Gospodarenje sitnom plavom ribom analizom uzoraka ribarskih lovina istočnog dijela Jadranskog mora

Plan upravljanja ribolovom se dijelom temelji i na poznavanju bioloških parametara ribljih vrsta. Sitna plava riba je gospodarski iznimno značajna za RH. S obzirom na već zabilježene fluktuacije pojedinih vrsta, preporuča se učestali monitoring populacija svih vrsta sitne plave ribe, uz analizu njihovih ihtioloških parametara. U ovom radu su prikazani rezultati analiza uzoraka ribarskih lovina sitne plave ribe u razdoblju od 2. lipnja 2014. do 22. travnja 2015. godine iz Jadranskog mora. Ukupno je obrađeno 17 uzoraka (N=2377) koji su potjecali iz sljedećih ribolovnih zona (podzona): A (a3), B (b2 i b3), C (c1),E (e2, e5 i e6) i F (f1 i f2) . Promatrajući zastupljenost vrsta u uzorcima, utvrđeno je da je srdela Sardina pilchardus (64,79%) bila najzastupljenija vrsta. Po zastupljenosti je slijedio inćun Engraulis encrasicolus (28,82%), zatim šarun (šnjur) Trachurus trachurus (3,11%), plavica (lokarda) Scomber japonicus (1,73%), srdela golema Sardinella aurita (1,05%), papalina Sparttus sprattus (0,46%) i iglica Belone belone (0,05%). Uredbom vijeća (EZ-a) br. 1967/2006 o mjerama upravljanja za održivo iskorištavanje ribljih resursa u Sredozemnom moru, dane su minimalne lovne dužine za sitnu plavu ribu. Prema podacima ovog istraživanja, nisu uočena prekoračenja minimalnih dozvoljenih lovnih dužina najzastupljenijih vrsta: srdele i inćun

MORFOMETRIJSKA I MERISTIČKA OBILJEŽJA SRDELE (Sardina pilchardus, Walbaum, 1792.) IZ ZADARSKOGA RIBOLOVNOG PODRUČJA

This paper presents the results of some morphometric and meristic parameters of sardine, Sardina pilchardus (Walbaum, 1792) from coastal (Virsko more) and open waters (Dugi Otok) of the Zadar area, during the period from March 2004 to February 2005. The total length of all analyzed specimens ranged from 13.0 to 19.0 cm and weights ranged between 16.72 g and 51.45 g, respectively. Body length analysis indicated greater values for sardine females (N=541) than males (N=668) in all observed lengths (LT, LF, LS, LA, LH, OK, LP and BD), except for the eye diameter (ED), where both sexes had equal average value. The length–weight relationship indicated negative allometric growth (b=2.5538, a=0.0261). In length–length relationships, statistical significance occurred in the following relationships: eye diameter in head length (2.78%) and head length in total length (9.01%). For vertebrae analysis, two groups were compared according to their length: the first one obtained specimens smaller than 16.0 cm in total length (LT), whereas samples longer than 16.0 cm belonged to the second group. The number of vertebrae in both groups ranged between 48 and 52 with the most abundant vertebrae class of 50 vertebrae (37.7 %), whereas a minimal number of sardines (4.9 %) had 48 vertebras. A statistically significant difference between the two analyzed groups was not found (t=0.86). The number of rays (RD) in the dorsal fin ranged from 17 to 19 and the average value was 18.11 ± 0.51.U ovom su radu prikazane neke morfometrijske i merističke značajke srdele Sardina pilchardus (Walbaum, 1792.) iz obalnog (Virsko more) i otvorenog (Dugi otok) mora zadarskog područja tijekom razdoblja od ožujka 2004. do veljače 2005. Totalna dužina (LT) svih analiziranih jedinki varirala je od 13,0 do 19,0 cm, a težine su bile u rasponu od 16,72 do 51,45 g. Ženke (N=541) su pokazale veće dužine od mužjaka (N=668) u svim analiziranim tjelesnim dimenzijama (LT, LF, LS, LA, LH, OK, LP i BD), osim kod promjera oka (ED), gdje su vrijednosti u oba spola bile izjednačene. Utvrđen je negativan alometrijski rast srdele (b = 2,5538, a = 0,0261). U dužinsko–dužinskim odnosima zabilježena je statistički značajna razlika između spolova pri odnosu promjera oka i dužine glave (t = 2,78), te dužine glave u totalnoj dužini tijela (t = 9,01). Za analizu broja kralježaka ribe su podijeljene u dvije grupe: prva je sadržavala jedinke totalnih dužina manjih od 16,0 cm, a u drugoj su grupi bile ribe veće od 16,0 cm. Broj je kralježaka u obje skupine varirao od 48 do 52, s modalnim razredom od 50 kralježaka (37,7%), dok je samo 4,9% jedinki srdele imalo 48 kralježaka. Nije utvrđena statistički značajna razlika između dviju promatranih skupina (t = 0,86). Broj šipčica na leđnoj peraji kolebao je od 17 do 19, sa srednjom vrijednošću od 18,11 ± 0,51

