Evaluating the Efficacy of Predicting Bycatch Mortality Using Reflex Impairment through an Assessment of Crab Discards

• Main Author: Yochum, Noëlle
• Other Authors: Sampson, David B., Schreck, Carl, Sylvia, Gil, Needham, Mark, Murtaugh, Paul, Rose, Craig, Fisheries and Wildlife, Oregon State University. Graduate School
• Format: Doctoral or Postdoctoral Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Dungeness crab > Mortality; Tanner crabs > Mortality; Groundfish fisheries > Bycatches; Reflexes > Testing; Bycatches (Fisheries) > Mortality > Forecasting; Dungeness crab fisheries > Bycatches; Bycatches (Fisheries) > Effect of stress on; The Ramp; Chionoecetes bairdi; Tanner crab
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/st74ct23w

All animals that interact with fishing gear are not necessarily captured, and all animals that are captured are not necessarily retained. Fishing practices and gear configuration, management regulations, and markets dictate which animals ultimately are retained or discarded. The impact of a fishery and the efficacy of management regulations can depend on the mortality rate of the animals that interact with the gear or are discarded. The Reflex Action Mortality Predictor (RAMP) is a simple, non-invasive, and inexpensive approach that has been used to evaluate this component of fishing mortality. The RAMP approach relates the degree of reflex impairment in an animal to the probability the animal will die. Since its introduction in 2006, the RAMP approach has been utilized in the U.S. and abroad to evaluate mortality for a variety of species, fishing gear types, and stressors. Although there have been numerous applications of the RAMP approach in mortality estimation studies, there has been limited research to directly evaluate RAMP estimates and some skepticism remains in the fisheries science and management communities about the reliability and accuracy of the approach. The goal of this dissertation was to conduct research to assess RAMP and to synthesize findings from previously completed RAMP studies. The three research studies described in this dissertation consider: (1) the accuracy of applying an established relationship between reflex impairment and mortality probability to predict overall mortality attributed to novel stressors; (2) the development and utilization of a RAMP relationship to evaluate discard mortality in a fishery with management regulations that mandate discarding of certain categories of animals; and (3) whether the RAMP approach produces accurate estimates of mortality if survival is determined through laboratory captive holding. The first study estimated a relationship between reflex impairment and mortality probability for Tanner crab (Chionoecetes bairdi) discarded from the groundfish ...