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1.
Holding wild Snow crab,Chionoecetes opilio: effects of stocking density and feeding on survival and injury 
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下载免费PDF全文 Sten Ivar Siikavuopio Philip James Bjørn Ronald Olsen Tor Evensen Atle Mortensen Stein Harris Olsen 《Aquaculture Research》2017,48(4):1590-1595
In this study the effects of different stocking densities on survival, injury and weight of captive male snow crab were examined. The first experiment (I) was carried out in square plastic tanks (700 L) with stocking densities of 100 (L), 150 (M) and 200 kg m?3 (H) for 30 days. In a second experiment (II) snow crabs were kept at a stocking density of 50 kg m?3 and were either fed (F) or not fed (S) for the same period of 35 days. The last experiment (III), was carried out with stocking densities of 25 kg m?3 for 21 days with two groups, one with inactivated claw and one without rubber bands, with three replicates per treatment. In the first experiment mortality (H = 27, M = 26 and L = 36%) and occurrence of injuries (H = 27, M = 20 and L = 16%) were high in all groups. The weight loss during the experimental period was; H = 15.3, M = 10.9 and L = 15.5 g, and was not significant different between the groups. In experiment II the mortality (F = 13% and S = 14%) and injuries were lower (F = 12% and S = 17%). The average weight increased in the fed treatment and decreased in the starved treatments. In the last experiment there was no mortality in any of the groups and the levels of injury were low (5% and 7%). The results show that adult male snow crab cannot be stored at densities equal to or higher than 25 kg m?3 for 3 weeks without risk of mortality. 相似文献
2.
The snow crab (Chionoecetes opilio) is one of the most important commercial crabs in the world; it is heavily exploited in Atlantic Canada, Alaska, the Sea of Japan and the Barents Sea. Catches in the Barents Sea north of Norway have increased dramatically in the last decade. Most of the world's catch is processed, frozen and exported overseas. However, recently there has been considerable interest in exporting live snow crab, particularly in Norway. The stress of capture and live transport can result in significant mortalities. In order to establish a live export industry for snow crab, the welfare of the animal must be monitored throughout all the steps of the live transport process. In this study the reactions of snow crabs exposed to increasing periods of air exposure were measured in terms of reflex indicators, incidence of mortality, blood lactate levels and blood protein and haemocyanin. Although this is not a specific live holding or live transport process the aim was to test the suitability of reflex indicators to reflect vitality (stress) and not just to predict mortality. This would be compared with traditional blood biochemistry techniques for measuring crustacean stress. The study demonstrated that the reflex index score (RIS) is suitable to assess the vitality of snow crab. Longer air exposure periods render higher mortality rates and less vital individuals. The authors believe using vitality reflex indicators would be a suitable way of measuring crab welfare during the live holding and transport process. 相似文献
3.
A total of 12,755 adult male snow crabs (Chionoecetes opilio) were tagged with spaghetti–Carlin tags in 33 sites throughout the southern Gulf of St. Lawrence (sGSL) and eastern Nova Scotia (eNS) between 1993 and 2003. Of the 1971 tag returns obtained between 1994 and 2004, 1703 had accurate geographical recapture positions. The average distance travelled was 16.7 km for sGSL (maximum 165 km) and 61.5 km for eNS (maximum 368 km). The release site and the number of days at liberty before recapture were significant factors affecting the distance travelled by the crabs. Size had no significant effect on the distance travelled or the direction of movement. The present observations support the sedentary nature previously reported for the sGSL snow crab stock, but not the eNS stock, where the movement of snow crab was more dynamic. In both regions, there were movements between management areas, which indicates that managing the fisheries in discrete units is not warranted. 相似文献
4.
Larval rearing experiments were conducted to examine the potential for mass seed production of the snow crab Chionoecetes opilio using a total of eight 20-kL tanks. Tanks were equipped with agitators, which move the water using a rectangular blade to
prevent the zoeas sinking to the bottom of the tank. Larval rearing water was treated with sodium nifurstyrenate once a week
to reduce the chance of larval infection by pathogenic bacteria. Zo eas were fed with rotifers and Artemia nauplii. A total of 122 830 megalops and 16 660 first-stage crabs were produced. Thus, the potential for mass seed production
of snow crab was determined. Survival rates up to the megalopal stage were high in tanks with a feeding regime that fed rotifers
to larvae through an entire zoeal stage. This study also describes the fatty acid composition of snow crab larvae. It revealed
that the first zoeas had a high DHA content and DHA/EPA ratio, but these values significantly decreased in the second stage
zoeas and megalops. Improving the DHA content and/or DHA/EPA ratio of larvae should be important in studies on mass seed production
technology of the snow crab. 相似文献
5.
