Showing papers by "Branko Glamuzina published in 2007"

Age and growth of sharpsnout seabream Diplodus puntazzo (Cetti, 1777) in the Eastern Adriatic Sea

Abstract: The age and growth parameters of Diplodus puntazzo from the eastern middle Adriatic Sea were studied. Total lengths (TL) of 630 specimens ranging from 13.3 to 46.7 cm were obtained from commercial fishery catches by "tramata" fishing (2004-2005). All specimens sampled were fully mature above 22 cm TL. The male-female ratio for all fish combined was 0.75:1.00, but the ratio changed according to length classes. The mean lengths, as well as the age frequency distributions of males and females were not significantly different. Scales showed clearly the ring pattern common to teleost fishes. The opaque ring was deposited during the summer months. The length-weight relationship showed an isometric growth (b = 3.001; R 2 = 0.988). The parameters of the von Bertalanffy growth equation were: L° = 45.28 cm; K = 0.191 per year; t0 = -0.306 year; R 2 = 0.953. This study revealed that D. puntazzo is a relatively slow growing and long-lived species with a life span in excess of 18 years.

Some biological parameters of the thin-lipped mullet liza ramada (pisces, mugilidae) in the neretva river delta (eastern adriatic, croatian coast)

Abstract: -Aspects concerning age, growth, reproduction and recruitment were analysed in the thin-lipped mullet, Liza ramada, collected in Neretva River delta estuary (East Adriatic, Croatian coastline). The study was based on the collection of a total of 362 individuals on a monthly basis. The von Bertalanffy growth curve parameters were estimated: TL∞ = 59.96 cm, K = 0.269 year-', to = -0.455. Natural mortality was estimated at 0.32 year -1 . Total mortality (Z) was estimated at 0.70 year -1 (range 0.55-0.85 year -1 ). Fishing mortality was estimated at 0.38 year -1 and the exploitation ratio at E = 0.54. The gonado-somatic index profile shows a single peak during the year in October. The sex ratio profile shows skewed sex ratios throughout the year except the period prior to reproduction peak. This L. ramada population is suggested to be in good status.

Recruitment and food composition of juvenile thin-lipped grey mullet, Liza ramada (Risso, 1826), in the Neretva River estuary (Eastern Adriatic, Croatia)

Abstract: The present paper describes the recruitment and food composition of thin-lipped grey mullet, Liza ramada (Risso, 1826) juveniles in the estuary of the Neretva River in the southeastern Adriatic. Thin-lipped mullet appeared in the Port of PlaCe in February. The relationships between total length, standard length, and weight showed a remarkably good fit to the expected allometric model, with b=3 for total length. Twelve different animal food categories were identified. The greatest diversity was recorded in April at the Port of PloCe when 10 categories were present. In addition, six diatom taxa were noted. Harpacticoid copepods were the most common prey (39%) in these samples, followed by insects (32%) and cladocerans (12%). All other prey accounted for less than 4%. Insects represented 99% of prey in the stomachs of specimens sampled from the freshwater Crna Rijeka River. Thin-lipped mullet juveniles were not found on sandy beaches or natural bays around the port. It thus appears that juveniles find the port area to be a habitat with the favorable characteristics of a brackish water nursery: of predators, lower salinity, and high food availability. These all promote better survival and recruitment in this area of the Croatian Adriatic.

A list of Y-O-Y fish species found in the littoral shallows of the Neretva and Mala Neretva estuaries (Eastern Adriatic, Croatian coast)

Abstract: Young-of-the-Year (Y-O-Y) fish in the littoral shallows of the Neretva and Mala Neretva estuaries comprises a highly diverse fish community composed of 68 species representing 28 families. Gobiidae represent the most diverse family followed by Sparidae, Mugilidae and Soleidae. Moreover, more than 64.7% (44 species) of the Y-O-Y species caught are among the species that form the main targets for commercial fisheries in the southern Adriatic.

