A synthesis of large-scale patterns in the planktonic prey of larval and juvenile cod (Gadus morhua)     

M. R. HEATH  R. G. LOUGH 《Fisheries Oceanography》2007,16(2):169-185

Data from 40 published studies of the diet composition of larval and juvenile cod (Gadus morhua) from around the northern North Atlantic were summarized to assess generic patterns in ontogenetic and regional variability in the key prey. The results showed that larvae at the northern edge of the latitudinal range of cod depend primarily on development stages of the copepod Calanus finmarchicus, whilst those at the southern edge depend on Para‐ and Pseudocalanus species. Juvenile cod preyed on a wider range of taxa than larvae, but euphausiids were the main target prey. Analysis of regional variations in the relative abundances of C. finmarchicus and Para/Pseudocalanus spp. in the plankton, as estimated by the continuous plankton recorder (CPR) surveys, showed a similar geographical pattern to the larval cod stomach contents. Comparison of CPR data from the 1960s and 70s with data from the 1990s showed that the boundary between C. finmarchicus and Para/Pseudocalanus spp. dominance has shifted northwards on both sides of the Atlantic, whilst the abundance of euphausiids in the southern cod stock regions has declined. The results are discussed in relation to regional differences in the response of cod stocks to climate variability.  相似文献   

Nutrient composition and metamorphosis success of Atlantic halibut (Hippoglossus hippoglossus, L.) larvae fed natural zooplankton or Artemia   总被引：1，自引：0，他引：1  

K. HAMRE  I. OPSTAD  M. ESPE  J. SOLBAKKEN  G.-I. HEMRE  & K. PITTMAN 《Aquaculture Nutrition》2002,8(2):139-148

Atlantic halibut larvae were fed docosohexanoic acid- (DHA) selco enriched Artemia (RH-cysts) or wild zooplankton in duplicate tanks from first-feeding and 60 days onward. The zooplankton were collected from a fertilized sea water pond and consisted mainly of different stages of Eurytemora affinis and Centropages hamatus . There were no differences in survival, or in growth during the first 45 days of feeding, between larvae fed the two prey items, but the larvae fed Artemia showed much higher incidence of malpigmentation and impaired eye migration than larvae fed zooplankton. The prey organisms contained similar amounts of dry matter and protein, but Artemia was higher in lipid and glycogen than the zooplankton. Larvae fed Artemia were higher in both glycogen and lipid than the zooplankton-fed larvae towards the end of the feeding period. There were large differences between the prey organisms in the concentrations of essential fatty acids (% of total fatty acids) which was reflected in the fatty acid composition of the larval body. It is concluded that the macronutrient composition of Artemia in the present study was probably within the optimal range for promotion of growth and survival in young Atlantic halibut. The concentration of n-3 HUFA, and especially DHA, is however, very much lower in enriched Artemia than in copepods, and may be one of the factors triggering developmental errors in Atlantic halibut.  相似文献   

我国远洋渔业的发展浅析     

吕祥  李璐  骆乐 《渔业经济研究》2007,(3):20-22

我国远洋渔业自新中国成立后有了长足发展，但是，仍然面临着严重的问题。尤其是《国际海洋法》生效后，我国远洋渔业的发展环境将更加严峻。因此，政府应该通过加大投资力度、开展渔业外交、寻找新的合作伙伴等措施来积极推动远洋渔业的发展。  相似文献   

Carbon source and trophic position of pelagic fish in coastal waters of south-eastern Izu Peninsula,Japan, identified by stable isotope analysis     

Noriyuki Takai  Noriyuki Hirose  Takuya Osawa  Kazuyuki Hagiwara  Takahito Kojima  Yuji Okazaki  Tomohiro Kuwae  Toru Taniuchi  Kiyoshi Yoshihara 《Fisheries Science》2007,73(3):593-608