Yuji Ueda Masaki Ito Tsutomu Hattori Yoji Narimatsu Daiji Kitagawa 《Fisheries Science》2009,75(1):47-54
Terminal molting probability (TMP) of snow crab Chionoecetes opilio was estimated using instar- and state-structured model incorporating the terminal molt in the waters off the Pacific coast
of northern Honshu, Japan. TMP is defined as the probability that terminal molt occurs within a year in an instar and is an
important parameter for stock assessment. TMP was estimated from the model and the rate of terminal molted crabs (RTM) for
instars, which means carapace widths over 30 mm. Carapace widths at RTM of 0.5 were 81 mm for males and 66 mm for females.
TMP was estimated as 0.23 and 0.29 for these carapace widths, respectively. Carapace widths at TMP of 0.5 were 94 mm for males
and 71 mm for females, and for these carapace widths 57% of male and 50% of female crabs were considered as old-shell which
had survived 1 year or more from terminal molt. Changing the fishing or natural mortality by ±0.1, the maximum difference
of TMP was less than 0.1 from default estimates. 相似文献
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7.
James E. Overland Nicholas A. Bond & Jennifer Miletta Adams 《Fisheries Oceanography》2001,10(1):69-80
In the summer of 1997, positive sea surface temperature anomalies (SSTA) extended across the Gulf of Alaska (GOA) and into the eastern Bering Sea (EBS). The SSTA in the EBS are at least in part due to atmospheric causes. Anomalously high 925 mb temperatures and 700 mb geopotential heights and low 925 mb relative humidities, and hence decreased low cloud cover, occurred over the region during April to August. This resulted in enhanced warming of the GOA and EBS owing to increased insolation. The anomalous solar heating was particularly great in the EBS from mid-May to mid-July. The pattern of positive 700 mb height anomalies for April to August 1997 is similar to its counterpart formed by compositing the April to August anomalies that occurred during previous El Niños. The positive equatorial SSTA for 1997 was one of the strongest on record for summer months. The existence of an equatorial/high-latitude connection and the strength of the summer equatorial SSTA in 1997 suggest an El Niño/Southern Oscillation (ENSO) influence in the GOA and EBS. The warming in the Bering Sea and North Pacific during summer 1997 appears to be due in part to the confluence of three meteorological factors which favoured clear skies. There was not only an El Niño influence, but also a decadal trend toward higher 700 mb geopotential heights and a particularly strong blocking ridge weather pattern over the Gulf of Alaska in May. 相似文献
8.
Effects of water temperature and wind on year-class success of Tanner crabs in Bristol Bay, Alaska 总被引：2，自引：0，他引：2
We investigated five a priori hypotheses on factors affecting year-class success of commercially exploited Tanner crabs, Chionoecetes bairdi , in Bristol Bay, Alaska, through correlation analysis and multiple regression modelling. Estimates of recruitment from Zheng et al .' s (1998 ; Can. Spec. Publ. Fish. Aquat. Sci. 125:97–105) length-based analysis of assessment survey and commercial catch data were used to index year-class strength. This work extends results of an earlier study ( Rosenkranz et al ., 1998 ; Alaska Fish. Res. Bull. 5:18–24), which reported positive correlations between Tanner crab year-class size and north-east (NE) winds during the spring larval period, by considering the effects of nondirectional wind speed, bottom and surface water temperature, and abundance of the potential predators sockeye salmon ( Oncorhynchus nerka ) and Pacific cod ( Gadus macrocephalus ). No relationships were found between year-class size and mean wind speed or predator abundance, but positive correlations were found with bottom temperatures during gonadal development and egg incubation. Linear regression models with the independent variables NE wind and bottom temperature accounted for about half the variability in the year-class strength index ( r 2 =0.50 for males, r 2 =0.48 for females). Anomalously cold bottom temperatures may adversely affect the Tanner crab reproductive cycle, and NE winds may promote coastal upwelling while advecting larvae to regions of fine sediments favourable for survival upon settling. The role of Bering Sea oceanography on decadal-scale variability in Tanner crab population dynamics could not be resolved with the relatively short (∼ two decades) time series of stock assessments. 相似文献
9.
Shifts in climate regime are prominent features of the physical environment of the eastern Bering Sea and in recent years have been documented in approximately 1977 and 1989. Average snow crab (Chionoecetes opilio) recruitment decreased sharply after the 1989 fertilization year. Models in which control of snow crab recruitment shifts between drivers dependent on climate ‘regime’ are presented. These models are evaluated using cross‐validation and retrospective analysis, both of which indicate that the relationships are relatively robust to varying levels of information. Larval survival as influenced by food availability in the pelagic phase and advection to suitable nursery grounds are the hypothesized mechanisms driving recruitment dynamics. 相似文献
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