Usporedba dužinske raspodjele srdele goleme (Sardinella aurita) iz obalnog i otvorenog mora istočnog dijela srednjeg Jadrana

Round sardinella, Sardinella aurita specimens (N= 2,033) were caught in inshore (Virsko more) and offshore waters (Dugi otok) of the eastern middle Adriatic Sea by commercial purse seine, monthly from November 2007 to January 2009. Out of all specimens, 983 were male (48.4%), 1,021 were female (50.2%) and 29 (1.4%) were undetermined specimens, giving an overall sex ratio of m/ f=0.96. Round sardinella specimens from inshore waters (N=526) and offshore waters (N=1,507) showed total length (LT) range 13.0-32.5 cm and 10.0-30.0 cm, respectively. In total, they showed positive allometry (b=3.2266). Fulton’s mean condition factor for round sardinella from inshore waters was K =0.76 ± 0.23, and for samples from offshore waters, it was K =0.73 ± 0.05. Females indicated better condition ( K =0.75 ± 0.05) in both analyzed areas than males ( K =0.74 ± 0.05).U radu se uspoređuje dužinski sastav, dužinsko maseni odnos i kondicija srdele goleme Sardinella aurita iz obalnog (virsko more) i otvorenog (Dugi otok) mora istočnog dijela srednjeg Jadrana. u svrhu navedenih istraživanja su korišteni mjesečni uzorci iz lovina plivarice ostvarenih tijekom razdoblja studeni 2007.- siječanj 2009. god. ukupno je analizirano 2 033 jedinki, od čega 983 mužjaka, 1021 ženka i 29 jedinki kojima nije bilo moguće odrediti spol. odnos spolova je iznosio m/ž=0,96. totalne dužine (LT) jedinki iz uzoraka lovina obalnog mora (N=526) su kolebale od 13,0 do 32,5 cm, te od 10,0 do 30,0 cm kod jedinki iz otvorenog mora (N=1507). ukupno su jedinke pokazale pozitivan alometrijski rast (b=3,2266). kubični faktor kondicije (K) je za jedinke iz obalnog mora iznosio K =0,76 ± 0,23 a za srdelu golemu s područja otvorenog mora je bio K=0,73 ± 0,05. Ženke su pokazale bolju kondiciju ( K =0,75 ± 0,05) od mužjaka ( K =0,74 ± 0,05) u oba analizirana područja

MORFOMETRIJSKA I MERISTIČKA OBILJEŽJA SRDELE (Sardina pilchardus, Walbaum, 1792.) IZ ZADARSKOGA RIBOLOVNOG PODRUČJA

