Age determination and growth of leaping mullet, (Liza saliens R.1810) from the Messolonghi Etoliko lagoon (western Greece)

This study is the first detailed work on the age and growth of the leaping mullet (Liza saliens, Risso 1810) in the central Mediterranean. During the period 1991-1995 the age and growth of leaping mullet from the Messolonghi -Etoliko lagoon system (western Greek coast) were studied. Age and growth determinations were based upon otolith samples taken from 537 fish. Marginal increment analysis was used to validate age determination. Annulus formation took place around November each year. The back-calculated lengths at age estimated from the otoliths showed no differences between sub-areas of the lagoon system and the recorded limited between-years variability showed no persistent temporal pattern. The maximum age of leaping mullet in the Messolonghi - Etoliko lagoon was 5 years for males and 6 years for females. The von Bertalanffy equation (L‡=32.99±1.25 cm, k=0.258 ±0.017 year-1, t0=-0.47±0.04 year) accurately describes the growth of the total length of leaping grey mullet for all life stages (fry, juveniles and adults). A large spread and length overlap characterized the age groups. The estimated Length-Weight relationships were common for the two sexes (W=0.0079L3.01)

The Atlantic blue crab Callinectes sapidus in southern European coastal waters: distribution, impact and prospective invasion management strategies

[EN] The native distribution of the blue crab Callinectes sapidus in the western Atlantic extends from Nova Scotia to Argentina. Introduced to Europe at the beginning of the 20th century, it is currently recorded almost ubiquitously in the Mediterranean and in the Black Sea. An overview of the occurrence, abundance, and ecological impact of the species in southern European waters is provided; additionally, we present a pragmatic assessment of its management scenarios, explicitly considering the dual nature of C sapidus as both an invasive species and a fishery resource. We emphasise that the ongoing expansion of C sapidus in the region may represent a stimulating challenge for the identification and implementation of future strategies in the management of invasive crustaceans. The impact of the invader could be converted into an enhancement of the services delivered by southern European coastal ecosystems, while mitigation costs could be transformed into profits for local populations. (C) 2017 Elsevier Ltd. All rights reserved.Funding from FUR 2013-2014 and 2014-2015 to G. M. is acknowledged. The European Fisheries Fund (FEP) Puglia Region (Italy) supported L. C. (CIP 04/OPI/010) as the scientific head of the MOLEVAR project (Pilot Project for the production of soft crabs from Carcinus aestuarii in Varano lagoon). The Portuguese Science Foundation (FCT) supported F. R. (SFRH/BPD/46761/2008) with a post-doctoral research grant from the Programa Operacional Potencial Humano/Fundo Social Europeu (POPH/FSE). F. R. and P. C. were also supported by the strategic MARE plan - Marine and Environmental Sciences Centre (UID/MAR/04292/2013).Mancinelli, G.; Chainho, P.; Cilenti, L.; Falco, S.; Kapiris, K.; Katselis, G.; Ribeiro, F. (2017). The Atlantic blue crab Callinectes sapidus in southern European coastal waters: distribution, impact and prospective invasion management strategies. Marine Pollution Bulletin. 119(1):5-11. https://doi.org/10.1016/j.marpolbul.2017.02.050S511119

On the Atlantic blue crab (Callinectes sapidus Rathbun 1896) in southern European coastal waters: Time to turn a threat into a resource?

[EN] The blue crab Callinectes sapidus is native to the coastal waters of the western Atlantic Ocean, and along the US coasts the species supports an important fishery. The crab was introduced to Europe at the beginning of the 20th century. To date, the species is considered invasive and it has been extensively recorded in southern European waters (SEW), where it is starting to penetrate the shellfish market. Here, an integrated management strategy is proposed for the blue crab in SEW, including the Mediterranean and Black Sea and the eastern Atlantic coasts of the Iberian Peninsula. Taking as introductory examples two case studies represented by the red king crab Paralithodes camtschaticus and the green crab Carcinus maenas, a framework of key issues is reviewed, considering the double nature of the species as invaders and shellfish products. A SWOT analysis is eventually presented for C. sapidus, in order to perform a state-of-the-art synthesis of the proposed scenario, highlighting the potential opportunities as well as the weaknesses related with the limited knowledge of the ecological and economic impact of the species in invaded habitats. The review is concluded by an appraisal of the current trends in global and European crustacean fisheries. The ongoing expansion of C. sapidus might represent a useful management case study, where the need to control an invasive species and mitigate its ecological impact can be harmonized with the opportunity to value it as a fishery resource.Funding from FUR 2013-2014 and 2015-2016 to G. M. is acknowledged. The European Fisheries Fund (FEP) Puglia Region (Italy) supported L. C. (CIP 04/OPI/010). The Portuguese Science Foundation (FCT) supported F. R. (SFRH/BPD/46761/2008). F. R. and P. C. were also supported by the strategic MARE plan Marine and Environmental Sciences Centre (UID/MAR/04292/2013). Constructive comments from two anonymous reviewers on an earlier version of the paper are gratefully acknowledged. This paper is dedicated to Sofia Mancinelli, thy eternal summer shall not fade.Mancinelli, G.; Chainho, P.; Cilenti, L.; Falco, S.; Kapiris, K.; Katselis, G.; Ribeiro, F. (2017). On the Atlantic blue crab (Callinectes sapidus Rathbun 1896) in southern European coastal waters: Time to turn a threat into a resource?. Fisheries Research. 194:1-8. https://doi.org/10.1016/j.fishres.2017.05.002S1819

Use of Melanophore Patterns On The Ventral Side Of The Head To Identify Fry Of Grey Mullet (Teleostei: Mugilidae)

