Francesc Ordines

Performance of artificial neural networks and discriminant analysis in predicting fishing tactics from multispecific fisheries

In the Mediterranean, bottom trawlers are multispecific and frequently apply different fishing tactics (FTs) even during the same fishing trip. Up to four individual FTs were distinguished in the study area where fishermen usually use mixtures of different FTs in daily fishing trips. Identifying the FTs actually performed is a key issue in traditional stock assessment methods. In this paper, we compare the performance of discriminant analysis and artificial neural networks for predicting FTs from the species composition of daily sale bills. We used data on the landings of each vessel from daily sale bills along with information on the FT actually performed, which was obtained by onboard observers who interviewed skippers about the FTs that they planned to employ. Discriminant analysis and artificial neural networks achieved comparable overall results and the success of predictions depended on both the sample size of the different data subsets (balancing) and the similarity between the species composition ...

Ecology and fishery of the deep-water shrimp, Aristeus antennatus (Risso, 1816) off Algeria (south-western Mediterranean)

Life-history traits and exploitation of the red shrimp, Aristeus antennatus (Risso, 1816) (Decapoda, Aristeidae) on the Algerian slope (south-western Mediterranean) have been studied through monitoring of the commercial trawl fishery between 1999 and 2006 at two different ports on the west coast, as well as through monthly biological sampling of these catches from April 2005 to September 2006. This information was completed with data from experimental bottom trawls, carried out in the area during 2003 and 2004. A continuous increase of the trawl fleet and the landings of red shrimp during the study period were detected. Although this fishery takes place only in a very limited part of the distribution range of the species (around depths of 300-525 m), experimental data gave a continuous increase of red shrimp density from 400 to 700 m. The Algerian fishery showed seasonal variation in yields, with a maximum during summer and autumn, although the average daily yields were clearly higher than those from other western Mediterranean fisheries. Experimental trawls detected two distinct demersal assemblages on the slope grounds of the study area, separated approximately by the 400 m isobath. Decapod crustaceans constituted the dominant group in these assemblages, with the pink shrimp (Parapenaeus longirostris (Lucas, 1846)) and the red shrimp as their most important and abundant species, and either shallower, or deeper than that isobath, respectively. Both species of shrimp showed one of the highest abundance indices estimated in the Mediterranean yet. Fishes were also important in these assemblages, the composition of which suggested high species diversity, with complex and extensive trophic webs. Monthly length frequency distribution of commercial catches showed that the carapace length (CL) of female shrimps ranged between 18 and 65 mm, while males ranged from 16 to 41 mm CL. Females represented more than 70% of the individuals caught, although the sex-ratio by length showed a predominance of males for individuals ≤18 mm CL and of females for individuals ≥25 mm CL, while their monthly development also showed a predominance of females from April to September and a similar proportion of sexes from October to March. Ripening gonads of females were mostly found from June to August, and the gonadosomatic index also showed a clear peak during this period. The length at which 50% of females were mature was estimated as 27.7 mm CL. The length-weight relationship showed a strongly negative allometry for both sexes (b = 2.4), while the Von Bertalanffy growth parameters differed greatly between them, with values for maximum theoretical size and for the growth coefficient of females (L∞ = 70.6 mm CL and k = 0.5 year−;1, respectively) being higher than those for males (L∞ = 43.0 mm CL; k = 0.3 year−;1). The growth performance index (Φ) for females (3.4) was also higher than that for males (2.7). Se ha estudiado la estrategia vital y la explotacion de la gamba roja Aristeus antennatus (Risso, 1816) (Decapoda, Aristeidae) en el talud de Argelia (Mediterraneo sudoccidental), a partir del seguimiento de la pesqueria comercial de arrastre entre 1999 y 2006 en dos puertos de la costa occidental y del muestreo biologico mensual de las capturas entre Abril 2005 y Septiembre 2006. Esta informacion se completo con datos procedentes de pescas experimentales de arrastre de fondo, realizadas en el area en 2003 y 2004. Durante el periodo de estudio, se ha detectado un incremento continuo de la flota de arrastre y los desembarcos de gamba roja. Aunque esta pesqueria se lleva a cabo solamente en un rango muy limitado de la distribucion batimetrica de la especie (aproximadamente entre 300 y 525 m), la informacion procedente de las pescas experimentales mostro un continuo incremento de la densidad de gamba roja desde 400 hasta 700 m de profundidad. La pesqueria argelina mostro variaciones estacionales en los rendimientos, con maximos durante verano y otono, si bien sus valores medios diarios fueron claramente superiores a los de otras pesquerias del Mediterraneo occidental. Las pescas experimentales de arrastre mostraron la presencia de dos comunidades demersales distintas en los fondos de talud del area de estudio, separadas aproximadamente por la isobata de 400 m. Los crustaceos decapodos constituyeron el grupo predominante de estas comunidades, siendo la gamba blanca (Parapenaeus longirostris (Lucas, 1846)) y la gamba roja sus especies mas importantes y abundantes a 400 m de profundidad, respectivamente. Ambas especies mostraron unos de los mayores indices de abundancia estimados en el Mediterraneo. Los peces fueron tambien importantes en estas comunidades, con una diversidad de especies elevada y redes troficas amplias y complejas. La distribucion mensual de tallas de las capturas mostro que la longitud cefalotoracica (LCT) en las hembras oscilo entre 18 y 65 mm, mientras que en los machos entre 16 y 41 mm LCT. Las hembras representaron mas del 70% de los individuos en la captura, aunque la proporcion de sexos mostro una predominancia de machos en individuos ≤18 mm LCT y de hembras en individuos ≥25 mm LCT, mientras que su evolucion mensual tambien mostro una predominancia de hembras desde Abril hasta Septiembre y una proporcion similar de ambos sexos entre Octubre y Marzo. Se encontraron hembras en maduracion principalmente desde Junio hasta Agosto, y su indice gonadosomatico tambien mostro un maximo durante este periodo. La talla a la cual el 50% de las hembras fueron maduras se estimo en 27,7 mm LCT. La relacion talla-peso mostro una acusada alometria negativa en ambos sexos (b = 2,4), mientras que los parametros de crecimiento de Von Bertalanffy mostraron claras diferencias entre sexos, con valores de talla maxima teorica y coeficiente de crecimiento en hembras (L∞ = 70,6 mm LCT y k = 0,5 ano−1, respectivamente) mayores que en machos (L∞ = 43,0 mm LCT; k = 0,3 ano−1). El indice de crecimiento (Φ) en hembras (3,4) fue tambien mayor que en machos (2,7).

