Abundances Of Freshwater Fish, Mussels and Beavers Often Underestimated
Posted on: Tuesday, 1 September 2009, 09:41 CDT
Steep reductions in the abundance of fish, shellfish, and other aquatic fauna in recent centuries are not restricted to animals that live in the sea: historical records show that species in rivers and lakes worldwide also experienced sharp declines. Yet the significance of these declines in freshwater species is frequently overlooked by natural resource managers, according to an article in the September 2009 issue of BioScience.Authors Paul Humphries and Kirk Winemiller argue that as a result of this neglect of historical records, watershed planning is often built on estimates of baseline abundances of fish, freshwater mussels, and beavers that are much lower than actual past abundances. Planners consequently underestimate the likely far-reaching effects such animals had on their ecosystems before European colonization.
Although precise historical numbers cannot be known, written accounts dating from the 1600s suggest that abundances were much greater than they are today . Travelers and diarists reported rivers so full of fish that a spear thrown into the water only rarely missed one, salmon runs that spanned the whole width of a river, and fish so plentiful that they were used as pig feed.
Humphries and Winemiller point out that European colonizers in North America and Australia, in particular, could easily move inland from coastal communities to supplement their seafood with food taken from freshwaters. Then, within a few decades, they started constructing weirs and mills that impeded the migration of fishes and put further pressure on stocks. Stocks of fish and shellfish declined rapidly after colonization. The effects of this early loss of wildlife on the river ecosystems, the authors contend, has not been adequately considered.
Freshwater systems that have been little exploited seem to confirm the strong effects of fishing pressure in freshwater systems. Humphries and Winemiller cite the case of rivers in the Lake Eyre Basin, in central Australia, where fish are much more abundant than in comparable systems that are more heavily exploited.
Humphries, of Charles Sturt University in New South Wales, Australia, and Winemiller, of Texas A&M University in College Station, support the reintroduction of top predators and keystone species recently extirpated from freshwaters, and urge the creation of freshwater protected areas. Some of these protected areas could be used for restoration experiments in which the effects of reintroduced species could be explored.
------------
On The Net:
American Institute of Biological Sciences
Related Articles
- Data Released at an International Stem Cell Meeting Highlights Effectiveness of New Patient Education System Developed to Support Federal and State Guidelines on Cord Blood Education
- Lockheed Martin, Viking Life-Saving Equipment Norge Team to Develop Safer, More Cost-Effective Sea-Borne Crew Transfer System
- Reliability, Cost Effectiveness Make RadarFind the Tracking System Choice for Our Lady of Lourdes Medical Center
- Obagi Medical Products and Syneron to Study Effect of Obagi's Skin Care System As an Adjunct to Aesthetic Procedures
- Tiny Shrimp Species Found in Pa. River
- Scientists Hope to Aid Growing Demand for Cobia: Marine Researchers Are Releasing Hatchery-Reared Fish to Stock the Salty Waters of the York River.
- Letters: Japan Seeks to Catch Only Species That Are Abundant
- Downtown Firms Weigh Effect of University of Maine System Relocation
- Five Years Ago, Conservationists Identified 25 Sites Around the World Where Plant and Animal Species Are Most Abundant
- Effects of Tirofiban on Acute Systemic Inflammatory Response in Elective Percutaneous Coronary Interventions
Rating: 4.5 / 5 (2 votes)
 |
 |
Rate this article:
User Comments (0)
RSS Feeds