Preliminary biological data on the northeast Mediterranean conger eel Conger conger L., 1758

Los ejemplares de congrio Conger conger L., 1758 provenientes de las campañas de primavera Medits (Mediterranean International Trawl Survey, primavera de 2002) y de otoño Grund (National Group for Demersal Resource Evaluation, otoño de 2001 y 2002) en el mar Adriático (Mediterráneo nororiental), entre 0 y 400 m de profundidad, tienen una longitud que oscila entre 21 y 130 cm y, con mayor frecuencia, entre 30 y 50 cm. La edad, determinada mediante la cuenta de los anillos y la medición del eje mayor de los estatolitos, se estima entre 3 y 8 años, con predominio de ejemplares de 4 y 5 años. El análisis histológico de las gónadas ha permitido identificar solo óvulos inmaduros. La dieta, más abundante en otoño, se constituye principalmente a base de Osteichthyes, Crustacea y Mollusca.Specimens of conger eel Conger conger L., 1758 from spring Medits (Mediterranean International Trawl Survey, spring 2002) and autumn Grund (National Group for Demersal Resource Evaluation, autumn 2001 and 2002) trawl surveys in the Adriatic (northeast Mediterranean) at depths of between 0 and 400 m, were found to measure in length from 21 to 130 cm, with greater frequency in the 30 to 50 cm range. Age determined on the basis of ring count and the length of the greater otolith axis was found to be between 3 and 8 years, with the majority of specimens in the 4- to 5-year range. Histological gonad analysis only revealed immature ovaries. The specimens were found to feed chiefly on Osteichthyes, Crustacea and Mollusca, which are most abundant in autumn.Instituto Español de Oceanografí

Histological changes in the ovary of Palaemon serratus (Crustacea, Decapoda) from the North Adriatic Sea.

Despite its considerable commercial importance, the ovarian maturation of the prawn Palaemon serratus (Crustacea, Decapoda) has been scarcely studied, especially in the marine habitats of Italian waters. For the purpose of the present study female samples were collected in the North Adriatic Sea for a one year. Gonadal tissue sections were prepared using current histological techniques. The ovaries feature a \u201cproliferative centre\u201d from which oocytes maturing in a centrifugal direction branch out. Oocyte (n=554) size in μm was determined at various stages of development using a semiautomatic computerized imaging scanner. Five peaks at around 60, 120, 180, 240, 700 μm of diameter were recorded in germinal cells distribution frequency during maturation of ovary (Spring-Summer). Only two Gaussian peaks around 60 and 120 μm were observed in germinal cells distribution frequency in immature ovary (Autumn-Winter). The present study provide information about the reproductive cycles of this resource

Annual gonadal cycle in Engraulis encrasicolus L. (Clupeiformes, Teleostea) in the northern-middle Adriatic Sea.

Histocytologic investigations of the monthly morphological changes in the ovary and testis of 454 specimens of anchovy (Engraulis encrasicolus L.) ranging in size from between 91 and 160 mm were conducted for the purpose of determining the annual gonadal cycle of this fish. The gonado-somatic index and histological results both pointed to a parallel trend in both sexes, with gonadal maturity peaking between May and July

REPRODUCTIVE BIOLOGY OF MERLANGIUS MERLANGUS L. (OSTEICHTHYES, GADIDAE) IN THE NORTHERN ADRIATIC SEA.

The present paper investigates the reproductive biology of Merlangius merlangus. The reproductive period ranged November-May, based on the gonad-somatic index and gonad development in histological and anatomical terms. The length of first maturity was determined when over 50% of the sample was mature and was about 25 cm for females and 24 cm for males. No significant differences were found in sex ratio between specimens in different maturity stages

Ovarian cycle of the shrimp Palaemon serratus (Pennant, 1777) in the Po River Delta.

The ovarian cycle of Palaemon serratus (Crustacea, Decapoda) was studied in a number of specimens caught in brackish waters in the Comacchio wetlands of the Po River delta between March 2000 and March 2001. Qualitative (histological) and quantitative (cytometric) analyses revealed the reproductive period to stretch from March through to June and oviposition to be asynchronous

THE USE OF DIGITAL MICROPHOTOGRAPHY FOR STUDIES ON FEEDING HABITS: PRELIMINARY DATA ON THE ADRIATIC RED MULLET, MULLUS BARBATUS L. DELL'ADRIATICO.

The feeding habits of Mullus barbatus in the North Adriatic Sea was studied using digital micrograph and five quantitative methods (numeric and percentage weight, frequency of occurrence, relative frequeny and relative important index of prey). The diet includes principally Crustacea, Polichaeta, Mollusca. Crustacea constituing the favorite preys. Within Crustacea the favorite preys are Amphipoda and within Amphipoda the favorite prey is Westwodilla rectirostris

Use of citometry for the \u201creproductive model\u201d assessment of the shrimp Palaemon serratus (Pennant, 1777)

The reproductive biology of the shrimp Palaemon serratus (Crustacea, Decapoda), fisheries resources, has been scarcely studied, especially in the marine habitats of Italian waters. For this purpose, in the present study, monthly samples were taken in brackish waters of the Po River Delta in the North Adriatic Sea. The annual maturative cycle of the ovary was assessed both qualitative, on the basis of histological findings, and quantitative terms, by cytometry. The ovaries feature a proliferative centre from which maturing oocytes branch out in a centrifugal direction. The reproductive period falls between March and June. During the non-reproductive period oocyte diameter ranged from 24 to 153 ?m, whilst during the reproductive period ranged from 24 to 733 ?m. The oviposition pattern may be described as \u201cfractioned\u201d, since it is recurrent. In fact, histological and cytometric findings of the Spring catch revealed that the females had both issued eggs that were still attached to the abdomen, as well as oocytes in all stages of vitellogenesis. The size at first maturity was around 51 mm of length. In conclusion, the histo-cytological approach applied throughout the ovary maturation cycle is a good \u201creproductive model\u201d assessment and an environmental test because the gonadal maturation is closely dependent on enviromental conditions

Indagini preliminari sulla distribuzione e biologia del grongo, Conger conger (Linneo, 1758) in Adriatico.

Sono stati analizzati alcuni aspetti circa la distribuzione, l'accrescimento, la riproduzione e la dieta del grongo in Adriatico

Use of cytometry for the "reproductive model" assessment of the shrimp Palaemon serratus (Pennant, 1777).

The reproductive biology of the shrimp Palaemon serratus (Crustacea, Decapoda), fisheries resources, has been scarcely studied, especially in the marine habitats of Italian waters. For this purpose, in the present study, monthly samples were taken in brackish waters of the Po River Delta in the North Adriatic Sea. The annual maturative cycle of the ovary was assessed both qualitative, on the basis of histological findings, and quantitative terms, by cytometry. The ovaries feature a proliferative centre from which maturing oocytes branch out in a centrifugal direction. The reproductive period falls between March and June. During the non-reproductive period oocyte diameter ranged from 24 to 153 \uf06dm, whilst during the reproductive period ranged from 24 to 733 \uf06dm. The oviposition pattern may be described as \u201cfractioned\u201d, since it is recurrent. In fact, histological and cytometric findings of the Spring catch revealed that the females had both issued eggs that were still attached to the abdomen, as well as oocytes in all stages of vitellogenesis. The size at first maturity was around 51 mm of length.In conclusion, the histo-cytological approach applied throughout the ovary maturation cycle is a good \u201creproductive model\u201d assessment and an environmental test because the gonadal maturation is closely dependent on enviromental conditions