Growth of juvenile sharpsnout seabream, Diplodus puntazzo (Teleostei: Sparidae) in the Kornati Archipelago, eastern Adriatic Sea

Abstract: Growth of juvenile Diplodus puntazzo from the Kornati Archipelago, eastern middle Adriatic Sea was analysed. A total of 663 juveniles, ranging in length from 1.6 to 9.3 cm, were caught. Most individuals (98.80%) belonged to the 0 cohort. The first settlers, aged 2.0-2.5 months, were recorded at the end of November. Relationship between total length and weight indicates positive allometric growth (b = 3.181). The condition factor, as a consequence of length-weight relationship, was CF = 1.55. The Gompertz equation (c = 0.038 mm days-1 ; R2 = 0.832) seems to be the most appropriate for the description of young D. puntazzo growth.

Some biological characteristics of the endemic Neretvan nase, Chondrostoma knerii Heckel, 1843, in the Hutovo Blato wetlands (Bosnia and Herzegovina)

Abstract: The paper presents for the first time important information regarding population structure, growth rate, length-weight relationships and reproductive aspects of the Neretvan nase, Chondrostoma knerii, a fish species endemic to the Neretva River. Chondrostoma knerii is mainly distributed in the lower parts and delta of the Neretva River wetlands and its tributaries (Krupa River, Hutovo Blato wetlands) shared between Croatia and Bosnia Herzegovina. Samples were collected between 2000 and 2001 during the reproduction period of the species in the Hutovo Blato wetlands area. Population structure analysis indicates that all ages appear, from 0 to 7+. Longevity was estimated at 7.5 years. Main age classes were 3, 4 and 5 years, totalling 91.00% of all individuals. Males ranged between 2 and 5+ years of age, and females between 1 and 7+ years of age. Maximum length was 28.04 cm and maximum weight, estimated from the length-weight relationship, as 206.8 g. Found scattered in streams of high water velocity, eggs were attached to the substrate (aquatic plants or solid objects). Correlation between egg number and length and weight was extremely low. The gonad-somatic index distribution showed an inverse proportionality with total length. Main length classes for reproduction ranged from 20 to 24 cm, while fecundity ranged between 2000 and 16 000 eggs per female.

A new maximum length for Anguilla anguilla (Anguillidae)

Abstract: One specimen of the eel Anguilla anguilla (Linnaeus, 1758), was caught in the vicinity of the town of Ploce (eastern Adriatic, Croatian coast). Its total length TL=1487 mm represents maximum reported length for this species.

Some Biological Parameters of the Thin-Lippes Mullet Liza Ramada (Pisces, Mugilidae) in the Neretva River Delta (Eastern Adriatic, Croatian Coast)

Abstract: Aspects concerning age, growth, reproduction and recruitment were analysed in the thin-lipped mullet, Liza ramada collected in Neretva river delta estuary (East Adriatic, Croatian coastline). The study was based on the collection of a total of 362 individuals on a monthly basis. The Bertalanffy growth curve parameters were estimated: TL∞ =59.96 cm, K=0.269 year-1, to=-0.455. Natural mortality was estimated at 0.32 year-1. Total mortality (Z) was estimated at 0.70 year-1 (range 0.55-0.85 year-1). Fishing mortality was estimated at 0.38 year-1 and the exploitation ratio at E=0.54. The gonad-somatic index profile shows a single peak during the year in October. The sex ratio profile shows skewed sex ratios throughout the year except the period prior to reproduction peak.

Endemic gobies (G0obiidae) of the Hutovo blato wetland (Neretva river basin, Bosnia and Herzegovina), threats and their conservation status

Abstract: Na podrucju u mocvare Hutovo Blato (sliv rijeke Neretve, Bosna i Hercegovina) zabilježene su dvije razlicite vrste slatkovodnih endemicnih glavoca. Na temelju dijagnostickih znacajki, prva vrsta je vrlo slicna vrgorackoj gobici Knipowitschia croatica, dok je druga nova vrsta, također iz roda Knipowitschia. Nova se vrsta od ostalih pripadnika roda razlikuje vecom udaljenoscu između leđnih peraja, te prisustvom, položajem, rasporedom i brojem ljuski na tijelu. U cilju daljneg utvrđivanja taksonomskog položaja i zastite neophodna su daljnja detaljna istraživanja kako morfoloskih i molekularnih znacajki, tako i istraživanja ekologije i nacina ponasanja ovih vrsta. Zoogeografska i taksonomska važnost pronalaska ovih vrsta raspravljana je u odnosu na lokalne ekolosko-hidroloske uvjete, vrlo ogranicenu podrucje rasprostranjenosti i moguci kriticno ugroženi status.