This paper presents the results of some morphometric and meristic parameters of sardine, Sardina pilchardus (Walbaum, 1792) from coastal (Virsko more) and open waters (Dugi Otok) of the Zadar area, during the period from March 2004 to February 2005. The total length of all analyzed specimens ranged from 13.0 to 19.0 cm and weights ranged between 16.72 g and 51.45 g, respectively. Body length analysis indicated greater values for sardine females (N=541) than males (N=668) in all observed lengths (LT, LF, LS, LA, LH, OK, LP and BD), except for the eye diameter (ED), where both sexes had equal average value. The length–weight relationship indicated negative allometric growth (b=2.5538, a=0.0261). In length–length relationships, statistical significance occurred in the following relationships: eye diameter in head length (2.78%) and head length in total length (9.01%). For vertebrae analysis, two groups were compared according to their length: the first one obtained specimens smaller than 16.0 cm in total length (LT), whereas samples longer than 16.0 cm belonged to the second group. The number of vertebrae in both groups ranged between 48 and 52 with the most abundant vertebrae class of 50 vertebrae (37.7 %), whereas a minimal number of sardines (4.9 %) had 48 vertebras. A statistically significant difference between the two analyzed groups was not found (t=0.86). The number of rays (RD) in the dorsal fin ranged from 17 to 19 and the average value was 18.11 ± 0.51.U ovom su radu prikazane neke morfometrijske i merističke značajke srdele Sardina pilchardus (Walbaum, 1792.) iz obalnog (Virsko more) i otvorenog (Dugi otok) mora zadarskog područja tijekom razdoblja od ožujka 2004. do veljače 2005. Totalna dužina (LT) svih analiziranih jedinki varirala je od 13,0 do 19,0 cm, a težine su bile u rasponu od 16,72 do 51,45 g. Ženke (N=541) su pokazale veće dužine od mužjaka (N=668) u svim analiziranim tjelesnim dimenzijama (LT, LF, LS, LA, LH, OK, LP i BD), osim kod promjera oka (ED), gdje su vrijednosti u oba spola bile izjednačene. Utvrđen je negativan alometrijski rast srdele (b = 2,5538, a = 0,0261). U dužinsko–dužinskim odnosima zabilježena je statistički značajna razlika između spolova pri odnosu promjera oka i dužine glave (t = 2,78), te dužine glave u totalnoj dužini tijela (t = 9,01). Za analizu broja kralježaka ribe su podijeljene u dvije grupe: prva je sadržavala jedinke totalnih dužina manjih od 16,0 cm, a u drugoj su grupi bile ribe veće od 16,0 cm. Broj je kralježaka u obje skupine varirao od 48 do 52, s modalnim razredom od 50 kralježaka (37,7%), dok je samo 4,9% jedinki srdele imalo 48 kralježaka. Nije utvrđena statistički značajna razlika između dviju promatranih skupina (t = 0,86). Broj šipčica na leđnoj peraji kolebao je od 17 do 19, sa srednjom vrijednošću od 18,11 ± 0,51

Prehrana brgljuna Engraulis encrasicolus (Linnaeus, 1758) tijekom mrijesta u istočnom dijelu Jadranskoga mora

The objective of this study was to determine, both quantitatively and qualitatively, the variability in the diet of the anchovy, Engraulis encrasicolus, during its spawning period. Samples were obtained from commercial purse seine catches (April 2014 – September 2016) from coastal and offshore fishing areas of different trophic states and zooplankton composition over the eastern Adriatic Sea. In general, decapod larvae comprise the main source of diet during the anchovies’ spawning period in terms of frequency and abundance, followed by calanoid copepods. The main copepod prey that was identified for anchovy along the eastern Adriatic coast was calanoid Temora stylifera, followed by Oncaeid copepods and Corycaeidae. Although no significant differences in diet composition regarding the anchovy’s size was observed, the contribution of copepods decreased in larger individuals, and were gradually substituted by large crustaceans - decapods, euphausiids, mysids and amphipods. However, a significant difference in prey composition between coastal and offshore areas was observed (global R=0.164, p<0.05). Beside adult copepods, offshore water anchovy fed mainly on decapod larvae and their megalopa stage, and amphipods. In the stomach of the fish caught in the coastal waters, higher contributions of euphausiids, mysids and fish eggs were observed. Prey diversity was greater in the stomach of specimens caught offshore (H’=0.59) than in the costal Adriatic waters (H’=0.40).Cilj ovog rada bio je utvrditi kvantitativnu i kvalitativnu varijabilnost u prehrani brgljuna Engraulis encrasicolus tijekom mrijesta. Uzorci iz komercijalnih ulova plivaricom (travanj 2014 – rujan 2016), obuhvatili su ribolovna područja obalnog i otvorenog mora duž istočne obale Jadrana, različitog trofičkog stanja i sastava zooplanktona. Ličinke deseteronožaca općenito su glavni izvor hrane tijekom mrijesta brgljuna, a prate ih kalanoidni veslonošci. Unutar veslonožaca najzastupljenija je bila vrsta kalanoida Temora stylifera, a slijede veslonošci skupine Oncaea i porodica Corycaeidae. Premda nisu utvrđene značajne razlike u sastavu prehrane u odnosu na dužinu ribe, udio veslonožaca smanjio se porastom dužine brgljuna, a postupno su ih nadomještali veliki rakovi - deseteronošci, eufazidi, rašljonožci i rakušci. Međutim, uočena je značajna razlika u sastavu plijena između obalnog i otvorenog mora (globalni R = 0.164, p <0.05). Pored odraslih veslonožaca, brgljun otvorenog mora hranio se uglavnom ličinkama deseteronožaca i njihovih megalopa stadija te rakušci. U želucu ribe ulovljene u obalnim vodama primijećen je veći doprinos eufauzida, rakušcima i ribljih jaja. Raznolikost plijena bila je veća u želucima jedinki ulovljenih u otvorenim vodama (H’=0.59) nego u obalnom dijelu Jadrana (H’=0.40)

