23 results on '"Spisula solida"'
Search Results
2. Pea crabs (Pinnotheres pisum) colonisation of five commercial bivalve species from southern Portugal.
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Nicolau, Lídia, Vasconcelos, Paulo, Pereira, Fábio, Carvalho, André N., Piló, David, and Gaspar, Miguel B.
- Abstract
This study reports the spatial and depth distributions, occurrence and prevalence, infestation rate and intensity of the pea crab Pinnotheres pisum colonising five commercial bivalve species (Chamelea gallina , Donax semistriatus , Donax trunculus , Donax vittatus, and Spisula solida) along the south and southwest coasts of Portugal. In addition, the study also analysed the colonisation pattern, morphometric measurements and relative growth of P. pisum inhabiting those bivalve species. Overall, 33,370 bivalves were analysed, collected in 371 sampling stations at depths ranging from 3 to 25 m. A total of 102 bivalves hosted 106 P. pisum , corresponding to an infestation rate of 0.31%. Besides 13 juveniles, were recorded 60 males and 33 females of P. pisum , corresponding to a male-biased sex ratio (1M: 0.6F). Pea crabs carapace width ranged from 1.3 to 13.5 mm and males were smaller than females (hard females were also smaller than ovigerous soft females). In general, larger and heavier bivalves hosted larger and heavier P. pisum. Pea crabs morphometric relationships presented negative allometries, reflecting slower growth rates in carapace length and total weight compared to carapace width throughout the species ontogeny. Overall, this study provides valuable insights into diverse descriptors of bivalves' colonisation by P. pisum , comparing the main results and trends with analogous information available throughout the species distributional range. Although the current fairly low infestation by P. pisum does not constitute a health concern for these bivalve species, its evolution under a climate change scenario should be periodically monitored in the mid- and long-term. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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3. The influence of dredge design on the catch of Callista chione (Linnaeus, 1758)
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Gaspar, M. B., Dias, M. D., Campos, A., Monteiro, C. C., Santos, M. N., Chicharo, A., Chicharo, L., Dumont, H. J., editor, and Burnell, Gavin, editor
- Published
- 2001
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4. New species in aquaculture: are the striped venus clam Chamelea gallina (Linnaeus, 1758) and the surf clam Spisula solida (Linnaeus 1758) potential candidates for diversification in shellfish aquaculture?
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Joaquim, Sandra, Matias, Domitília, Matias, Ana Margarete, Gonçalves, Rui, Chícharo, Luís, and Gaspar, Miguel B
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SPISULA solidissima , *CLAMS , *SPAWNING , *CRUSTACEAN larvae , *AQUACULTURE - Abstract
The surf Spisula solida and the striped venus Chamelea gallina clams support important fisheries in Europe. These fisheries have been affected by inter-annual fluctuations in stock abundance and recruitment failures. Aquaculture could contribute to address these problems through the production of larvae or juveniles for stock-enhancement programmes. In the present study, the prerequisites to produce these species in hatchery were established. Of the different methods used to obtain gametes (thermal stimulation, scarification and flow through), C. gallina spawned in the flow through only. By its turn, the best method for obtaining gametes for S. solida was stripping. Higher survivals of D-larvae were found at 15 and 17°C. The greatest larval survival and growth rates were obtained from larvae fed Isochrysis aff. galbana ( T-iso). First C. gallina and S. solida pediveliger larvae were found at day 8 and day 26 respectively. The presence of metamorphosed larvae found even in the unfed treatment for C. gallina and for S. solida is an advantage for aquaculture production. After metamorphosis, the S. solida juveniles' survival was quite low, whereas there was no mortality for C. gallina juveniles reared without substrate regardless the diet provided. Juveniles fed the binary diet ( Chaetoceros calcitrans - C. cal + T.iso) and the monodiet T-iso showed relatively higher growth in shell length and weight than C. cal. The hatchery production of these two species was possible, however the results of this study showed that C. gallina can be more attractive for aquaculture than S. solida. [ABSTRACT FROM AUTHOR]
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- 2016
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5. Commercial catch rates of the clam Spisula solida reflect local environmental coastal conditions.
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Baptista, V. and Leitão, F.