Effects of the recent hydrological changes on abundance and spawning of commercially interesting fish species in Hutovo blato wetlands

Abstract: Ribarstvo je oduvijek predstavljalo znacajnu gospodarsku aktivnost u mocvari Hutovo blato, povijesno kao dodatni izvor prihoda za lokalno stanovnistvo, te kasnije komercijalizirano 1970-1990-ih kroz rad drustvenog poduzeca. Sredinom dvadesetog stoljeca zabilježeni su godisnji ulovi sarana od 150-200 tona, 50 tona jegulje, 80 tona plotice, 30 tona cipola i 10 tona iverka (Aganovic, 1952). U usporedbi sa sadasnjim ulovom, ovi podaci djeluju kao znanstvena fantastika. Međutim ovi se podaci odnose na vrijeme prije velikih isusivanja mocvara Hutova blata. Melioracije su prepolovile mocvarna podrucja i s prethodnih 6000 hektara dospjele su na svega 600 hektara koliko iznosi trenutacna povrsina. U uvjetima kada su sve vodene povrsine i mocvare proglasene Parkom prirode uz stalan ucinkovit nadzor, postavlja se pitanje regulacije ribolova u komercijalne svrhe kroz kontrolirani izlov i sportsko-rekreacijski ribolov, kako bi se dodatno osnažile temeljne funkcije zastite i ocuvanja biraznolikosti mocvare Hutovo blato. Međutim, uslijed niza zahvata u okolnom prostoru, posebice rad i izgradnja hidroenergetskih postrojenja, hidroloski režim jezera i mocvara je znacajno izmjenjen, sto utjece na životne i reprodukcijske cikluse važnih vrsta riba. Gospodarski su najzanimljivije vrste riba u mocvarama Hutovo blato: jegulja, Anguilla anguilla, saran, Cyprinus carpio, linjak-cinkva, Tinca tinca, cipol batas, Mugil cephalus, cipol balavac, Liza ramada, iverak, Platichthys flesus, plotica, Rutilus rubilio i podustva, Chondrostoma knerii. Neke vrste stalno žive u Hutovu blatu, kao saran i plotica. Dok ostale tu provode samo dio životnog ciklusa, bilo da hladne potoke i jezera koriste kao mrjestilista (podustva), ili kao rastilista (jegulja, cipoli, iverak). Hidroloske promjene mogu znacajno utjecati, bilo na mrijestenje pojedinih vrsta ili na migracije tijekom dolaska ili odlaska iz Hutova blata. Tako je kod sarana u pojedinim godinama zabilježen potpun izostanak mrijescenja uslijed prodora hladne vode iz Neretve nastale naglim ispustanjem velikih kolicina vode iz akumulacija. Kada se i izmrijesti onda se uslijed vecih kolebanja razine vode u jezerima uslijed istog razloga, veca kolicina ikre nađe na suhom te ugiba. Sve ovo zadnjih desetak godina rezultira slabim prirodnim mrijestom i novacenjem mlađi, te vodi stalnoj potrebi za poribljavanjem iz drugih ribnjaka. Ovakvi nagli prodori vode u Gornje blato tijekom jeseni, znacajno mijenjaju i migracijske navike jegulje, sto se ocituje u smanjenim ulovima. Mrijescenje i ostalih vrsta je uslijed hidroloskih promjena znacajno naruseno. Tako je 2000. godine zbog slabih dotoka izvora oko Londže, zabilježeno veliko ugibanje odložene ikre podustve uslijed gljivicnih infekcija, koje su karakteristicne za spore vode. Posebnu opasnost za sve ribe predstavlja stalno oplicavanje i okopnjivanje vodenih povrsina, cime se stalno smanjuje životni prostor. Ekstremna situacija je zabilježena u ljeto, 2007. kada je pola Deranskog jezera, kao najznacajnijeg ribolovnog podrucja ostalo suho. Sve ovo ima za posljedicu otežano gospodarenje pojedinim vrstama ribe koje predstavljaju znacajan resurs, te je tesko predvidjeti kakve ce biti dugorocnije posljedice recentnih hidroloskih promjena.

