucja estuarija Zrmanje pozitivnu. Usporedba indeksa kondicije (K sub(a)) srdele raspona istih duzina jedinki u oba podrucja izmedju 13,0 i 16,0 cm je pokazala da su vise vrijednosti bile u srdele iz uzoraka lovina ostvarenih u podrucju Dugog otoka (K sub(a) =0.467) nego iz podrucja estuarija rijeke Zrmanje (Novigradsko more) (K sub(a)=0.331), posebice tijekom 2003 (K sub(a) =2.653). U odnosu na indeks abundancije, primjecene su sezonske fluktuacije -najvisi su iznosi zabiljezni tijekom jeseni u podrucju Dugog otoka, a u podrucju estuarija rijeke Zrmanje tijekom proljeca.
This paper presents the biometry analysis of the Atlantic bonito, Sarda sarda (Bloch, 1793), population in the eastern mid Adriatic Sea for 1997-2000. A total of 665 specimens were analyzed. Fork ...length ranged 33.0-67.0 cm. Nine morphometric and seven meristic characters were assessed. Sexual dimorphism was noticed in two meristic and three morphometric characters. The relation between total length and fork length is presented. Relative growth was studied by comparing changes in morphological characters with growth in fork length. Length-weight relationship is presented as well.Original Abstract: U radu su analizirane biometrijske karakteristike palamide, Sarda sarda (Bloch, 1793), koja je prikupljena na podrucju istocnog dijela srednjeg Jadranskog mora u razdoblju od 1997. do 2000. godine. Ukupno je obradjeno 665 primjerka ove ribe. Vilicna duzina se kretala u rasponu izmedju 33,0 i 67,0 cm. Analizirano je 9 morfometrijskih i 7 meristickih obiljezja ove vrste. Utvrdjeno je da je kod 3 morfometrijska i 2 meristicka obiljezja postojala znacajna razlika izmedju muzjaka i zenki. Zabiljezene su promjene morfometrijskih odnosa s porastom vilicne duzine (LF). Analizom duzinsko-masenog odnosa palamide je utvrdjena pozitivna alometrija.
