A review of endangered and threatened chondrostean (sturgeon and paddlefish) species is given It is shown that at least three species from the territory of the former Soviet Union are the most endangered Among them is the large Amu-Dar shovelnose Pseudoscaphirhynchus kaufmanni, which seems to be the last survivor of the most primitive group among sturgeons, still living in the region where it originated These facts call for quick conservation efforts Because of the present economic crisis in Russia, there is no hope that such effort can be made by Russian scientists alone Saving sturgeons should be a goal of the international community



Resumen: Se presenta una revision de especies condrosteas (esturion y pez espatula) en peligro y amenazadas Se muestra que por lo menos tres especies del territorio de la ex Union Sovietica son las mas comprometidas Entre ellas se encuentra el gran Amu-Dar Pseudoscaphirhyncus kaufmanni, que parece ser el ultimo sobreviviente del grupo mas primitivo de esturiones, que aun vive en la region donde fue originado Estos hechos claman un pronto esfuerzo conservacionista Debido a la crisis economica actual en Rusia, no hay esperanzas de que tales esfuerzos puedan ser realizados solo par cientificos rusos La salvacion de los esturiones deberia ser un objetivo de la comunidad internacional

Sturgeons and Paddlefishes: Threatened Fishes in Need of Conservation

The 27 extant species of sturgeons and paddlefishes (Order Acipenseriformes) represent a unique and relict lineage of fishes. Producers of coveted black caviar, sturgeons are one of the most valuable wildlife commodities on earth. The group is among the most endangered fishes with all species listed under Convention on International Trade in Endangered Species (CITES) Appendix I (two species) or II (25 species), only two species considered Lower Risk by IUCN, four of the nine US taxa and one Caspian species protected under the Endangered Species Act, and local extinctions recorded for 19 of 27 species. Despite their well-publicized imperilled status, commercial pressure on 15 species persists. Here, after reviewing the biological characteristics of sturgeons and paddlefishes and their commercial use, an overview of global fisheries is presented. The synopsis demonstrates that, with few exceptions, sturgeon and paddlefish are imperilled across the globe and long-term survival in the wild is in jeopardy. All major sturgeon fisheries have surpassed peak productivity levels, with 70% of major fisheries posting recent harvests <15% of historic peak catches and 35% of the fisheries examined crashing within 7–20 years of inception. Even in Caspian Sea fisheries, the most important globally, present catches are below 10% of historic peak landings. Improved domestic and international fisheries management and attention to habitat and species restoration is now needed. Although captive rearing offers promise for caviar alternatives and endangered species restoration, it must advance cautiously to avoid environmental harm. To ensure a continued supply of caviar and the survival of these unique fishes we offer recommendations for priority conservation action for the future.

http://www.oceanconservationscience.org/publications/files/papers/FAFv2.pdf

Status, trends and management of sturgeon and paddlefish fisheries

Multiple readings and recaptures of marked fish were used to estimate precision and accuracy of age estimates from cross sections of pectoral fin rays of white sturgeons Acipenser transmontanus collected in impoundments of the Columbia River. Ages ranged from 2 to 104 years but only 37% of samples were assigned the same age by two readers. Percent error in multiple readings averaged 5.9% and the coefficient of variation averaged 7.8%, indicating low precision relative to reported values for other species. An injected dosage of 25 mg oxytetracycline (OTC) per kilogram of body weight marked 216 of 220 fin ray samples for validation and did not reduce white sturgeon growth. Accuracy was improved by identifying the period of annulus formation (May–June) from the position of an OTC mark relative to translucent zones in fin ray cross sections. However, age was underestimated from counts of translucent zones formed after injection with OTC, especially for slow-growing and large fish. We conclude that ag...

Accuracy and Precision of White Sturgeon Age Estimates from Pectoral Fin Rays

Population Characteristics and Movements of Lake Sturgeon in the Sturgeon River and Lake Superior

This paper reviews the life history and habitat requirements of sturgeons, alternatives for their protection and restoration in North America, and a typical protection and enhancement program in the Columbia River. Sturgeon are uniquely adapted to mainstem river systems which are characterized by their large scale. diverse habitats. and dynamic nature. Adaptations include mobility, opportunistic food habits, delayed maturation, longevity, and high individual fecundity. Unfortunately these life history characteristics are now a handicap for sturgeon because of fragmentation and destruction of their habitat. A variety of habitat-related alternatives for the protection and restoration of sturgeon were identified in a review of the literature and a survey of sturgeon biologists and managers throughout North America. However, harvest restrictions and supplementation using aquaculture are much more likely to be implemented than the system-wide measures needed to affect sturgeon habitat. A program for white sturgeon protection and enhancemment in the Columbia River is a typical case where harvest management and supplementation measures are being used to optimize production of existing habitat but significant changes in water use and hydropower operation are needed to restore sturgeon to historic levels of production.

Alternatives for the protection and restoration of sturgeons and their habitat

The age and growth of lake sturgeons (Acipenser fulvescens) were investigated in the lower Moose River system in the Hudson Bay lowland. The effects of current fishing methods also were reviewed in order to recommend procedures for a sustained-yield fishery. The population estimate of lake sturgeon in the study area was 7,088 with 95% confidence limits of 5,774-8,919. Sex ratios of all fish sampled throughout the summer were 1:1 and the length-weight relationship showed allometric growth with no significant differences between sexes. The age of first spawn for females was approximately 20 years but that for males was suspect due to small sample sizes of ripe males. Tissue mercury analyses showed relatively high levels of mercury in lake sturgeons longer than 102 cm. Growth was calculated from the Brody-Bertalanffy relationship that was employed in the Beverton-Holt yield model. This model indicated that increases in fishing intensity under present fisheries regulations would result in overexploit...

C. S. Broussaeu

Papers

Biology and Management of the Lake Sturgeon in the Moose River, Ontario