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 (ρav = 0.385, P = 0.007). Stations with similar hydrographic conditions had similar species richness and assemblages. Statistically significant differences were not noted between seasons (ρav = 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 istočnom 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 istočnom dijelu Jadrankog mora. Analiziran je sadržaj želudca 203 jedinke (11.5 – 32.9 cm TL) prikupljenih pridnenom povlačnom mrežom koćom. Opće su prihvaćene metode i ključevi za determinaciju korišteni za određivanje sastava ishrane i determinaciju plijena. Istraživanjem je određeno 39 identificiranih vrsta plijena koji spadaju u 11 glavnih skupina: rakovi, puževi, školjkaši, ribe, žarnjaci, bodljikaši, mnogočetinaši, oblići, mahovnjaci, alge i krednjaci. Dominantna i poželjna kategorija plijena bili su dekapodni rakovi unutar svih veličinskih kategorija, dok je samo kod najvećih jedinki pronađena dominantnost školjkaša, a slijede ih mnogočetinaši i rakovi. Najveće jedinke također su pokazale veću raznolikost u konzumaciji različitih vrsta plijena i prosječno veći broj jedinki plijena u odnosu na manje ribe. Nije pronađena značajna razlika u ishrani između mužjaka i ženki ((p>0.05)) i s obzirom na sezonu Istraživana je ishrana trlje kamenjarke, Mullus surmuletus u istočnom dijelu Jadrankog mora. Analiziran je sadržaj želudca 203 jedinke (11.5 – 32.9 cm TL) prikupljenih pridnenom povlačnom mrežom koćom. Opće su prihvaćene metode i ključevi za determinaciju korišteni za određivanje sastava ishrane i determinaciju plijena. Istraživanjem je određeno 39 identificiranih vrsta plijena koji spadaju u 11 glavnih skupina: rakovi, puževi, školjkaši, ribe, žarnjaci, bodljikaši, mnogočetinaši, oblići, mahovnjaci, alge i krednjaci. Dominantna i poželjna kategorija plijena bili su dekapodni rakovi unutar svih veličinskih kategorija, dok je samo kod najvećih jedinki pronađena dominantnost školjkaša, a slijede ih mnogočetinaši i rakovi. Najveće jedinke također su pokazale veću raznolikost u konzumaciji različitih vrsta plijena i prosječno veći broj jedinki plijena u odnosu na manje ribe. Nije pronađena značajna razlika u ishrani između mužjaka i ženki ((p>0.05)) i s obzirom na sezonu ((p>0.05)). Hranjenje širokim spektrom plijena bez značajnih 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 načinom hranjenja istraživane vrste na muljevitim detritičnim dnima. Hranjenje širokim spektrom plijena bez značajnih 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 načinom hranjenja istraživane vrste na muljevitim detritičnim dnima

Fekunditet traglja, Spicara maena L. (Teleostei: Centracanthidae) u istočnom 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.Proučavan je fekunditet traglja, Spicara maena L. uzorkovanog na istočnoj obali srednjeg Jadrana u vrhuncu mrijesta (od 16. rujna do 10. listopada). Ženke, uslijed protoginije, su utvrđene do ukupne dužine od 20,0 cm. Apsolutni fekunditet je kolebao od 42 140 kod drugog godišta do maksimalnih 80 509 u trećem godištu. Srednji je promjer oocita bio od 1,68 do 1,92 mm. Odnos između apsolutnog fekunditeta i ukupne dužine, odnosno ukupne mase, određen je slijedećim eksponencijalnim jednadžbama: Fl = 33,4 TL2.6 (R2 = 0,933) i Fw = 560.2Wt + 15874 (R2 = 0.693). Nije bilo značajne korelacije između veličine oocita i veličina ženki

Kljunasta končarica 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 končarica Nemichthys scolopaceus, ulovljen 18. rujna 2016. godine u južnom Jadranu pelagičkom kočom na dubini od cca. 120 metara. Nalaz se odnosi na ličinku leptocefala te uključuje detaljan opis jedinke s morfometrijskim i merističkim oso- binama. Svakako su potrebna daljnja istraživanja kako bi se otkrilo više o rasprostranjenosti i poten- cijalnim područjima mrijesta i hranilištima ove vrste, kao i o mehanizmu raspršivanja i zadržavanja njihovih ličinki u Jadranu

El gallano, Labrus mixtus (Pisces: Labridae): índices biológicos para documentar la historia vital de la especie y contribuir a su conservación

