44 research outputs found
Species composition, seasonal fluctuations, and residency of inshore fish assemblages in the Pantan estuary of the eastern middle Adriatic
A total of 9434 fishes, mainly juveniles, belonging to 15 families and 42 species were caught at six stations in the Pantan estuary in the eastern mid Adriatic. Using a 50 m beach seine, 1493 specimens
of 25 species were caught in summer, 2594 specimens of 26 species in autumn, 3626 of 24 species in winter, and 1721 of 30 species in spring. Seven species comprised 87.8% of the total: Atherina boyeri (33.2%), Pomatoschistus marmoratus (28.1%), Liza aurata (8.3%), Liza ramada (7.1%), Aphanius fasciatus (5.5%), Diplodus annularis (2.9%) and Mugil cephalus (2.6%). An ANOSIM2 test for unreplicated 2-way layouts revealed significant differences in species assemblages among the sites (Ļav = 0.385, P = 0.007). Stations with similar hydrographic conditions had similar species
richness and assemblages. Statistically significant differences were not noted between seasons (Ļav = 0.221, P = 0.057) although some seasonal differences, especially between summer and winter, were observed on nMDS plots. The most important ecological category was planktivorous fishes (39.4%), followed by benthic mesocarnivorous fishes (33.9%), and particulate organic matter
feeders (21.3%). Twenty-two species were permanent estuary residents, 14 opportunists, and six transients. This study demonstrates that the Pantan estuary is an important fish nursery habitat that, although small, has great spatial fish diversity and therefore deserves special protection
Ishrana trlje kamenjarke, Mullus surmuletus u istoÄnom Jadranskom moru
Feeding habits of the striped red mullet, Mullus surmutetus
in the eastern Adriatic Sea were investigated. Stomach contents of 203 specimens (11.5 - 32.9 cm TL) collected by bottom trawling
were analyzed. Commonly accepted procedures were followed during the diet composition inspection and standard keys were used for food items determination. Examinations showed that 39 identified prey taxa belong to 11 major systematic groups: Crustacea, Gastropoda, Bivalvia, Pisces, Cnidaria, Echinodermata, Polychaeta, Nematoda, Bryozoa, Algae and Rhizaria. The predominant
and preferred prey category was decapod crustaceans within all size categories and only in the largest individuals, the dominance of Bivalvia followed by Polychaeta and Crustacea were found.
The largest individuals also showed more variety in consumption of different prey categories and a higher mean number of prey items in comparison with smaller fish. No significant differences in
prey foraging between males and females ((p>0.05)) and regarding to season ((p>0.05)) were found. Feeding on such wide spectra of prey without significant variations regarding to sex and season suggests that the striped red mullets are able to adapt to shifts in spatio-temporal variations in the abundance of potential prey. Presence of detritus in the digestive tracts is highly related to its foraging behaviour on muddy detritic bottoms.Istraživana je ishrana trlje kamenjarke, Mullus surmuletus u istoÄnom dijelu Jadrankog mora. Analiziran je sadržaj želudca 203 jedinke (11.5 ā 32.9 cm TL) prikupljenih pridnenom povlaÄnom
mrežom koÄom. OpÄe su prihvaÄene metode i kljuÄevi za determinaciju koriÅ”teni za odreÄivanje sastava ishrane i determinaciju plijena. Istraživanjem je odreÄeno 39 identificiranih vrsta plijena koji
spadaju u 11 glavnih skupina: rakovi, puževi, Å”koljkaÅ”i, ribe, žarnjaci, bodljikaÅ”i, mnogoÄetinaÅ”i, obliÄi, mahovnjaci, alge i krednjaci. Dominantna i poželjna kategorija plijena bili su dekapodni
rakovi unutar svih veliÄinskih kategorija, dok je samo kod najveÄih jedinki pronaÄena dominantnost Å”koljkaÅ”a, a slijede ih mnogoÄetinaÅ”i i rakovi. NajveÄe jedinke takoÄer su pokazale veÄu raznolikost
u konzumaciji razliÄitih vrsta plijena i prosjeÄno veÄi broj jedinki plijena u odnosu na manje ribe. Nije pronaÄena znaÄajna razlika u ishrani izmeÄu mužjaka i ženki ((p>0.05)) i s obzirom na sezonu
