Rockfish acoustic telemetry

Cowcod are the primary species that have influenced groundfish regulations since 2001 in California waters. More progressive management approaches have been adopted during this time, and many rockfish species, including cowcod, now appear to be rebuilding. This rebuilding has recently translated into increased cowcod catches by both recreational and commercial fishers, and the use of descending devices has become a popular method for releasing these fish with as little harm as possible. However, post-release mortality of cowcod associated with the use of these descending devices is still unclear. We have tagged __ adult individuals using acoustic telemetry methods, and analyses of these movement data are currently underway. We will also tag juvenile and sub-adult cowcod in an effort to estimate size-dependent post-release mortality and movement patterns. This will give us a better understanding of the rebuilding status of the species, and how changes in fishing regulations might affect this rebuilding.

Recent population assessments of cowcod suggest the species is rebuilding, and increased interactions with commercial and recreational fisheries also suggest increasing numbers of cowcod. However, it is unclear how these increased catch-and-release events translate to impacts on the stock, and how changes in fishing depth restrictions might affect cowcod mortality. We will use acoustic telemetry to measure post-release mortality and movement patterns of cowcod, as well as the effectiveness of descending devices for releasing individuals back to depth.

These data are unclassified.

Data will be stored on a SWFSC server.

The data are not scheduled for release, and will be accessible to the researchers conducting the study.

Vemco designs the acoustic telemetry equipment to maximize representativeness of the parameters being measured, such as presence/absence, depth, temperature, etc.

Transmitter sensor accuracy is published by Vemco, and is based on the pre-programmed specifications of the model(s) being used.

These data will be comparable with several other studies because Vemco acoustic telemetry equipment is one of the most popular companies among fisheries researchers. The data are collected exactly the same way in studies that use the same equipment types.

All detection data obtained specific to the individuals that we tag will be usable for analyses.

The precision of the transmitter sensors is published in the manual for the models specified.

Transmitter sensors will only allow measurements if they are in range of a receiver, so there are spatial limits on detection capabilities.