Righting and recessing ability of wild and naive cultivated scallops

Minchin, Dan; Skjæggestad, Hanne; Haugum, Geir Askvik; Strand, Øivind

doi:10.1046/j.1365-2109.2000.00460.x

Cited by 15 publications

(6 citation statements)

References 4 publications

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“…On the contrary, Maguire et al (2002a) stated that uncaught scallops might su¡er enhanced mortality due to dredge-induced stress in the same way as undersized discards. Several authors (Minchin et al, 2000;Maguire et al, 2002b) observed that undersized scallop discards are more susceptible to predation due to a reduction in their response or inability to recess; indicating that indirect ¢shing induced mortality can be signi¢cant. Such mortality is, however, not relevant in the Portuguese clam ¢shery when the grid dredge is used, such as in this study and Gaspar et al (2001), due to the selectivity of this gear.…”

Section: Aggregationmentioning

confidence: 99%

Recovery of substrates and macro-benthos after fishing trials with a new Portuguese clam dredge

et al. 2003

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The e¡ect of dredging on bottom structure was assessed, to estimate the damage in£icted on the benthic macrofauna left on the dredge path and to evaluate aggregations of scavengers within the track. Sediment suspended during dredging rapidly resettled both on sand and sandy-mud bottoms. Dredge tracks were deeper on sandy-mud sediments and persisted longer than in sandy sediments. The disappearance of tracks in both sediment types depended both on current strength and wave action. Damage and mortality induced by dredging on the macrobenthic animals left on the dredge path was relatively low. Post-¢shing diver observations showed that damaged animals left on the dredge path rapidly attracted scavengers, mainly Ophiura albida. Immediately after the tow ophiuras reached densities 8 times greater in the track region than in the background. However, they dispersed again rapidly because only few damaged fauna were available on the dredge tracks. Undamaged or slightly damaged shell¢sh started to rebury immediately after escaping from the dredge. INTRODUCTIONClam dredges disturb the sediment and may have an impact on the structure and composition of the seabed. For example, changes in grain-size of the sediment may occur as a result of the transport of ¢ne sediments during sediment suspension.Dredges also induce mortality in non-target benthic species and undersized individuals of the target species that are discarded or left in the dredge path. Animals dislodged or damaged by the passage of a dredge and left on the dredge path are known to attract mobile epifauna (eg. Medcof & Bourne, 1964;Caddy, 1973;Kaiser & Spencer, 1994). Scavenger activity within a dredge path is determined by the number of damaged fauna left on the track.Recently, a new dredge was introduced in the Portuguese bivalve ¢shery, which is more e⁄cient and selective than the traditional dredge used by the commercial £eet (Gaspar et al., 2001; Gaspar et al., in press). However, the general e¡ect of this new dredge, both on the substratum and macrobenthic fauna left within the dredge path, was unknown. The present study reports the results of a diving investigation to assess the e¡ects of dredging on bottom substrata, to estimate the damage in£icted by this new dredge on benthic macrofauna left on the dredge path, and to evaluate aggregation of scavengers within the track. MATERIALS AND METHODSThe study was undertaken in July 2000 o¡ Lagos (south Portugal) on-board the RV Donax. The dredge was identical to those used by the commercial dredge £eet (Gaspar et al., in press). During ebb tide tows were made parallel to the coastline in an east-west direction. Due to dive time constraints the studies concerning 'Mortality of the macrofauna left on the track' and ' Aggregation' were only undertaken on hauls performed on sandy bottoms at 5 m depth. Track con¢guration and breakdownTo evaluate the in£uence of depth and sediment type on structure and persistence of dredge tracks, tows were made at depths of 5 and 12 m, in sand and sandy-mud bottoms. For each depth/...

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Section: Aggregationmentioning

confidence: 99%

Recovery of substrates and macro-benthos after fishing trials with a new Portuguese clam dredge

et al. 2003

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“…The extent of divots in Explorers Cove is surprising, but similar features are documented outside of polar regimes. At least seven other species are known to occupy recesses in the substrate, and Pecten maximus has been observed to excavate a depression in a few minutes by ejecting jets of water and positioning itself in the recess after construction (e.g., Minchin et al 2000;Brand 2006). Recesses can reduce predation via sediment camouflage and decreased visibility in the complex topography, and they can increase food availability in areas of strong current flow because suspended organic matter tends to be deposited in the depressions (Brand 2006).…”

Section: Activity Of Adamussium Colbecki and Ophionotus Victoriaementioning

confidence: 98%

“…Minimal currents aid feeding and reduce the need for energetically expensive claps to right themselves if flipped (Kirby-Smith 1972;Minchin et al 2000).…”