Istraživana je ishrana trlje kamenjarke, Mullus surmuletus u istoÄnom dijelu Jadrankog mora. Analiziran je sadržaj želudca 203 jedinke (11.5 ā 32.9 cm TL) prikupljenih pridnenom povlaÄnom
mrežom koÄom. OpÄe su prihvaÄene metode i kljuÄevi za determinaciju koriÅ”teni za odreÄivanje sastava ishrane i determinaciju plijena. Istraživanjem je odreÄeno 39 identificiranih vrsta plijena koji
spadaju u 11 glavnih skupina: rakovi, puževi, Å”koljkaÅ”i, ribe, žarnjaci, bodljikaÅ”i, mnogoÄetinaÅ”i, obliÄi, mahovnjaci, alge i krednjaci. Dominantna i poželjna kategorija plijena bili su dekapodni
rakovi unutar svih veliÄinskih kategorija, dok je samo kod najveÄih jedinki pronaÄena dominantnost Å”koljkaÅ”a, a slijede ih mnogoÄetinaÅ”i i rakovi. NajveÄe jedinke takoÄer su pokazale veÄu raznolikost
u konzumaciji razliÄitih vrsta plijena i prosjeÄno veÄi broj jedinki plijena u odnosu na manje ribe. Nije pronaÄena znaÄajna razlika u ishrani izmeÄu mužjaka i ženki ((p>0.05)) i s obzirom na sezonu
((p>0.05)). Hranjenje Å”irokim spektrom plijena bez znaÄajnih varijacija u vezi sa spolom i sezonom sugerira da se trlja od kamena može prilagoditi pomacima u prostorno-vremenskim varijacijama
obilja potencijalnog plijena. Prisutnost detritusa u probavnom traktu povezana je s naÄinom hranjenja istraživane vrste na muljevitim detritiÄnim dnima. Hranjenje Å”irokim spektrom plijena bez znaÄajnih varijacija u vezi sa spolom i sezonom sugerira da se trlja od kamena može prilagoditi pomacima u prostorno-vremenskim varijacijama
obilja potencijalnog plijena. Prisutnost detritusa u probavnom traktu povezana je s naÄinom hranjenja istraživane vrste na muljevitim detritiÄnim dnima
Fekunditet traglja, Spicara maena L. (Teleostei: Centracanthidae) u istoÄnom dijelu srednjeg Jadrana
We studied the fecundity of Spicara maena L. collected in the eastern central Adriatic Sea at the peak of the spawning period (from 16 September to 10 October). Due to protogyny, females up to
a total length of 20.0 cm were observed. Absolute fecundity varied from a minimum of 42140 eggs for two-year-olds to a maximum of 80509 for three-year-olds. The mean oocyte diameter ranged
1.68-1.92 mm. The relationships between absolute fecundity and total weight and length of the females were best described by the following exponential equations: Fl = 33.4 TL2.6 (r2 = 0.933) and
Fw = 560.2Wt + 15874 (r2 = 0.693). There was no significant correlation between oocyte size and maternal size.ProuÄavan je fekunditet traglja, Spicara maena L. uzorkovanog na istoÄnoj obali srednjeg Jadrana u vrhuncu mrijesta (od 16. rujna do 10. listopada). Ženke, uslijed protoginije, su utvrÄene do ukupne dužine od 20,0 cm. Apsolutni fekunditet je kolebao od 42 140 kod drugog godiÅ”ta do maksimalnih 80 509 u treÄem godiÅ”tu. Srednji je promjer oocita bio od 1,68 do 1,92 mm. Odnos izmeÄu apsolutnog fekunditeta i ukupne dužine, odnosno ukupne mase, odreÄen je slijedeÄim eksponencijalnim jednadžbama: Fl = 33,4 TL2.6 (R2 = 0,933) i Fw = 560.2Wt + 15874 (R2 = 0.693). Nije bilo znaÄajne korelacije izmeÄu veliÄine oocita i veliÄina ženki
Kljunasta konÄarica Nemichthys scolopaceus Richardson, 1848 (Pisces: Nemichthydae), novi pripadnik ihtiofaune Jadranskog mora
The paper reports the first record of Nemichthys scolopaceus leptocephalus in the Adriatic Sea,
including a detailed description of the specimen with morphometric measurements and meristic
counts. A single leptocephalus specimen was caught on 18th September 2016 in south Adriatic with
a small mid-water trawl at a depth of approx. 120 meters. Further research is needed to reveal more
information about the distribution and potential spawning and nursery areas of slender snipe eel as
well as the mechanism of retention and dispersion of their larvae in the Adriatic.U radu je prikazan prvi nalaz vrste kljunasta konÄarica Nemichthys scolopaceus, ulovljen 18.
