Biological and ecological characteristics of stargazer Uranoscopus scaber Linnaeus, 1758 in southern Adriatic Sea

Tijekom ovog istraživanja na području južnog Jadrana prikupljeno je ukupno 1279 jedinki bežmeka Uranoscopus scaber Linnaeus, 1758. Raspon ukupnih duljina tijela jedinki bio je od 8,45 do 36,0 cm (18,12 ± 3,54 cm), a mase od 11,52 do 618,7 g (102,25 ± 59,27 g). Omjer ženki i mužjaka u uzorku iznosio je 1:0,82. Statistički značajne razlike zabilježene su u srednjim vrijednostima jedanaest mofometrijskih odnosa između ženki i mužjaka. Duljinsko-maseni rast bežmeka je izometrijski (b = 3,016), a srednja vrijednost indeksa kondicije iznosila je 1,541. Intenzitet hranjenja najveći je u proljeće, a ribe su neophodna i glavna hrana tijekom godine. Starost bežmeka je određena očitavanjem otolita. Najstarija ženka imala je 8 godina, a najstariji mužjak 6 godina. Rast bežmeka je opisan von Bertalanffyjevim modelom rasta L∞ = 48,93 cm, K = 0,12, t0 = -1,6, R2 = 0,94. Mužjaci bežmeka postaju spolno zreli (Lt = 12,19 cm) pri manjim ukupnim duljinama tijela nego ženke (Lt = 14,12 cm). Fekunditet je bio relativno nizak, a sezona mriještenja bežmeka u južnom Jadranu je od ožujka do listopada. Najveće srednje vrijednosti gonadosomatskog indeksa zabilježene su u svibnju za ženke i u lipnju za mužjake. Vrijednosti ribolovne smrtnosti (F = 0,411) su bile veće od vrijednosti prirodne smrtnosti (M = 0,128).In the present study, a total of 1279 specimens of the stargazer Uranoscopus scaber Linnaeus, 1758. were collected. Total lenght of stargazer ranged from 8.45 to 36.0 cm (18.12 ± 3.54 cm), while total weight ranged from 11.52 to 618.7 g (102.25 ± 59.27 g). Female to male ratio was 1:0.82. The differences between the eleven mean values of the measured morphometric characteristics in females and males were statistically significant. The length-weight relationship showed isometric growth (b = 3.016) and estimated condition factor was 1.541. The highest feeding intensity of the stargazer was recorded during spring and the dominat food component was fish. Age of the stargazer was determined by otolith reading. Maksimum ages for females and males were 8 and 6. The growth of fish was described using the von Bertalanffy growth model: L∞ = 48.93 cm, K = 0.12, t0 = -1.6, R2 = 0.94. Males of the stargazer reached maturity (TL = 12.19 cm) at smaller lengths than females (TL = 14.12 cm). The fecundity of females was relatively low, while spawning of the stargazer in southern Adriatic Sea takes place between March and October. The highest mean values of gonadosomatic index were recorded in May for females and in June for males. Fishing mortality values of the stargazer (F = 0.411) were higer than values of natural mortality (M = 0.128)

"Pod pritiskom" - rock hit kao inspiracija za nesvakidašnji postav

Prilagodbe dubokomorskih organizama niskoj temperaturi, ograničenoj dostupnosti hrane, visokom tlaku, smanjenom udjelu kisika i nedostatku svjetlosti bile su inspiracija za naslov izložbe. Dakle: nelagoda, stres, pritisak – Pod pritiskom! Likovni postav povezan je s velikim hitom Under Pressure grupe Queen, a narator izložbe je riba barjaktarka odjevena u najpoznatija modna izdanja pjevača Freddieja Mercuryja

Biological and ecological characteristics of stargazer Uranoscopus scaber Linnaeus, 1758 in southern Adriatic Sea