Demersal chondrichthyans in the western Mediterranean: assemblages and biological parameters of their main species

The composition and structure of demersal chondrichthyan assemblages and the biological parameters of their main species were compared in four geographical subareas (GSAs) established by the General Fisheries Commission for the Mediterranean in the western Mediterranean:northern Alboran Sea (GSA01) and Alboran Island (GSA02), Balearic Islands (GSA05) and northern Spain (GSA06), with the first two being considered jointly. Data were obtained from 199 hauls undertaken from May to June 2013 during the Spanish International Bottom Trawl Survey in the Mediterranean (MEDITS). Twenty-five different chondrichthyan species were caught in all GSAs: seven were common to all areas, five appeared only in GSA01, nine appeared only in GSA05 and one appeared only in GSA06. Analysis of community structure (clusters, multidimensional scaling, analysis of similitude) revealed two assemblages related to depth, with very similar bathymetric ranges in all GSAs, namely continental shelf (from 41 to 252m) and slope (from 284 to 813m). The highest diversity, biomass and abundance values on the shelf and slope assemblages were recorded in GSA05 and GSA01 respectively. These results highlight the effects of the distinct fishing and oceanographic parameters related to the GSAs. Generally, the biological parameters of the most important species did not show differences between GSAs, which could suggest the existence of a single population in the western Mediterranean.

Biology, Feeding, and Habitat Preferences of Cadenat's Rockfish, Scorpaena Loppei (Actinopterygii: Scorpaeniformes: Scorpaenidae), in the Balearic Islands (Western Mediterranean)

The genus Scorpaena occurs worldwide in tropical and temperate seas accommodating 62 valid species (Froese and Pauly 2011). Six of them are present in the Mediterranean, where in some littoral communities such as rocky reefs and/or meadows of Neptune grass, Posidonia oceanica, the biomass of the scorpionfish of the genus Scorpaena is substantial in relation to other fish species (Harmelin-Vivien et al. 1989). Scorpaena species have received relatively little attention worldwide, with the exception of Scorpaena guttata Girard, 1854 and Scorpaena cardinalis Solander et Richardson, 1842 (see: Love et al. 1987, Stewart and Hughes 2010). In contrast, in the Mediterranean the biology of the majority of the Scorpaena species such as Scorpaena scrofa L.; Scorpaena porcus L.; Scorpaena notata Rafinesque, 1810; Scorpaena elongata Cadenat, 1943; and Scorpaena maderensis Valenciennes, 1833 have been studied (Bradai and Bouain 1988, 1990a, 1990b, 1991, Harmelin-Vivien et al. 1989, Morte et al. 2001, Ragonese et al. 2003, La Mesa et al. 2005, Muñoz et al. 2005, Ordines et al. 2009), leaving Scorpaena loppei Cadenat, 1943 as the only species of this genus whose biology is almost unknown. The Cadenat’s rockfish, S. loppei Cadenat, 1943, is a small benthic scorpion fish, distributed in the eastern Atlantic from the Bay of Biscay to Mauritania and the ACTA ICHTHYOLOGICA ET PISCATORIA (2012) 42 (1): 21–30 DOI: 10.3750/AIP2011.42.1.03

