Inferring individual fate from aquatic acoustic telemetry data

Abstract

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Toward a better understanding of fish‐based contribution to ocean carbon flux

“…For instance, supply in one area of the Angola continental margin was estimated at 0.4 mg C m −2 d −1 (equivalent to 4% of the estimated particulate carbon flux) (Higgs et al 2014). Data on natural mortality of fishes are limited and difficult to observe in the field, but telemetry (Bird et al 2017; Villegas‐Ríos et al 2020) or size‐dependent relationships with mortality (Lorenzen 1996; Sogard 1997) may offer insights. For example, over a period of 7 yr, natural senescence was observed in 17% of cod ( Gadus morhua ) tagged with acoustic transmitters in a coastal marine reserve where fishing is prohibited (Villegas‐Ríos et al 2020).…”

“…Data on natural mortality of fishes are limited and difficult to observe in the field, but telemetry (Bird et al 2017; Villegas‐Ríos et al 2020) or size‐dependent relationships with mortality (Lorenzen 1996; Sogard 1997) may offer insights. For example, over a period of 7 yr, natural senescence was observed in 17% of cod ( Gadus morhua ) tagged with acoustic transmitters in a coastal marine reserve where fishing is prohibited (Villegas‐Ríos et al 2020). The practice of discarding unwanted catch by fishery vessels has increased carcass‐bound carbon fluxes worldwide (Ramsay et al 1997); about 9.1 million tonnes were discarded annually between 2010 and 2014 (Pérez Roda et al 2019), which could have contributed approximately 0.91 million tonnes C yr −1 from bycatch alone.…”

Sea temperature effects on depth use and habitat selection in a marine fish community

“…the no-take marine reserve; Figure 1) were also removed from the dataset. Data were inspected for individual fate, namely death and dispersal, following the method described in Villegas-Ríos et al (2020). Data obtained after natural mortality events, characterized by stabilized vertical and horizontal movements, were removed from the datasets.…”

Predicting the factors influencing the inter‐ and intraspecific survival rates of riverine fishes implanted with acoustic transmitters

“…One fate not considered here is the possible consumption of tagged fish by aquatic predators ( e.g ., pike, otters), with the acoustic tags still appearing active in the study system. Elsewhere, this is typically identified by uncharacteristic changes in depth or horizontal space use (Klinard & Matley, 2020; Villegas‐Ríos et al ., 2020), but given the nature of the study system ( i.e ., shallow and relatively spatially confined), the movements of bream or pike and their predators were considered difficult to distinguish. The use of new telemetry technology designed to definitively identify predation events (Halfyard et al ., 2017) has revealed acoustic transmitters may be retained for a substantial time in the guts of piscivorous predators (>150 days; Klinard et al ., 2019), meaning survival may have been overestimated here.…”

“…This includes the planning of sampling and release protocols, tagging procedures and timeframes of subsequent telemetry (Bolland et al ., 2019). However, of studies that apply acoustic telemetry to aquatic ecology/behavioural research, around 50% fail to account for or acknowledge the mortality of the study species (Klinard & Matley, 2020), and a standardized method for identifying the fates of tagged fish ( e.g ., survival, natural mortality, fishing mortality) has only recently been developed (Villegas‐Ríos et al ., 2020). Consequently, as the diversity of tracking technologies and tracked fish species expands, including a wider range of fish sizes and morphologies, such as Anguillids and flatfish (Neves et al ., 2018; Thorstad et al ., 2013), knowledge gaps surrounding the effects of telemetry are potentially widening.…”