Discard analysis and damage assessment in the wedge clam mechanized dredging fisheries of the northern Alboran Sea (W Mediterranean Sea)

Urra, Javier; Garcı́a, Teresa; Gallardo-Roldan, Helena; León, Estefanía; Lozano, M.; Baro, J.; Rueda, José L.

doi:10.1016/j.fishres.2016.10.018

Cited by 22 publications

(27 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fact that previous studies recorded considerable amounts of bycatch in the bivalve dredge fisheries along the Algarve coast, even exceeding the catch of the target species in late spring and early summer (Gaspar and Chícharo 2007), reinforces the importance of the present study and the need for further investigation on this important subject. Other studies have reported seasonal trends in the bycatch collected by mechanical bivalve dredges: namely an increase in flatfish discards in autumn on the Algarve coast (Palma et al 2003), possibly associated with greater abundances in benthic communities in this area during this season (Alves et al 2003), and also higher discards of D. trunculus in spring and summer in the northern Alboran Sea (Urra et al 2017).…”

Section: Discussionmentioning

confidence: 88%

“…However, it is crucial to analyse the composition of discards in order to propose new strategies to minimize their impact (Urra et al 2017). Indeed, fisheries management policies recommend a reduction in the discards (Catchpole et al 2005) and the adoption of market-based approaches to promote added value for bycatch species (Leitão and Baptista 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Many studies on this topic have focused on bycatch and mortality resulting from fish and shrimp trawling (for a review, see Broadhurst et al 2007), but few have dealt with discard mortality in bivalve dredge fisheries (e.g. Hauton et al 2003, Leitão et al 2009, Urra et al 2017). …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Bycatch and discard survival rate in a small-scale bivalve dredge fishery along the Algarve coast (southern Portugal)

et al. 2018

View full text Add to dashboard Cite

Summary:Although the bivalve dredge used on the Algarve coast (southern Portugal) is highly selective for the target species, in some periods of the year the bycatch can exceed the catch of the commercial species. The present study aimed to quantify the bycatch and discards, estimate damage and mortality, and propose management measures to minimize discards and mortality. A total of 15 fishing surveys (60 tows) were performed using two types of dredges ("DDredge" targeting Donax trunculus and "SDredge" targeting Spisula solida and Chamelea gallina). Of the 85257 individuals (392.4 kg) of 52 taxa that were caught, 73.4% belonged to the target species, 22.1% to commercially undersized target species and 4.5% to bycatch species. Bycatch rates were lower for SDredge (13.5% in number and 6.3% in weight) than for DDredge (46.0% in number and 32.9% in weight). Damage and mortality rates were also lower using SDredge (1.3% and 1.0% of the total catches, respectively) than using DDredge (4.0% and 2.8% of the total catches). Survival experiments revealed the diverse vulnerability of the taxa and confirmed the influence of the damage score on the mortality rate. The results gathered in the present study encourage the adoption of a bycatch reduction device to reduce both direct and indirect mortality.Keywords: bivalve dredging; bycatch; discards; damage score; survival rate; metallic grid dredge; fishing gear technical design; bycatch reduction device Tasa de supervivencia de capturas incidentales y descartes en una pesquería a pequeña escala de bivalvos con rastro remolcado en la costa del Algarve (sur de Portugal) Resumen: Aunque la draga de bivalvos utilizada en la costa del Algarve (sur de Portugal) es altamente selectiva para las especies objetivo, en algunos períodos del año la captura incidental puede exceder la captura de las especies comerciales. En este contexto, el presente estudio tuvo como objetivo cuantificar las capturas incidentales y los descartes, estimar el daño y la mortalidad, y proponer medidas de gestión para minimizar los descartes y la mortalidad. Se realizaron un total de 15 embarques (60 arrastres) utilizando dos tipos de dragas ("DDredge" dirigida a Donax trunculus y "SDredge" dirigida a Spisula solida y Chamelea gallina). En total, se capturaron 85257 individuos (392.4 kg) pertenecientes a 52 taxones, distribuidos entre especies objetivo (73.4%), especies objetivo por debajo de la talla legal (22.1%) y especies de captura incidental (4.5%). Las tasas de captura incidental fueron menores en SDredge (13.5% número y 6.3% peso) que en DDredge (46.0% número y 32.9% peso). Las tasas de daños y mortalidad también fueron menores usando SDredge (1.3% y 1.0% de las capturas totales) que usando DDredge (4.0% y 2.8% de las capturas totales). Los experimentos de supervivencia revelaron la diferente vulnerabilidad de los taxones y confirmaron la influencia del nivel de lesiones en la tasa de mortalidad. Los resultados del presente estudio fomentan la adopción de un dispositivo de reducción de capturas inciden...

