Can fear conditioning repel California sea lions from fishing activities ?

10 Marine mammal interactions with fisheries create conflicts that can threaten human safety, 11 economic interests, and marine mammal survival. A deterrent that capitalizes on learning 12 mechanisms, like fear conditioning, may enhance success while simultaneously balancing 13 welfare concerns and reduce noise pollution. During fear conditioning, individuals learn the cues 14 that precede the dangerous stimuli, and respond by avoiding the painful situations. We tested the 15 efficacy of fear conditioning using acoustic stimuli for reducing California sea lion (Zalophus 16 californianus) interactions from two fishing contexts in California, USA; bait barges and 17 recreational fishing vessels. We performed conditioning trials on 24 individual sea lions 18 interacting with bait barges. We tested for acquisition of conditioned fear by pairing a neutral 19 tone with a startle stimulus. Avoidance was strongest in response to the startle stimulus alone, 20 but low when paired with a neutral tone. From actively fishing vessels we tested for fear 21 conditioning by exposing sea lions to a neutral tone followed by a startle pulse, a startle pulse 22 alone, or a no sound control. We conducted playbacks from 146 (including 48 no sound control) 23 Schakner et al. (2017) in Animal Conservation, doi: 10.1111/acv.12329 2 stops over two summer fishing seasons (2013, 2014). The startle stimulus decreased surfacing 24 frequency, reduced bait foraging and increased surfacing distance from the vessel while the 25 conditioned stimulus only caused a mild reduction in surfacing frequency with no other 26 behavioral change. Exposing animals to a pair of a conditioned stimulus with a startle pulse did 27 not achieve the intended management outcome. Rather, it generated evidence (in two study 28 contexts) of immediate learning that led to the reduction of the unconditioned response. Taken 29 together, our results suggest that for fear conditioning to be applied as a non-lethal deterrent, 30 careful consideration has to be given to individual behavior, the unconditioned/conditioned 31 responses, and the overall management goals. 32 33 Introduction 34 As part of rapid anthropogenic environmental change, wildlife are increasingly turning to 35 human-derived resources such as fish from fishing lines or nets (Zollett & Read, 2006), 36 domesticated livestock (Muhly & Musiani, 2009) or garbage cans (Baruch-Mordo et al., 2013). 37 Animals exploiting these resources create human-wildlife conflicts, ultimately threatening 38 human safety, economic interests, and their own survival (Woodroffe et al., 2005). In the marine 39 environment, marine mammal depredation, or the removal of fish from lines or nets, creates 40 scientific, management, and conservation concerns that include socio-economic losses upon 41 fisheries (Hamer et al., 2012), increased marine mammal entanglements, and potential (and 42 realized) retaliatory actions by fisherman (Powell & Wells, 2011; Read, 2008). As a consequence 43 of these conflicts, there is increasing demand for effective non-lethal mitigation techniques, such 44 as effective deterrents to reduce conflicts (Berrow et al., 2008; Forrest et al., 2009; Gordon & 45 Northridge, 2002; Götz & Janik, 2015, 2016). 46 Schakner et al. (2017) in Animal Conservation, doi: 10.1111/acv.12329 3 Deterrents use aversive stimuli to prevent animals from acquiring human resources (Ramp et 47 al., 2011). Deterrent stimuli use a variety of mechanisms to elicit defensive responses in animals 48 (Götz & Janik, 2010; Schakner & Blumstein, 2013). A range of different presumably aversive 49 stimuli, such as intense acoustic signals, can elicit avoidance in marine mammals (Berrow et al., 5