Boško Skaramuca

Incidence of spinal deformities in natural populations of sandsmelt, Atherina boyeri (Risso, 1810) in the Neretva river estuary, middle Adriatic

Information is presented on the occurrence of spinal deformities in natural populations of sandsmelt, Atherina boyeri in the Neretva River estuary, middle eastern Adriatic. During 1998 and 1999, the spinal deformity levels varied between 2.02% and 10.30% in four samplings, and 3.58% in total catch. The spine is deformed in one to a few places from vertical to horizontal angles, and the deformities are visible on the fish body immediately after catching. The possible reasons for such deformities are discussed.

Preliminary information on feeding and growth of pompano, Trachinotus ovatus (Linnaeus, 1758) (Pisces ; Carangidae) in captivity

Although the chances of successfully farming Trachinotus ovatus on a commercial scale are limited by the low food conversion rates, this species deserves further applied studies on the basis of their quick adaptation to confinement and their tolerance of captivity conditions.

First record of Idas simpsoni (Mollusca: Bivalvia: Mytilidae) in the Adriatic Sea

More then 127 specimens of the bivalve mollusc Idas simpsoni were collected from the skull of a fin whale Balaenoptera physalus. The skull was trawled up from a depth of 430 m near Mljet Island in the soiuth Adriatic Sea. This is first finding of I. simpsoni in the Adriatic Sea.

Embryonic and larval development of the brown wrasse Labrus merula (Pisces: Labridae)

In March 1997 one male and one female brown wrasse Labrus merula spawned spontaneously in aquaria conditions. Eggs were incubated at ambient temperature, salinity, oxygen and pH. The development of the eggs, yolk-sac larvae and larvae is described and illustrated with particular emphasis on features of practical value for identification of specimens from plankton. The ripe egg of brown wrasse is a typical labrid egg with a mean diameter of 0.93±0.05 mm. The incubation period was 106 h 45 min at a mean temperature of 14.3°C. Newly hatched yolk-sac larvae were 3.8±0.02 mm, while the yolk-sac was resorbed when larvae reached 4.68±0.15 mm in total length. Some characteristics which may be useful for identification are described and compared with some other labrid yolk-sac larvae and larvae. The length of newly hatched yolk-sac larvae of brown wrasse was significantly larger ( t -test, P Labrus bergylta . During the first 16 d (after resorption of yolk-sac) brown wrasse larvae does not possess a double crescent of melanophores on top of the head, but has a few melanophores on the anal fin which is very similar to the pigmentation of Symphodus ( Crenilabrus ) melops larvae, although there is a difference in length between them. Larvae older than 16 d have a double crescent of melanophores on the top of the head with melanophores on the anal fin-fold identical to L. bergylta larvae, but the difference in larvae length also exists.

Diet and diel feeding activity of juvenile pompano ( Trachinotus ovatus ) (Teleostei: Carangidae) from the southern Adriatic, Croatia

Food and feeding activity of juvenile pompano Trachinotus ovatus collected in the summer-autumn in 2003 in coastal shallow water bays in the southeastern Adriatic were examined. Juvenile pompano were exclusively daytime feeders and feeds in whole water column, from surface to bottom taking not only plankton, but benthic and terrestrial species as well. Of eighteen prey taxa identified, crustaceans, particularly copepods, were the major group, followed by benthic foraminiferans and insects. Feeding on benthic species is reported for the first time in this study.

The age, growth and feeding habits of the European conger eel, Conger conger (L.) in the Adriatic Sea

Abstract This study determined basic biological data for the European conger eel Conger conger (L.) population in the coastal waters of the eastern Adriatic Sea. Juveniles and immature females dominated the coastal population, whereas males were relatively uncommon. The population structure determined by the study suggested spatial separation of sexes and spawning grounds in deeper waters. Both edge-type and marginal increment analyses confirmed the formation of a single growth annulus per year on the ground otoliths. The observed maximum age of the coastal conger eels was 8 years, although most of the sampled fish were 5 years old. The estimated parameters of the von Bertalanffy growth model suggested that the growth of the conger eels was relatively slow. C. conger is an opportunistic predator. Its diet was composed primarily of fishes, followed by crustaceans and cephalopods. Due to the evident site fidelity of the species, the wide prey spectrum of the conger eels (33 taxa) reflected the local benthic community structure.