Oogenesis and spermatogenesis in round sardinella (Sardinella aurita Valenciennes, 1847) from the eastern part of the Adriatic Sea

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

Usporedba dužinske raspodjele srdele goleme (Sardinella aurita) iz obalnog i otvorenog mora istočnog dijela srednjeg Jadrana

Round sardinella, Sardinella aurita specimens (N= 2,033) were caught in inshore (Virsko more) and offshore waters (Dugi otok) of the eastern middle Adriatic Sea by commercial purse seine, monthly from November 2007 to January 2009. Out of all specimens, 983 were male (48.4%), 1,021 were female (50.2%) and 29 (1.4%) were undetermined specimens, giving an overall sex ratio of m/ f=0.96. Round sardinella specimens from inshore waters (N=526) and offshore waters (N=1,507) showed total length (LT) range 13.0-32.5 cm and 10.0-30.0 cm, respectively. In total, they showed positive allometry (b=3.2266). Fulton’s mean condition factor for round sardinella from inshore waters was K =0.76 ± 0.23, and for samples from offshore waters, it was K =0.73 ± 0.05. Females indicated better condition ( K =0.75 ± 0.05) in both analyzed areas than males ( K =0.74 ± 0.05).U radu se uspoređuje dužinski sastav, dužinsko maseni odnos i kondicija srdele goleme Sardinella aurita iz obalnog (virsko more) i otvorenog (Dugi otok) mora istočnog dijela srednjeg Jadrana. u svrhu navedenih istraživanja su korišteni mjesečni uzorci iz lovina plivarice ostvarenih tijekom razdoblja studeni 2007.- siječanj 2009. god. ukupno je analizirano 2 033 jedinki, od čega 983 mužjaka, 1021 ženka i 29 jedinki kojima nije bilo moguće odrediti spol. odnos spolova je iznosio m/ž=0,96. totalne dužine (LT) jedinki iz uzoraka lovina obalnog mora (N=526) su kolebale od 13,0 do 32,5 cm, te od 10,0 do 30,0 cm kod jedinki iz otvorenog mora (N=1507). ukupno su jedinke pokazale pozitivan alometrijski rast (b=3,2266). kubični faktor kondicije (K) je za jedinke iz obalnog mora iznosio K =0,76 ± 0,23 a za srdelu golemu s područja otvorenog mora je bio K=0,73 ± 0,05. Ženke su pokazale bolju kondiciju ( K =0,75 ± 0,05) od mužjaka ( K =0,74 ± 0,05) u oba analizirana područja

Comparison of Growth Parametres Between Sardine Sardina Pilchardus (Walbaum, 1792) and Anchovy Engraulis Encrasicolus (Linnaeus, 1758) from the Eastern Adriatic Sea