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OCEANOGRAPHY , *OCEAN temperature , *HYDROLOGY , *FISHING , *CLIMATOLOGY , *STREAM measurements - Abstract
Abstract: The effect of environmental variables and fishing pressure (explanatory variables were lagged 1year) on commercial catch rates of the clam Spisula solida was studied on an annual basis over a 21year period in three areas off the Portuguese coast (the Northwest, the Southwest and the South) between 1989 and 2009. Each area showed distinct environmental (oceanographic and hydrological) characteristics. Different sensitivities of S. solida fishing grounds to environmental variables were found among the study areas. On the Northwest coast, the combined effect of NAO indices and sea surface temperature had a positive effect on S. solida fisheries, particularly during the spawning season. On the Southwest coast, the variation of S. solida catches was negatively associated with wind magnitude and positively related with South–Southeast winds. Winter river discharges and summer sea surface temperature negatively affected S. solida catches on the South coast. Fishing effort also affected S. solida catch rates in the South. However, “extreme” changes in environmental conditions were the main drivers of short-term variations in catch rates. These results indicate that variations of S. solida catches strongly reflect a regional signature of local climatic features off the coast. Information on local environmental conditions should therefore be used for the purpose of identifying management actions to ensure long-term sustainability of S. solida fisheries. [Copyright &y& Elsevier]
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- 2014
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6. The reproductive cycle of white clam Spisula solida (L.) (Mollusca: Bivalvia): Implications for aquaculture and wild stock management
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Joaquim, Sandra, Matias, Domitília, Lopes, Belisandra, Arnold, William S., and Gaspar, Miguel B.
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REPRODUCTION , *AQUACULTURE , *SEAWATER - Abstract
Abstract: The dynamics of the white clam''s (Spisula solida) reproductive cycle along with its nutrient storage and exploitation strategy in the Algarve coast (Portugal) was studied throughout the year 2003. The timing of gametogenic development and spawning of S. solida were analysed through histological preparation using qualitative and quantitative criteria. Condition index and biochemical composition were determined in order to provide information on energy storage and utilization. Seawater temperature is a primary environmental factor determining reproductive development and spawning of S. solida; reproductive activity occurred during low temperatures. The spawning period began in late winter as a consequent response to the increase in seawater temperature and extended through spring. During this period, the condition index and the gonadal index decreased. In June, most of the population was spent and big resting oocytes appear dispersed in the gonad. In summer, the specimens were found to be in the resting phase and condition index increased to its maximum value as a consequence of reserves storage. Gametogenic activity was initiated coincident with decreasing temperature in September, but a sudden increase of this environmental parameter in October disturbed the gametogenic process and a second spawning occurred. In this period, the synchronism between males and females of the population was lost. The striking consumption of glycogen reserves developed during the previous August and consequent biosynthesis of lipids during gamete formation occurred. In the following two months, reproductive synchronism was restored, and storage of reserves and gametogenesis took place concurrently. In December the entire population was in the ripe stage of gonadal development. Moreover than a consequence of gametogenesis during autumn/winter, lipid behaviour reflected the energy accumulation process and its conversion to somatic development in spring/summer. The reproductive strategy adopted by S. solida makes possible broodstock manipulation in terms of conditioning in aquaculture. The information obtained in this study is important for assessing sustainable management of wild stocks as well as for estimating its potential for aquaculture production. [Copyright &y& Elsevier]
- Published
- 2008
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7. Rebuilding viable spawner patches of the overfished Spisula solida (Mollusca: Bivalvia): a preliminary contribution to fishery sustainability.
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Joaquim, Sandra, Gaspar, Miguel B., Matias, Domitília, Ben-Hamadou, Radhouan, and Arnold, William S.
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SPAWNING , *FISHERIES , *DAMS , *FISH populations , *AQUATIC sciences - Abstract
Joaquim, S., Gaspar, M. B., Matias, D., Ben-Hamadou, R., and Arnold, W. S. 2008. Rebuilding viable spawner patches of the overfished Spisula solida (Mollusca: Bivalvia): a preliminary contribution to fishery sustainability. – ICES Journal of Marine Science, 65: 60–64. Populations of commercially important bivalves along the coast of Portugal are depleted as a consequence of natural and anthropogenic causes. A pilot experiment was designed to determine the feasibility of transplanting individuals from natural clam beds to a closed fishing area in an effort to rebuild relatively high-density patches of Spisula solida. For this purpose, clams were equally partitioned into two groups (undersize and legal clams) and transplanted at a density of 40 clams m−2 into two areas 50 m2. Transplanted and control clams were sampled to estimate survival, condition index, biochemical composition, and reproductive condition. Generally, the physiological condition of clams was not affected by the method of transplanting. One year after transplanting, survival was 45%. The increase in local abundance of mature clams should facilitate successful fertilization and increase the residual reproductive value of each clam relative to its pre-transplant value. Transplanting undersize clams may be more advantageous because they are more likely to spawn at least once before harvest. The experiments demonstrate that spawner transplants may strengthen S. solida populations and can be used in stock-enhancement programmes which, in conjunction with effective management measures, can contribute to the sustainability of the S. solida fishery. [ABSTRACT FROM PUBLISHER]