ABSTRACT:   It is important to clarify trophic dynamics in marine ecosystems for management of the fishing ground. Organic carbon sources and trophic position of pelagic fishes in the coastal waters of the south-eastern Izu Peninsula, Japan, were examined on the basis of carbon and nitrogen stable isotope distributions. The δ¹³C of the fishes was mostly distributed from −19 to −16‰ for nektonic fishes (13 species of adults and immatures) and planktonic fishes (10 species of larvae and juveniles), close to the δ¹³C values of particulate organic matter and planktonic decapods. These δ¹³C signatures for the inhabitants of the water column were in contrast with the high δ¹³C values (mainly −16 to −13‰) for demersal fishes of Scorpaeniformes and benthic polychaetes collected in the surf zone. These results indicate that nektonic and planktonic fishes depend on phytoplankton for carbon supply. The δ¹⁵N signatures suggest that the trophic position ranged 3.1–4.5 for the nektonic fishes and 2.9–3.7 for the planktonic fishes, premised on trophic level 3 for larval Japanese anchovy Engraulis japonicus . Thus, planktivorous fishes should be mainly assigned to trophic levels 3 and 4 in this area.  相似文献   

Influence of storage conditions on viability of quiescent copepod eggs (Acartia tonsa Dana): effects of temperature, salinity and anoxia     

Martin Holmstrup  Johannes Overgaard  Thomas F. Sørensen  Guillaume Drillet  Benni W. Hansen  Hans Ramløv  & Kirsten Engell-Sørensen 《Aquaculture Research》2006,37(6):625-631

Copepods have proven to be an ideal source of live food for the production of marine fish larvae in aquaculture. Therefore, there is a need to develop new methods for production and storage of copepod eggs that can be hatched and used at fish farms. In the present study quiescent eggs of Acartia tonsa were stored for periods up to 35 weeks at different temperatures, salinities and oxygen conditions in a full factorial experiment. None of these storage conditions seemed to induce diapause in eggs even though this has been reported by other authors. The most promising storage conditions were those involving low temperature (<5°C), medium salinity (10–20 ppt) and anoxia. The practical aspects of these results for aquaculture are discussed.  相似文献   

Hypoxia-based habitat compression of tropical pelagic fishes   总被引：2，自引：0，他引：2  

ERIC D. PRINCE  C. PHILLIP GOODYEAR 《Fisheries Oceanography》2006,15(6):451-464

Large areas of cold hypoxic water occur as distinct strata in the eastern tropical Pacific (ETP) and Atlantic oceans as a result of high productivity initiated by intense nutrient upwelling. We show that this stratum restricts the depth distribution of tropical pelagic marlins, sailfish, and tunas by compressing the acceptable physical habitat into a narrow surface layer. This layer extends downward to a variable boundary defined by a shallow thermocline, often at 25 m, above a barrier of cold hypoxic water. The depth distributions of marlin and sailfish monitored with electronic tags and average dissolved oxygen (DO) and temperature profiles show that this cold hypoxic environment constitutes a lower habitat boundary in the ETP, but not in the western North Atlantic (WNA), where DO is not limiting. Eastern Pacific and eastern Atlantic sailfish are larger than those in WNA, where the hypoxic zone is much deeper or absent. Larger sizes may reflect enhanced foraging opportunities afforded by the closer proximity of predator and prey in compressed habitat, as well as by the higher productivity. The shallow band of acceptable habitat restricts these fishes to a very narrow surface layer and makes them more vulnerable to over‐exploitation by surface gears. Predictably, the long‐term landings of tropical pelagic tunas from areas of habitat compression have been far greater than in surrounding areas. Many tropical pelagic species in the Atlantic Ocean are currently either fully exploited or overfished and their future status could be quite sensitive to increased fishing pressures, particularly in areas of habitat compression.  相似文献   

Interannual variation in Neocalanus biomass in the Oyashio waters of the western North Pacific     

KAZUAKI TADOKORO  SANAE CHIBA  TSUNEO ONO  TAKASHI MIDORIKAWA  TOSHIRO SAINO 《Fisheries Oceanography》2005,14(3):210-222

