Cruz M.J.,University Dos Ac ores |
Jordao V.L.,University Dos Ac ores |
Pereira J.G.,University Dos Ac ores |
Santos R.S.,University Dos Ac ores |
And 2 more authors.
ICES Journal of Marine Science | Year: 2014
Depredation by cetaceans is a growing problem that may have serious economic implications for fisheries and for dolphin conservation. Weinvestigated depredation by Risso's dolphin (Grampus griseus) in the hand-jig squid fishery around the Azores to determine the factors that may influence depredation behaviour and impacts on the fishery, and conducted experiments to evaluate the effectiveness of acoustic deterrent devices. Monitoring of the interaction between dolphins and the fishery was carried out through interviews with fishers and observations made from fishing vessels. Depredation was reported in 50% of the 506 interviews conducted from 2009 to 2011 and Risso's dolphins were reportedly responsible for 92% of the depredation events. Risso's dolphin depredation was recorded in 33% of the observed fishing trips (n = 96). Generalized additive models revealed that depth, sea surface temperature, and fishing time were important factors affecting depredation probability. Generalized linear models showed that fishing time also influenced the number of squids depredated, with greater catch losses predicted as duration of the fishing events increased. Depredation rate was calculated at 3% yielding an estimate of 8-12 t of squid lost to dolphins per year and an annual economic loss of €50 000 for the squid fishery of S. Miguel. The use of pingers had no significant effect on the catch per unit effort of squids. Depredation rates were similar for the control (0.20), inactive (0.19), and active (0.19) pinger conditions. Models indicated no significant effect of pinger brand and condition on cetacean depredation. This study is the first attempt to monitor depredation by Risso's dolphins on a hand-jig squid fishery providing a scientific basis for future management of interactions between cetaceans and fisheries. © International Council for the Exploration of the Sea 2014. All rights reserved.
Rodrigues P.,University Dos Ac ores |
Mironov S.,Russian Academy of Sciences |
Sychra O.,University of Veterinary And Pharmaceutical Sciences Brno |
Resendes R.,University Dos Ac ores |
Literak I.,University of Veterinary And Pharmaceutical Sciences Brno
Parasite | Year: 2015
Ten passerine species were examined on three islands of the Azores (North Atlantic) during 2013 and 2014 in order to identify their feather mite assemblages. We recorded 19 feather mite species belonging to four families of the superfamily Analgoidea (Analgidae, Proctophyllodidae, Psoroptoididae and Trouessartiidae). A high prevalence of feather mite species was recorded on the majority of the examined host species. Only three passerine species (Sylvia atricapilla, Regulus regulus and Serinus canaria) presented the same full complex of mite species as commonly occurs in the plumage of their closest relatives in continental Europe. Passer domesticus presented the same limited fauna of feather mites living in the plumage as do its co-specifics in continental Europe. Carduelis carduelis bears the same feather mite species as do most of its continental populations in Europe, but it lacks one mite species occurring on this host in Egypt. Turdus merula, Pyrrhula murina and Fringilla coelebs are missing several mite species common to their continental relatives. This diminution could be explained by the founder effect, whereby a limited number of colonizing individuals did not transport the full set of feather mite species, or by the extinction of some mite species after initially having reached the Azores. The only individual of Motacilla cinerea sampled in this study presented a new host record for the mite species Trouessartia jedliczkai. © P. Rodrigues et al., published by EDP Sciences, 2015.
Pinho M.,University Dos Ac ores |
Diogo H.,University Dos Ac ores |
Carvalho J.,University Dos Ac ores |
Pereira J.G.,University Dos Ac ores
ICES Journal of Marine Science | Year: 2014
Blackspot sea bream (Pagellus bogaraveo) is the most important economical resource of Azorean fisheries. Juveniles (age 0 and 1) were detected along island coastlines in nursery grounds that sheltered individuals of up to 13 cm (fork length). Juveniles occurred in coastal areas in all seasons, but higher catch per unit efforts occurred during summer. Larger individuals tended to be caught on the shelves and slopes of the islands and seamounts by the demersal, mixed hook, and line fisheries. Juveniles were exclusively found at inshore areas, while spawners were distributed over offshore areas (islands shelf/slope and seamounts), suggesting an inter-connected cycle of recruitment in coastal areas and ontogenetic migration of juveniles from inshore to offshore areas, while eggs and larvae drift in the opposite direction. Juveniles were found to be targeted by three types of fisheries, amounting to cumulative annual catches of ∼36 t. Shore angling was the most important fishing method, followed by bait fishing for tuna and the coastal pelagic live-bait fishery. Fishery managers have enforced several measures to protect juveniles, although our results indicate that effective interdiction of juvenile catch would provide a long-term increase of 15 and 8% in spawning-stock biomass and catch, respectively, as well as ∼13% increase in the value of landings. Although this measure could improve the protection of a species in an advanced state of overexploitation, our results showed that a decrease in fishing effort would be necessary to achieve sustainability of the stock. © International Council for the Exploration of the Sea 2014. All rights reserved.