show abstract

Section: Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Bycatch and discard survival rate in a small-scale bivalve dredge fishery along the Algarve coast (southern Portugal)

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Clams harvesting represents an important fishing activity in the Mediterranean Sea and in the Black Sea, but these fisheries (i.e., dredge fisheries) create a very high share of discards (over 15%) in almost all the subregions where these activities take place. A large proportion of the discarded catch is mainly composed of undersized commercial individuals and non-commercial specimens of molluscs, decapods, and echinoderms (Urra et al, 2017). Furthermore, a significant proportion of target species caught or left on the dredge path have damaged shells (with chipped margins, holed umbos, broken or smashed valves), which causes indirect shellfish mortality and economic loss (Moschino et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Impact on Macro-Benthic Communities of Hydraulic Dredging for Razor Clam Ensis minor in the Tyrrhenian Sea

et al. 2020

View full text Add to dashboard Cite

Bivalve molluscs fishery is of great importance along the Italian coasts, both in economic and landing terms, and different edible bivalve species are harvested both in Adriatic and Tyrrhenian Seas. A medium-term assessment of the impact of the hydraulic dredges targeting razor clam Ensis minor on macro-benthic community was made during two surveys carried out in winter 2017 and late spring -summer 2018 in central Tyrrhenian Sea, which represents the main fishing ground for this species. The study area was located between 1 and 4 m depth, within 0.3 nautical miles from the coast. A net sampler (40 cm width, 18 cm height, and 14 mm mesh size) was mounted on a commercial dredge (3 m width) and enabled to collect specimens of the smallest sizes for the entire community present in the areas. A control area was identified where fishing does not occur, in order to compare exploited and not exploited sea bottoms. The results show that benthic assemblages found in dredged areas are characterized by species living in high-energy habitat, due to the closeness to the shore, and thus showing a high resilience at medium-term disturbs. Differences in species richness were not clearly evident both for the entire community and for the mollusc assemblages evaluated over the two surveys, among the control and the impacted areas, with few exceptions mainly depending on local conditions and anthropic pressure. Thus, even if the benthic community is typical of a moderately disturbed environment, the effects of fishing on the community structure are still discernible over and above the natural variation.

show abstract

“…The main results obtained were related to the fishing gear used, catches of target species, catches per unit of effort, size frequency distributions of catches, size-weight relationships, and mapping of natural shellfish beds (Baro et al, 1992). Since then, the only studies dealing with fisheries have focused on discard analysis and damage to discarded species (Urra et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Exploitation status and stock assessment of the smooth clam Callista chione (Linnaeus, 1758) in the northern Alboran Sea (GSA01-W Mediterranean Sea)

et al. 2018

Self Cite

View full text Add to dashboard Cite

The smooth clam, Callista chione (Linnaeus, 1758), is a venerid bivalve widely appreciated in southern Spain where it represents the top commercial bivalve species in terms of landings and economic value. In this area, a total of 223 artisanal boats (68% of the artisanal fleet) are involved in shellfishing targeting bivalve molluscs, including the smooth clam. The artisanal mechanised dredging that targets C. chione in the northern Alboran Sea is described and the current exploitation status of its populations is analysed. A surplus-production model was run using ASPIC and used to assess the temporal variation in the levels of fishing for this bivalve throughout the study period (2002-2015), as well as to suggest conservation reference points that could guarantee the sustainable exploitation of this resource. During the study period, the maximum C. chione catch was registered in 2003 (306 t) and the minimum in 2006 (93 t). The ASPIC model for C. chione stock suggests that a Maximum Sustainable Yield (MSY) of 216 t could be produced from a total stock biomass of 983 t (Bmsy) at a fishing mortality rate of total biomass of 0.22 (Fmsy), with B/Bmsy and F/Fmsy values of 1.34 and 0.82, respectively, indicating that the stock is approaching good status.

show abstract

Discard analysis and damage assessment in the wedge clam mechanized dredging fisheries of the northern Alboran Sea (W Mediterranean Sea)

Cited by 22 publications

References 24 publications

Bycatch and discard survival rate in a small-scale bivalve dredge fishery along the Algarve coast (southern Portugal)

Bycatch and discard survival rate in a small-scale bivalve dredge fishery along the Algarve coast (southern Portugal)

Impact on Macro-Benthic Communities of Hydraulic Dredging for Razor Clam Ensis minor in the Tyrrhenian Sea

Exploitation status and stock assessment of the smooth clam Callista chione (Linnaeus, 1758) in the northern Alboran Sea (GSA01-W Mediterranean Sea)

Contact Info

Product

Resources

About