Seasonal spatial distribution of juvenile lake sturgeon in Muskegon Lake,Michigan, USA

We examined seasonal spatial distribution and diel movements of juvenile lake sturgeon Acipenser fulvescens in Muskegon Lake, Michigan (a protected, drowned river mouth lake that links the Muskegon River to Lake Michigan). We surgically implanted ultrasonic tags in 20 juveniles (age 1–7) captured in gill nets to track their locations during August–December 2008/2009 and September 2010–October 2011. Most juveniles were observed ≤1.5 km from the mouth of the Muskegon River in Muskegon Lake at a mean depth of 7.5 m (SE = 1.3 m) during summer. In fall, juveniles moved away from the river mouth to the deepest part of Muskegon Lake and were observed at a mean depth of 15.8 m (SE = 1.3 m) during winter. The shift in spatial distribution coincided with fall turnover (i.e., loss of thermal stratification) and with changes in dissolved oxygen (DO) concentrations in the hypolimnion. During summer, DO concentrations in the hypolimnion were typically <4 mg·l^?1 in the deepest part of Muskegon Lake and DO concentrations at locations of tagged lake sturgeon were >7 mg·l^?1 in 94% of instances. Tracking in 2009 revealed no significant change in depth distribution or movement over the diel cycle. We only observed two tagged juveniles immigrating to Lake Michigan, suggesting that juveniles use Muskegon Lake for multiple years. Our results suggest that: (i) Muskegon Lake serves as an important nursery habitat for juvenile lake sturgeon that hatched in the Muskegon River before they enter Lake Michigan and (ii) seasonal changes in DO concentration in the hypolimnion likely affect the spatial distribution of juveniles in Muskegon Lake.     

五种养殖鲟、鳇鱼DNA含量的比较

采用德国Partec Pas Ⅲ型流式细胞仪,以鸡红细胞为标准DNA(含量为2.3pg/N),测定了俄罗斯鲟(Acipenser gueldenstaedti Brandt)、西伯利亚鲟(Acipenser baerii Brandt)、史氏鲟(Acipenser schrencki Brandt)、小体鲟(Acipenser ruthenus Linnaeus)和达氏鳇(Huso dauricus Ceorgi)的体细胞DNA含量。结果表明,在上述五种鲟鱼类的DNA含量中,俄罗斯鲟、西伯利亚鲟和史氏鲟的DNA含量非常接近,分别为12.24pg/N,11.60ps/N,11.59pg/N,三种鲟鱼相比较差异并不显著。小体鲟和达氏鳇的DNA含量是6.06pg/N和4.77pg/N,两种鱼相比较差异也不显著。但与上述三种鲟鱼相比较DNA含量几乎相差1倍。从测定的结果并结合已发表的有关鲟鱼类资料可以确定俄罗斯鲟,西伯利亚鲟和史氏鲟属于八倍体类型,而小体鲟和达氏鳇则属于四倍体类型。     

Bayesian modelling suggests that the sterlet (Acipenser ruthenus,Linnaeus 1758) population is ageing in the middle Danube River

1. In the past, sturgeons played an important role in commercial and recreational fisheries in the Danube River and its tributaries. Human impacts in the Danube River Basin coupled with exploitation of sturgeon stocks led to all species being either locally extinct, critically endangered or of unknown status.
2. Sterlet (Acipenser ruthenus, Linnaeus 1758) is the last known sturgeon species occurring in the upper and middle Danube; however, the population of this species is considered unbalanced and decreasing since the beginning of the twenty-first century.
3. The decline of sturgeon stocks has been noted before owing to their economic importance. With commercial fisheries being forbidden in the Slovak section of the Danube River, there is generally no information available about the status of what is considered a local population.
4. Databases containing recreational catch of sterlet (2003–2018) and historical records of commercial harvest (1961–1990) were used to describe the trend in the weight and number of sterlet caught over the following years.
5. Modelling indicated that the number of fish caught each year appears to be lower, while the average weight of each individual is increasing. This might suggest that the population is ageing.
6. Although older individuals can contribute a great deal more to spawning because they produce a greater number of eggs, several problems are apparent. The number of spawners might be decreasing as a result of bycatch or fishing, their ability to spawn might be obstructed, or annual recruitment may fail owing to unpredictable events.
7. Although restocking programmes are in place to help maintain the sterlet population in the Danube River, their efficiency seems to be drastically low. In fact, restocking could be of little value unless studies on the availability of key habitats are conducted and their protection and restoration are ensured.