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- 2008
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8. Profiles of paralytic shellfish poisoning toxins in shellfish from Portugal explained by carbamoylase activity
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Artigas, Mireia Lara, Vale, Paulo João Vieira, Gomes, Susana Sousa, Botelho, Maria João, Rodrigues, Susana Margarida, and Amorim, Ana
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PARALYTIC shellfish poisoning , *GYMNODINIUM , *TOXINS , *AQUATIC invertebrates - Abstract
Abstract: The presence of paralytic shellfish poisoning (PSP) toxins has not been recorded in the Portuguese coast since 1995. A bloom of Gymnodinium catenatum occurred in the NW coast of Portugal in the autumn of 2005, and PSP profiles were determined in several inshore and offshore shellfish species by HPLC after pre-column oxidation. Most of the species studied contained a complex toxin profile, typically representative of contamination by G. catenatum. However, clams such as Spisula solida contained mainly decarbamoyl toxins, while less extensive transformation was found in Scrobicularia plana. In vitro incubation of S. solida digestive glands with PSP standards revealed a rapid transformation of carbamate and N-sulfocarbamoyl toxins into their corresponding decarbamate analogues. After 24h, less than 5% of the carbamate or N-sulfocarbamoyl toxins tested remained. After a 24h in vitro incubation of S. plana digestive glands, no decarbamate analogues were detected. Artificial toxification of S. plana with cultures of G. catenatum revealed the conversion into decarbamoyl analogues progressed slowly: initially dcGTX2+3 and dcSTX accounted only for 5% of total non N-1 hydroxilated toxins, after 6 days these toxins accounted for 41% of the toxin composition. In vitro incubations of digestive glands from other commercial bivalves did not reveal production of decarbamoyl analogues over a 24h period. [Copyright &y& Elsevier]
- Published
- 2007
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9. Differential dynamics of dinophysistoxins and pectenotoxins, part II: Offshore bivalve species
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Vale, Paulo
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DETOXIFICATION (Alternative medicine) , *ANTITOXINS , *BIVALVES , *AQUATIC invertebrates - Abstract
Abstract: Different dinophysistoxin''s profiles have been found repeatedly amongst some offshore bivalve molluscs. Species such as the clam, Spisula solida, esterify dinophysistoxins to a great extent, and contain always more okadaic acid (OA) than dinophysistoxin-2 (DTX2). In contrast, the clam Donax trunculus has a much higher percentage of non-esterified toxins, and often contains more DTX2 than OA. A detoxification experiment with D. trunculus and S. solida showed that the higher percentage of DTX2 in Donax was due to this toxin being eliminated more slowly than OA. The ester analogues of OA and DTX2 were eliminated faster than free OA and free DTX2 in D. trunculus. As D. trunculus esterifies OA to a greater extent than DTX2, the greater proportion of the free form of DTX2 explains why there is a gradual increase in total DTX2 over time. This slow elimination of free toxins contributes to wild D. trunculus specimens being, on average, six times more toxic than S. solida specimens on the Portuguese south coast. The commercial shellfish species more often monitored along the coast of Portugal between 2003 and 2004 (eight species in total) were examined for DTX2 content. The maximal percentage of total DTX2 in the total DSP toxins (OA+DTX2) was 40% in all species (clams, razors, cockles, oysters) except D. trunculus and Mytilus galloprovinciallis, in which it reached 70–90%. This phenomenon is seen only when contamination is due to the microalga Dinophysis acuta. The other important DSP-producer, Dinophysis acuminata, causes contamination only with OA. Current data suggest that D. acuta along the Portuguese coast always produces OA and DTX2 in a fixed ratio of 60:40. When this alga is dominant, contamination of bivalves occurs in a OA/DTX2 ratio of 60:40. In bivalves in which these toxins are esterified to a great extent, this profile is maintained due to the parallel elimination of OA and DTX2 esters at similar rates. However, in species with lower esterification, the relative proportion of OA and DTX2 rapidly decreases due to the selective retention of free DTX2. Elimination of pectenotoxin-2 seco acids (PTX2sa), the main pectenotoxin form found in both offshore species studied, followed an exponential decay. The half-lives of PTX2sas found in D. trunculus and S. solida were similar to that found in a previous study with the cockle, Cerastoderma edule, but longer than found in the blue mussel M. galloprovinciallis. [Copyright &y& Elsevier]
- Published
- 2006
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10. Population structure and species dynamics of Spisula solida, Diogenes pugilator and Branchiostoma lanceolatum along a temporal–spatial gradient in the south coast of Portugal
- Author
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Dolbeth, M., Viegas, I., Martinho, F., Marques, J.C., and Pardal, M.A.
