Browsing by Author "Olsen, Esben Moland"
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- Among-individual variation in white seabream (Diplodus sargus) spatial behaviour and protection in a coastal no-take areaPublication . De Benito Abelló, Carmela; Bentes, Luis; Sousa, Inês; Pedaccini, Marie; Villegas-Ríos, David; Olsen, Esben Moland; Gonçalves, Jorge Manuel Santos; Horta E Costa, BarbaraMarine protected areas (MPAs), and specially no-take areas (NTAs), play an important role in protecting target populations from fisheries. When developing spatial conservation and management tools, the design has mainly focused on population-level measures of fish home ranges, spawning and feeding areas, and migration routes. Intraspecific differences in fish behaviour, however, are often not accounted for, even though they could influence the level of realized protection. In this study, we investigated the intraspecific variation in spatial behaviour of a harvested fish, Diplodus sargus, and how it impacts the degree of protection granted by a NTA in the south of Portugal. We identified four behavioural types according to their spatial behaviour: residents, commuters, seasonal visitors, and single users. Time at risk (i.e. outside the NTA) greatly varied among the four groups, but also over the year for the seasonal and the single users. Our study shows how acoustic telemetry can assist spatial conservation and fisheries management and provides novel insight regarding the role of individual variation in behaviour to understand protection granted by MPAs to harvested species. It also suggests that incorporating such information into all stages of MPA design and implementation can result in increased resilience of the protected populations.
- Fully protected marine areas linked to reduced home ranges of fishesPublication . Ohayon, Sarah; Abecasis, David; Almeida, Pedro R.; Alós, Josep; Aspillaga, Eneko; Belo, Ana Filipa; Costa, José Lino; Di Franco, Antonio; Di Lorenzo, Manfredi; Ferguson, Adrian; Guidetti, Paolo; Kraft, Sebastian; La Mesa, Gabriele; Olsen, Esben Moland; Parsons, Darren; Pickholtz, Renanel; Quintella, Bernardo R.; Silva, Ana Filipa; Taylor, Brett M.; Villegas‐Ríos, David; Belmaker, JonathanHome range size is a fundamental trait that can affect the probability of fish being harvested and, at the same time, may be affected by fishing. The relationship between home range size and fishing will impact the effectiveness of fully protected areas (FPAs), as it will influence the number of fish moving into fished areas, affecting both spillover and edge effects. One hypothesis is that individuals within FPAs will present reduced home range size relative to individuals in fished areas. This pattern can be driven by demographic selection (e.g. fishing of individuals with large home ranges leaving the FPAs), improved habitat requiring less foraging movements, or behavioural changes associated with reduced fishing threats. To test the relationship between home range size and protection, we compiled 1143 individual-level home range sizes based on acoustic tracking, covering 17 species from 11 FPAs in 7 countries, with information on distance from FPA borders. A dichotomic analysis (in/out of FPAs) did not support a significant change in the home range size between FPAs and fished areas. However, continuous analysis across the FPA borders demonstrated reduced home range size within the FPAs. We did not find an effect of FPA age or size on this pattern. While we cannot pinpoint the underlying mechanism for the pattern revealed, we suggest behavioural changes as the main driver for reduced home range within FPAs. This mechanism will lead to more resident populations within FPAs, reducing fishing mortality within FPAs yet limiting spillover benefits to adjacent fisheries.