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 Océano Atlántico, incluyendo el Mediterráneo y el Mar Negro. En general, los lábridos son especies de pequeño tamaño que habitan en aguas costeras, siendo vulnerables a la degradación antrópica del hábitat y, a pesar de ser comercialmente poco importantes, forman una parte importante de los descartes de la pesca profesional. Estos peces también son intensamente capturados por la pesca recreativa o de subsistencia. Se requiere, pues, una información biológica básica para conocer el estado de los stocks y asegurar su conservación. Los estudios sobre la edad, el crecimiento, la reproducción y la alimentación de L. mixtus no se han realizado hasta ahora en el Adriático. La edad máxima observada en esta especie ha sido de 10 años, si bien la mayoría de los peces capturados se situaba en los 7 años. Los parámetros estimados a partir de la ecuación de crecimiento de Von Bertalanffy sugieren que el crecimiento de L. mixtus es rápido durante los primeros años de vida. L. mixtus es una especie hermafrodita proterogínica y el cambio de sexo se produce a los 26 cm de longitud, mientras que el gran incremento del índice gonadosomático en el mes de abril confirma que el periodo de reproducción se produce durante la primavera. El gallano es un depredador oportunista que se alimenta preferentemente de crustáceos, gasterópodos y peces. La información que se da en este artículo sobre los índices biológicos es necesaria para conocer las características vitales de esta especie y para adoptar futuras medidas de conservación de su población en el Adriático

Škrpun Scorpaena porcus (Pisces, Scorpaenidae), novi domaćin za parazitske jednakonošce 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 jednakonošci Nerocila orbigny i Ceratothoa parallela (Crustacea, Isopoda, Cymothoidae) su po prvi put zabilježeni na škrpunu, Scorpaena porcus, na području istočnog Jadrana. Od ukupnog broja pregledanih škrpuna, ovi rakovi su utvrđeni 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 20–34 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 „Lastovsko otočje“ je 2010. godine shodno Pravilniku o unutarnjem redu usvojio posebni ribolovni režim. U ovom radu bit će prezentirano stanje godinu dana nakon uspostave ovakvog režima u usporedbi s nultim stanjem 2010. godine. Ribolov je obavljan trostrukim mrežama stajačicama, a analizirano je ukupno obilje, biomasa i raznolikost riba te struktura zajednica. Iako još uvijek nisu zamijećena statistički značajna poboljšanja prosječnog bogatstva riba, ukupnog obilja i biomase, ipak se nazire pozitivna promjena. Naime, u dvije trenutno zaštićene zone zamijećeno je za 14% veće bogatstvo vrsta, 9% više obilje i 19% viša ukupna biomasa, dok se u izlovljavanim zonama vidi pad od 7% bogatstva vrsta, 12% niže obilje i za 24% niža biomasa. Kako promjena nije značajna i može biti rezultat slučajnosti (odražavajući prirodnu, prostornu i vremensku varijabilnost) nužno je analizirati ulov u 2012. godini radi točnijeg određivanja trenda. Ulov po jedinici ribolovnog napora (kg/33m mreže) je 1,6 ± 0,1 kg / mreži što spada u dobre lovine. Ipak, biološke karakteristike ciljanih vrsta još uvijek ne upućuju na oporavak. Zaključno, objašnjenje za zatečeno stanje 18 mjeseci nakon uspostave posebnog režima treba tražiti u činjenici da još nije prošlo dovoljno vremena da bi se vidjele značajne promjene i da se u zaštićenim zonama ipak odvijaju određene ribolovne aktivnosti. Svakako, potrebno je uključiti dodatni napor, u smislu ljudskog i financijskog potencijala, u narednom razdoblju ukoliko se želi postići vidljiva učinkovitost zaštite unutar ovog zaštićenog područja. Dodatno, potrebno je uspostaviti valoriziranje i brandiranje ribe ulovljene u ovom području kako bi daljnje akcije zaštite bile vidljivije i razumljivije široj zajednici, a isplativije lokalnom stanovništvu. Promoviranje zdravog proizvoda iz zaštićenog područja na hrvatskim i evropskim ribarnicama je svakako jedan od načina 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 ± SE = 1,6 ± 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, staništu, ekološkim svojstvima, strukturi populacije i prijetnjama neretvanskoj plotici (Basak) Rutilus basak (Heckel, 1843). Navedena vrsta nastanjuje ograničeno područje jadranskog riječnog sliva u Republici Hrvatskoj i Bosni i Hercegovini. Najveće prijetnje vrsti su gubitci staništa uzrokovani značajnim hidrološkim promjenama vodnog režima na njenom distributivnom području te introdukcija alohtonih ribljih vrsta. Ipak, R. basak je prilično rasprostranjena vrsta koju se često 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