Tijekom ovog istraživanja na području južnog Jadrana prikupljeno je ukupno 1279 jedinki bežmeka Uranoscopus scaber Linnaeus, 1758. Raspon ukupnih duljina tijela jedinki bio je od 8,45 do 36,0 cm (18,12 ± 3,54 cm), a mase od 11,52 do 618,7 g (102,25 ± 59,27 g). Omjer ženki i mužjaka u uzorku iznosio je 1:0,82. Statistički značajne razlike zabilježene su u srednjim vrijednostima jedanaest mofometrijskih odnosa između ženki i mužjaka. Duljinsko-maseni rast bežmeka je izometrijski (b = 3,016), a srednja vrijednost indeksa kondicije iznosila je 1,541. Intenzitet hranjenja najveći je u proljeće, a ribe su neophodna i glavna hrana tijekom godine. Starost bežmeka je određena očitavanjem otolita. Najstarija ženka imala je 8 godina, a najstariji mužjak 6 godina. Rast bežmeka je opisan von Bertalanffyjevim modelom rasta L∞ = 48,93 cm, K = 0,12, t0 = -1,6, R2 = 0,94. Mužjaci bežmeka postaju spolno zreli (Lt = 12,19 cm) pri manjim ukupnim duljinama tijela nego ženke (Lt = 14,12 cm). Fekunditet je bio relativno nizak, a sezona mriještenja bežmeka u južnom Jadranu je od ožujka do listopada. Najveće srednje vrijednosti gonadosomatskog indeksa zabilježene su u svibnju za ženke i u lipnju za mužjake. Vrijednosti ribolovne smrtnosti (F = 0,411) su bile veće od vrijednosti prirodne smrtnosti (M = 0,128).In the present study, a total of 1279 specimens of the stargazer Uranoscopus scaber Linnaeus, 1758. were collected. Total lenght of stargazer ranged from 8.45 to 36.0 cm (18.12 ± 3.54 cm), while total weight ranged from 11.52 to 618.7 g (102.25 ± 59.27 g). Female to male ratio was 1:0.82. The differences between the eleven mean values of the measured morphometric characteristics in females and males were statistically significant. The length-weight relationship showed isometric growth (b = 3.016) and estimated condition factor was 1.541. The highest feeding intensity of the stargazer was recorded during spring and the dominat food component was fish. Age of the stargazer was determined by otolith reading. Maksimum ages for females and males were 8 and 6. The growth of fish was described using the von Bertalanffy growth model: L∞ = 48.93 cm, K = 0.12, t0 = -1.6, R2 = 0.94. Males of the stargazer reached maturity (TL = 12.19 cm) at smaller lengths than females (TL = 14.12 cm). The fecundity of females was relatively low, while spawning of the stargazer in southern Adriatic Sea takes place between March and October. The highest mean values of gonadosomatic index were recorded in May for females and in June for males. Fishing mortality values of the stargazer (F = 0.411) were higer than values of natural mortality (M = 0.128)

Feeding habits of stargazer (Uranoscopus scaber Linnaeus, 1758) in the southern Adriatic Sea (Croatia)

The feeding habits of the stargazer Uranoscopus scaber Linnaeus, 1758 were analysed using 360 stomachs of specimens collected in southern Adriatic Sea between October 2011 and September 2012. The total body length of the specimens ranged from 9.7 to 32.1 cm (18.89 ± 3.34 cm) and weight from 11.7 to 618.7 g (112.79 ± 63.17 g). In the sampled population there were 213 females (59.17%) and 147 males (40.83%). Stargazer is carnivorous fish and its diet in Adriatic Sea was composed of teleost fish, cephalopods and crustaceans. According to numerical abundance fish predominated followed by crustaceans, while according to the gravimetric composition fish predominated followed by cephalopods. Teleost fish were dominant prey in all seasons, and the principal prey were hake Merluccius merluccius and argentine Argentina sphyraena. Argentine was primary food in summer (IRI = 61.63), while hake occur in other seasons. In relation to the total body length teleost fish dominated in diet of stargazer whose total body length was < 25 cm. In size group I and II (TL < 20 cm) A. sphyraena was the main food, while M. merluccius was dominant prey in the size group III (TL = 20 – 25 cm). Vacuity index in the sampled population was relatively low (%V = 11.11%). During seasons the percentage of empty stomachs varied significantly with the highest value in winter (%V = 15.55%) and the lowest in spring (%V = 7.78%). In relation to the total body length the highest vacuity index was recorded for size group II (%V = 5.83) and the lowest for group VI (%V = 0)