The use of Artificial Neural Networks (ANNs) in aquatic ecology

Complex network systems are pervasive in life sciences at all levels, from molecules and genes to organisms and ecosystems. All these systems are characterized by being constituted of numerous components or nodes (molecules, genes, cells, tissues, organisms), which are interconnected by many links in an intricate tangle, just as biological neural networks consist of many interacting neurons (Fig. 1). Apart from its structural complexity, complex networks are inherently difficult to understand because interactions are non-linear, distributed non-randomly, and are adaptive, that is, changing continuously in response to the state of the system itself (Strogatz, 2001; Pascual & Dunne, 2006). Understanding the functioning of these systems consisting of a large number of strongly interacting units represents therefore a major endeavour for biologists and ecologists. As complex networks, ecosystems are non-linear systems constituted by countless interacting pieces, both biotic and abiotic, constituting the entangled web of life. In a world threatened by global environmental problems such as biodiversity loss, climate change, fishing overexploitation or pollution, ecologists are challenged by the need to understand and predict the dynamics of ecosystems as never before. Along with the complexity of ecological systems, ecologists are also faced with a huge amount of information that recent advances in data collection technology such as remote sensing have produced. To cope with the ecosystem complexity and large data sets currently available, ecologists nowadays have the opportunity to use machine-like learning techniques such as the artificial neural networks (ANNs). As their name implies, ANNs are biologically inspired and were initially intended to mimic the neural activity in the human or animal brains (Garson, 1991; Goh, 1995; Stern, 1996). ANNs models are based on the same learning processes as the animal brain, which gathers information from the environment (input data) and gives an answer (output data) after using learned training algorithms. However, given that the architecture and dynamics of the animal brain is exceedingly complex, even the most elaborated ANN models are mere caricatures of the biological brain. Although the original works on ANNs date back to the forties (McCulloch & Pitts, 1943; Pitts & McCulloch, 1947), they not became really popular until the eighties after the work of the physicist John Hopfield. Hopfield (1982) introduced an oversimplified neural network, comprising a set of fully connected binary units, as a metaphor of neural computation. The most remarkable feature of this model was that it could learn by association and was quiet insensitive to noise. This capacity to recognize previously learned patterns, which was thought to be an exclusive property of brains, is precisely what the Hopfield model does (Sole & Goodwin, 2000).

Harvest Strategies for an Ecosystem Approach to Fisheries Management in Western Mediterranean Demersal Fisheries

The serious overfishing of most Mediterranean stocks demands urgent reforms of the management measures aiming to guarantee the sustainability of resources, notably when compared with the improvement observed in other European areas. The new EU Common Fisheries Policy (CFP) constitutes an excellent opportunity to introduce the changes needed for such a reform. According to this CFP, all European fish stocks should be brought to a state where they can produce at MSY by 2020 at the latest. The CFP also establishes that the objective of sustainable exploitation should be achieved through multiannual plans (MAPs) adopted in consultation with relevant stakeholders having fisheries management interests such as fishermen, nongovernmental organizations and policy makers. Together with the MSY and MAP approaches, the new CFP contains several other measures, directed to guarantee the ecological and socio-economic sustainability of fisheries by means of the implementation of the ecosystem approach to fisheries management (EAFM). With this new perspective, the CFP wants to avoid past failures of fisheries management based on monospecific approaches. This study is a first step towards the application of the EAFM in the Balearic Islands by means of the development of a harvest strategy with defined objectives, targets, limits and clear management control rules aimed at optimizing socioeconomic and ecological objectives in the framework of the new CFP. Different management scenarios designed to achieve that goal were modelled for the main demersal commercial fisheries from the study area, the bottom trawl and small-scale fisheries. The work begins with a general description of those fisheries, their main fishing grounds and assessments of the exploitation status of the main target stocks in order to establish the current situation. Secondly, alternative management scenarios to maximize catch and profits while considering societal objectives were evaluated by means of bio-economic models. Thirdly, management measures were provided based on the previous modelling and discussions with stakeholders. Finally, a monitoring scheme was outlined to assess the progresses of the proposed management actions. This work is intended to be a working example of co-management (fishers, policy-makers and scientists) in the Mediterranean in the framework of the new EU CFP.

