Reference points for predators will progress ecosystem‐based management of fisheries

Abstract

Ecosystem‐based management of fisheries aims to allow sustainable use of fished stocks while keeping impacts upon ecosystems within safe ecological limits. Both the FAO Code of Conduct for Responsible Fisheries and the Aichi Biodiversity Targets promote these aims. We evaluate implementation of ecosystem‐based management in six case‐study fisheries in which potential indirect impacts upon bird or mammal predators of fished stocks are well publicized and well studied. In particular, we consider the components needed to enable management strategies to respond to information from predator monitoring. Although such information is available in all case‐studies, only one has a reference point defining safe ecological limits for predators and none has a method to adjust fishing activities in response to estimates of the state of the predator population. Reference points for predators have been developed outside the fisheries management context, but adoption by fisheries managers is hindered a lack of clarity about management objectives and uncertainty about how fishing affects predator dynamics. This also hinders the development of adjustment methods because these generally require information on the state of ecosystem variables relative to reference points. Nonetheless, most of the case‐studies include precautionary measures to limit impacts on predators. These measures are not used tactically and therefore risk excessive restrictions on sustainable use. Adoption of predator reference points to inform tactical adjustment of precautionary measures would be an appropriate next step towards ecosystem‐based management.

Successful ecosystem-based management of Antarctic krill should address uncertainties in krill recruitment, behaviour and ecological adaptation

“…Climate change implications for krill dynamics and management. Climate change impacts on the krill population are not explicitly included in krill fisheries management, where catch limits do not change from year to year 82 . However, given the farreaching implications of any possible climate change-related declines in krill stocks for the Antarctic marine ecosystem, there is a need to incorporate environmental variability into the management framework explicitly by, for example, adjusting catch limits based on environmental predictors or in response to variations in stock size as is common practice in other fisheries 82 .…”

A global population assessment of the Chinstrap penguin (Pygoscelis antarctica)

“…dynamics 8,[15][16][17] . Other potential impacts, including tourism, extreme weather events, and disease outbreaks, may be important at local scales or for short periods of time, but are less compelling explanations for the widespread changes observed across the Antarctic penguins 3,18,19 .…”

Seabird‐induced natural mortality of forage fish varies with fish abundance: Evidence from five ecosystems

“…Seabirds are more threatened, and declining faster, than other groups of birds (Dias et al, 2019 To conclude, our study is important as it contributes to the growing literature in support of an ecosystem approach to fisheries (EAF; Dickey-Collas et al, 2014;Hill et al, 2020;Koehn et al, 2017;Pikitch et al, 2004). While top-down processes due to predation of forage fish by seabirds did not seem to control forage fish dynamics in any of the five ecosystems we considered, the predation pressure sometimes attained high levels, which signals the need for fisheries management to account for ecosystem constraints when setting catch limits in periods of low forage fish biomass.…”