Fish sound production and acoustic telemetry reveal behaviors and spatial patterns associated with spawning aggregations of two Caribbean groupers

Abstract

Regional abundances of Nassau grouper Epinephelus striatus and yellowfin grouperMycteroperca venenosa have declined due to overfishing of their spawning aggregations, prompting permanent and seasonal fisheries closures in the US Virgin Islands (USVI). As both species produce sounds associated with reproductive behaviors (courtship-associated sounds; CAS), passive acoustic and acoustic telemetry methods were used to determine temporal patterns of reproductive activity, site usage, and fish movements in order to assess the effectiveness of current management strategies at 2 marine protected areas (MPAs) in the USVI: the Grammanik Bank (GB) and Hind Bank Marine Conservation District (MCD). Patterns of sound production and ultrasonic acoustic tag detections showed that both species formed spawning aggregations from January through May at the GB, highlighting the current seasonal regulations (1 February to 30 April) as insufficient for protecting spawning stocks during the entire reproductive season. Acoustic tagging confirmed connectivity between the GB and MCD and exposed the broad extent of habitat used, including non-protected areas, during the spawning season. Spawning did not likely occur within the MCD, but the MPA did support abundances of calling individuals during spawning periods, indicating that both species produce CAS away from their spawning sites. This finding coupled with the detection of routine migrations between spawning and non-spawning sites presents a potential mechanism to lead conspecifics to the aggregation site and thereby increase reproductive fitness and spawning output. KEY WORDS: Nassau grouper • Epinephelus striatus • Yellowfin grouper • Mycteroperca venenosa • Passive acoustics • Ultrasonic acoustic tagging • Fish movement patterns • Marine protected area Resale or republication not permitted without written consent of the publisher

Movement patterns of juvenile hawksbill turtles Eretmochelys imbricata at a Caribbean coral atoll: long-term tracking using passive acoustic telemetry

“…Passive acoustic telemetry is a technique by which focal animals can be tracked using a fixed array of hydrophones, previously used extensively with marine mammals (e.g. Soldevilla et al 2014, Miller et al 2015, where animals are detected from their vocalizations, and fish, where animals are equipped with individualized transmitters that are de tected by receivers (Heupel & Hueter 2001, Rhodes & Tupper 2008, Rowell et al 2015. Al though it can be costly in terms of the initial financial input for receivers and transmitters, and the routine maintenance of equipment, this long-term monitoring enables the continuous collection of data not influenced by survey effort or observer presence (Lowe et al 2006, Cooke 2008, Zeh et al 2015.…”

Reproductive behaviour and concurrent sound production of Gulf grouper Mycteroperca jordani (Epinephelidae) at a spawning aggregation site

“…Sound production did not exhibit patterns in relation to lunar phase, as has been described in a number of related species (Rowell et al ., ; Schärer et al ., ), indicating that courtship and spawning may occur continuously during the reproductive season and are not driven by lunar forces. This claim is supported by observations of spawning occurring from 2 dbfm to 13 dafm, a duration that exceeds the number of days typical for epinephelids that spawn following lunar periodicity (Nemeth, ).…”

“…As fishes produce sounds associated with agonistic, disturbance and reproductive behaviours (Lobel, 1992;Lobel et al, 2010;, visual observations coupled with passive acoustic monitoring have increasingly been used to characterize spatio-temporal patterns of habitat use, courtship, spawning and acoustic behaviours in a number of epinephelid species (Mann et al, 2010;Nelson et al, 2011;Schärer et al, 2012b;Rowell et al, 2015), including the yellowfin grouper Mycteroperca venenosa (L. 1758) (Schärer et al, 2012a) and black grouper Mycteroperca bonaci (Poey 1860) (Schärer et al, 2014;Locascio & Burton, 2016;Sanchez et al, 2017), which are native to the western Atlantic Ocean and the closest living relatives to M. jordani (Craig & Hastings, 2007 (Bertucci et al, 2015;Mann & Lobel, 1998;Nelson et al, 2011), thereby permitting the monitoring of validated, acoustic behaviours using passive acoustics outside of observational periods (Rountree et al, 2006). With knowledge of the behaviours associated with sound production during spawning aggregations, long-term acoustic monitoring complement visual observations to deduce the daily timing and seasonality of spawning (Schärer et al, 2012a(Schärer et al, ,b, 2014 and estimate abundances remotely from recorded sound metrics .…”

Patterns of courtship acoustics and geophysical features at spawning sites of black grouper (Mycteroperca bonaci)

“…With passive acoustic monitoring, therefore, it is possible to conduct a more detailed analysis of the courtship patterns of black grouper than current methods allow (Rowell et al, 2011(Rowell et al, , 2015. Traditionally, FSAs are monitored by using diver surveys and analysis of gonadal-somatic indices (GSIs).…”