rujna 2016. godine u južnom Jadranu pelagiÄkom koÄom na dubini od cca. 120 metara. Nalaz se
odnosi na liÄinku leptocefala te ukljuÄuje detaljan opis jedinke s morfometrijskim i meristiÄkim oso-
binama. Svakako su potrebna daljnja istraživanja kako bi se otkrilo viŔe o rasprostranjenosti i poten-
cijalnim podruÄjima mrijesta i hraniliÅ”tima ove vrste, kao i o mehanizmu rasprÅ”ivanja i zadržavanja
njihovih liÄinki u Jadranu
El gallano, Labrus mixtus (Pisces: Labridae): Ćndices biolĆ³gicos para documentar la historia vital de la especie y contribuir a su conservaciĆ³n
The cuckoo wrasse, Labrus mixtus, is widely distributed in the moderate warm waters of the Atlantic Ocean, including the Mediterranean and Adriatic Seas. Generally, labrids are small inshore coastal species susceptible to anthropogenic habitat degradation and, although without commercial importance, they make up a significant part of the by-catch and discard. Also, these fishes are intensively caught in recreational and subsistence fisheries. Basic biological information is required for their stock assessment and conservation. Studies of the age, growth, reproduction and feeding of L. mixtus have not been undertaken previously in the Adriatic Sea. The observed maximum age of the cuckoo wrasse was 10 years, although most of the sampled fish were 7 years old. The estimated parameters of the von Bertalanffy growth model suggested that the growth of L. mixtus was relatively fast in the first four years of life. L. mixtus is a protogynous hermaphrodite and sex change occurred at 26 cm, while the greatest increase in gonadosomatic index in April confirmed spring as the spawning period. The cuckoo wrasse is an opportunistic predator, feeding primarily on crustaceans, gastropods and fishes. The information provided on biological indices is necessary for life history pathways and future conservation measures of this population in the Adriatic Sea.El gallano, Labrus mixtus, se halla ampliamente distribuido en las zonas templadas del OcĆ©ano AtlĆ”ntico, incluyendo el MediterrĆ”neo y el Mar Negro. En general, los lĆ”bridos son especies de pequeƱo tamaƱo que habitan en aguas costeras, siendo vulnerables a la degradaciĆ³n antrĆ³pica del hĆ”bitat y, a pesar de ser comercialmente poco importantes, forman una parte importante de los descartes de la pesca profesional. Estos peces tambiĆ©n son intensamente capturados por la pesca recreativa o de subsistencia. Se requiere, pues, una informaciĆ³n biolĆ³gica bĆ”sica para conocer el estado de los stocks y asegurar su conservaciĆ³n. Los estudios sobre la edad, el crecimiento, la reproducciĆ³n y la alimentaciĆ³n de L. mixtus no se han realizado hasta ahora en el AdriĆ”tico. La edad mĆ”xima observada en esta especie ha sido de 10 aƱos, si bien la mayorĆa de los peces capturados se situaba en los 7 aƱos. Los parĆ”metros estimados a partir de la ecuaciĆ³n de crecimiento de Von Bertalanffy sugieren que el crecimiento de L. mixtus es rĆ”pido durante los primeros aƱos de vida. L. mixtus es una especie hermafrodita proterogĆnica y el cambio de sexo se produce a los 26 cm de longitud, mientras que el gran incremento del Ćndice gonadosomĆ”tico en el mes de abril confirma que el periodo de reproducciĆ³n se produce durante la primavera. El gallano es un depredador oportunista que se alimenta preferentemente de crustĆ”ceos, gasterĆ³podos y peces. La informaciĆ³n que se da en este artĆculo sobre los Ćndices biolĆ³gicos es necesaria para conocer las caracterĆsticas vitales de esta especie y para adoptar futuras medidas de conservaciĆ³n de su poblaciĆ³n en el AdriĆ”tico
Å krpun Scorpaena porcus (Pisces, Scorpaenidae), novi domaÄin za parazitske jednakonoÅ”ce Nerocila orbigny i Ceratothoa parallela (Crustacea, Isopoda, Cymothoidae)
Two isopod species, Nerocila orbigny and Ceratothoa parallela (Crustacea, Isopoda, Cymothoidae) are reported for the first time on and in the black scorpionfish, Scorpaena porcus, collected from the eastern Adriatic Sea. Cymothoids parasitized 5.5 % (6 of 109) of the collected fish.Parazitski jednakonoÅ”ci Nerocila orbigny i Ceratothoa parallela (Crustacea, Isopoda, Cymothoidae) su po prvi put zabilježeni na Å”krpunu, Scorpaena porcus, na podruÄju istoÄnog Jadrana. Od ukupnog broja pregledanih Å”krpuna, ovi rakovi su utvrÄeni u 5.5% cjelokupnog uzorka (6 od 109 jedinki)
