Science for Ecosystem Management Approach to Management

Conservation strategies for managing fisheries:

Researchers at the St. Andrews Biological Station provide the science to support fisheries management decisions in the Maritimes Region Recent changes in the management approach, called Ecosystem Approach to Management (EAM), have caused a shift in the aim of traditional fisheries management, which was to maintain productivity of only the harvested resources, to one that allows sustainable utilization of a healthy and productive ecosystem.

The ecosystem approach involves management of human activities to ensure that marine ecosystems, their structure (e.g. species diversity), function (e.g. productivity) and overall environmental quality (e.g. water and habitat quality) are not compromised. It means understanding how human activities impact the ecosystem and how ecosystem dynamics influence management of those activities.

While there are also social and economic objectives, the emphasis of science in support of EAM for fisheries is mostly related to the three conservation objectives:  to maintain productivity, to conserve biodiversity and to protect habitat. The first important change is that EAM expands the scope of conservation considerations within each managed activity. The second is that EAM requires consideration over all sector activities in a managed area to account for cumulative effects.

SABS scientists have worked with colleagues and stakeholders to develop a practical comprehensive suite of strategies (see table) to achieve these objectives. While these strategies should be considered in all fisheries management plans, every strategy will not deserve equal attention in all fisheries. Some aspects will have high priority and others may not be relevant at all.

Science activities support the development of practical and measurable indicators for the conservation strategies (these measure the ecosystem response to the fishery) and suitable associated reference points (these signal when a condition is unacceptable). Management measures are then identified to reduce the risk that the indicator will exceed the reference point.  For example, management will set a Total Allowable Catch (TAC) to reduce the risk that the fishing removals will exceed 20% of the population biomass.

Three important impacts have been identified for fisheries. They are: direct mortality associated with harvesting; unintended by-catch mortality, and physical disturbance of habitat by gear. Therefore, management measures need to address controlling exploitation (harvesting), managing discards and incidental mortality (by-catch) and limiting the impact of gear on benthic habitat. The challenge lies in striking a balance in how much attention is given to the emerging priorities of by-catch and impact on habitat and how much attention continues on controlling exploitation to maintain productivity of commercially harvested resources.

Science advice on suitable harvest levels is of paramount importance to maintain productivity of the exploited populations and to permit those species to fill their traditional role in the ecosystem. SABS scientists continue to evaluate stock status, determine appropriate harvest strategies and consider the consequences of alternative Total Allowable Catch (TAC) for fisheries.

Various fish species intermingle within diverse habitats and, as a result, by-catch mortality is an unintended consequence in most fisheries. More attention needs to be given to managing discards of harvested species and limiting incidental mortality of non-harvested species. This can be accomplished by finding ways to limit by-catch (eg. area closures, gear modifications) and improved accounting of the by-catch mortality in resource evaluation and allocation.

Fisheries scientists are working to support managing disturbance of human activities on the physical makeup of the ocean floor - whether it is gravel, boulders, coral areas and so on - or in the water column such as lost gear and noise disturbance for species at risk. This work involves classifying habitat, understanding the impacts of fishing on various habitats and identifying the areas affected by fishing activities.

Making EAM operational will require review of existing management plans to incorporate all pertinent strategies, enhanced fisheries monitoring to capture information on discards and fishing location, and identification of performance indicators to measure the response of the ecosystem to the fishery.