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AQUATIC resources , *AGRICULTURE , *FISHERIES - Abstract
Abstract: The population structure, dynamics and distribution of Spisula solida, Diogenes pugilator and Branchiostoma lanceolatum, common species in the south coast of Portugal, were studied in a spatial–temporal manner in order to understand the influence of cross-shore sediment transport and anthropogenic activities. Spisula solida is harvested commercially, whereas D. pugilator and B. lanceolatum are non-target species, with little information available on the population dynamics of these species. The study was performed in 2001–2002, and along a gradient of 100–5000m from the coastline, corresponding to a depth gradient of between 1 and 32m deep. Spisula solida was distributed preferentially at 3–12m deep, and its distribution appeared to be influenced seasonally by the cross-shore sediment dynamics. Results suggested benthic recruitment in June. Some recruitments had no expression (year 2001) since adults were not present, which seems to be a direct impact of clams'' fisheries. Diogenes pugilator showed preferential distribution at shallow depths, from 1.3 to 8m. Results suggested recruitments every 4 months, in June, February and October. Branchiostoma lanceolatum showed the widest distribution, from 7 to 26m deep. Recruitment seemed to start in June until October, when it attained an abundance peak of juveniles. For both non-target species no clear effects of the cross-shore dynamics or the clams'' fisheries impact were visible. [Copyright &y& Elsevier]
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- 2006
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11. Chronic effects of dredging-induced stress on the clam (Spisula solida): nucleic acid and lipid composition
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Chícharo, Maria A., Chícharo, Luis, Amaral, Ana, Condinho, Sílvia, and Gaspar, Miguel
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CLAMS , *BIOCHEMISTRY , *SPAWNING - Abstract
Responses of the clam Spisula solida to stress imposed by dredging were analyzed in terms of changes in chronic indices of biochemical conditions (RNA/DNA ratio and neutral/polar (N/P) lipid ratio). Cumulative stress on undersized (<25 mm) S. solida from repeated habitat disturbance by dredging was simulated in the laboratory and measured with in situ studies off the southern coast of Portugal, in April and July 1999. Laboratory simulations on undersized bivalves indicated decreases in RNA/DNA and N/P lipid ratios. Responses were sublethal; however, even though survival was not directly threatened, decreases in condition suggest that bivalves are more susceptible to predation when they have been left in the seabed after the dredging activity. Moreover, the in situ study revealed that this effect could be especially critical during spawning. [Copyright &y& Elsevier]
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- 2003
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12. A comparison of direct macrofaunal mortality using three types of clam dredges
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Gaspar, M.B., Leitão, F., Santos, M.N., Chícharo, L., Dias, M.D., Chícharo, A., and Monteiro, C.C.
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BENTHIC animals , *MORTALITY - Abstract
The white clam Spisula solida is harvested along the entire coast of Portugal using mechanical dredges. In this study, the total direct mortality of the macrobenthic community caused by three types of clam dredges (north dredge—ND, traditional dredge—TD, and the metallic grid dredge—GD) used in the S. solida fishery was determined and compared. The relationship between mortality and catching efficiency for each type of dredge was also assessed. Our results showed significant differences for total direct mortality between the ND and both the GD and TD dredges. This difference was largely attributed to the mortality of animals that died in the dredge track as a direct result of the physical damage inflicted by the dredge passing. It was also found that the damage to uncaught individuals is directly related to gear efficiency. The lower catching efficiency of the ND (64%) led to a higher proportion of damaged individuals being left in the dredge path, when compared with the more efficient GD (98%) and TD (90%) dredges. Short and long-term implications of the impact of dredging on the composition of benthic communities are discussed. From fisheries management and ecological points of view, there are obvious advantages to introduce into the bivalve dredge fisheries more efficient and selective dredges in order to reduce the number of damaged individuals and by-catch, and consequently decreasing the impact on the macrobenthic communities. [Copyright &y& Elsevier]
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- 2003
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13. Size selectivity of the Spisula solida dredge in relation to tooth spacing and mesh size
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Gaspar, M.B., Leitão, F., Santos, M.N., Sobral, M., Chıcharo, L., Chıcharo, A., and Monteiro, C.C.
