Delay in fishery management: diminished yield, longer rebuilding, and increased probability of stock collapse1

Abstract

Shertzer, K. W., and Prager, M. H. 2007. Delay in fishery management: diminished yield, longer rebuilding, and increased probability of stock collapse. ICES Journal of Marine Science, 64: 149–159. When a stock is depleted, catch reductions are in order, but typically they are implemented only after considerable delay. Delay occurs because fishery management is political, and stricter management, which involves short-term economic loss, is unpopular. Informed of stock decline, managers often hesitate, perhaps pondering the uncertainty of scientific advice, perhaps hoping that a good year class will render action moot. However, management delay itself can have significant costs, when it exacerbates stock decline. To examine the biological consequences of delay, we simulated a spectrum of fisheries under various degrees of delay in management. Increased delay required larger catch reductions, for more years, to recover benchmark stock status (here, spawning-stock biomass at maximum sustainable yield). Management delay caused stock collapse most often under two conditions: (1) when the stock–recruitment relationship was depensatory, or (2) when catchability, unknown to the assessment, was density-dependent and fishing took juveniles. In contrast, prompt management resulted in quicker recoveries and higher cumulative yields from simulated fisheries. Benefits to stock biomass and fishery yield can be high from implementing management promptly.

System Dynamics Modeling of Individual Transferable Quota Fisheries and Suggestions for Rebuilding Stocks

“…Therefore, it becomes a rational policy for fishery managers to delay decisions that may have a negative impact on the community and to wait for better scientific information and reductions in uncertainty [7]. However, a common scenario is that the scientific information provided was in fact reasonable and the stock will likely continue to decline since management has delayed taking action [8]. When this occurs management is forced to take even more extreme measures to help stock recovery.…”

A cold oceanographic regime with high exploitation rates in the Northeast Pacific forecasts a collapse of the sardine stock

“…Therefore, assessment models likely overestimate reproductive success at low population sizes (37). Consequently, management inadvertently can allow overharvesting, which may cause subsequent stock recovery to be slow and incomplete (33,35,36,38).…”

Current Problems in the Management of Marine Fisheries

“…However, unless a harvest strategy is defined, with pre-agreed, legally binding decision rules requiring reductions of effort when stock sizes decline below limit reference points, most management authorities will still delay taking action to recover stocks. Some of this delay may arise from uncertainty in the science, but mostly it arises from an unwillingness to take decisions that will create hardship for fishers, and usually a delay will exacerbate stock decline (35).…”