Topic II Management of River Systems

The Problem with Aliens - Invasive Fish II

Invasive Fish in British Waters

A sheet with the  notes below was handed out in the lecture. For an extended version as a Word File click here : (will open or download depending on browser settings)

Global distribution of fish

Original distribution over Geological time due to 'geography'

Tropical Communities

Temperate Communities

Natural processes

Introduction and Redistribution

Impacts of redistribution and introduction

• the introduction and spread of disease
• competition for resources
• piscivory
• habitat destruction
• food chain destabilisation
• behavioural interference
• genetic dilution and hybridisation

Why are the problems being seen today?

Changing society and peoples choices
Disturbed ecosystems

Environmental impacts due to 'Fish stocking'

Common carp (Cyprinus carpio) and bream (Abramis brama) - can cause macrophyte decline
What are mechanisms behind this macrophyte decline?
Why was the increase in periphyton occurring?

Problems with Piscivores

Zander (Stizostedion lucioperca) or Pike-Perch

The management of zander

• Leave it alone
• Cull
• Partial cull

The Ruffe

(Last Updated 30/10/02)

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