Low-cost device for retrieval of moorings deployed with underwater remote release systems

Abstract

Underwater acoustic and timed-release systems are commonly deployed with sensors and other equipment for ecological and oceanographic research in aquatic environments. These systems allow equipment deployed at depth to be remotely released from their moorings for retrieval. However, a current limitation is that most systems do not incorporate mechanisms for retrieval of the mooring anchor and attachments (e.g. shackles, cable). Herein we provide a detailed description and evaluation of a ‘retrieval pod’ that can be attached directly to remotely released underwater devices to facilitate mooring retrieval. The system was tested using acoustic release telemetry receivers under field conditions in a large estuary in the Northern Territory, Australia. Six receivers fitted with pods were retrieved from the field after two consecutive 6-month deployments (12 retrievals in total) with no failed mooring retrievals. Although our tests were confined to shallow depths (<8m), it should be straightforward to modify the system for use in deeper water by increasing the spool capacity. The retrieval pods are reusable, require minimal construction skills and can be assembled from basic equipment available at most hardware or boating stores, making them a convenient and low-cost option for the retrieval of moorings deployed with remote release systems.

Fisheries Volume 49 Number 6 June 2024

“…Acoustic telemetry is likely the most widespread in application, where transmitters are affi xed to aquatic animals that are passively tracked using networks of underwater acoustic receivers (Cooke et al 2004 ;Brownscombe et al 2019 ). Acoustic receivers are typically deployed in a range of water depths and habitat types within the waterbody of interest, secured to an anchor in a variety of mooring designs (Crook et al 2017 ). Practitioners typically recover these receivers every 6-12 months to download data and perform routine maintenance (e.g., battery replacement, cleaning, fi rmware updates; Heupel et al 2006 ).…”

“…Due to the challenges with equipment recovery, much effort has gone into designing and refi ning methods. To date, recovery methods commonly involve grappling or scuba diving (Crook et al 2017 ), each having unique challenges. Grappling requires the deployment of an impermanent anchoring system that can be retrieved, and a second anchor with a ground line that is hooked by dragging a grappling hook device.…”

A Novel Technological Approach to Recover Aquatic Research Equipment from Depth

“…Acoustic telemetry is likely the most widespread in application, where transmitters are affixed to aquatic animals that are passively tracked using networks of underwater acoustic receivers (Cooke et al 2004;Brownscombe et al 2019). Acoustic receivers are typically deployed in a range of water depths and habitat types within the waterbody of interest, secured to an anchor in a variety of mooring designs (Crook et al 2017). Practitioners typically recover these receivers every 6-12 months to download data and perform routine maintenance (e.g., battery replacement, cleaning, firmware updates; Heupel et al 2006).…”

“…Due to the challenges with equipment recovery, much effort has gone into designing and refining methods. To date, recovery methods commonly involve grappling or scuba diving (Crook et al 2017), each having unique challenges. Grappling requires the deployment of an impermanent anchoring system that can be retrieved, and a second anchor with a ground line that is hooked by dragging a grappling hook device.…”

“…Acoustic receivers are typically deployed in a range of water depths and habitat types within the waterbody of interest, secured to an anchor in a variety of mooring designs (Crook et al. 2017). Practitioners typically recover these receivers every 6–12 months to download data and perform routine maintenance (e.g., battery replacement, cleaning, firmware updates; Heupel et al.…”