Discards from Deep-water Bottom Trawling in the Eastern-Central Mediterranean Sea and Effects of Mesh Size Changes

D’Onghia, Gianfranco; Carlucci, Roberto; Maiorano, P.; Panza, M.

doi:10.2960/j.v31.a19

Cited by 40 publications

(30 citation statements)

References 9 publications

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“…Recent studies have estimated the amount of trawling discards as 20 to 50% of the biomass caught in different Mediterranean areas (Moranta et al, 2000;Machias et al, 2001;D'Onghia et al, 2003;Sartor et al, 2003;Sanchez et al, 2004). About half of the discarded biomass is composed of species of commercial interest and the rest is made up of species without economic value.…”

Section: Discussionmentioning

confidence: 99%

Trawl catch composition during different fishing intensity periods in two Mediterranean demersal fishing grounds

Sánchez¹,

Sartor²,

Recasens³

et al. 2007

Sci. Mar.

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Section: Discussionmentioning

confidence: 99%

Trawl catch composition during different fishing intensity periods in two Mediterranean demersal fishing grounds

Sánchez¹,

Sartor²,

Recasens³

et al. 2007

Sci. Mar.

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“…Before 2004-5, the fleet trawled for hake in the spring, and also for rose shrimps Parapenaeus longirostris and red shrimps Aristeus antennatus and Aristeomorpha foliacea. In recent years stocks have dwindled, and now the fleet operates almost exclusively on the continental shelf between 15 m (the minimum depth allowed by law) and 150 m. This trend towards shallower trawls is in opposition to the efforts in other Mediterranean fisheries, for which regulation of shallow trawling has led to the development of deep-sea trawl fisheries (D'Onghia et al, 2003, Esmeralda-Costa et al, 2008. Such spatial changes in fishing effort alter species compositions, and therefore more Lessepsian migrants are caught by trawlers fishing in the shallows (see Results).…”

Section: Description Of the Fishing Fleet Study Area And Typical Catmentioning

confidence: 99%

“…Depth and fishing season were found to be the major factors contributing to the discard rate and catch composition in many Mediterranean trawl fisheries (Stergiou et al, 1998, Machias et al, 2001, D'Onghia et al, 2003, Sánchez et al, 2004, 2007. These findings have been used to justify and manage seasonal trawl closures and minimal trawling depth limitations.…”

Section: Introductionmentioning

confidence: 99%

“…85% of these discards originated in the trawl fisheries, which were estimated to have a 45-50% discard ratio. Various other studies (Stergiou et al, 1998, Machias et al, 2001, D'Onghia et al, 2003, Sánchez et al, 2004, 2007 have assigned discard ratios of 20-50% to various trawl fisheries in the western and central Mediterranean. El-Mor et al (2002) and Alsayes et al (2009), however, found that only 15-25% of the catch was discarded in Egypt.…”

Section: Introductionmentioning

confidence: 99%

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Spatiotemporal patterns of catch and discards of the Israeli Mediterranean trawl fishery in the early 1990s: ecological and conservation perspectives

Edelist¹,

Sonin²,

Golani³

et al. 2011

Sci. Mar.

