Fisheries management under climate and environmental uncertainty: control rules and performance simulation

Abstract

The ability of management strategies to achieve the fishery management goals are impacted by environmental variation and, therefore, also by global climate change. Management strategies can be modified to use environmental data using the “dynamic B0” concept, and changing the set of years used to define biomass reference points. Two approaches have been developed to apply management strategy evaluation to evaluate the impact of environmental variation on the performance of management strategies. The “mechanistic approach” estimates the relationship between the environment and elements of the population dynamics of the fished species and makes predictions for population trends using the outputs from global climate models. In contrast, the “empirical approach” examines possible broad scenarios without explicitly identifying mechanisms. Many reviewed studies have found that modifying management strategies to include environmental factors does not improve the ability to achieve management goals much, if at all, and only if the manner in which these factors drive the system is well known. As such, until the skill of stock projection models improves, it seems more appropriate to consider the implications of plausible broad forecasts related to how biological parameters may change in the future as a way to assess the robustness of management strategies, rather than attempting specific predictions per se.

Fishing amplifies forage fish population collapses

“…systems were adaptive to indicators (8) but many more failures when environmental proxies did not give accurate predictions (20). The second tool admits these limitations and thereby, relies on a risk-based approach (21), where fishing is restricted during high-risk periods to account for this uncertainty.…”

Shifts in fisheries management: adapting to regime shifts

“…Fundamental to the precautionary approach is the inclusion of uncertainty in estimating stock status relative to biological reference points. In particular, the determination of biological reference points given environmental forcing and regime states has been well investigated in an MSE framework and several approaches have been explored and are outlined below [71].…”

System-level optimal yield: increased value, less risk, improved stability, and better fisheries

“…Events in the 1940s such as the Thompson-Burkenroad debate (cf. Skud 1975;Smith 1994), similar discourse again in the 1950s-1960s ecological literature (Andrewartha and Birch 1954;Hairston et al 1960), and continuing to this day (Walters and Collie 1988;Rose 2000;Punt et al 2014;Szuwalski et al 2015) all represent snapshots of the overarching debate regarding the prominence of internal versus external factors that shape the dynamics of fish stocks. In my view, the debate has become somewhat artificial and has remained singularly philosophical rather than having pragmatic solutions -of course both densitydependent and -independent factors influence fish stocks; of course both fishing and the environment influence fish stocks.…”

“…There is a long history of why and how this came about (Smith 1994;Finley 2011). In many ways this has been embodied in the either-or debates noted above (Andrewartha and Birch 1954;Hairston et al 1960;Skud 1975;Smith 1994;Walters and Collie 1988;Rose 2000;Punt et al 2014;Szuwalski et al 2015), with reductionism leading to interminable debates, whereas holism leading to systematic solutions -that is, where there is clear recognition that a range of factors can and does influence fish stock and aggregate groups thereof. Reasonable minds are recognizing that we need to maintain the stockoriented perspective in many instances, but that the scale and scope of challenges facing the discipline of fisheries is forcing an evaluation of methods and means towards a broader consideration of issues.…”