» Current Issues and Publications

A Big-Picture Approach to Fisheries Management

U.S. fishery managers often focus on one species at a time when determining how, when, and where fishing takes place. But each fish population is part of an interconnected ecosystem in which they interact with other fish, ocean wildlife, and habitats. Fish are also directly affected by changing environments and human activities. Threats such as ocean acidification, warming waters, overfishing, and habitat destruction can damage ecosystems and cause ripple effects, such as the decline of important fish populations. Read More

Hepatotoxicity of Mercury to Fish

Tissue samples from spotted gar (Lepisosteus oculatus) and largemouth bass (Micropterus salmoides) were collected from Caddo Lake. Gar and bass livers were subjected to histological investigation and color analysis. Liver color (as abs at 400 nm) was significantly correlated with total mercury in the liver (r2 = 0.57, p = 0.02) and muscle (r2 = 0.58, p = 0.01) of gar. Evidence of liver damage as lipofuscin and discoloration was found in both species but only correlated with liver mercury concentration in spotted gar. Inorganic mercury was the predominant form in gar livers. In order to determine the role of mercury speciation in fish liver damage, a laboratory feeding study was employed. Zebrafish (Danio rerio) were fed either a control (0.12 ± 0.002 µg Hg.g-1 dry wt), inorganic mercury (5.03 ± 0.309 µg Hg.g-1 dry wt), or methylmercury (4.11 ± 0.146 µg Hg.g-1 dry wt) diet. After 78 days of feeding, total mercury was highest in the carcass of zebrafish fed methylmercury (12.49 ± 0.369 µg Hg.g-1 dry wt), intermediate in those fed inorganic mercury (1.09 ± 0.117 µg Hg.g-1 dry wt), and lowest in fish fed the control diet (0.48 ± 0.038 µg Hg.g-1 dry wt). Total mercury was highest in the viscera of methylmercury fed zebrafish (11.6 ± 1.86 µg Hg.g-1 dry wt), intermediate in those fed inorganic diets (4.3 ± 1.08 µg Hg.g-1 dry wt), and lowest in the control fish (below limit of detection). Total mercury was negatively associated with fish length and weight in methylmercury fed fish. Condition factor was not associated with total mercury and might not be the best measure of fitness for these fish. No liver pathologies were observed in zebrafish from any treatment. Read More

From the Edge: Science to Support Restoration of Pacific Salmon

Library Holdings. According the preface, this report represents the scientific understanding of salmon and salmon declines in the year 2000. The report provides an overview of salmon population trends, and ways to aid in and measure recovery. Read More

Radionuclide Data and Calculations and Loss-On-Ignition, X-Ray Fluorescence, and ICP-AES Data from Cores in Catchments of the Animas River, Colorado

The U.S. Departments of Agriculture and Interior Abandoned Mine Lands (AML) Initiative is focused on the evaluation of the effect of past mining practices on the water quality and the riparian and aquatic habitats of impacted stream reaches downstream from historical mining districts located primarily on Federal lands. This problem is manifest in the eleven western states (west of longitude 102 degrees) where the majority of hardrock mines that had past production are located on Federal lands. In areas of temperate climate and moderate to heavy precipitation, the effects of rapid chemical and physical weathering of sulfides exposed on mine-waste dumps and acidic drainage from mines have resulted in elevated metal concentrations in the stream water and stream-bed sediment. The result of these mineral weathering processes has an unquantified impact on the quality of the water and the aquatic and riparian habitats that may limit their recreational resource value. One of the confounding factors in these studies is the determination of the component of metals derived from hydrothermally altered but unmined portions of these drainage basins. Several watersheds have been studied to evaluate the effects of acid mine drainage and acid rock drainage on the near-surface environment. The Animas River watershed in southwestern Colorado contains a large number of past-producing metal mines that have affected the watershed. Beginning in October 1996, the U.S. Geological Survey (USGS) began a collaborative study of these effects under the USGS-AML Initiative. In this report, we present the radionuclide and geochemical analytical results of sediment coring during 1997-1999 from two cores from oxbow lakes 0.5 mi. upstream from the 32nd Street Bridge near Durango, Colo., and from three cores from beaver ponds within the Mineral Creek drainage basin near Silverton, Colo. Read More

Marine Mammal Commission

The Commission was created under Title II of the Marine Mammal Protection Act of 1972, which took effect on 21 December of that year. The Commission’s primary focus and duties are the protection and conservation of marine mammals. Read More

Iowa's Farm Ponds

This Iowa Department of Natural Resources site contains the following sections: farm pond facts, introduction, pond construction, stocking your pond with fish, managing your pond for fishing, reproduction and growth of fishes, is your pond in balance, how to catch’em, aquatic vegetation control, pond damage prevention and control, renovating fish populations in your pond, and wildlife benefits. Read More

Penn State Pond Management Publications

This site contains over 30 pond management publications that would be useful for owners of farm ponds. References are divided into general, fisheries, and aquatic plant categories. Read More

Indiana Fish Pond Management:

This 24-page guide includes information on physical, chemical, and biological features of ponds. Recommendations on stocking of fish are included. Read More

Fisheries and Pond Management Extension

This reference has a five-chapter section on pond management. Additional information on this site includes aquatic weed management and pond construction. Read More

Fish Anatomy

Overview diagrams of the external anatomy of fish are provided. Links to other areas, including a Kid’s Page. Read More


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