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CLAMS , *DREDGES - Abstract
A study was undertaken on the northwestern coast of Portugal to evaluate the selectivity effect of both tooth spacing and mesh size on the catch of the white clam (Spisula solida). Two typical clam dredges, equipped with different tooth spacing and mesh size, were towed side by side. Three tooth spacing (20, 40 and 60 mm) and three mesh sizes (35, 40 and 50 mm) were investigated. The dredge selectivity experiments were performed by attaching a cover bag with a 20 mm mesh to the gear. Individual hauls were analysed by the SELECT model. The Fryer’s mixed model of between-haul variation was also applied to data. The results showed that the space between teeth does not have an effect on selectivity. Tooth length was directly related to the dredge’s capture efficiency. The only factor that contributed to dredge size selection was mesh size. The 50% retention lengths estimated for mesh sizes 30, 40 and 50 mm were 25.68, 26.35 and 31.94 mm, respectively. For all mesh sizes, very narrow selection ranges were observed. The most appropriate mesh size to be enforced within the Portuguese northwestern S. solida fishery should be 40 mm. [Copyright &y& Elsevier]
- Published
- 2003
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14. Reburial time and indirect mortality of Spisula solida clams caused by dredging
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Chıcharo, L., Chıcharo, M., Gaspar, M., Regala, J., and Alves, F.
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CLAMS , *MORTALITY , *INTERMENT - Abstract
Clam-dredging results in the exposure of Spisula solida individuals not caught by the dredge. Subsequent survival depends on clam damage, reburial time, and the time needed by predators to reach the impacted area. We analyse these variables and discuss the importance of predation on exposed S. solida caused by dredge fishing. Sampling was performed in July 2000 off the southern coast of Portugal, at Vilamoura, a traditional S. solida sandy fishing ground. We compared the time needed for S. solida individuals to rebury themselves, relative to the abundance of potential predators. Bivalves collected by divers were placed on the seabed, and the times required for reburial were measured. These were compared with the times needed for reburial of the clams exposed by dredge impact. At each of three dredge tracks, we analysed the number of predators that entered three equal quadrats (0.0250 m2) per minute. These results were compared with a non-affected control area. Impact caused by the fishing dredge significantly increases the number of exposed S. solida clams
(p<0.05) and the abundance of potential predatory species(p<0.05) . The brittle star Ophiura texturata was the most abundant and first species to reach the dredge track (less than 3 min after dredge impact). Other species reaching the dredge track were Pomatochistus spp. (6 min after impact), Diogenes pugilator, and Nassarius reticulatus (both 9 min after impact). Although predators reached the impacted area while S. solida bivalves were still exposed, our results suggest that predation on the non-buried clams in the dredge track is not a major factor for subsequent indirect mortality of S. solida. [Copyright &y& Elsevier]- Published
- 2002
15. Effect of tooth spacing and mesh size on the catch of the Portuguese clam and razor clam dredge.
- Author
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Gaspar, M. B., Castro, M., and Monteiro, C. C.
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CLAMS ,FISHERIES ,FISHING ,ESTUARIES ,DREDGES - Abstract
Experiments on the selectivity of the clam and razor clam dredges were carried out during July 1995, on the south coast of Portugal. The effects of mesh size and tooth spacing were investigated for both the clam and razor clam dredges. Four different mesh sizes (25, 35, 40, and 50 mm) and three different tooth spacings (15, 20, and 25 mm for the clams Spisula solida and Venus striatula, and 10, 15, and 20 mm for the razor clam Ensis siliqua) were used. The results indicated that the tooth spacing did not have an effect on the selectivity. The best mesh sizes were 40 mm for the clam fishery (S. solida and V. striatula) and 66 for the razor clam (E. siliqua). These mesh sizes will result in considerable reduction in the numbers of small- and medium-sized individuals in the catch. [ABSTRACT FROM PUBLISHER]
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- 1999
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16. Synaptic structure in the visceral ganglion of the lamellibranch mollusc, Spisula solida.