Population Dynamics and Reproduction of Mediterranean Green Crab Carcinus aestuarii in Parila Lagoon (Neretva Estuary, Adriatic Sea, Croatia) as Fishery Management Tools
AbstractPopulation structure, age, growth, mortality, and reproduction patterns of the Mediterranean green crab Carcinus aestuarii were determined for the native population in Parila Lagoon (Neretva Estuary, Middle Adriatic, Croatia). The population size structure showed two distinct cohorts: (1) specimens with a carapace width of 20ā34 mm and dominated by females and (2) large-sized specimens with a carapace width > 34 mm with males significantly dominating and no females found above 46 mm. Males appeared to grow faster than females in the first and second year of the life cycle. Most of the natural mortality (70.4%) occurred during the first year of life. This indicates high predation pressure from fish and other crab species on small-sized (less than 25 mm) C. aestuarii cohorts. The peak of ovigerous female occurrence occurred in January 2015. A very small percentage of ovigerous females appeared in June 2015. The 50% ovigerous size for the population was estimated at a carapace width of 29.65 mm and w..
A HEALTHY APPROACH TO HEALTHY FOOD FROM THE HEALTHY SEA: EVALUATION OF FISH ORIGINATING FROM THE PROTECTED AREA
Park prirode āLastovsko otoÄjeā je 2010. godine shodno Pravilniku o unutarnjem redu usvojio posebni ribolovni režim. U ovom radu bit Äe prezentirano stanje godinu dana nakon uspostave ovakvog režima u usporedbi s nultim stanjem 2010. godine. Ribolov je obavljan trostrukim mrežama stajaÄicama, a analizirano je ukupno obilje, biomasa i raznolikost riba te struktura zajednica. Iako joÅ” uvijek nisu zamijeÄena statistiÄki znaÄajna poboljÅ”anja prosjeÄnog bogatstva riba, ukupnog obilja i biomase, ipak se nazire pozitivna promjena. Naime, u dvije trenutno zaÅ”tiÄene zone zamijeÄeno je za 14% veÄe bogatstvo vrsta, 9% viÅ”e obilje i 19% viÅ”a ukupna biomasa, dok se u izlovljavanim zonama vidi pad od 7% bogatstva vrsta, 12% niže obilje i za 24% niža biomasa. Kako promjena nije znaÄajna i može biti rezultat sluÄajnosti (odražavajuÄi prirodnu, prostornu i vremensku varijabilnost) nužno je analizirati ulov u 2012. godini radi toÄnijeg odreÄivanja trenda. Ulov po jedinici ribolovnog napora (kg/33m mreže) je 1,6 Ā± 0,1 kg / mreži Å”to spada u dobre lovine. Ipak, bioloÅ”ke karakteristike ciljanih vrsta joÅ” uvijek ne upuÄuju na oporavak. ZakljuÄno, objaÅ”njenje za zateÄeno stanje 18 mjeseci nakon uspostave posebnog režima treba tražiti u Äinjenici da joÅ” nije proÅ”lo dovoljno vremena da bi se vidjele znaÄajne promjene i da se u zaÅ”tiÄenim zonama ipak odvijaju odreÄene ribolovne aktivnosti. Svakako, potrebno je ukljuÄiti dodatni napor, u smislu ljudskog i financijskog potencijala, u narednom razdoblju ukoliko se želi postiÄi vidljiva uÄinkovitost zaÅ”tite unutar ovog zaÅ”tiÄenog podruÄja. Dodatno, potrebno je uspostaviti valoriziranje i brandiranje ribe ulovljene u ovom podruÄju kako bi daljnje akcije zaÅ”tite bile vidljivije i razumljivije Å”iroj zajednici, a isplativije lokalnom stanovniÅ”tvu. Promoviranje zdravog proizvoda iz zaÅ”tiÄenog podruÄja na hrvatskim i evropskim ribarnicama je svakako jedan od naÄina postizanja tog cilja.The Lastovo Archipelago Nature Park (NP) adopted a special fishing protocol in conformity with its Code of Conduct. The present study analyses the littoral fisheries resources of the NP and compares them to baseline data from 2010 to evaluate possible changes produced by the proclaimed fisheries management. Littoral fisheries resources were sampled by experimental trammel net. Analyses were performed on total fish abundance and biomass, diversity indices and multivariate abundance and biomass structure of caught assemblages. Although no significant difference in the catches was found regarding average species richness, total abundance and biomass, there appears to be a weak indication of change. Namely, an inclining trend was observed at protected zones (14% higher species richness, 9% higher total abundance and 19% higher total biomass), while fishing zones showed a declining trend (7% lower species richness, 12% lower total abundance and 24% lower total biomass). Since the variation in average species richness, total abundance and biomass is not significant and could therefore be coincidental (reflecting natural spatial and temporal variability), it is necessary to analyse the 2012 catch data in order to establish whether the