13 - Artificial propagation of freshwater fishes: benefits and risks to recipient ecosystems from stocking, translocation and re-introduction

Summary

We must not think that the highly laudable but expensive art and science of restoration ecology is going to put back ecosystem integrity, even though it ‘regreens’ with a highly convincing look-alike. –

M. J. Samways (1996)

INTRODUCTION

This book examines emerging and historical perspectives and approaches to the conservation of inland fish biodiversity and the freshwater ecosystems upon which this diversity relies. Together, these approaches present enormous opportunities, yet daunting challenges, in efforts to sustain viably functioning freshwater ecosystems with the full complement of ecosystem services and societal values they provide. In this chapter, we focus the reader's attention to a set of interrelated practices aimed at augmenting the production of new recruits to a targeted population and ecosystem often as means to restore or conserve fish populations. These practices include artificial propagation and stocking, direct translocation and re-introduction (NB: key terms used herein are italicised on first use and defined in Box 13.1. Many of these terms have no widely accepted definitions in practice. Therefore, we provide these as they relate to our usage). Widely used in fisheries management, aquatic conservation and restoration, these activities are the subject of considerable scrutiny and lingering debate as to whether they truly provide a demonstrable ecological benefit as opposed to a suite of more societal benefits (economic, cultural, political, and so on). Moreover, critical examination of whether such benefits justify or balance the attendant risks to recipient biodiversity and ecosystems are generally lacking. We address both sides of the debate by presenting a general discussion of the kinds, range and magnitude of benefits and risks associated with artificial enhancement practices including those used under the banner of ‘conservation’, but also more generally. Where space and information permit, we also provide evidence gleaned from specific cases documented from the literature or the authors’ experiences. We acknowledge a bias toward examples gleaned from our North American experiences with inland and anadromous species, but suggest that underlying concepts are common and broadly relevant to any fauna regardless of geographical location.