Robert L. Stephenson

Stock complexity in fisheries management : a perspective of emerging issues related to, population sub-units

Abstract The common approaches to evaluation and management of marine finfish stocks assume discrete populations. While it has long been recognized that this assumption is complicated to some degree by migrations and mixing between management units, there has been little attention paid recently to the complexity of spawning components within management units. Several marine finfish species appear to have more complex stock structure than is recognized, and in many cases, management units contain stock complexes or metapopulations with several spawning components rather than single discrete populations. Unfortunately, these spawning components are typically difficult to define from traditional fisheries data, or to discriminate by conventional stock identification techniques. Failure to recognize or to account for this complex stock structure in management, however, may lead to erosion of spawning components, with unknown ecological consequences. The management of complex fish stocks, at appropriate scales, so as to preserve stock complexity, therefore, remains a major challenge. Maintenance of the full diversity of spawning locations and times is an important aspect of topical discussions of biodiversity and marine protected areas. Consequently, the importance of stock identification will increase as a result of a new emphasis on management which takes into account stock complexity within areas traditionally assumed to contain a single stock. This new emphasis on stock complexity is necessary if management is to comply with a “precautionary approach” to fisheries management.

Institutional arrangements for fisheries: alternate structures and impediments to change

The precarious state of many of the worlds important commercial fisheries have called into question the ability of government agencies to carry out mandates related to stock conservation and sustainability. This paper argues that the prominent role of government agencies in building fisheries management systems of the past few decades, has led to the prevalent situation that management is top-down and has fostered the view that these institutions are in control. In that view, the fishing sector has generally been excluded from management and is depicted as fundamentally irresponsible with regard to resource sustainability. A paternal government-industry relationship diminishes the opportunity for the fishing industry to become a responsible partner in fisheries management. We argue that institutional arrangements are a major impediment to effective management change. We consider the problem of managing commercial fisheries under current institutional structures by examining the Canadian Department of Fisheries and Oceans as a case study. We outline the benefits of alternative bottom-up and participative decision making for fisheries and discuss the requirements for more effective institutional arrangements that would empower stakeholders toward building a real stakeholders-government partnership.

The relationship between winter lake cover, radiation receipts and the oxygen deficit in temperate lakes

Abstract The composition, timing and duration of winter lake cover are shown to produce significant spatial and temporal variations in the radiation received at the surface of the water column, and are linked to the timing and rate of oxygen depletion of a temperate lake. In particular, the first snowfall to accumulate on the ice cover reduces radiation input to nearly zero and coincides with the initiation of the linear phase of oxygen depletion. Ablation of the snow cover in spring results in increased radiation receipts and oxygen levels. A simple model shows that the conversion of snow to white ice, which normally occurs during the midwinter period, increases radiation receipts and oxygen levels. Manipulation of the cover by artificially induced slushing is suggested as a management technique in the control of winter oxygen deficits.

Integrated Systems Analysis for Marine Site Evaluations and Multicriteria Decision Support for Coastal Aquaculture

Traditional fisheries are based on wild, spatially uncontrolled stocks whose habitats are the coastal and marine environments. Aquaculture attempts to control and manage the supply of products from the sea by establishing designated marine farms. In recent years, the aquaculture industry is growing more rapidly than all other animal food producing sectors (Allen et al. 1992; Fletcher and Neyrey 2003). However, aquaculture has also been challenged by complex interactions between marine resources, ecosystems and multiple resource users. An integrated valuation approach that incorporates the ecosystem, aquaculture, and other marine activities is needed to promote sustainable development in the coastal zone and to find feasible solutions to resolve conflicts (Nath et al. 2000). While the benefits of coastal aquaculture have been widely recognized (CAIA 2003), Barg (1992) noted “. . . aquaculture may increasingly be subject to a range of environmental, resource and market constraints. Aquaculture is competing for land and water resources, which in some cases resulted in conflicts with other resource users. Also, there is growing concern about the environmental implications of aquaculture development, comprising the adverse effects of aquaculture operations on the environment as well as the consequences of increasing aquatic pollution affecting feasibility and sustainable development of aquaculture.” Similarly, Brindley (1991) pointed out the necessity to evaluate coastal aquaculture from different points of view and that a multi-disciplinary team, including specialists involved in decision making, should consider the economic, social, cultural and environmental aspects to assess all possible impacts of coastal aquaculture development (Lane and Stephenson 1998). At the Department of Fisheries and Oceans, the Oceans Action Plan featured in the recent 2005 federal budget (Department of Finance Canada 2005, p. 194) acknowledge that improved integration of marine impacts is an important matter for management of our ocean ecosystems.

A social–ecological study of stock structure and fleet dynamics in the Newfoundland herring fishery

A social–ecological study of stock structure and fleet dynamics in the Newfoundland herring fishery Barbara Paterson*, Barbara Neis, and Robert L. Stephenson School of the Environment, Department of Environmental Science, Saint Mary’s University, NS, Canada, B3H 3C3 Marine Research Institute, Department of Biological Sciences, University of Cape Town, Rondebosch 7701, South Africa Department of Sociology, Memorial University, St. John’s, NL, Canada A1C 5S7 Canadian Fisheries Research Network, University of New Brunswick, Fredericton, NB E3B 5A3, Canada Fisheries and Oceans, St. Andrews Biological Station, St. Andrews NB E5B 2L9, Canada *Corresponding author: tel: þ 1 902 491 6406; fax: þ 1 902 491 6406; e-mail: barbara.paterson@smu.ca