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Cobb, James and Mullins, Pamela
- Abstract
An examination using the electron microscope was carried out on the visceral ganglion of the marine bivalve mollusc Spisula solida. A range of fixation, block staining and section staining technique was used to study the structure of chemical synapses. Phosphotungstic acid employed as a block stain specifically stained pre- and post-synaptic structures associated with the membrane at synapses as well as one class of granular vesicle. The specialised contacts were however shown to be rare and in many parts completely absent. Many axons, containing several types of vesicle, were shown to be varicose and it is proposed that they may function in a similar way to the unspecialised varicose terminals of vertebrate autonomic neurons. The role of membrane specialisations in intercellular adhesion is discussed. This study concludes that many synapses may be morphologically unidentified using present criteria. [ABSTRACT FROM AUTHOR]
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- 1973
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17. SURVIVAL ESTIMATES OF BYCATCH INDIVIDUALS DISCARDED FROM BIVALVE DREDGES
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Francisco Leitão, Miguel B. Gaspar, and Pedro Range
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0106 biological sciences ,Bycatch, Mortality of discards ,Spisula solida ,Fisheries ,GC1-1581 ,Oceanography ,01 natural sciences ,Dredging ,Commercial fishing ,lcsh:Oceanography ,Clam dredge ,Espécies descarregadas ,lcsh:GC1-1581 ,14. Life underwater ,Mortality ,Polybius henslowii ,Survivor experiments ,biology ,010604 marine biology & hydrobiology ,Mortalidade das rejeições ,Longline ,Trachinus ,Portuguese clam dredge ,04 agricultural and veterinary sciences ,Trawl ,biology.organism_classification ,Management ,Dicologlossa ,Fishery ,Bycatch ,Size selectivity ,Vipera ,Experiências de sobrevivência ,Mesh size ,040102 fisheries ,0401 agriculture, forestry, and fisheries ,Fisheries Research ,Catch ,Ganchorra para bivalves - Abstract
The fate of released bycatch is an issue of great interest for fisheries research and management. Survival experiments were carried out to assess the survival capacity of animals damaged and discarded during clam dredging operations. Three common bycatch species, two fish (Trachinus vipera; Dicologlossa cuneata) and one crab (Polybius henslowii), were collected during the sorting of catches from a commercial dredging boat. An arbitrary score scale was used to quantify the type and extent of damage to the organisms. Onboard, damaged individuals were placed in tanks containing seawater which were subsequently transferred to the laboratory. Survival experiments were conducted during the subsequent 48h. D. cuneata exhibited the lowest mortality after 48h (54%), followed by P. henslowii (65%) and T. vipera (81%). Despite the magnitude of the percentage mortalities determined, the average number of individuals estimated to die during a 15 minutes tow (standard commercial fishing time) was relatively small: 1.2, 3.24 and 11 for D. cuneata, T. vipera and P. henslowii, respectively. Nevertheless, when these figures are extrapolated to cover all the dredging fleet the impact of this practice on the populations of the species studied can be significant, particulary for D. cuneata. O destino de capturas acessórias rejeitadas ao mar é uma questão de grande interesse para a pesquisa e gestão das pescas. Foram realizadas experiências de sobrevivência para avaliar a capacidade de sobrevivência dos animais danificados e rejeitados durante as operações com ganchorra, uma draga utilizada na pesca de amêijoa (bivalves). Três espécies capturadas acidentalmente, dois peixes (Trachinus vipera; Dicologlossa cuneata) e um caranguejo (Políbio henslowii), foram recolhidos durante a triagem das capturas realizadas a bordo de um barco de pesca comercial que opera com ganchorra. Uma escala de pontuação arbitrária foi utilizada para quantificar o tipo e amplitude dos danos inflingidos nos organismos. A bordo, os indivíduos danificados foram colocados em tanques com água do mar, que foram posteriormente transferidos para o laboratório. Experiências de sobrevivência foram realizadas durante as 48h subsequentes. A espécie D. cuneata exibiu a menor mortalidade após 48 horas (54%), seguido do P. henslowii (65%) e T. vipera (81%). Apesar dos valores de mortalidade percentuais determinados, o número médio de indivíduos que morreram durante 15 minutos de arrasto (tempo de pesca comercial padrão) foi relativamente pequeno, 1.2, 3.24 e 11 para D. cuneata, T. vipera e P. henslowii, respectivamente. No entanto, quando esses números são extrapolados para toda a frota da ganchora o impacto desta prática sobre as populações das espécies estudadas pode ser significativo, particularmente para a D. cuneata.
- Published
- 2014
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18. Reburial time and indirect mortality of Spisula solida clams caused by dredging
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Maria Alexandra Chícharo, J. Regala, Miguel B. Gaspar, Luís Chícharo, and Filipe Alves
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0106 biological sciences ,Fishing dredge ,Reburial time ,biology ,010604 marine biology & hydrobiology ,Fishing ,Diogenes pugilator ,Spisula solida ,Disturbance ,Aquatic Science ,Bivalvia ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Predation ,Dredging ,Fishery ,Nassarius reticulatus ,Oceanography ,Fishing impact ,Macrofauna ,14. Life underwater ,Indirect mortality ,Spisula - Abstract
Clam-dredging results in the exposure of Spisula solida individuals not caught by the dredge. Subsequent survival depends on clam damage, reburial time, and the time needed by predators to reach the impacted area.We analyse these variables and discuss the importance of predation on exposed S. solida caused by dredge fishing. Sampling was performed in July 2000 off the southern coast of Portugal, at Vilamoura, a traditional S. solida sandy fishing ground.We compared the time needed for S. solida individuals to rebury themselves, relative to the abundance of potential predators. Bivalves collected by divers were placed on the seabed, and the times required for reburial were measured. These were compared with the times needed for reburial of the clams exposed by dredge impact. At each of three dredge tracks, we analysed the number of predators that entered three equal quadrats (0.0250 m2) per minute. These results were compared with a non-affected control area. Impact caused by the fishing dredge significantly increases the number of exposed S. solida clams ðp < 0:05Þ and the abundance of potential predatory species ðp < 0:05Þ. The brittle star Ophiura texturata was the most abundant and first species to reach the dredge track (less than 3 min after dredge impact). Other species reaching the dredge track were Pomatochistus spp. (6 min after impact), Diogenes pugilator, and Nassarius reticulatus (both 9 min after impact). Although predators reached the impacted area while S. solida bivalves were still exposed, our results suggest that predation on the non-buried clams in the dredge track is not a major factor for subsequent indirect mortality of S. solida.
