Recent Trends and Impacts of Fisheries Exploitation on Mediterranean Stocks and Ecosystems

This review focuses on the recent data on Mediterranean fishing fleets and landings, results from stock assessments and ecosystem models to provide an overview of the multiple impacts of fishing exploitation in the different Mediterranean geographical sub-areas (GSAs). A fleet of about 73,000 vessels is widespread along the Mediterranean coasts. Artisanal activities are predominant in South Mediterranean and in the eastern basin, while trawling features GSAs in the western basin and the Adriatic Sea. The overall landings of fish, crustaceans and cephalopods, after peaking during mid 90s at about one million tons, declined at about 700,000 tons in 2013. However, while landings are declining in EU countries since the 90s, in non-EU countries a decreasing trend was observed only in the last 5–10 years. The current levels of fishing effort determine a general overexploitation status of commercial stocks with more than 90% of the stock assessed out of safe biological limits. Indicators obtained from available ecosystem models were used to assess the sustainability of the fisheries. They included primary production required to sustain fisheries (PPR), mean trophic level of the catch (mTLc), the loss in secondary production index (L index), and the probability of the ecosystem to be sustainably exploited (psust). In areas exploited more sustainably (e.g., Gulf of Gabes, Eastern Ionian, and Aegean Sea) fishing pressure was characterized by either low number of vessels per unit of shelf area or the large prevalence of artisanal/small scale fisheries. Conversely, GSAs in Western Mediterranean and Adriatic showed very low ecosystem sustainability of fisheries that can be easily related with the high fishing pressure and the large proportion of overfished stocks obtained from single species assessments. We showed that the current knowledge on Mediterranean fisheries and ecosystems describes a worrisome picture where the effect of poorly regulated fisheries, in combination with the ongoing climate forcing and the rapid expansion of non-indigenous species, are rapidly changing the structure and functioning of the ecosystem with unpredictable effects on the goods and services provided. Although this would call for urgent conservation actions, the management system implemented in the region appears too slow and probably inadequate to protect biodiversity and secure fisheries resources for the future generations

Identification and characterization of nursery areas of red mullet Mullus barbatus in the Central Tyrrhenian Sea

Red Mullet Mullus barbatus is an important target of fishing activities in the central Tyrrhenian Sea, so it is essential to identify its critical habitats in order to manage this resource efficiently. Our research specifically focused on the identification and characterization of nursery areas. The use of spatial interpolation techniques enabled us to identify five nurseries that were highly persistent through time. Moreover, the estimate of juvenile density confirmed the strong aggregation effect of these nursery grounds, as a great portion of young individuals were concentrated in a relatively small surface of the study area. The environmental characterization of these areas showed that juveniles were mainly distributed on bottoms with a relatively high percentage of sand (>70%; P <0.05). Shannon biodiversity index analysis indicated that the southern nurseries reached the highest values of habitat quality (P < 0.0001). Multivariate analysis showed that nursery grounds were divided into three main groups, and analysis of spatial dynamics showed that two different strategies characterized Red Mullet juveniles when density changes over time. In particular, in some areas young individuals selected habitats in a density-dependent way following the basin model scheme, while in other zones they selected habitats in a density-independent way according to the proportional density model. Results also showed that juveniles followed the proportional density model strategy into nursery areas with the highest Shannon biodiversity index values

Growth and reproduction of <i>Xyrichthys novacula</i> (Pisces: Labridae) in the Mediterranean Sea

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The spiny spider crab Maja goltziana (Crustacea: Majidae) in the south Lebanese waters.