     

5种鲟、鳇鱼基因组DNA遗传多样性分析

以史氏鲟(Acipenserschrencki)、达氏鳇(Husodauricus)俄罗斯鲟(A.gueldenstaedti)、小体鲟(A.ruthenus)西伯利亚鲟(A.baeri)的基因组DNA为实验材料,用改进的DNA提取方法获得了完整的基因组DNA片段。通过25个SSLP及Ⅰ型引物对5种鲟鳇鱼的基因组DNA进行PCR多态性引物筛选,获得11个能扩增出遗传多态性的有效引物,通过对5种鱼的PCR分析,平均遗传距离为0.748,遗传距离最大的为达氏鳇和小体鲟之间为0.9355,DNA分析结果还显示,鲟鳇鱼的遗传多样性程度十分低下(47.93%)。同时建立了5种鲟鳇鱼的聚类图。     

五种养殖鲟、鳇鱼DNA含量的比较

采用德国Partec Pas Ⅲ型流式细胞仪,以鸡红细胞为标准DNA(含量为2.3pg/N),测定了俄罗斯鲟(Acipenser gueldenstaedti Brandt)、西伯利亚鲟(Acipenser baerii Brandt)、史氏鲟(Acipenser schrencki Brandt)、小体鲟(Acipenser ruthenus Linnaeus)和达氏鳇(Huso dauricus Ceorgi)的体细胞DNA含量。结果表明,在上述五种鲟鱼类的DNA含量中,俄罗斯鲟、西伯利亚鲟和史氏鲟的DNA含量非常接近,分别为12.24pg/N,11.60ps/N,11.59pg/N,三种鲟鱼相比较差异并不显著。小体鲟和达氏鳇的DNA含量是6.06pg/N和4.77pg/N,两种鱼相比较差异也不显著。但与上述三种鲟鱼相比较DNA含量几乎相差1倍。从测定的结果并结合已发表的有关鲟鱼类资料可以确定俄罗斯鲟,西伯利亚鲟和史氏鲟属于八倍体类型,而小体鲟和达氏鳇则属于四倍体类型。     

Characterization of two molecular forms of vasoactive intestinal polypeptide (VIP) from the pallid sturgeon, Scaphirhynchus albus (Acipenseriformes)

Vasoactive intestinal polypeptide (VIP) was isolated in two molecular forms from an extract of the gastroenteropancreatic system of the pallid sturgeon Scaphirhynchus albus (Acipenseriformes). VIP-1 was identical to the peptide previously isolated from the rainbow trout Oncorhynchus mykiss and the bowfin, Amia calva, consistent with the proposed sister group relationship of the Acipenseriformes and the Neopterygii. Sturgeon VIP-2 contained the amino acid substitution (Ala⁴ to Ser) at a site previously regarded as invariant. The isolation of two distinct VIP gene products provides some support for the hypothesis that S. albus, with approximately 120 chromosomes, is functionally tetraploid but the alternative view that the species is functionally diploid and the two peptides arose from a local duplication of the VIP gene within the Scaphirhynchus lineage cannot be rejected. This revised version was published online in August 2006 with corrections to the Cover Date.     

Viability of diploid and triploid larvae of Siberian sturgeon and bester hybrids

The aim of the present study was to produce Acipenser baeri× (Huso huso×Acipenser ruthenus) hybrids in a diploid and triploid state and to study their viability in comparison with the A. baeri from the fish farm stock. A heat shock (37°C) in the 18th minute after fertilization was applied to induce triploidy. The survival rate and the ploidy level of the hybrids obtained were studied. The mortality of triploid hybrids was approximately twice as high as the mortality of diploid hybrids. No significant difference in the survival rate between Siberian sturgeon and their diploid hybrid with bester was noted. Cytogenetic analysis was performed by preparing chromosomes from the gill epithelium. The results showed that all studied fish from the heat‐shocked group were triploid.     

Test of Mendelian segregation among 10 microsatellite loci in the fourth generation of bester (Huso huso L. ×Acipenser ruthenus L.)

Ten microsatellite loci were tested on Mendelian segregation in the bester – hybrid of beluga, Huso huso L. and sterlet, Acipenser ruthenus L. in the fourth generation. All studied loci showed disomic inheritance and Mendelian segregation of their alleles. The molecular approach by microsatellite DNA analysis represents a reliable tool for interspecific characterization of sturgeons and their hybrids (different alleles of several loci are present in sturgeon fishes, and interspecific hybrids posesses both maternal and paternal specific alleles). This is the first report of the Mendelian segregation testing in interspecific hybrid of acipenserid fishes using microsatellite DNA markers.     

Inheritance of microsatellite loci in polyploid Siberian sturgeon (Acipenser baeri Brandt) based on uniparental haploids

Haploid gynogenesis was induced in Siberian sturgeon (Acipenser baeri Brandt) using UV‐irradiated bester (hybrid of Huso huso L. and Acipenser ruthenus L.) sperm. The inactivated heterologous sperm was used successfully to produce gynogenetic haploids of Siberian sturgeon. All haploid progeny were screened using microsatellite DNA analysis and uniparental transmission in gynogenetic haploids was confirmed. The objective of this study was to obtain haploids of Siberian sturgeon and describe the inheritance of microsatellite loci in haploid embryos of this species. This initial work, based on inheritance in haploid Siberian sturgeon, suggests that three studied microsatellite loci segregate disomically, three tetrasomically and one octasomically.     

我国鲟鱼类养殖现状及发展前景

我国鲟鱼类天然资源数量稀少，难以满足市场巨大需求，近年来鲟鱼养殖在我国各地快速发展。本文总结了我国鲟鱼养殖的主要种类史氏鲟、俄罗斯鲟、西伯利亚鲟、匙吻鲟等生物学特性．鲟鱼养殖的主要方式网箱养殖、池塘养殖和工厂化养殖．并且阐述了目前我国鲟鱼养殖的规模和发展前景．预计鲟鱼可能是我国海水网箱养殖的优良新品种。