Section: Relative Uniqueness Of Explorers Covementioning

confidence: 99%

BIOTURBATION BY THE COMMON ANTARCTIC SCALLOP (ADAMUSSIUM COLBECKI) AND OPHIUROID (OPHIONOTUS VICTORIAE) UNDER MULTI-YEAR SEA ICE: ECOLOGIC AND STRATIGRAPHIC IMPLICATIONS

Broach¹,

Miller²,

Bowser³

2016

PALAIOS

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The abundant epifaunal scallop Adamussium colbecki and ophiuroid Ophionotus victoriae bioturbate the seafloor under the multi-year sea ice in Explorers Cove, western McMurdo Sound, Antarctica by churning the upper few centimeters of the sandy substrate. Laboratory investigation of these animals' activities demonstrates that the scallops on average resuspend 45 cm 3 d À1 ind À1 via water jets ejected during swimming and clapping movement and that the ophiuroids on average disrupt 861 cm 3 d À1 ind À1 via rowing motion and self-burial in the upper centimeters of the substrate. At observed densities in Explorers Cove, bioturbation rates greatly exceed sediment accumulation rates and physical reworking processes, resulting in homogenized sediment lacking both lamination and discrete traces that would signal its biogenic modification. Adamussium colbecki employs water jets to resuspend the limited phytodetritus needed by the suspension-feeding scallop in the quiet sub-sea ice conditions and produces depressions~3 cm deep that increase substrate surface area and microtopography in Explorers Cove. The scallop thus acts as an ecosystem engineer, modifying the sediment and controlling the flux of materials between the substrate and water as it claps for food gathering rather than for predator evasion like other scallops. The resulting rapid, shallow diffuse bioturbation differs from the more commonly reported vertical bioturbation by infaunal animals recorded in cores, yet it exerts strong control on the sedimentary record and may be characteristic of low-energy, oligotrophic environments beneath multi-year sea ice around Antarctica where a lack of fast predators and low sedimentation rate allow proliferation of epifaunal animals.

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“…In addition, inverted scallops were marked as compromised. Dredging is likely to cause inversion and may leave the animal stressed and unable to normally right itself, potentially increasing vulnerability to predation (Caddy 1989, Minchin et al 2000. Because 5%-10% of sea scallops are albino and have white right valves (D. Hart, Northeast Fisheries Science Center, personal communication), righted albino scallops were differentiated from inverted scallops by the presence of biological growth on the right valve exposed to the water column.…”

Section: Image Processing and Annotationmentioning

confidence: 99%

Estimates of Sea Scallop (Placopecten magellanicus) Incidental Mortality from Photographic Multiple Before—After-Control—Impact Surveys

Ferraro

Trembanis

Miller

et al. 2017

Journal of Shellfish Research

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After several decades of stock decline, the Atlantic sea scallop (Placopecten magellanicus) resource has rebounded to become one of the most valuable fisheries in the United States. The continued sustainability of this fishery is supported by catch limits determined by annual stock projection models. Incidental mortality is an important term in these projection models, but is historically difficult to measure. Current estimates are derived from field experiments that relied heavily on qualitative observations and as a result are based on limited data with low precision. To better quantify incidental mortality, a multiple before-after-control-impact experimental design was used to measure the effect of scallop dredging on the disposition of sea scallops that remain uncaptured on the seafloor following dredging. An autonomous underwater vehicle was used to collect color photographs and side-scan sonar images of the seafloor before and after controlled dredge treatments in the mid-Atlantic and Georges Bank regions. Approximately 170,000 photographs were annotated for instances of mortality. Dredge-induced incidental mortality of 2.5% and 8% was estimated for the mid-Atlantic Bight and Georges Bank sites, respectively, a difference that is likely attributable to the relatively harder substrate of the scallop habitat on Georges Bank that results in greater physical trauma to the uncaptured scallops. This study provides a quantitative estimate of incidental mortality using a noninvasive platform that offers precise mission navigation for repeated surveys. The spatial scale and distribution of the study sites are broad relative to past incidental mortality studies, and the substrate types at each are common in the sea scallop fishery. Estimated mortality rates are lower than the values currently used in fishery stock models and suggest the existing values are conservative, but likely appropriate estimates for management purposes.

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Righting and recessing ability of wild and naive cultivated scallops

Cited by 15 publications

References 4 publications

Recovery of substrates and macro-benthos after fishing trials with a new Portuguese clam dredge

Recovery of substrates and macro-benthos after fishing trials with a new Portuguese clam dredge

BIOTURBATION BY THE COMMON ANTARCTIC SCALLOP (ADAMUSSIUM COLBECKI) AND OPHIUROID (OPHIONOTUS VICTORIAE) UNDER MULTI-YEAR SEA ICE: ECOLOGIC AND STRATIGRAPHIC IMPLICATIONS

Estimates of Sea Scallop (Placopecten magellanicus) Incidental Mortality from Photographic Multiple Before—After-Control—Impact Surveys

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