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SUMMARY:The spatiotemporal patterns of discards and catch composition of Israeli trawlers were examined using a 4-year (1990-1994), 324 haul dataset. Haul depth was found to be the main grouping variable for hauls, although significant seasonal differences were also found. 28.3% of the total catch was discarded, and there was a 40.1% discard percentage in shallow hauls. According to these figures, annual discards for the Israeli trawl fleet for the study period are estimated at ca. 440 to 700 t. Both the biomass and the number of discarded specimens peaked in summer, as well as the percentage of juvenile fish of commercial species. These findings suggest that a summer moratorium on trawling would reduce discards. The percentage of specimens of Indo-Pacific origin decreased from 51% in depths shallower than 37 m to 24% between 38 and 73 m, and 8% in deeper strata. Discards along the Israeli coast were comparable to those observed elsewhere in the Mediterranean. The findings presented here are the first quantitative account of fish community assemblages in the nearshore waters of the easternmost part of the Mediterranean, and thus provide valuable information for comparisons with more current datasets that are currently being assembled.Keywords: bottom-trawl, Israel, discards, catch composition, Lessepsian migration, fishery management. RESUMEN:Patrones espacio-temporales de la captura y los descartes de pesquería de arrastre mediterránea israelí al inicio de la década de los noventa: perspectivas ecológicas y de conservación. -Se analizaron los patrones espacio-temporales de los descartes y la composición de la captura de la flota de arrastre de Israel utilizando datos de 4 años (1990)(1991)(1992)(1993)(1994), 324 caladas. La profundidad resultó ser el principal factor en la agrupación de las caladas, si bien se encontraron asimismo diferencias significativas entre estaciones. Se descartó el 28.3% de la captura total, alcanzándose el 40.1% en las caladas realizadas en las aguas más someras. Según estos porcentajes, se estimó una captura anual descartada por la flota de Israel en ese período de 440-700 t. La biomasa, el número de ejemplares descartados, así como el porcentaje de juveniles de especies comerciales fue mayor en verano. Estos resultados sugieren que una veda de arrastre en verano favorecería la disminución de la captura descartada. El porcentaje de ejemplares de origen indo-pacífico descendió desde 51% en aguas de una profundidad inferior a 37 m, al 24% entre 38-73 m y al 8% en el estrato más profundo. Los descartes en la costa israelí fueron similares a los observados en otras zonas del Mediterráneo. Se presentan por primera vez resultados cuantitativos relativos a comunidades de las aguas costeras del extremo oriental del Mediterráneo, aportándose información para su comparación con datos más recientes que en la actualidad están siendo obtenidos.Palabras clave: arrastre de fondo, Israel, descartes, composición de la captura, migración lessepsiana, gestión de pesquerías.

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“…Ungaro et al 1998;Colloca et al 2003;D'Onghia et al 2003). Techniques for measuring diversity have varied over time, and include taxonomic, phylogenetic, morphological and functional indices (Clarke and Warwick 2001;McClain et al 2004;Petchey and Gaston 2006;Vellend et al 2011;Farré et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Testing otolith morphology for measuring marine fish biodiversity

Tuset¹,

Farré²,

Otero-Ferrer³

et al. 2016

Mar. Freshwater Res.

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Abstract.To check the suitability of otoliths for measuring biodiversity, the contour and shape of the sulcus acusticus of sagittal otoliths were described using geometric morphological analysis. Thirteen and fourteen points were used to define these structures respectively. Three current coastal fish assemblages of the north-western Mediterranean were selected for the present study. The results demonstrate that the relative warps generated in the geometric analysis explained both characteristics related to contour and the otolith sulcus. A comparative study with body fish shape using morphospaces and clusters revealed that otolith shape is a better variable for explaining the ecological structure of a fish assemblage. Moreover, three morphological indices (morphological richness (MR), morphological disparity and the morphogeometric index) were estimated from relative warps of otoliths and were compared with ecological, taxonomic, functional and morphological (from body shape) indices. MR increased with functional diversity and average taxonomic distinctness, reflecting the ecological and taxonomic character of otolith morphology. These findings suggest that otoliths could be a useful tool for studying the diversity of present and past fish assemblages.

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Discards from Deep-water Bottom Trawling in the Eastern-Central Mediterranean Sea and Effects of Mesh Size Changes

Cited by 40 publications

References 9 publications

Trawl catch composition during different fishing intensity periods in two Mediterranean demersal fishing grounds

Trawl catch composition during different fishing intensity periods in two Mediterranean demersal fishing grounds

Spatiotemporal patterns of catch and discards of the Israeli Mediterranean trawl fishery in the early 1990s: ecological and conservation perspectives

Testing otolith morphology for measuring marine fish biodiversity

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