A total of 52 specimens (45–115 mm carapace length) of Maja goltziana d’Oliveira 1888, was collected along the Lebanese coasts (south-eastern Mediterranean Sea) in 2006–2007. This species, till now considered rare in the Mediterranean Sea, is common and abundant along the deep shelf-upper Lebanese coast where a local population is present

Evaluación crítica de la comprensión y del conocimiento actuales en el contexto de una aproximación ecosistémica a la gestión pesquera en el Mar Mediterráneo y el Mar Negro

A critical review was carried out involving experts from 17 countries, to identify, summarize and evaluate the current understanding related to the Ecosystem Approach to Fisheries management (EAF) in the Mediterranean and Black Seas. The existing information available at country level, coming from research and monitoring projects and other types of activities, was explored. The evaluation was done following a standardized protocol and using simple semi-quantitative methods. The results highlighted an overall low-medium degree of fulfilment of the requirements of the EAF, with some differences related to the different issues considered. The highest scores were reported for the knowledge related to fleet structure/ behaviour and species/habitat distribution, whereas the lowest scores were reported for modelling, and socio-economic and management issues. Although only semi-quantitative, these results provided an initial picture at a broad regional level on the state of knowledge with a view to a proper implementation of the EAF in the Mediterranean and Black Seas, and identified gaps in scientific knowledge that should be covered.Se llevó a cabo una revisión crítica con la intervención de expertos de 17 países para la identificación, resumen y evaluación del conocimiento actual en relación a la Aproximación Ecosistémica a la Gestión Pesquera (EAF) en el Mar Mediterráneo y el Mar Negro. Se explora la información existente a nivel de cada país, derivada de proyectos de investigación y seguimiento, así como otros tipos de actividades. Se llevó a cabo una evaluación siguiendo un protocolo estandardizado y el uso de métodos semi-cuantitativos. Los resultados muestran que en general el grado de cumplimiento con los requerimientos de EAF es bajo-medio, con algunas diferencias relacionadas con los distintos aspectos considerados. Las puntuaciones más elevadas correspondieron al conocimiento relacionado con la estructura de flota y su comportamiento, así como con la distribución espacial de hábitats y especies. Las puntuaciones más bajas correspondieron a aspectos relacionados con la modelización, la socio-economía y la gestión. A pesar de su carácter semi-cuantitativo, estos resultados proporcionan una primera imagen a nivel regional del estado de conocimiento del que se parte para una implementación adecuada de EAF en el Mar Mediterráneo y el Mar Negro y ayuda a identificar las carencias en el conocimiento científico que deben ser corregidas

Patrón reproductivo y características de la población de la salema, Sarpa salpa (Osteichthyes: Sparidae) en el mar Mediterráneo

The sexual maturation and the growth of the salema, Sarpa salpa (Linnaeus, 1758), along the Italian Mediterranean coast (central Italy), were studied in fish (n = 105) killed incidentally by underwater explosions during the construction of Civitavecchia harbour in 1999 and specimens collected with trammel nets (n = 339). This species is characterized by a protandric hermaphroditism and the sex change process occurs between 24 and 31 cm TL corresponding to a wide range of ages (3-7 years). Size at maturity (L50) was 19.5 cm, at which almost all the individuals were males. Two distinct spawning periods were observed: one in spring, from March to May, and the other in autumn, from the end of September to November. During the first year, compensatory growth occurred in the individuals born in the two periods. An annual regular pattern of ring deposition was identified in the otoliths: the translucent ring was laid down during the winter months, while the opaque ring was formed during the summer months. Back-calculated lengths at age were used to estimate the parameters of the Von Bertalanffy growth equation which were: L∞ = 37.27 cm, K = 0.27 year-1 and t0 = -0.53 year. Salema showed isometric growth (b = 3.04; P = 0.84; t = 0.19).La maduración sexual y crecimiento de Sarpa salpa (Linnaeus, 1758) en las costas del Mediterráneo italiano (Italia central) fueron estudiadas a partir de la recolecta de ejemplares muertos accidentalmente (n = 105) como consecuencia de las explosiones submarinas acaecidas durante la construcción del puerto de Civitavecchia en 1999, así como de ejemplares recolectados mediante redes de arrastre (n = 339). Esta especie se caracteriza por un hermafroditismo protándrico, ocurriendo el proceso de cambio sexual entre los 24 y 31 cm TL, los cuales corresponden a un amplio rango de edades (3-7 años). La talla de maduración (L50) fue de 19,5 cm, siendo la casi la totalidad de los individuos eran de sexo masculino. Se observaron dos períodos diferentes de reproducción: uno en primavera, de marzo a mayo y otro en otoño, de finales de septiembre a noviembre. Se observó, durante el primer año, un crecimiento compensatorio ocurrido entre los individuos nacidos en los dos períodos. Se identificó en los otolitos un modelo anual y regular de deposición de anillos. Se observó el depósito de un anillo translúcido durante los meses invernales, mientras que otro opaco se formó durante los meses de verano. Las composición por edades y tallas retrocalculadas se utilizaron para estimar los parámetros de la ecuación de crecimiento de Von Bertalanffy, es decir: L∞ = 37,27 cm, K = 0,27 año-1 y t0 = -0,53 año. S. salpa demostró un crecimiento isométrico (b = 3,04; P = 0,84; t = 0,19)

