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Does the California market squid 

 (Loligo opalescens) spawn naturally during 

 the day or at night? A note on the successful use 

 of ROVs to obtain basic fisheries biology data 



John Forsythe 



National Resource Center for Cephalopods 

 University of Texas Medical Branch at Galveston 

 301 University Blvd 

 Galveston, Texas 77555-1163 

 E-mail address: |ohn forsythetg' utmb.edu 



Nuutti Kangas 



Roger T. Hanlon 



Marine Resources Center 

 Marine Biological Laboratory 

 Woods Hole, Massachusetts 02543 



The California market squid iLoligo 

 opalescens Berry), also known as the 

 opalescent inshore squid ( FAO ), plays a 

 central role in the nearshore ecological 

 communities of the west coast of the 

 United States (Morejohn et al., 1978; 

 Hixon, 1983) and it is also a prime 

 focus of California fisheries, ranking 

 first in dollar value and tons landed 

 in recent years (Vojkovich, 1998). The 

 life span of this species is only 7-10 

 months after hatching, as ascertained 

 by aging statoliths ( Butler et al., 1999; 

 Jackson, 1994; Jackson and Domier, 

 2003) and mariculture trials (Yang, et 

 al., 1986). Thus, annual recruitment is 

 required to sustain the population. The 

 spawning season ranges from April to 

 November and spawning peaks from 

 May to June. In some years there can 

 be a smaller second peak in November. 

 In Monterey Bay, the squids are fished 

 directly on the egg beds, and the con- 

 sequences of this practice for conser- 

 vation and fisheries management are 

 unknown but of some concern (Hanlon, 

 1998). Beginning in April 2000, we 

 began a study of the in situ spawning 

 behavior of L. opalescens in the south- 

 ern Monterey Bay fishing area. 



The prevailing thought is that the 

 majority of spawning activity takes 

 place at night because fishermen have 

 observed these squids mating under 

 their bright lights (which are used to 



attract and capture squids) and be- 

 cause television documentaries have 

 revealed mating and spawning activ- 

 ity in large aggregations at night. The 

 scientific literature on reproductive 

 behavior is sparse. There are some cur- 

 sory observations of actively spawning 

 L. opalescens during diver surveys 

 of egg beds (McGowan, 1954; Fields, 

 1965; Hobson, 1965; Hurley, 1977). 

 Some daytime spawning has been 

 seen both in southern and northern 

 California but Fields ( 1965 ) and Hixon 

 (1983) suggested indirectly that most 

 spawning occurs at night. Shimek et 

 al. (1984) also suggested night spawn- 

 ing by L. opalescens in Canada. Other 

 loliginid squids whose natural behav- 

 ior has been studied in the field were 

 found to be daytime spawners (e.g., L. 

 pealeii, L. vulgaris reynaudii, Sepioteu- 

 this sepioidea; summarized in Hanlon 

 and Messenger, 1996). 



To help resolve this issue, we con- 

 ducted three field expeditions (28 

 April-8 May 2000, 10-17 September 

 2000, and 16-21 August 2001) using 

 remotely operated vehicles (ROVs) de- 

 ployed either from the RV John Martin 

 (Moss Landing Marine Laboratory) or 

 the commercial squid FV Lady J. The 

 ROVs were tethered vehicles with on- 

 board video cameras and lights. Live 

 video signals were transmitted by 

 the tether to shipboard VCRs where 



observational data were viewed and 

 recorded. For the first field trip, a 

 large S4 Phantom ROV was used; it 

 was outfitted with a video camera and 

 zoom lens with tilt capability, and the 

 video was recorded on Hi8 format video 

 decks. For the second and third trips, 

 a smaller S2 inspection-class Phantom 

 ROV on loan from the NOAA Sustain- 

 able Seas Expeditions was used; this 

 ROV had a customized fiber-optic teth- 

 er and the video data were recorded on 

 mini-digital video cassettes. Our goal 

 was to make ROV dives each day from 

 approximately dawn to dusk and to 

 make a few comparable all-night sur- 

 veys. A combination of adverse weather 

 conditions and technical problems with 

 the ROVs rarely allowed continuous 

 video observations. During dives, if 

 squids were encountered, we used 

 video to conduct focal animal samples 

 on females (which were paired) for as 

 long as squids were present, or as long 

 as we could keep track of the same 

 individuals. Unless absolutely neces- 

 sary to see the squids (for instance at 

 night or at depths greater than 30 m 

 in turbid daytime conditions), lights 

 were not used for video taping in an 

 effort to minimize their impact on 

 the mating squids. Squids acclimated 

 within minutes to the ROVs. After the 

 expeditions, the videotapes were stud- 

 ied and the behavioral and biological 

 data were quantified on a multimotion 

 playback VCR. 



By "mating" we refer to the peculiar 

 mating behavior of this species that 

 is unique among loliginid squids. The 

 male firmly grasps the female from her 

 ventral side and holds her for minutes 

 or hours in a "copulatory embrace" in 

 a nearly vertical position. Both copula- 

 tion (i.e., transfer of spermatophores) 

 and deposition of egg capsules occur 

 in this posture. For example, as the 

 female exudes a new egg capsule, the 

 male and female lower themselves in 

 unison to the egg bed where the female 

 deposits the egg capsule in the sand. 

 We have reported elsewhere on egg- 



Manuscript approved for publication 

 20 January 2004 by Scientific Editor. 



Manuscript received 25 January 2004 

 at NMFS Scientific Publications Office. 



Fish. Bull. 102:389-392 (2004). 



