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Background: Acoustic telemetry allows detailed observations of the movement behaviour of many species and as tags get smaller, smaller organisms may be tagged. The number of studies using acoustic telemetry to evaluate marine invertebrate movement is growing, but novel attachment methods include unknowns about the effects of tagging procedures on individual survival and behaviour. This study compared methods of tag attachment on green sea urchins (Strongylocentrotus droebachiensis) to determine the feasibility of using acoustic transmitters to track echinoid movement. Four tagging methods were compared in the lab and tag retention, urchin condition, and survival analysed. Two tagging methods (Dyneema® fishing line and T-bar tags) were evaluated in the field using an existing acoustic telemetry array. Urchins were tagged and the study area revisited one week and 2 months post-release by scuba divers to estimate movement and tag retention. Results: The best methods in the lab, with high tag retention, survival, and minimal effects on urchin condition, were fishing line methods. T-bar tags, although showing high tag retention, caused significant mortality and had deleterious long-term effects on urchin condition and behaviour. After 2 months in the field, as in the lab, fishing line was a more effective tagging method. Urchins tagged with fishing line showed increased estimates of space occupancy compared to T-bar-tagged urchins and a single fishing-line tagged individual was found by divers in good health after 80 days. Combined, these laboratory and field results demonstrate the feasibility of using acoustic telemetry to observe urchin movement. Conclusions: Results strongly suggest that surgical attachment methods that minimize injuries at the attachment site should be prioritized for echinoid tagging studies. Together, lab and field tests indicate that acoustic telemetry is a promising method to examine marine echinoid movement over ecologically relevant spatial and temporal scales. [ABSTRACT FROM AUTHOR]

The post-smolt phase is considered a critical period for Atlantic salmon (Salmo salar). Hence, identifying migration routes used by post-smolts is needed to protect the habitats they require to successfully complete their life cycle. We used a biophysical model coupled with output from a water circulation model (FVCOM) to simulate dispersal of Atlantic salmon post-smolts in a semi-enclosed bay: Passamaquoddy Bay, New Brunswick, Canada. The model was run with nine post-smolt behaviours and six swimming speeds, and then tested against acoustic telemetry data. While no modelled behaviour entirely captured observed salmon migration routes, we identified some behaviours that could allow salmon to successfully leave the bay and resulted in predictions that matched observations reasonably well (e.g., swimming southwest, negative, or tide-varying rheotaxis). We could also rule out several behaviours as unlikely to be used by Atlantic salmon post-smolts in this area (e.g., passive dispersal, orienting based on salinity or temperature, and positive rheotaxis). Hence, with suitable behaviours and models, this approach can provide estimates of the essential habitats and migration routes of wild post-smolts. [ABSTRACT FROM AUTHOR]