We examined the interannual variation in Neocalanus copepod biomass in the Oyashio waters in spring and summer from 1972 to 1999. In the mid‐1970s, mesozooplankton biomass in spring was high; however, it decreased significantly in the late 1970s. The timing of the decrease in mesozooplankton biomass corresponded to the 1976/77 climatic regime shift. The biomass of N. flemingeri, which dominated the Neocalanus community, was roughly constant from 1980 to 1999. Although species‐level estimates of Neocalanus biomass were not available for the 1970s, a previous study reported that Neocalanus copepods were the predominant mesozooplankton in the Oyashio waters in spring during the 1970s. Neocalanus copepods dominated the mesozooplankton community throughout the 1970s, and their biomass decreased in the late 1970s. Springtime net community production, an index of new production, also decreased in the late 1970s. We suggest that the reduction in new production negatively affected Neocalanus food availability, resulting decreased copepod biomass. New production may have been limited by a combination of subsurface iron supplies, increased vertical density gradient, and reduced vertical water mixing in winter, which resulted in diminished iron entrainment in winter. In summer, mesozooplankton biomass significantly decreased and increased synchronously with the 1976/77 and 1988/89 climatic regime shifts. The biomass of N. plumchrus, which dominated the Neocalanus community, was low in the 1980s and increased in the early 1990s. The biomass of the second‐most dominant copepod, N. cristatus, also increased in the early 1990s. Neocalanus copepods were reported to be a dominant component of the mesozooplankton community in the 1970s; Neocalanus biomass was high in the mid‐1970s and decreased in the late 1970s. Japanese sardine (Sardinops melanostictus), an important predator of Neocalanus copepods, exhibited interannual variation in standing stock that was inversely related to mesozooplankton biomass. At their peak in 1984, sardines consumed 32–138% of the daily Neocalanus production during summer. Therefore, predation pressure on Neocalanus by Japanese sardine is likely to affect interannual variation in mesozooplankton biomass during the summer.  相似文献   

Newly designed quantitative frame trawl for sampling larval and juvenile pelagic fish   总被引：1，自引：1，他引：1  

Yoshioki  OOZEKI  Fuxiang  HU  Hiroshi  KUBOTA  Hiroya  SUGISAKI  Ryo  KIMURA 《Fisheries Science》2004,70(2):223-232

  相似文献   

光诱鱿鱼浮拖网渔具渔法试验          下载免费PDF全文

戴天元  洪明苇等 《上海海洋大学学报》2001,(1):26-30

首先对诱鱼光场进行计算，并分析其对光诱鱿鱼浮拖网作业的影响，据此合理配置了灯光强度及其布局，探讨了一套较有效的诱导渔方法。根据鱿鱼的趋光习性及浮拖网的特点，设计了适应在较深渔场作业的光诱浮拖网渔具，并成功地试验了光诱鱿鱼浮拖网柔性网板；取得了良好的社会生态效益和经济效益。  相似文献   

Effect of environmental conditions on the seasonal and inter‐annual variability of small pelagic fish abundance off North‐West Africa: The case of both Senegalese sardinella          下载免费PDF全文

Modou Thiaw  Pierre‐Amaël Auger  Fambaye Ngom  Timothée Brochier  Saliou Faye  Ousmane Diankha  Patrice Brehmer 《Fisheries Oceanography》2017,26(5):583-601

The objective of this study was to assess the effect of environmental variations on the abundance of Sardinella aurita and Sardinella maderensis in Senegalese waters in the upwelling system. Monthly data indicating the abundance of sardinella were first estimated from commercial statistics, using Generalized Linear Model from 1966 to 2011. Abundance indices (AIs) were then compared with environmental indices, at the local scale, a Coastal Upwelling Index (CUI) and a coastal Sea Surface Temperature (SST) index, and on a large scale, the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO) and the Multivariate El Niño Southern Oscillation Index (MEI), using correlations and times series analyses. The results showed that the abundance of sardinella is determined by a strong seasonal pattern and inter‐annual fluctuations. The abundance of S. aurita peaked in spring and in autumn, whereas that of S. maderensis peaked in the warm season (July–September). The trend of the sardinella abundance was significantly correlated with the CUI, especially in autumn and spring. Interannual fluctuations of S. maderensis and S. aurita abundance are, respectively, driven by the precocity and the duration of the upwelling season that is attributed to distinct migration patterns. Both sardinella species also respond with a delay of around 4 years to the winter NAO index and the autumn CUI, and the AMO index, respectively, both related to migration patterns. The wide variations in sardinella biomass are caused by variations in environmental conditions, which should be considered in the implementation of an ecosystem‐based approach in sardinella stocks management.  相似文献