First substantiated record of Raja asterias Delaroche, 1809 (Elasmobranchii: Rajiformes: Rajidae) in the Gulf of Cádiz, North-eastern Atlantic

The Mediterranean starry ray, Raja asterias, considered endemic in the Mediterranean, has recently been reported by other authors from Atlantic fisheries in southern Portugal and northern Morocco. There has been, however, no substantiated record of the species outside the Mediterranean. This fact and the easiness of confusion of R. asterias with other species have probably prevented those records from being taken into account in the recent catalogue of North Atlantic elasmobranchs species, in the assessment of the population status of this species, and in recent annotated global checklists of chondrichthyans. In our study, a specimen of R. asterias was collected from the Gulf of Cádiz and its species identity was assessed based on morphological and molecular methods. The presently reported finding constitutes a substantiated record of R. asterias from the Atlantic. Based on this record, previously reported catches of the Mediterranean starry ray in the Atlantic should be confirmed, and if so, these populations should be included in future assessments of this vulnerable species and in the description of its geographic distribution.

The evolutionary history of Mediterranean Batoidea (Chondrichthyes: Neoselachii)

Batoidea (rays, skates and their relatives) is the largest group included in the subclass Elasmobranchii. Mediterranean Batoidea fauna is relatively diverse, characterised by a history of isolation and connectivity resulting from tectonic movements and changes in ocean circulation. The evolutionary histories of Batoidea species in the Mediterranean were estimated from two mitochondrial markers (COI and NADH2) through dating and Bayesian analyses. Additionally, two species delimitation analyses (Poisson Tree Process and General Mixed Yule Coalescent) were conducted to elucidate species boundaries. The relationship between Raja species—their ecological traits and species level phylogeny—was also studied to understand speciation in this genus. Results concerning the phylogenetic relationship between Batoidea species were largely consistent with recent molecular studies. Divergence times show a parallel evolutionary history of Batoidea fauna and Mediterranean history, which began from the Triassic. Three important speciation events were detected (a) throughout the Jurassic, when the major lineages were split (b) at the Eocene–Oligocene, when almost all genera of Batoidea were branched, and (c) during the Miocene, when almost all current species of Batoidea derived. These diversification events correspond to crucial paleoclimatic and paleogeographical events that took place at the global and local scale. Phylogenetic and species delimitation analyses revealed the presence of 18 species. Raja species showed different ecological preferences related to depth and habitat, which indicated a genus speciation process driven by different habitat characteristics.

First record of the Reticulated dragonet, Callionymus reticulatus Valenciennes, 1837 (Actinopterygii: Callionymiformes: Callionymidae), from the Balearic Islands, western Mediterranean.

Background. The reticulated dragonet, Callionymus reticulatus, was originally described based on a single specimen, the holotype from Malaga, Spain, south-western Mediterranean, probably collected before 1831. The holotype is now disintegrated; the specific characteristics are no longer discernible. The species was subsequently recorded from several north-eastern Atlantic localities (Western Sahara to central Norway), but missing in the Mediterranean. Material and methods. Specimens of C. reticulatus were observed and collected during two cruises in 2014 and 2016 in the Balearic Islands off Mallorca and Menorca. The collected specimens (8 females) have been deposited in the collection of the Hebrew University of Jerusalem (HUJ). All individuals of C. reticulatus were collected from beam trawl samples carried out during the DRAGONSAL0914 in September 2014, and during the MEDITS_ES05_16 bottom trawl survey in June 2016, on shelf and slope bottoms around the Balearic Islands. Both surveys used a ‘Jennings’ beam trawl to sample the epi-benthic communities, which was the main objective of the DRAGONSAL0914 and a complementary objective in the MEDITS_ES05_16. The ‘Jennings’ beam trawl has a 2 m horizontal opening, 0.5 m vertical opening and a 5 mm diamond mesh in the codend. Trawls had duration of 1 to 3 min of effective sampling (bottom time) at a speed of 2 knots. Catches were sorted out to species and standardized abundances of callionymid species (individuals per 500 m2) were obtained by calculating the sampled surface (distance covered × beam trawl horizontal opening). Results. Callionymus reticulatus is recorded from the Balearic Islands for the first time; the specimens are described and illustrated. Conclusions. The new record confirms that the species is still extant in the Mediterranean. A key to Mediterranean callionymid fishes is provided to distinguish C. reticulatus from other species of the family in the area. The callionymid fish fauna of the Mediterranean now comprises 11 species, including three Lessepsian migrants originating from the Red Sea.