Reproduktivna strategija kokotića, Lepidotrigla dieuzeidei Blanc and Hureau, 1973 iz jugoistočnog dijela Jadranskog mora

This study provides the first data on the reproductive biology of the spiny gurnard Lepidotrigla dieuzeidei. A total of 1027 individuals were collected monthly from September 2011 to August 2012. The total length of the individuals in the sample ranged from 7.46 cm to 14.62 cm with a female to male ratio of 1 to 0.59. Positive allometric growth was observed for both females (b=3.07) and males (b=3.08). Variations of condition factor were similar in both sexes with mean values of 1.07 for females and 1.01 for males. The fish L. dieuzeidei had a long spawning period extending from November to July based on monthly values of gonadosomatic index. Histological analysis showed that this fish was multiple synchronous developments of ovaries with multiple spawning events. The ovaries were always represented with a group of primary oocytes and a diverse population of vitel-logenic oocytes, each specially recruited during the final stages of maturation in uniform or uneven phases. Batch fecundity was estimated gravimetrically using the hydrated oocyte method and was estimated to be around 558 to 10.230 oocytes per female. L. dieuzeidei is an important by-catch species and data from this study represent a valuable contribution to stock management.Ovo istraživanje donosi prve podatke o reproduktivnoj biologiji kokotića, Lepidotrigla dieuzei-dei. Ukupno je prikupljeno 1027 jedinki, uzorkovano je mjesečno od rujna 2011. do kolovoza 2012. Ukupna duljina jedinki bila je u rasponu od 7,46 cm do 14,62 cm s omjerom spolova ženke:mužjaci 1:0,59. Pozitivan alometrijski rast zabilježen je i kod ženka (b = 3,07) i kod mužjaka (b = 3,08). Promjene indeksa kondicije bile su slične kod oba spola sa srednjim vrijednostima od 1,07 za ženke i 1,01 za mužjake. Temeljem mjesečnih vrijednosti gonadosomatskog indeksa utvrđeno je da kokotić ima dugo razdoblje mriješćenja, od studenog do srpnja. Histološka analiza pokazala je multipli sinkroni razvoj jajnika s više razdoblja mriješćenja. U jajnicima su uvijek bile zastupljene skupine primarnih oocita i raznovrsni stadiji vitelogenih oocita, koji su regrutirani u posljednjim stadijima sazrijevanja u jednoličnim ili neravnomjernim fazama. Fekunditet je procijenjen gravimetrijski primjenom metode hidratiziranih oocita i iznosi oko 558 do 10230 oocita po ženki. Kokotić je važna vrsta u prilovu i podatci iz ovog istraživanja predstavljaju značajan doprinos upravljanja stockom

THE QUANTITATIVE-QUALITATIVE CONTENT OF JUVENILE FISH AT THE MOUTH OF THE RIVERS NERETVA AND MALA NERETVA DURING THE SUMMER-AUTUMN PERIOD

