Dužinsko – maseni odnosi i kondicijski čimbenici gavuna veleljuskaša Atherina boyeri (Risso, 1810) iz komercijalnih i eksperimentalnih ulova u jezeru Trichonis (zapadna Grčka)

Total length-weight relationships (LWRs) from 3583 individuals of Atherina boyeri (Risso, 1810) caught in Lake Trichonis (Western Greece), using a commercial encircled net and experimental Nordic type benthic and pelagic multi-mesh gillnets, were estimated during 2019-2020. The variation of the parameter b for all seasons combined was significantly allometric, for both encircled towed and gillnets, with a quite robust fit (R2 equals 0.925 and 0.947, respectively) and values equal to 2.254 and 2.089, respectively. The specimens were significantly lighter in summer than in the other seasons. The slopes of the LWRs significantly differ between seasons and exhibited relatively low values when compared to other ecosystems worldwide and in the same ecosystem in previousperiods of time. Τhe estimated values of the Le Cren index were significantly higher than the Allometricand the Fulton ones.Dužinsko-maseni odnosi (LWRs) su izračunati za 3583 jedinke gavuna veleljuskaša Atherina boyeri (Risso, 1810) ulovljenih u jezeru Trichonis (Zapadna Grčka), tijekom razdoblja 2019-2020. Jedinke su ulovljene komercijalnim mrežama i eksperimentalnim mrežama nordijskog tipa bentoskih i pelagičnih mreža različitih oka. Varijacija parametra b za sva godišnja doba bila je značajno alometrijska, i za zaokružne povlačne mreže i za mreže stajačice, s prilično robusnim vrijednostima koeficijenta korelacije (r2 je 0,925 odnosno 0,947) i vrijednostima jednakim 2,254 odnosno 2,089. Primjerci su ljeti bili znatno lakši nego u ostalim godišnjim dobima. Nagibi LWR-a značajno se razlikuju između godišnjih doba i pokazali su relativno niske vrijednosti u usporedbi s drugim ekosustavima diljem svijeta i u istom ekosustavu u prethodnim vremenskim razdobljima. Procijenjene vrijednosti Le Crenovog indeksa bile su znatno veće od alometrijskih i Fultonovih

Notes on the Summer Life History Traits of the Non-Native Pumpkinseed (<i>Lepomis gibbosus</i>) (Linnaeus, 1758) in a High-Altitude Artificial Lake

In the present study, the biology of the pumpkinseed Lepomis gibbosus in the artificial lake of Aoos, located in northwestern Greece, was investigated. The samplings of the pumpkinseed were conducted from the shore using a portable electrofishing device over a 4-month period (July 2021–October 2021). A total of 581 specimens were caught, with an average length of 62 mm. The sex ratio of female to male was estimated to be 1.0:1.7, and the percentage of mature specimens was estimated for all of the months to be above 52%, matching the highest percentage in July (57.4%). The b value of the length–weight relationship ranged from 3.16 in September to 3.31 in July. The value of the L∞ and K was estimated to be equal to 119 mm and 0.36 years−1, respectively, and the value of φ′ was equal to 3.707. The total mortality was estimated to be equal to 1.63 ± 0.48 y−1 (R2 = 0.96), and the natural and fishing mortalities were 0.83 and 0.80, respectively. The maximum age was 6 years, and the theoretical maximum age was 8 years. In the current study, the value of the L∞ was estimated to be near the European average but significantly lower than the North American one, whereas the value of the K was slightly higher than the European average. The small size of the specimens obtained in Aoos Springs was most likely owed to the combined impact of the investigated lake’s high altitude and low food availability, resulting in a limited factor for species expansion

Investigating the Acceptance of a New Bivalve Product in the Greek Shellfish Market: The Non-Indigenous Pearl Oyster Pinctada imbricata radiata

Greece exhibits the lowest seafood per capita consumption amongst European Mediterranean countries, and the investigation of consumer attitudes to new seafood products would bridge the gap among producers and consumers by promoting the vertical integration of the supply chain. However, limited information exists about consumer preferences for bivalves in the Mediterranean and for wild bivalves in particular. The present study aims to investigate, for the first time, consumers&rsquo; attitudes towards the purchase and consumption of bivalves, and more specifically, towards the edible pearl oyster Pinctada imbricata radiata, in the Greek shellfish market. Adult participants from the entire country completed a questionnaire covering the basic marketing aspects of bivalve and pearl oyster consumption, such as choice, purchase, reasons for consuming bivalves, confidence in product&rsquo;s hygiene certification, media influence, etc. Data analysis included uni- and multi-variate statistics to examine the possible relations between the consumers&rsquo; demographics and socio-economic characteristics, and bivalve marketing aspects. Results showed that the majority of Greek consumers chooses traditional shellfish shops for purchasing pearl oysters, prefers a certification of quality, and trusts the confirmation provided by the veterinary authorities. Consumers&rsquo; attitudes vary considerably according to their demographics and socio-economic characteristics. Multivariate models revealed that the married, highly educated consumers that live in urban places were more reluctant to try new shellfish products and to accept an innovative way of market supply. The results reflect the positive attitude of Greek consumers towards the consumption of pearl oyster, a fact that would be helpful for decision makers in the planning of production, which in turn would promote bivalve consumption in the Greek shellfish market

Value Chain for Non-Indigenous Bivalves in Greece: A Preliminary Survey for the Pearl Oyster <i>Pinctada imbricata radiata</i>

The present study investigates through an integrated survey, for the first time in Greek shellfish market, the marketing distribution towards a new edible shellfish product that of the non-indigenous pearl oyster Pinctada imbricata radiata. The survey conducted through personal interviews on sector entrepreneurs/staff of the supply (i.e., shellfish producers, wholesalers, fishmongers, owners of restaurants). Internet-based quantitative research was also conducted to explore the market supply of the pearl oyster covering all nine regional units of Greece. The market for pearl oyster seems to be there as a substitute of the major commercial species in seasons of shortages. There is a specimen mislabeling throughout Greece, thus, extraction of significant information about the market supply of pearl oyster is deficient. Further knowledge on the bivalve shellfish value chain is needed, to define how the wild and the farmed species (mussels) interact in the market and in the distribution channels, toward a product-easy to use in the supply chain and friendly to the consumer. Findings also raises additional concerns as a priority for conservation, and the current practices do not satisfy the Common Fisheries Policy in terms of traceability