Reframing protected species interactions with commercial fishing gear: Moving toward estimating the unobservable

Traditional methods for estimating sea turtle, marine mammal, and seabird bycatch in commercial fisheries risk underestimating the number of “takes,” or “interactions,” as defined by protective legislation. We propose a conceptual framework within which fisheries interactions can be classified as “observable” and can be quantified through fisheries observer data, or as “unobservable” and can sometimes be quantified through fisheries observer data or experimental research. Some unobservable interactions will remain unquantifiable. We describe the research goal to develop methods of quantifying those interactions that are currently unquantifiable, and to assess the rate of serious injury or mortality associated with all types of fisheries interactions.

► Bycatch estimation methods can underestimate legally defined protected species takes. ► We define “interactions” as “takes” and classify them as observable or unobservable. ► We can estimate observable interactions through fisheries observer data. ► We can possibly estimate unobservable interactions with observer or experimental data. ► Mortality rates for all interactions are needed to assess population-level effects.