Examination of fry of five species of grey mullet revealed that the shape of the lower jaw and the melanophore patterns along the edge of the lower jaw and the ventral side of the head are species-specific. Mugil cephalus is characterized by an acute angle of the dentary symphysis and lightly pigmented ventro-opercular and gular regions of the head. In Liza aurata, the mandibular region has spots of pigment at the corners of the mouth, the gular region is lightly pigmented with a single row of melanophores, the ventro-opercular region of the head has two rows that form a distinct arch and, in specimens over 20 mm TL, at least one of these rows extends to the posterior ventro-opercular region. In Liza ramada, the pigmentation is darkest in the mandibular and gular regions of the head, the melanophores in the mandibular region in specimens of 30-40 mm TL are concentrated around the anterior tip of the jaw and the corners of the mouth, and the anterior ventro-opercular region usually has a single row of melanophores that may extend into the posterior ventro-opercular region. In Chelon labrosus, there are two rows of melanophores in the ventro-opercular region and one or two rows in the gular region which usually extend beyond the eye into the posterior sector. In Liza saliens, there are two rows of melanophores in the ventro-opercular region and two in the gular region which rarely extend beyond the eye to the posterior sector. These observations were used to create a key which may be useful for identifying fry of grey mullet species grown in aquaculture in the Mediterranean region

Use of morphological differences for the identification of two picarel species Spicara flexuosa and Spicara maena (Pisces: Centracanthidae)

The recognition and identification of the two species of Spicara genus (Spicara flexuosa, picarel and Spicara maena, blotched picarel) is difficult, due to a systematic confusion until now. In the present work a number of external morphometric features (ten body ratios) are evaluated for their diagnostic possibilities. According to Principal Component Analysis results, the body ratios head length to standard length, head height to head length and the ratios of two body heights, indicated that these characters were not related to the maturity stage of the species. The discriminant analysis based on the above body ratios, indicated rather high level of discrimination (83.2%) of the examined samples in two species. The results are discussed, and possibilities of improvement in the identification methodology for the two species are proposed

Taphonomy of mass mollusc shell accumulation at Amvrakikos Gulf lagoon complex sandy barriers (NW Greece)

The preservation status of the mollusc shell accumulation of sandy barriers at the Amvrakikos Gulf lagoon complex was studied. Taphonomic shell analysis of dead mollusc depositions was undertaken in the summer of 2016 at Amvrakikos lagoon complex within the Tsoukalio and Logarou sandy barriers, which showed significant differences among the major abundant bivalve species of Cerastoderma glaucum and Polititapes aureus. Both hydrodynamic transport and differential exposure to environmental conditions differ among the accumulated shells depositions of the lagoonal sandy barriers. The heavier and more durable shells of C. glaucum are frequently found concentrated at the Tsoukalio lagoon accumulations and show a higher intensity of fragmentation whereas at Logarou lagoon the bioerosion and abrasion is more intense. On the other hand, the lighter, thinner, and thus more fragile shells of P. aureus show higher concentration and intensity of fragmentation and bioerosion at Logarou lagoon sandy barriers. The continuous deposition of shells at Tsoukalio lagoonal sandy barriers, contrary to the longterm deposition at Logarou lagoon, explains the different types of accumulations among the lagoons which are attributed to the geomorphology of the sandy shores as well as the morphological characteristics of the different shells

Empirical approach to risk management strategies of Mediterranean mussel farmers in Greece

Risk perception and risk responses of Greek mussel farmers are important for understanding their risk behavior and the likely success of different risk mitigation strategies. This allows policy makers and actuarial companies to decide what risk management products to offer to address specific types of risks. Results from an empirical survey showed that ex-farm prices and health/disability status of farmers are perceived as the most important sources of risk. Risk management decisions were strongly influenced by the attitudes of mussel farmers rather than their socioeconomic status or perception of risk sources. Financial reserves and an alternative source of stable income are both preferred by mussel farmers as risk management strategies, while optimizing farm management to produce at the lowest possible cost is commonly practiced to eliminate losses. Farmers recommend that for certain types of risks that lead to total losses, e.g. anoxia, tsunamis, harmful algal blooms (HABs), insurance contracts should be provided by the public sector, as in similar situations in agriculture. For other needs, customized insurance contracts should be provided by the actuarial market. © 2021 John A. Theodorou et al., published by Sciendo

Length–weight relations of 34 fish species caught by small-scale fishery in Korinthiakos Gulf (Central Greece)

Length–weight (L–W) relations are presented for 34 fish species covering a full annual fishing period (231 fishing days) of professional small-scale fishery in Korinthiakos Gulf during 2008–2009. These were the typical fish species caught by Greek small-scale fishery. Mean annual values of b ranged from 2.751 to 3.704. The L–W relations were positively allometric for 12 species, negatively allometric for seven species and isometric for 15 species. Twenty-two out of 66 species-season combinations showed that the intercept a and/or slope b values differed significantly among seasons. For Greek waters no information regarding the L–W relations existed for three of the 34 recorded species (i.e., Dentex macrophthalmus, Trachinotus ovatus, and Scyliorhinus canicula)

Length–weight relations of 34 fish species caught by small-scale fishery in Korinthiakos Gulf (Central Greece)

Length–weight (L–W) relations are presented for 34 fish species covering a full annual fishing period (231 fishing days) of professional small-scale fishery in Korinthiakos Gulf during 2008–2009. These were the typical fish species caught by Greek small-scale fishery. Mean annual values of b ranged from 2.751 to 3.704. The L–W relations were positively allometric for 12 species, negatively allometric for seven species and isometric for 15 species. Twenty-two out of 66 species-season combinations showed that the intercept a and/or slope b values differed significantly among seasons. For Greek waters no information regarding the L–W relations existed for three of the 34 recorded species (i.e., Dentex macrophthalmus, Trachinotus ovatus, and Scyliorhinus canicula)