Tijekom kolovoza, listopada i prosinca 2008. na postajama uz ušće Neretve i ušće Male Neretve istraživane su promjene sastava i brojnosti vrsta lokalnih ihtiozajednica. Pridnenom mrežom potegačom prikupljeno je ukupno 690 jedinki od čega 437 na ušću Neretve, a 253 na ušću Male Neretve. Jednike su razvrstane ih u 14 porodica i 19 vrsta. Najzastupljenije vrste u ukupnom ulovu pripadaju porodicama Atherinidae (40 %), Mugilidae (15,79 %), Gobiidae (15,50 %) i Sparidae (13,04 %). Margalefov indeks bogatstva vrsta je veći na područjima u kojima obitava veći broj vrsta, a utvrđen je od 1,66 u kolovozu do 4,13 u listopadu, dok je prema Simpsonovom indeksu najveća raznolikost od 0,393 zabilježena u prosincu i najmanja od 0,923 u listopadu. Najviša vrijednost Shannon Wienerovog indeksa od 1,18 je utvrđena u prosincu, a najniža u listopadu (0,36) jer su gotovo 90 % ulova predstavljale samo dvije vrste. Pielouv indeks, koji brojčano opisuje raznolikost ihtiocenoza, bio je od 0,14 u listopadu do 0,74 u prosincu. Istraživane postaje s obzirom na sastav vrsta pokazuju velike sličnosti, dok su razlike u kvantitativnoj strukturi. Postaja ušće Male Neretve je bogatija vrstama u odnosu na postaju ušća Neretve na kojoj nailazimo na manji broj vrsta, ali veću brojnost jedinki.A study was carried out on the changes in content and abundance of local juvenile fish community species at stations along the mouth of the Rivers Neretva and Mala Neretva during August, October and December 2008. A total of 690 specimens were collected using a small coastal trawl, out of which 437 were collected at the mouth of the River Neretva and 253 at the mouth of the River Mala Neretva. The specimens were categorized into 14 families and 19 species. The most abundant species from the total catch belonged to the families Atherinidae (40%), Mugilidae (15.79%), Gobiidae (15.50%) and Sparidae (13.04%). The Margalef index on specie richness was greater in the regions inhabited by larger numbers of species, ranging between 1.66 in August and 4.13 in October, wheras the highest diversity ranging between 0.393 in December and 0.923 in October was noted using the Simpson index. The highest value using the Shannon Wiener index was 1.18 in December and the lowest at 0.36 was in October, as almost 90% of the catch consisted of only two species. The Pielou index, which describes the variety of ichtiocenoza numerically, ranged between 0.14 in October and 0.74 in December. The stations investigated showed great similarities considering specie content, wheras there were differences in quantitative structure. The station at the mouth of the River Mala Neretva was richer in species as compared to the station at the mouth of the River Neretva, where we came across a smaller number of species, but a greater number of specimens

Biological and ecological characteristics of stargazer Uranoscopus scaber Linnaeus, 1758 in southern Adriatic Sea

Tijekom ovog istraživanja na području južnog Jadrana prikupljeno je ukupno 1279 jedinki bežmeka Uranoscopus scaber Linnaeus, 1758. Raspon ukupnih duljina tijela jedinki bio je od 8,45 do 36,0 cm (18,12 ± 3,54 cm), a mase od 11,52 do 618,7 g (102,25 ± 59,27 g). Omjer ženki i mužjaka u uzorku iznosio je 1:0,82. Statistički značajne razlike zabilježene su u srednjim vrijednostima jedanaest mofometrijskih odnosa između ženki i mužjaka. Duljinsko-maseni rast bežmeka je izometrijski (b = 3,016), a srednja vrijednost indeksa kondicije iznosila je 1,541. Intenzitet hranjenja najveći je u proljeće, a ribe su neophodna i glavna hrana tijekom godine. Starost bežmeka je određena očitavanjem otolita. Najstarija ženka imala je 8 godina, a najstariji mužjak 6 godina. Rast bežmeka je opisan von Bertalanffyjevim modelom rasta L∞ = 48,93 cm, K = 0,12, t0 = -1,6, R2 = 0,94. Mužjaci bežmeka postaju spolno zreli (Lt = 12,19 cm) pri manjim ukupnim duljinama tijela nego ženke (Lt = 14,12 cm). Fekunditet je bio relativno nizak, a sezona mriještenja bežmeka u južnom Jadranu je od ožujka do listopada. Najveće srednje vrijednosti gonadosomatskog indeksa zabilježene su u svibnju za ženke i u lipnju za mužjake. Vrijednosti ribolovne smrtnosti (F = 0,411) su bile veće od vrijednosti prirodne smrtnosti (M = 0,128).In the present study, a total of 1279 specimens of the stargazer Uranoscopus scaber Linnaeus, 1758. were collected. Total lenght of stargazer ranged from 8.45 to 36.0 cm (18.12 ± 3.54 cm), while total weight ranged from 11.52 to 618.7 g (102.25 ± 59.27 g). Female to male ratio was 1:0.82. The differences between the eleven mean values of the measured morphometric characteristics in females and males were statistically significant. The length-weight relationship showed isometric growth (b = 3.016) and estimated condition factor was 1.541. The highest feeding intensity of the stargazer was recorded during spring and the dominat food component was fish. Age of the stargazer was determined by otolith reading. Maksimum ages for females and males were 8 and 6. The growth of fish was described using the von Bertalanffy growth model: L∞ = 48.93 cm, K = 0.12, t0 = -1.6, R2 = 0.94. Males of the stargazer reached maturity (TL = 12.19 cm) at smaller lengths than females (TL = 14.12 cm). The fecundity of females was relatively low, while spawning of the stargazer in southern Adriatic Sea takes place between March and October. The highest mean values of gonadosomatic index were recorded in May for females and in June for males. Fishing mortality values of the stargazer (F = 0.411) were higer than values of natural mortality (M = 0.128)