Food preferences of the Mediterranean moray eel, Muraena helena (Pisces: Muraenidae), in the southern Adriatic Sea

Abstract The food and feeding habits of the Mediterranean moray eel, Muraena helena, collected in the southern Adriatic Sea by bottom longline fishing, were examined. Of the total 146 specimens, 37 had almost or totally empty stomachs. Muraena helena is a carnivorous species whose diet primarily includes benthic fishes and crustaceans. The diet consisted of at least 27 different prey taxa belonging to 8 major groups. The dietary preferences among the sexes and seasons did not differ statistically, but diet depended on age and reflected differences in prey availability. Also, diet composition significantly differed according to depth, with the cephalopod Octopus vulgaris occurring in the diet of morays caught just below 30 m, while crustaceans were more common in the diet of specimens sampled in shallower waters. Results indicated that M. helena is an opportunistic species that feeds on motile prey. Furthermore, a continuing study with a well-designed sample collection is needed to accurately assess the trophic status and the predatory impact of M. helena within the Mediterranean coastal communities.

Comparative hematology of wild Anguilliformes (Muraena helena, L. 1758, Conger conger, L. 1758 and Anguilla anguilla L. 1758)

The objective of this study was to compare circulating blood cell counts and morphology of three eel species: Muraena helena (moray), Conger conger (European conger) and Anguilla anguilla (European common eel). Moray and conger were collected from the Adriatic Sea at the Elaphite Islands near Dubrovnik, Croatia; common eels were collected in the Neretva River, Croatia. Hematological comparison was conducted using Natt-Harrick’s and May-Grunwald Giemsa staining methods. The hematocrit of moray and conger were similar, while common eel had higher values by 60%. Manual cell count showed that common eel had the highest erythrocyte count. Conger had a higher erythrocyte count than moray, with a higher percentage of proerythrocytes and senescent erythrocytes compared to moray and common eel. The leukocyte count was similar in common eel and moray and slightly lower in conger. The thrombocyte count was highest in conger and lowest in moray. In all three species, the neutrophil (heterophil) nuclei appeared as either circular or bi-lobed. Moray had the highest neutrophil (heterophil) percentage and a subtype with intensively basophilic cytoplasm appearing in a similar percentage as the normal type. In common eel, neutrophils (heterophils) were the only detected granulocytes. Basophils were detected in conger eels. Eosinophils were not detected in any of the sampled fish. The size of all cell types in moray was slightly larger than in other two species. In conclusion, our findings reveal major differences in the cell count and diversity in cell subtypes between three kin species of eels.

FIRST SUBSTANTIATED RECORD OF THE BLACK-STRIPED PIPEFISH, SYNGNATHUS ABASTER (ACTINOPTERYGII: SYNGNATHIFORMES: SYNGNATHIDAE), IN THE FRESHWATERS OF BOSNIA AND HERZEGOVINA

Although the ichthyofauna of Bosnia and Herzegovina has been relatively well studied, the knowledge remains incomplete. This report confirms the occurrence of the black-striped pipefish Syngnathus abaster Risso, 1827 in the freshwaters o f Bosnia and Herzegovina. A sample specimen of the black-striped pipefish was obtained from the Neretva River in Bosnia and Herzegovina in July 2011. The morphometric measurements and meristic counts were taken. Although the black-striped pipefish has previously been reported to exist in this region, the data were not reliable or conclusive. Therefore the finding reported herewith can be considered the first substantiated record from Bosnia and Herzegovina and extends t he previously known distribution range for this species into freshwaters.

Record of a live sharksucker, Echeneis naucrates (Osteichthyes: Echeneidae) from the south-eastern Adriatic (Croatian coast)

On 23 July 2007 a specimen of very rare live sharksucker Echeneis naucrates was caught in Ombla River near Dubrovnik, south-eastern Adriatic. First data on biometric lengths and morphology of this species are presented for the eastern Adriatic.