谈美国红鱼海水养殖技术

美国红鱼是一种具有很高的游钓和商业价值,红鱼的肉质鲜美,鱼刺较少,并且含有不饱和脂肪酸,这种鱼类非常受欢迎。笔者主要进行探讨美国红鱼的养殖技术以及在红鱼养殖的过程中应注意的事项。     

Sensory Quality and Shelf Life of MAP Redfish (Sebastes marinus) Fillets as Affected by Previous MA Bulk Storage of Whole Fish

Abstract

The shelf life of iced redfish is known to be 16–19 days. This study evaluated the effects of modified atmosphere (CO₂/N₂: 60/40) in bulk storage of redfish and subsequent modified atmosphere packaging (MAP) of fillets. Fish were evaluated by sensory, microbiological and chemical methods. Modified atmosphere (MA) bulk storage of whole fish for more than 5 to 10 days did not improve their sensory quality or significantly increase shelf life. In fact, the study showed negative effects in texture and overall appearance. MAP of fillets processed from 10-day MA bulk stored fish showed a modest increase in shelf life, but negatively affected their texture. Sensory qualities, i.e., tenderness, that decreased under MA bulk storage were improved upon aerobic storage for fish stored under MA for 5 to 10 days, but not 14 days. Lower microbial levels were found in MA bulk stored fish and MAP fillets compared to traditionally iced fish, while higher TMA levels were found in MAP fillets.     

Precision and Application of Electronic Nose for Freshness Monitoring of Whole Redfish (Sebastes marinus) Stored in Ice and Modified Atmosphere Bulk Storage

Abstract

An electronic nose with electrochemical gas sensors (CO, NH₃, SO₂ and H₂S) was used as a rapid technique to monitor changes in the headspace of whole ungutted redfish (Sebastes marinus) stored in ice and under various conditions of modified atmosphere (MA) bulk storage (CO₂/N₂:60/40). The precision of the electronic nose measurements was determined using standard compounds (ethanol, trimethylamine, acetal-dehyde and dimethyldisulfide). The response of the CO sensor, suggesting the formation of alcohols and carbonyls, increased with time for both aerobic and MA storage and correlated well with sensory analysis using the Quality Index Method. Slower spoilage rate reflected by lower intensities of sensors' responses, lower microbial counts and less TMA production were observed in MA-stored redfish compared with aerobic storage in ice.     

Dietary vitamin C requirement of red drum Sciaenops ocellatus

A feeding trial was conducted to determine the minimum dietary vitamin C requirement of juvenile red drum and characterize signs of vitamin C deficiency. Semipurified diets containing 400 g crude protein kg^–1 from lyophilized red drum muscle and crystalline amino acids were used in the feeding trial. The basal diet without supplemental vitamin C contained ≈ 6 mg vitamin C kg^–1 and was fed for a 1-week conditioning period. Red drum, initially averaging ≈ 3.6 g each, were fed diets supplemented with 0, 10, 20, 30, 45, 60, 75, or 150 mg vitamin C kg^–1 as ascorbate polyphosphate for a period of 10 weeks. Fish fed the basal diet began to exhibit overt signs of vitamin C deficiency, including reduced weight gain, lordosis, scoliosis and loss of equilibrium after 8 weeks. Total ascorbate was undetectable in liver of fish fed the basal diet while liver ascorbate levels in fish fed the other diets generally reflected dietary supplementation. Regression analysis of weight gain data using the broken-line model resulted in a minimum vitamin C requirement ( ± SE) of 15 ± 3 mg kg^–1 diet.     

Anisakid nematodes in beaked redfish (Sebastes mentella) from three fishing grounds in the North Atlantic,with special notes on distribution in the fish musculature

Parasitic anisakid nematodes commonly occur in the musculature and visceral organs of many fish species from the North Atlantic. In this respect, the presence of the third stage larvae of Anisakis spp. in the fish musculature may pose a potential consumer hazard due to the parasite's ability to cause anisakidosis. Thus, knowledge on the occurrence and distribution of these potentially zoonotic parasites in the commercially important North Atlantic fish species is crucial in order to evaluate and consequently prevent human infections.In the present study, 300 Sebastes mentella from three North Atlantic fishing grounds (Northern North Sea: Tampen; Barents Sea: off Bear Island; Irminger Sea: off SE Greenland) were examined for anisakid nematodes, with emphasis on occurrence and distribution in the musculature. Overall larval prevalence and mean intensity were significantly higher in redfish from Tampen (94%; 13.5 ± 20.0) and Bear Island (94%; 14.5 ± 19.4) than in fish from SE Greenland (75%; 6.0 ± 5.8; p < 0.01). The same trend was observed for larval infection in the musculature showing prevalence and mean intensities of 79%, 73%, and 55%, and 5.9 ± 6.6, 5.8 ± 6.5, and 3.2 ± 2.4, in the musculature of redfish from Tampen, Bear Island, and Greenland, respectively. Conventional microscopy and rDNA ITS-gene sequencing of various subsamples of muscle-dwelling nematode larvae of redfish from every catching locality revealed the presence of two anisakid species; Anisakis simplex sensu stricto and the non-zoonotic Hysterothylacium aduncum. Since the larvae of H. aduncum typically occur in or on the viscera of fish, our findings of two specimens in the belly flaps of redfish were unusual. Additionally, more than 92% of the muscle-dwelling larvae occurred in the belly flaps, i.e. the hypaxial part of the musculature surrounding the visceral organs on either fish side. Thus, trimming the fillets of beaked redfish by removal of most of the belly flaps would significantly reduce the probability of anisakid nematode larvae to be present in the final product.     

The role of environmental conditions and exploitation in determining dynamics of redfish (Sebastes species) in the Northwest Atlantic

The six stocks of redfish (Sebastes spp.) in the Northwest Atlantic have been fished for the past 60 years, during which time they have also experienced considerable variability in environmental conditions. Despite their close proximity and with life‐history features characteristic of many deep‐sea fishes (long‐lived, slow‐growing, late‐maturing, relatively low fecundity), each redfish stock has displayed quite different dynamics. Some have been able to support apparently sustainable fisheries, whereas others have been forced to close. The causes of such differences are unclear. We used dynamic factor analysis to determine the relative impacts of exploitation (days fishing for redfish, days fishing for shrimp, days fished by all fisheries, catch in the redfish fishery, total redfish catch) and environment (North Atlantic Oscillation, surface temperature, salinity, shallow, middle, and deep bottom temperatures) on trends of abundance in each stock over the years 1960–2004. The results showed that a mix of exploitation and environmental variability, with various and different lag times, accounted for observed trends. The Gulf of St. Lawrence stock was affected most by exploitation. Flemish Cap and northern Newfoundland‐Labrador stocks were mostly affected by environmental factors with longer time lags than more southerly stocks. We conclude that management of redfish must take into account individual responses to exploitation and environment over the time periods during which such factors operate, often decades or more, as opposed to the usual practice of reviewing only dynamics of the past few years. Deep‐sea populations cannot be managed on the same scales as shelf fisheries.