- Published
- 2002
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19. Population structure and species dynamics of Spisula solida, Diogenes pugilator and Branchiostoma lanceolatum along a temporal–spatial gradient in the south coast of Portugal
- Author
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Marina Dolbeth, Ivan Viegas, Filipe Martinho, João Carlos Marques, and Miguel A. Pardal
- Subjects
0106 biological sciences ,Population dynamics ,Diogenes pugilator ,Population ,Spisula solida ,Fisheries ,Aquatic Science ,Oceanography ,010603 evolutionary biology ,01 natural sciences ,Common species ,14. Life underwater ,Branchiostoma lanceolatum ,education ,Mollusca ,education.field_of_study ,biology ,Ecology ,010604 marine biology & hydrobiology ,Bivalvia ,biology.organism_classification ,Benthic zone ,Hydrodynamics ,Spisula - Abstract
The population structure, dynamics and distribution of Spisula solida , Diogenes pugilator and Branchiostoma lanceolatum , common species in the south coast of Portugal, were studied in a spatial–temporal manner in order to understand the influence of cross-shore sediment transport and anthropogenic activities. Spisula solida is harvested commercially, whereas D. pugilator and B. lanceolatum are non-target species, with little information available on the population dynamics of these species. The study was performed in 2001–2002, and along a gradient of 100–5000 m from the coastline, corresponding to a depth gradient of between 1 and 32 m deep. Spisula solida was distributed preferentially at 3–12 m deep, and its distribution appeared to be influenced seasonally by the cross-shore sediment dynamics. Results suggested benthic recruitment in June. Some recruitments had no expression (year 2001) since adults were not present, which seems to be a direct impact of clams' fisheries. Diogenes pugilator showed preferential distribution at shallow depths, from 1.3 to 8 m. Results suggested recruitments every 4 months, in June, February and October. Branchiostoma lanceolatum showed the widest distribution, from 7 to 26 m deep. Recruitment seemed to start in June until October, when it attained an abundance peak of juveniles. For both non-target species no clear effects of the cross-shore dynamics or the clams' fisheries impact were visible.
- Published
- 2006
20. A comparison of direct macrofaunal mortality using three types of clam dredges
- Author
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Gaspar, Miguel, Miguel de Sousa Leitão, Francisco, Santos, M. N., Chícharo, Luís, Dias, M. D., Chícharo, Alexandra, and Monteiro, C. C.
- Subjects
Fishing impacts ,Dredge ,Direct mortality ,Spisula solida ,Macrofauna ,Gear efficiency - Abstract
The white clam Spisula solida is harvested along the entire coast of Portugal using mechanical dredges. In this study, the total direct mortality of the macrobenthic community caused by three types of clam dredges (north dredge—ND, traditional dredge—TD, and the metallic grid dredge—GD) used in the S. solida fishery was determined and compared. The relationship between mortality and catching efficiency for each type of dredge was also assessed. Our results showed significant differences for total direct mortality between the ND and both the GD and TD dredges. This difference was largely attributed to the mortality of animals that died in the dredge track as a direct result of the physical damage inflicted by the dredge passing. It was also found that the damage to uncaught individuals is directly related to gear efficiency. The lower catching efficiency of the ND (64%) led to a higher proportion of damaged individuals being left in the dredge path, when compared with the more efficient GD (98%) and TD (90%) dredges. Short and long-term implications of the impact of dredging on the composition of benthic communities are discussed. From fisheries management and ecological points of view, there are obvious advantages to introduce into the bivalve dredge fisheries more efficient and selective dredges in order to reduce the number of damaged individuals and by-catch, and consequently decreasing the impact on the macrobenthic communities.