The present status, endangerment and conservation of endemic Neretvan roach, Rutilus basak (Heckel, 1843)(Cyprinidae) from the Hutovo Blato wetland (Neretva River basin, Bosnia and Herzegovina)

Abstract: U ovom su radu opisani trenutacni položaj, rasprostranjenost i stanista, populacijska struktura, uzroci ugroženosti i potrebe za zastitom endemicne plotice Rutilus basak u mocvari Hutovo Blato (sliv rijeke Neretve, Bosna i Hercegovina). Plotica je najbrojnije zastupljena endemicna vrsta mocvare Hutovo Blato. Ova je rezidentna vrsta uglavnom rasprostranjena u hladnijim vodenim povrsinama Gornjeg Blata, poput jezera Orah i Drijen i pripadajucih jaruga, naseljavajuci rubna plica podrucja obrasla uronjenom vegetacijom. U izboru stanista manje su razlike također zabilježene između nedoraslih i odraslih populacija. Iako se trenutacni populacijski položaj ove vrste u Hutovom Blatu može ocijeniti stabilnim, njena se buducnost može smatrati ugroženom ukoliko se nastavi trend raznih negativnih utjecaja koji ugrožavaju njenu opstojnost. Mocvarno podrucje Hutovog Blata, koje se odlikuje znacajnim brojem endemicnih vrsta uskog areala rasprostranjenosti, ugroženo je znacajnim negativnim promjenama stanista i nužne su hitne mjere ocjene i provedbe zastite. U cilju zastite statusa ove vrste kao i visoko znacajne ihtioloske raznolikosti ovog podrucja, od posebnog su znacenja djelotvorna zastita stanista, zajedno s poboljsanim mjerama vodnog gospodarenja i sprjecavanjem daljnjeg unosenja i sirenja alohtonih vrsta. Na osnovi trenutacnog položaja ove vrste, kao i njenog buduceg razvoja i IUCN kriterija, predlaže se donosenje IUCN statusa gotovo ugrožen (NT) u Bosni i Hercegovini.

Reproductive characteristics of baby clam Chamelea gallina Linnaeus, 1758 (Bivalvia, Mollusca) from the river Neretva estuary

Abstract: Kuae ; ; ica Chamelea gallina je skoljkas razdvojenog spola koji naseljava obalna podrue ; ; ja pjeskovite ili pjeskovitomuljevite podloge na dubinama do 20 m. Dostie spolnu zrelost u prvoj godini ivota, kad dostigne duljinu od 12 mm, ali se fekunditet poveae ; ; ava tek nakon sto preraste 20 mm duljine. Bioloski ciklus je pod znae ; ; ajnim utjecajem ekoloskih parametara, osobito temperature. Kako bi se pridonijelo poznavanju populacije radi odrivog prikupljanja ovog komercijalno znae ; ; ajnog skoljkasa, praae ; ; en je spolni ciklus od sijee ; ; nja 2003. do sijee ; ; nja 2004. godine na podrue ; ; ju usae ; ; a rijeke Neretve. Uzorci spolno zrelih jedinki su uzimani jedanput mjesee ; ; no, konzervirani u 6%-tnom formaldehidu radi izrade histoloskih preparata bojanih hematoksilinom i eozinom radi utvrð ; ; ivanja spolnog sastava, ciklusa sazrijevanja gonada i vremena razmnoavanja. Od ukupno 232 jedinke, utvrð ; ; eno je 97 enki i 130 mujaka, a za pet jedinki nije bilo moguae ; ; e. Postojanje hermafrodita nije utvrð ; ; eno. Preliminarnim istraivanjima je utvrð ; ; eno da su gonade mujaka i enki sinkronizirano sazrijevale. Mrijestenje je zabiljeeno od sijee ; ; nja do kraja kolovoza, a najizraenije je od travnja do srpnja. Od rujna slijedi razdoblje regresije. Poe ; ; etak gametogeneze zabiljeen je u listopadu i studenom, nakon e ; ; ega slijedi sazrijevanje spolnih produkata, a prvo mrijestenje je zabiljeeno u sijee ; ; nju.