WHO ARE THE LESSEPSIAN MIGRANTS?

Izložba Tko su lesepsijski migranti? otvorena je 23. prosinca 2013. u Prirodoslovnome muzeju Dubrovnik. Autori izložbe su Jadranka Sulić Šprem, kustosica Prirodoslovnog muzeja Dubrovnik, Frane Čizmić, ravnatelj Državnog arhiva Dubrovnik i Tatjana Dobroslavić, znanstvena novakinja sa Sveučilišta u Dubrovniku.The exhibition Who Are the Lessepsian Migrants? was opened on December 23 2013 in Dubrovnik Natural History Museum. The exhibition was devised by Jadranka Sulić Šprem, curator of the Dubrovnik Natural History Museum, Frane Čizmić, director of the State Archives in Dubrovnik and Tatjana Dobroslavić, research fellow at Dubrovnik University. The original idea for the exhibition came up after the family of Miroslav Palunk had in October 2012 donated to the museum a specimen of the Lessepsian migrant fish the silver cheeked toadfish or Lagocephalus sceleratus (Gmelin, 1789). The theme of the exhibition was the inroads made by Lessepsian migrants into the Adriatic and their biology and ecology. Since the Lessepsian migrants are aquatic organisms of various taxonomic groups, which have made their way from the Red into the Mediterranean Sea, further elaboration of the idea revealed the need to deal with the history of the cutting of the Suez Canal, and to place this grandiose undertaking within the wider geopolitical and economic context of events of the second half of the 19th century. And particular importance was assumed by the felt need to highlight the involvement of Croatian people in its production. Thus by collaboration of authors of different disciplines the first historical and natural historical exhibition in the Natural History Museum was agreed upon. The cutting of the Suez Canal had a great influence on the eastern part of the Mediterranean, where today more than 300 aquatic organisms (Lessepsian migrants) of different taxonomic groups have been recorded. At least 82 species of fish have been recorded; some of them, with their competitiveness and occupation of free ecological niches have changed the qualitative and quantitative composition of the ichthyofauna of the Mediterranean. To date, 14 fish species of Lessepsian migrants have been noted

THE QUANTITATIVE-QUALITATIVE CONTENT OF JUVENILE FISH AT THE MOUTH OF THE RIVERS NERETVA AND MALA NERETVA DURING THE SUMMER-AUTUMN PERIOD

A study was carried out on the changes in content and abundance of local juvenile fish community species at stations along the mouth of the Rivers Neretva and Mala Neretva during August, October and December 2008. A total of 690 specimens were collected using a small coastal trawl, out of which 437 were collected at the mouth of the River Neretva and 253 at the mouth of the River Mala Neretva. The specimens were categorized into 14 families and 19 species. The most abundant species from the total catch belonged to the families Atherinidae (40%), Mugilidae (15.79%), Gobiidae (15.50%) and Sparidae (13.04%). The Margalef index on specie richness was greater in the regions inhabited by larger numbers of species, ranging between 1.66 in August and 4.13 in October, wheras the highest diversity ranging between 0.393 in December and 0.923 in October was noted using the Simpson index. The highest value using the Shannon Wiener index was 1.18 in December and the lowest at 0.36 was in October, as almost 90% of the catch consisted of only two species. The Pielou index, which describes the variety of ichtiocenoza numerically, ranged between 0.14 in October and 0.74 in December. The stations investigated showed great similarities considering specie content, wheras there were differences in quantitative structure. The station at the mouth of the River Mala Neretva was richer in species as compared to the station at the mouth of the River Neretva, where we came across a smaller number of species, but a greater number of specimens