Comportamiento alimenticio y ración diaria de la solleta Citharus linguatula (Osteichthyes: Pleuronectiformes) en el mar Tirreno Central

Spotted flounder Citharus linguatula (Linnaeus, 1758) is one of the most abundant species within demersal fish assemblages next to the continental shelf (up to 200 m depth) of the Mediterranean Sea. In spite of the ecological importance of this species in the central Tyrrhenian Sea, many aspects of its biology (e.g. feeding behaviour) are poorly described. In order to analyze how feeding habits are related to the ontogenetic changes in this species, 2636 specimens (between 9 and 26 cm of total length TL) were collected from November 2000 to January 2002. During ontogenetic development spotted flounder occupied different trophic levels: diet shifted from mysids, predominantly in the smaller spotted flounder ( 19 cm TL). Before the transition to the icthyophagous phase, a more generalist foraging behaviour including decapods (Processa sp., Alpheus glaber), molluscs (Turitella sp.) and benthic fish (Lesuerigobius spp., Gobius niger, Callionymus spp., Arnoglossus laterna) dominated the diet. Seasonal analysis of the diet showed an increase in the presence of mysids in summer and autumn, and of decapods in summer and spring. Teleosteans are present throughout the year without significant variations. Daily ration values, computed from the Eggers method, ranged from 1.57% to 2.83% wet body weight, showing a negative relationship between reproduction and daily consumption rate.La solleta, Citharus linguatula, es una de las especies más abundantes entre las comunidades de peces de la plataforma continental (hasta los 200 m de profundidad) del Mediterráneo. A pesar de su importancia ecológica en el mar Tirreno central, muchos aspectos de la biología de C. linguatula (e.g. alimentación) continúan siendo desconocidos. Con el objetivo de investigar cómo los hábitos alimenticios están relacionados con los cambios ontogénicos en esta especie, se analizaron 2636 individuos, entre 9 y 26 cm de longitud total (LT), que fueron muestreados entre noviembre de 2000 y enero de 2002. Durante el desarrollo ontogénico C. linguatula ocupa diferentes niveles tróficos: la alimentación varía desde los misidáceos, que son predominantes para las solletas más pequeñas ( 19 cm LT). Antes de llegar a la fase piscívora, el régimen alimenticio es más generalista, incluyendo crustáceos decápodos (Processa sp., Alpheus glaber), moluscos (Turitella sp.) y peces bentónicos (Lesueurigobius spp., Gobius niger, Callionymus spp., Arnoglossus laterna). Los análisis estacionales de la dieta muestran un aumento de la presencia de misidáceos en verano y otoño, y un aumento de decápodos en verano y primavera. Los teleósteos están presentes todo el año sin ninguna variación significativa. Las valores de la tasa diaria de alimentación, calculados con el método de Eggers, variaron entre 1.57% y 2.83% del peso húmedo individual, con una relación negativa entre la reproducción y el consumo diario

