Effects of long-term physical disturbance by commercial scallop fishing on subtidal epifaunal assemblages and habitats

Veale, Lucy; Hill, A. S.; Hawkins, Stephen J.; Brand, A. R.

doi:10.1007/s002270000357

Cited by 69 publications

(39 citation statements)

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“…The untrawled Md site showed higher abundance of bivalves and fish, suggesting that this area might act as a refuge zone within the heavily trawled area (Allison et al, 1998). At the Medes Lm and Nm site the dominant organisms were the sessile suspension feeder cnidarians, which are known to be very sensitive to trawling due to high mortality with direct contact with the gear (Veale et al, 2000) and due to collapse of their filtering system with the increasing turbidity caused by trawling (Hill et al, 1999). The infaunal community was dominated by polychaetes, with the lowest dominance occurring at Nm in the MPA, which in turn showed a higher abundance of groups such as sipunculids, bivalves and ophiurids.…”

Section: Discussionmentioning

confidence: 99%

Exploring the degree of trawling disturbance by the analysis of benthic communities ranging from a heavily exploited fishing ground to an undisturbed area in the NW Mediterranean

Juan¹,

Demestre²,

Sánchez³

2011

Sci. Mar.

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SUMMARY: This study focuses on 4 sites in the northwestern Mediterranean to investigate the response of benthic fauna across a gradient of trawling impact. One site was located in a heavily exploited fishing ground. The second site was enclosed in the fishing ground but had not been trawled in twenty years. The third site was located adjacent to a marine protected area and was subjected to occasional trawling. The fourth site was located inside the marine protected area, where trawling was banned thirty years ago. Side-scan sonar records of trawl marks on the seabed confirmed the gradient of trawling intensity. We investigated the response of benthic fauna to trawling disturbance at the mesoscale of a fishing ground. We compared the observed patterns of abundance, biomass, diversity and community structure for epifauna and infauna with responses predicted from previous studies. Results showed that those communities less impacted by trawling sustained more biogenically habitat-structured communities (e.g. more abundance of sessile suspension feeders at the less disturbed sites against higher dominance of small invertebrates at the disturbed site). Moreover, these results confirm the benefits of restricting trawling activities for benthic communities, with marine reserves as the paradigm for the conservation of Mediterranean fishing grounds.Keywords: benthos, community composition, ecosystem management, fishing, marine reserves, Mediterranean Sea. RESUMEN: Análisis del grado de perturbación ocasionado por la pesca de arrastre considerando comunidades bentónicas de caladeros fuertemente explotados en áreas protegidas. -El presente estudio se centra en 4 áreas del noroeste mediterráneo para investigar la respuesta de la fauna bentónica considerando un gradiente de niveles de impacto provocado por la pesca de arrastre. Un área se sitúa en un caladero fuertemente explotado. La segunda se halla en el interior del caladero pero no ha sido explotada en 20 años. La tercera está situada en una zona adyacente a un área marina protegida sujeta ocasionalmente a la pesca de arrastre. Finalmente, la cuarta se sitúa en el interior del área marina protegida donde la pesca de arrastre está prohibida hace treinta años. Mediante las marcas de arrastre del fondo obtenidas con el sónar de barrido lateral se pueden confirmar los gradientes de intensidad de pesca de arrastre. Se analiza la respuesta observada de la fauna bentónica a la pesca de arrastre a mesoescala de un calador de pesca, comparando los patrones de abundancia, biomasa, diversidad y estructura de la comunidad de la epifauna y la infauna, comparándola con respuestas ya predichas en previos estudios. En general, los resultados mostraron que las comunidades menos impactadas por el arrastre están constituidas por comunidades más estructuradas (por ejemplo, más abundancia de filtradores suspensívoros sésiles en las zonas menos perturbadas frente una mayor dominancia de pequeños invertebrados en las zonas perturbadas). Al mismo tiempo, estos resultados confirman los beneficio...

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Section: Discussionmentioning

confidence: 99%

Exploring the degree of trawling disturbance by the analysis of benthic communities ranging from a heavily exploited fishing ground to an undisturbed area in the NW Mediterranean

Juan¹,

Demestre²,

Sánchez³

2011

Sci. Mar.

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“…Any scallops captured during this process were transferred to another area several kilometres away from the study sites. This dredging exercise was designed to simulate commercial exploitation, although the Bradda Inshore ground commonly experiences higher levels of fishing effort (Veale et al 2000). It should be noted, however, that experimental dredging continued throughout the closed season for Pecten maximus (June to October).…”

Section: Methodsmentioning

confidence: 99%

Benefits of closed area protection for a population of scallops

Stewart¹,

Vause²,

Mosley³

et al. 2005

Mar. Ecol. Prog. Ser.

