Choreography of the Squid's "Nuptial Dance"

Abstract

A mass spawning of squid resembles, at first glance, a chaotic "nuptial dance" (1). But for the first time, we have applied 3-D, radio-linked acoustic positioning (RAP) to this confusing process, and our early results now reveal a choreography that is, in fact, well organized in time and space. Remote tracking with RAP of individual Loligo vulgaris reynaudii off South Africa has provided insights into the daily sequence of behaviours that lead these animals to aggregate for sexual selection. Each dawn, the squid navigate for several kilometers, towards the shore, to small, well-defined zones near egg beds on the substrate. After several hours of circling above the egg beds, a pelagic, 3-D lek-like aggregation of large males forms: females are drawn in, and the aggregation condenses as the females and males pair, mate, and lay eggs. Smaller "sneaker males" remain on the periphery of the mating arena and, from this station, attempt extra-pair copulations (EPCs). The mating system of squids is thus unexpectedly complex, rivaling those of mammals and birds (2, 3). Commercial squid-jigging fishermen in South Africa have recently been attracted to the spawning grounds, and they have been successful. Moreover, their activities may be selective for large males. Thus, attention should be devoted to ensuring that such targeted fishing does not alter the characteristics of squid population genetics. Remote tracking and video observations, in combination with genetic analyses, may offer a new opportunity to monitor mating effort and reproductive success, and thus to manage the fishery.

Use of acoustic telemetry for spatial management of southern calamary Sepioteuthis australis, a highly mobile inshore squid species

“…Like most loliginds investigated thus far, Sepioteuthis australis arrive at dawn in the vicinity of the egg beds and probably spawn throughout the day (see Jantzen & Havenhand 2003) with reproductive activity waning at sunset, as with Loligo opalescens , Loligo vulgaris reynaudii (Sauer et al 1997), Loligo pealeii, and Sepioteuthis sepioidea (Hanlon & Messenger 1996). Females may be distributing reproductive effort over many different spawning beds, as they made more frequent but shorter trips in and around Great Oyster Bay after being detected on any of the spawning bed receivers, whereas males made fewer, longer trips.…”

“…20 to 40% of the estimated total lifespan. Most telemetry studies of cephalopods thus far have been limited to behavioural and/or energetics research using radio acoustic positioning and telemetry (RAPT) systems over small spatial and temporal scales (Sauer et al 1997, O'Dor et al 2000. Clearly, acoustic tracking is also a successful research tool by which to explore movement and migration of cephalopods over much larger spatial and temporal scales as demonstrated here, and also by Stark et al (2005) with Nototodarus gouldi, which were recorded for periods of up to 37 d using a system of VR2.…”

Multiple paternity and complex fertilisation dynamics in the squid Loligo vulgaris reynaudii

“…Previous behavioural observations have shown that individuals engage in complex mating behaviours in mating arenas situated over large communal spawning beds on the sea floor (Sauer & Smale 1993, Sauer et al 1997, Hanlon et al 2002. Females arriving on the spawning grounds often have sperm present in a storage organ below the buccal mass.…”

The Use of Acoustic Telemetry in South African Squid Research (2003-2010)

“…As a result, the majority of research on the chokka squid has focused on inshore spawning, i.e. environmental effects on spawning (Augustyn, 1990, Roberts, 1998, 2005Roberts & Sauer, 1994;Roberts & van den Berg, 2002, 2005Sauer et al , 1992, the impact of fishing on spawning concentrations (Hanlon et al, 2002;Oosthuizen et al, 2002a;Sauer, 1995;Schön et al 2002), biological studies (Augustyn 1990;Lipinski & Underhill, 1995;Olyott et al, 2006;Roel et al, 2000;Sauer & Lipinski, 1990;Sauer, 1995;Sauer et al, 1992Sauer et al, , 1999, life cycle (Augustyn, 1990(Augustyn, , 1991Olyott et al 2007;Roberts & Sauer, 1994), feeding on the spawning grounds (Augustyn, 1990;Sauer & Lipinski, 1991;Sauer & Smale, 1991Sauer et al, 1992), spawning behaviour (Hanlon et al, 1994(Hanlon et al, , 2002Sauer, 1995;Sauer et al 1992Sauer et al , 1997Shaw & Sauer, 2004), the inshore spawning environment (Augustyn, 1990;Roberts, 1998Roberts & Sauer, 1994;Roberts and van den Berg, 2002;Sauer et al , 1992, the location of spawning grounds (Augustyn, 1990;…”

“…Initial telemetry experiments, conducted in 1993(Sauer et al, 1997, made use of a four buoy radio-linked acoustic positioning system and simple acoustic transmitters. The use of this then "unorthodox technique" (Sauer et al, 1997) led to the discovery that the formation of spawning aggregations and mating behaviours is well organized in time and space. The advancement of telemetry systems has enabled researchers to apply this technique to many different areas of research.…”