Sardine Sardina pilchardus (Walbaum, 1792) and anchovy Engraulis encrasicolus (Linnaeus, 1758), besides being ecologically very important pelagic resources, are also the most numerous fish species in Croatian fisheries landings. Hence, the aim of this study was to compare sardine and anchovy growth parameters: length, length-weight relationship, condition and age population structure. All samples (N=3313) were collected from purse seine catches of eastern Adriatic Sea, during period June 2015 – August 2016. Total lengths of sardine and anchovy ranged from 10.5 to 17.5 cm (average ± SD: 13.94 cm ± 1.07) and from 10.0 to 17.5 cm (average ± SD: 14.09 cm ± 0.88), respectively. Both sardine and anchovy length-weight relationship indicated positive allometry, although allometric coefficient was higher in anchovy (b=3.201) than in sardine (b=3.069). In general, condition of both species grew with fish length. Sardine and anchovy age composition varied from one to five years, while most of the analysed samples belonged to the 3 year class. Growth parameters were for anchovy: L∞=18.36cm; K=0.317; t0= -1.89 and for sardine L∞=19.71 cm; K=0.286; t0= -1.82

Comparison of Growth Parametres Between Sardine Sardina Pilchardus (Walbaum, 1792) and Anchovy Engraulis Encrasicolus (Linnaeus, 1758) from the Eastern Adriatic Sea

Sardine Sardina pilchardus (Walbaum, 1792) and anchovy Engraulis encrasicolus (Linnaeus, 1758), besides being ecologically very important pelagic resources, are also the most numerous fish species in Croatian fisheries landings. Hence, the aim of this study was to compare sardine and anchovy growth parameters: length, length-weight relationship, condition and age population structure. All samples (N=3313) were collected from purse seine catches of eastern Adriatic Sea, during period June 2015 – August 2016. Total lengths of sardine and anchovy ranged from 10.5 to 17.5 cm (average ± SD: 13.94 cm ± 1.07) and from 10.0 to 17.5 cm (average ± SD: 14.09 cm ± 0.88), respectively. Both sardine and anchovy length-weight relationship indicated positive allometry, although allometric coefficient was higher in anchovy (b=3.201) than in sardine (b=3.069). In general, condition of both species grew with fish length. Sardine and anchovy age composition varied from one to five years, while most of the analysed samples belonged to the 3 year class. Growth parameters were for anchovy: L∞=18.36cm; K=0.317; t0= -1.89 and for sardine L∞=19.71 cm; K=0.286; t0= -1.82

EXPLOITATION AND MORTALITY OF GILT SARDINE SARDINELLA AURITA, VALENCIENNES, 1847 IN THE MIDDLE EASTERN ADRIATIC SEA

U ovom su radu prikazani rezultati istraživanja strukture populacije, mortaliteta i iskorištavanja srdele goleme Sardinella aurita, Valenciennes, 1847. iz uzoraka lovina ostvarenih u obalnom (Virsko more) i otvorenom moru (Dugi otok) zadarskog područja, u razdoblju od studenog 2007. do siječnja 2009. Ukupno su analizirane 2033 jedinke, od čega 983 mužjaka, 1021 ženka i 29 jedinki kojima nije bilo moguće odrediti spol. Odnos spolova je iznosio m/ž=0,96 u korist ženki. Totalne dužine (TL) svih analiziranih jedinki su se kretale od 10,0 do 32,5 cm, a srednja vrijednost je iznosila 22,0 ± 3,65 cm. Dob je varirala od prve godine (0+) do navršenih pet godina života (5+). Vrijednosti koeficijenta prirodne (M), ribolovne (F) i ukupne smrtnosti (Z), te indeksa preživljavanja (S) populacije su iznosile: M=0,46; F=0,23; Z=0,69 i S=0,60. Iako se na hrvatskom dijelu Jadranskog mora još uvijek statistički ne evidentira ulov srdele goleme, u svjetskim morima i oceanima su kroz posljednje desetljeće ukupni godišnji ulovi ove vrste bili na razini od oko 500 000 t.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