Dear Colleagues,

My co-authors and I are pleased to announce the publication of the
following paper:

Cruz MJ, Machete M, Menezes G, Rogan E , Silva MA. 2018. Estimating common
dolphin bycatch in the pole-and-line tuna fishery in the Azores. PeerJ
6:e4285; DOI 10.7717/peerj.4285

Small-scale artisanal fisheries can have a significant negative impact in
cetacean populations. Cetacean bycatch has been documented in the
pole-and-line tuna fishery in the Azores with common dolphins being the
species more frequently taken. Based on data collected by observers on ∼50%
of vessels operating from 1998 to 2012, we investigate the influence of
various environmental and fisheries-related factors in common dolphin
bycatch and calculate fleet-wide estimates of total bycatch using
design-based and model-based methods. Over the 15-year study dolphin
bycatch occurred in less than 0.4% of the observed fishing events.
Generalized additive modelling results suggest a significant relationship
between common dolphin bycatch and duration of fishing events, sea surface
temperature and location. Total bycatch calculated from the traditional
stratified ratio estimation approach was 196 (95% CI: 186–205), while the
negative binomial GAM estimated 262 (95% CI: 249–274) dolphins. Bycatch
estimates of common dolphin were similar using statistical approaches
suggesting that either of these methods may be used in future bycatch
assessments for this fishery. Our work shows that rates of common dolphin
bycatch in the pole-and-line tuna fishery in the Azores are low, despite
considerable variations between years. Dolphins caught were released alive
although the fate of these individuals is unknown. Continued monitoring
will provide a better understanding of dolphin bycatch and more accurate
estimates essential in the development of potential mitigation measures.

The paper is available in open access at:

Best regards,

Maria João Cruz

Department of Oceanography and Fisheries (DOP)
MARE-Marine and Environmental Sciences Centre
IMAR-Centre of the Institute of Marine Research
University of the Azores
9901-862 Horta, Portugal
Phone: (+351) 292 200 400
Fax: (+351) 292 200 411
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