6 research outputs found
I CROSTACEI DECAPODI DEL LAGO DI ACQUATINA: STRUTTURA DELLE POPOLAZIONI E CICLO RIPRODUTTIVO
The study analyses the structure of the Stagno di Acquatina Crustacean Decapods population and the reproductive biology, in the period from April 2006 to September 2007. The main species considered are: Carcinus aestuarii, Palaemon serratus, Palemon adspersus, Palaemon elegans and Palaemonetes antennarius; of them C. aestuarii resulted the more common species and P. elegans the less frequent one. Almost all the species presented a reduction in the capture in 2007, compared to 2006. The data on the biological composition and reproduction of the Crustacean Decapods represent an important instrument of a responsible management of the Stagno di Acquatina ecosystem
Composizione Strutturale e Dinamica del Pescato nel Lago di Acquatina
EnThe fish assemblages of the Stagno di Acquatina were studied from April 2006 to September 2007 and 65 species, 32 families, and 52 genera were determined. The more frequent species are: Atherina boyeri (32,9 %), Anguilla anguilla (15,5 %), Carcinus aestuarii (13,0 %), sparidae (6,1 %), mugilidae (6,0 %), the penaeid shrimp Melicertus kerathurus (5,4 %) and than Sciaena umbra (2,5 %), Palaemon serratus (2,5 %) and the family gobidae (2,3 %). The remaining 13,7 % is represented by fishes, crustaceans and molluscs; crustaceans are 22 % of the production. The fishery by fike-nets (production per hour) varied from a minimum of 3,4 g in winter to a maximum of 49,3 g in spring, with an average of 18,7 g. The study proved some populations are distributed according to an ecological gradient: C. aestuarii was significantly caught close to the connection with the sea; population of grey mullet, mainly Liza aurata, Liza saliens and Chelon labrosus, on the opposite, were catched far from the sea connection. In the fishery assemblage the marine species are represented almost exclusively by fry, that emphasizes the role of the Stagno di Acquatina as a natural nursery
Rast, smrtnost i prinos olige (Atherina boyeri Risso, 1810) iz lagune Lesina (Jadransko more, Italija)
Population structure, growth, age, mortality and exploitation status of Atherina boyeri, caught in the period from June 2013 to May 2014 in the Lesina lagoon (Apulia region, southern Adriatic) was studied. Samples were taken each month by using beach seines . The lengthâweight relationship of all sand smell specimens was described by the equation W=0.012*TL 3.10; (R2= 0.84). Population parameters including the asymptotic length (Lâ) and growth coefficient (K) were assessed to evaluate the stock status. The recruitment pattern was modeled with a FiSAT routine. The asymptotic length (Lâ) was 111.0 mm, while the growth coefficient (K) was 0.68 yearâ1. The growth performance index ((Ïâ) reached 3.92. The total mortality coefficient âZâ, the natural mortality coefficient âMâ and the fishing mortality coefficient âFâ were estimated as 2.24, 1.48 and 0.76 year-1, respectively. Exploitation rate for the population of A. boyeri in the Lesina lagoon estimated as 0.34 was resulted still lower than the predicted maximum value of Emax 0.59. The probability of capture indicated that L50 was of 55.57 mm, indicating that the stock of sand smelt in Lesina lagoon is not being over-fished.IstraĆŸivana je struktura populacije, rast, starost, smrtnost i status eksploatacije olige Atherinaboyeri, ulovljene u razdoblju od lipnja 2013. do svibnja 2014. u laguni Lesina (regija Apulija, juĆŸni Jadran). Uzorci su uzimani svaki mjesec pomoÄu mreĆŸe potegaÄe.DuĆŸinsko-maseni odnos opisan je jednadĆŸbom W = 0,012 * TL 3,10; (R2 = 0,84). UtvrÄeni su parametri populacije, ukljuÄujuÄi asimptotsku duljinu (Lâ) i koeficijent rasta (K), kako bi se procijenilo stanje zaliha. Obrazac novaÄenja modeliran je FiSAT rutinom. Asimptotska duljina (Lâ) iznosila je 111,0 mm, dok je koeficijent rasta (K) iznosio 0,68 godina â 1. Indeks uÄinka rasta (Ïâ) dosegnuo je 3,92. Ukupni koeficijent smrtnosti âZâ, koeficijent prirodne smrtnosti âMâ i koeficijent mortaliteta ribolova âFâ procijenjeni su na 2,24, 1,48 i 0,76 godina-1.Stopa eksploatacije populacije olige u Lesinskoj laguni procijenjena na 0,34 rezultirala je i dalje niĆŸom od predviÄene maksimalne vrijednosti Emax 0,59
Migrazione ed Accrescimento degli Stadi Giovanili di Melicertus Kerathurus ForskÀl 1775 (Crustacea,Decapoda,Penaeidae) nel Lago di Acquatina
EnThe penaeid shrimp Melicertus kerathurus is an important component of the aquatic migratory species entering into the Stagno of Acquatina. The adult specimens spawn in the sea from the end of May to the end of August and the juveniles enters the brackish lagoon in July-August and there they remain as long as the trophic and environmental conditions are favourable. In this study different migratory flows of ascent and descent fry were identified and the age-size classes that compose the cohorts were determined. In relation to the migratory flows and the age-size classes of fry, two separate reproductive cycles in the sea were assumed