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Despite the current interest in using closed areas for fisheries management, few studies have actually examined the benefits for invertebrate fisheries such as scallops. This study details the dynamics of a population of great scallops Pecten maximus (L.), within a closed area and an adjacent fished area off the Isle of Man, over a 14 yr period (1989 to 2003). Scallop densities were very low in both areas when the closed area was set up, but increased at an accelerated rate over time within the closed area. Scallop densities also increased on the adjacent fishing ground, but not to the same extent. Consequently, the density of scallops above the minimum legal landing size (110 mm SL) was more than 7 times higher in the closed area than in the fished area by 2003. There was also a shift towards much older and larger scallops in the closed area and, correspondingly, lower estimates of total mortality. Experimental dredging of 2 plots within the closed area confirmed that fishing drove these differences in population dynamics and structure. These patterns of scallop density, age and size structure resulted in the exploitable biomass (adductor muscle and gonad) of scallops being nearly 11 times higher in the closed area than in the fished area by 2003, and the reproductive biomass was 12.5 times higher. This is significant for fisheries management because the build up of high densities of large P. maximus individuals enhanced local reproductive potential and therefore the likelihood of export of larvae to the surrounding fishing grounds. Along with these direct benefits of closed area protection, juvenile scallops had higher survival and individual growth rates in the closed area, apparently in response to reduced fishing disturbance. Although juvenile scallops are not subject to direct removal by fishing, protection during this critical phase therefore appeared to assist the recovery of the closed area population. In summary, this study joins a growing number indicating that the use of closed areas offers a range of benefits over more traditional methods of managing fisheries. Fisheries for relatively sedentary and long-lived species such as P. maximus appear to be particularly suitable for this type of management.

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“…It is suggested here that bottom trawling may have had the same impact on the Dangeard and Explorer mini-mound provinces as documented by the variation in slope angle between the two provinces. In addition to the physical damage resulting from bottom trawling, as evidenced from the coral rubble observed on the interfluves, the long-term effects include the homogenisation of the sea bed, reduction in species diversity (Veale et al, 2000), and re-suspension of sediments (Jones, 1992, Martin et al, 2008, Pilskaln et al, 1998and Thrush et al, 2001. Martin et al (2008) document an increase in sediment accumulation rates within La Fonera/Palamós Canyon due to strong sea floor disturbances caused by the local fishing fleet in the last decades.…”

Section: Canyon and Mini-mound Faunamentioning

confidence: 99%

The Dangeard and Explorer canyons, South Western Approaches UK: Geology, sedimentology and newly discovered cold-water coral mini-mounds

Stewart

Davies

Guinan

et al. 2014

Deep Sea Research Part II: Topical Studies in Oceanography

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The Celtic Margin is a complex area in terms of sedimentary dynamics and evolution, with a number of submarine canyons dissecting the continental slope and outer continental shelf. The complex terrain and diverse range of sea-bed sediments play a part in submarine canyons being described as areas of high habitat heterogeneity. This study has concentrated on the heads of two canyons: Dangeard (also known as Dangaard) and Explorer (first named here) located in UK territorial waters, in water depths between 138 and 1165 m. Multibeam echosounder, 2D reflection seismic and photographic ground-truthing data have been combined to map the sea-bed geomorphology, sedimentary features and canyon megafauna of these canyons. In addition, two previously unknown provinces of cold-water coral (CWC) mini-mounds were discovered on the interfluves of the Dangeard and Explorer canyons.The study area comprises a dendritic network of gullies feeding into the canyon thalwegs. Amphitheatre rims, where slope angles are commonly in excess of 20°, occur along the margins and heads of both canyons and are interpreted as drainage basins indicative of retrogressive mass-wasting in a shelfward direction.The CWC mini-mounds occur in water depths between 250 m and 410 m, with more than 400 mounds identified. They are up to 3 m in height and 50-150 m in diameter with no sub-surface expression, suggesting these mounds are, in geological terms, relatively young and possibly Holocene in age. Biological analyses revealed that the mounds form a habitat for ophiuroids and Munida associated with Lophelia pertusa coral rubble, suggesting these mini-mounds are not present-day living features.

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Effects of long-term physical disturbance by commercial scallop fishing on subtidal epifaunal assemblages and habitats

Cited by 69 publications

References 0 publications

Exploring the degree of trawling disturbance by the analysis of benthic communities ranging from a heavily exploited fishing ground to an undisturbed area in the NW Mediterranean

Exploring the degree of trawling disturbance by the analysis of benthic communities ranging from a heavily exploited fishing ground to an undisturbed area in the NW Mediterranean

Benefits of closed area protection for a population of scallops

The Dangeard and Explorer canyons, South Western Approaches UK: Geology, sedimentology and newly discovered cold-water coral mini-mounds

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