Observations on the reproductive cycle, age and growth of the salema, <em>Sarpa salpa</em> (Osteichthyes: Sparidae) along the western central coast of Italy

La maduración sexual y crecimiento de Sarpa salpa (Linnaeus, 1758) en las costas del Mediterráneo italiano (Italia central) fueron estudiadas a partir de la recolecta de ejemplares muertos accidentalmente (n = 105) como consecuencia de las explosiones submarinas acaecidas durante la construcción del puerto de Civitavecchia en 1999, así como de ejemplares recolectados mediante redes de arrastre (n = 339). Esta especie se caracteriza por un hermafroditismo protándrico, ocurriendo el proceso de cambio sexual entre los 24 y 31 cm TL, los cuales corresponden a un amplio rango de edades (3-7 años). La talla de maduración (L50) fue de 19,5 cm, siendo la casi la totalidad de los individuos eran de sexo masculino. Se observaron dos períodos diferentes de reproducción: uno en primavera, de marzo a mayo y otro en otoño, de finales de septiembre a noviembre. Se observó, durante el primer año, un crecimiento compensatorio ocurrido entre los individuos nacidos en los dos períodos. Se identificó en los otolitos un modelo anual y regular de deposición de anillos. Se observó el depósito de un anillo translúcido durante los meses invernales, mientras que otro opaco se formó durante los meses de verano. Las composición por edades y tallas retrocalculadas se utilizaron para estimar los parámetros de la ecuación de crecimiento de Von Bertalanffy, es decir: L∞ = 37,27 cm, K = 0,27 año-1 y t0 = -0,53 año. S. salpa demostró un crecimiento isométrico (b = 3,04; P = 0,84; t = 0,19)

Feeding habits of European hake (Merluccius merluccius) in the central Mediterranean Sea

European hake (Merluccius merluccius) is an important predator of deeper shelf-upper slope Mediterranean communities. It is a nectobenthic species distributed over a wide depth range (20−1000 m) throughout the Mediterranean Sea and the north east Atlantic region (Fisher et al., 1987). Notwithstanding the ecological and economic importance (Oliver and Massutí, 1995) of hake in the Mediterranean, many aspects of its biology (e.g., recruitment and reproduction), due to multiple spawning (Sarano, 1986) and the current state of exploitation, are poorly understood (Arneri and Morales-Nin, 2000)

Feeding behaviour and daily ration of the spotted flounder <i>Citharus linguatula</i> (Osteichthyes: Pleuronectiformes) in the central Tyrrhenian Sea

Spotted flounder Citharus linguatula (Linnaeus, 1758) is one of the most abundant species within demersal fish assemblages next to the continental shelf (up to 200 m depth) of the Mediterranean Sea. In spite of the ecological importance of this species in the central Tyrrhenian Sea, many aspects of its biology (e.g. feeding behaviour) are poorly described. In order to analyze how feeding habits are related to the ontogenetic changes in this species, 2636 specimens (between 9 and 26 cm of total length TL) were collected from November 2000 to January 2002. During ontogenetic development spotted flounder occupied different trophic levels: diet shifted from mysids, predominantly in the smaller spotted flounder ( 19 cm TL). Before the transition to the icthyophagous phase, a more generalist foraging behaviour including decapods (Processa sp., Alpheus glaber), molluscs (Turitella sp.) and benthic fish (Lesuerigobius spp., Gobius niger, Callionymus spp., Arnoglossus laterna) dominated the diet. Seasonal analysis of the diet showed an increase in the presence of mysids in summer and autumn, and of decapods in summer and spring. Teleosteans are present throughout the year without significant variations. Daily ration values, computed from the Eggers method, ranged from 1.57% to 2.83% wet body weight, showing a negative relationship between reproduction and daily consumption rate