observed trends continued and whether they could be attributed to differing levels of protection. Average catch per unit effort - CPUE (unit effort being a 33 m long trammel net) is x Ā± SE = 1,6 Ā± 0,1 kg / net, which is rated as a \u27very good\u27 catch. In this respect the situation is quite favourable in the study area compared to many other sites in the Adriatic. However, biometry characteristics of commercially highly valuable and thus most targeted species show that average landing sizes are more than half the size of those attainable. Overall, plausible explanation for the observed limited effects of protection for the recovery of fisheries resources to date is that not enough time has passed to allow for significant changes. Another contributing factor reducing the recovery potential is that protected zones are not completely closed to all forms of fishing. Certainly, it is necessary to include additional effort, in terms of human and/or financial resources, in the future management actions if we want to achieve visible conservation effectiveness within this protected area. Further, it is necessary to establish the valuation and branding of fish caught in this protected area in order to make further action more visible and comprehensible to the wider community, as well as cost-effective for local inhabitants. Promoting a healthy product from a protected area on the Croatian and European fish markets is certainly one way of achieving this goal
Unusual findings of softmouth trout Salmo obtusirostris (Actinopteri: Salmonidae) in the marine environment along the middle Eastern Adriatic coast as a consequence of extreme weather events
The discovery of individuals of softmouth trout Salmo obtusirostris in the marine environment has been recorded several times in the period from 2015 to the present day in the wider area of the Neretva River delta and southern Adriatic coast. Although this phenomenon appears to be happening more frequently along the Adriatic coast, scientific reports regarding family Salmonidae species found in the marine environment are still very rare in the eastern Adriatic, especially for the softmouth trout. The findings reported here represent the first marine records of this endemic freshwater species. An increasing frequency of these findings may indicate that a higher number of individuals are ending up in the coastal environment during heavy storm events or other unusual hydrologic occurrence. Extreme weather conditions have become more frequent in recent years, mainly as a result of climate change and have led to unexpected phenomena and impacts on nature. The long-term effects on fish and community structure of rivers flowing into the sea require further research, as these weather-induced situations can be expected to become more common. Further investigation into the physiological costs and population consequences of these unusual ecological findings is warranted
LIFE HISTORY TRAITS OF NERETVA ROACH Rutilus basak (Heckel, 1843) (Pisces, Cyprinidae): BIOLOGICAL AND ECOLOGICAL CONTRIBUTION FOR BIODIVERSITY CONSERVATION OF FRESHWATER FISH
U radu je dan pregled relevantne znanstvene literature o trenutnom statusu, distribuciji, staniÅ”tu, ekoloÅ”kim svojstvima, strukturi populacije i prijetnjama neretvanskoj plotici (Basak) Rutilus basak (Heckel, 1843). Navedena vrsta nastanjuje ograniÄeno podruÄje jadranskog rijeÄnog sliva u Republici Hrvatskoj i Bosni i Hercegovini. NajveÄe prijetnje vrsti su gubitci staniÅ”ta uzrokovani znaÄajnim hidroloÅ”kim promjenama vodnog režima na njenom distributivnom podruÄju te introdukcija alohtonih ribljih vrsta. Ipak, R. basak je priliÄno rasprostranjena vrsta koju se Äesto nalazi u izobilju. Informacije objedinjene u radu bi mogle unaprijediti znanja o navedenoj vrsti.This paper is a review of the relevant scientific literature on the present status, distribution, habitat, ecological traits, population structure and threats of Neretva roach Rutilus basak (Heckel, 1843). The species inhabits a restricted area of the Adriatic Sea watershed in Croatia and Bosnia and Herzegovina. The major threats are habitat loss caused by significant hydrological changes in the water regime in the area of distribution and theintroduction of non-indigenous species. Still, R. basak is quite widespread and often abundant. Information brought together in this study will improve our knowledge about this species