- Published
- 2003
21. Chronic effects of dredging-induced stress on the clam (Spisula solida): nucleic acid and lipid composition
- Author
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Maria Alexandra Chícharo, Miguel B. Gaspar, Ana Amaral, Luís Chícharo, and Sı́lvia Condinho
- Subjects
Dredging ,Ecology ,Biochemical indices ,Lipid composition ,Spisula solida ,Pecten-maximus L ,Aquatic Science ,Biology ,Bivalvia ,biology.organism_classification ,Predation ,Sublethal effects ,Animal science ,Induced stress ,Nucleic acid ,Spisula ,Mollusca ,Larval fishes - Abstract
Submitted by maria chicharo (mchichar@ualg.pt) on 2013-02-19T15:30:50Z No. of bitstreams: 1 article FISH RES CHRONIC EFFECTS NUCLEIC ACID AND LIPIDS.pdf: 118928 bytes, checksum: 77a0a415f849d1fddb4fbdc1e8702a86 (MD5) Approved for entry into archive by Merja Muzavor (mmuzavor@ualg.pt) on 2013-02-26T15:54:29Z (GMT) No. of bitstreams: 2 9565998912592254.zip: 85507 bytes, checksum: 2e144f9f1ec4b29f71012a48081e13f5 (MD5) article FISH RES CHRONIC EFFECTS NUCLEIC ACID AND LIPIDS.pdf: 118928 bytes, checksum: 77a0a415f849d1fddb4fbdc1e8702a86 (MD5) Made available in DSpace on 2013-02-26T15:54:29Z (GMT). No. of bitstreams: 2 9565998912592254.zip: 85507 bytes, checksum: 2e144f9f1ec4b29f71012a48081e13f5 (MD5) article FISH RES CHRONIC EFFECTS NUCLEIC ACID AND LIPIDS.pdf: 118928 bytes, checksum: 77a0a415f849d1fddb4fbdc1e8702a86 (MD5) Previous issue date: 2003
- Published
- 2003
22. Size selectivity of the Spisula solida dredge in relation to tooth spacing and mesh size
- Author
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Gaspar, Miguel, Miguel de Sousa Leitão, Francisco, Santos, M. N., Sobral, M., Chícharo, Luís, Chícharo, Alexandra, and Monteiro, C. C.
- Subjects
Size selectivity ,Dredge ,Tooth spacing ,Spisula solida ,Mesh size ,Efficiency - Abstract
A study was undertaken on the northwestern coast of Portugal to evaluate the selectivity effect of both tooth spacing and mesh size on the catch of the white clam (Spisula solida). Two typical clam dredges, equipped with different tooth spacing and mesh size, were towed side by side. Three tooth spacing (20, 40 and 60 mm) and three mesh sizes (35, 40 and 50 mm) were investigated. The dredge selectivity experiments were performed by attaching a cover bag with a 20mm mesh to the gear. Individual hauls were analysed by the SELECT model. The Fryer’s mixed model of between-haul variation was also applied to data. The results showed that the space between teeth does not have an effect on selectivity. Tooth length was directly related to the dredge’s capture efficiency. The only factor that contributed to dredge size selection was mesh size. The 50% retention lengths estimated for mesh sizes 30, 40 and 50mm were 25.68, 26.35 and 31.94 mm, respectively. For all mesh sizes, very narrow selection ranges were observed. The most appropriate mesh size to be enforced within the Portuguese northwestern S. solida fishery should be 40 mm.
- Published
- 2003
23. Über die Trogmuschel und deren Nutzung in der Deutschen Bucht
- Author
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Meixner, R
- Subjects
stock data ,Fisheries ,Spisula solida ,fishing techniques ,by catch ,fishing capacity ,North Sea - Abstract
Obwohl seit längerem bekannt ist, dass diese wohlschmeckende Muschel in der Nordsee vorkommt, gab es dort bis vor wenigen Jahren keine Trogmuschelfischerei. Das änderte sich erst, als es niederländischen Muschelverarbeitungsfirmen gelungen war, aus Trogmuscheln ein exportfähiges Produkt herzustellen. Dementsprechend beantragte auch ein niederländischer Muschelfischerbetrieb als Erster eine erlaubnis zum Fischen von Trogmuscheln in deutschen Gewässern außerhalb von 3 Seemeilen. Inzwischen erhielten auch vier weitere Muschelkutter die Fangerlaubnis. Allerdings wird wegen der begrenzten Absatzmöglichkeiten nur zeitweilig gefischt. Deshalb sind bisher auch noch keine Anzeichen einer Überfischung zu sehen. Johann Heinrich von Thünen-Institut, Federal Research Institute for Rural Areas, Forestry and Fisheries began publishing the Informationen aus der Fischereiforschung = Information on Fishery research in 2010
- Published
- 1994
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