NOTE Forsythe et al.: Spawning patterns of Loligo opa/escens 



391 



Two other ascribed characteristics of L. 

 opalescens spawning are mass aggregations 

 at the sea floor and subsequent die-offs after 

 squids have spawned. Mass aggregations can 

 be detected by standard fathometers used by 

 commercial fishermen, who report that mass 

 aggregations on the sea floor are rare in Mon- 

 terey Bay. During our ROV operations we en- 

 countered only one large aggregation, which 

 occurred on 21 August 2001. We estimated 

 from our video recordings that there were ap- 

 proximately 3000-4000 squid in a 50-m 2 area 

 on the sea floor and that intermittent egg lay- 

 ing was occurring over an area of ca. 2000 m 2 

 during a period of about 3 hours. Collectively, 

 then, we recorded 154 very small spawning 

 groups and one large spawning group. There 

 was no mass die-off during or after this large 

 spawning aggregation. Instead, we consis- 

 tently observed in all spawning groups that 

 females actively broke the embrace of the 

 paired male and jetted strongly upwards away 

 from the spawning groups and rejoined large 

 schools in the upper water column. Thus, 

 squids that dispersed from the egg beds were 

 consistently in excellent condition — certainly 

 not senescent or moribund. These observa- 

 tions corroborate the results of other studies on loliginid 

 squids that spawn intermittently (Moltschaniwskyj, 

 1995; Maxwell and Hanlon, 2000 ). Twice we encountered 

 large numbers of dead squids on the sea floor in the early 

 morning, but in both instances the squid fishing fleet 

 had been working in the same area the night before and 

 it appeared as though these mortalities were associated 

 with the purse-seine fishery; there were few eggs in those 

 localities. McGowan ( 1954 ), Hobson ( 1965 ), and Cousteau 

 and Diole (1973) reported that squids died after spawn- 

 ing in S. California. Various Loligo spp. are noted for 

 flexible reproductive strategies (cf. Hanlon and Messen- 

 ger, 1996) so it should not be surprising if L. opalescens 

 occasionally engaged in large reproductive events. Our 

 data suggest that small groups of squids (20-200 indi- 

 viduals) generally descend during the day and lay eggs 

 for several hours before rejoining squids in the water 

 column. We encourage other researchers to use ROVs or 

 SCUBA without lights and with stealthy approaches to 

 determine the natural diurnal spawning of L. opalescens 

 throughout its range. Given our findings that active sex- 

 ual selection processes are occurring during the day and 

 that there is vertical migration between the large schools 

 of squid in the water column and the small spawning 

 groups at the substrate, it would be prudent, at the very 

 least, to restrict daytime fishing directly over egg beds 

 or to create protected spawning areas in southern Mon- 

 terey Bay. This strategy would allow the complex mating 

 system of L. opalescens to be played out without direct 

 disruption by fishing activity. In such a short-lived spe- 

 cies, annual recruitment to the population is necessary; 

 thus sufficient eggs must be laid for each new generation 

 to ensure a viable living resource. 



Acknowledgments 



We are most grateful for funding on NOAA grant UAF 98 

 0037 from the National Undersea Research Center (West 

 Coast). Additional funding was provided by the David and 

 Lucile Packard Foundation and the Sholley Foundation. 

 J. Forsythe gratefully acknowledges financial support for 

 travel from the National Institutes of Health, National 

 Center for Research Resources (grant P40 RR0102423- 

 23), and the Marine Medicine General Budget account of 

 the Marine Biomedical Institute. N. Kangas gratefully 

 acknowledges financial support from the Academy of 

 Finland. We thank Sylvia Earle for loan of the Sustain- 

 able Seas ROV and we appreciate the professional efforts 

 of Deep Ocean Exploration and Research (DOER) who 

 supported the ROV operations. We especially thank John 

 Rummel who helped begin this project, and Brett Hobson 

 who kept it going at a critical juncture. We are thankful for 

 expert shipboard assistance from the captains and crew of 

 the KVJohn Martin and the FV Lady J (especially Captain 

 Tom Noto). We benefitted from discussions with Bob Leos, 

 Bill Gilly, Annette Henry, John Butler, Teirney Thies, and 

 Sue Houghton. 



Literature cited 



Butler, J., D. Fuller, and M. Yaremko. 



1999. Age and growth of market squid iLoligo opalescens) 

 off California duringl998. CalCOFI Rep. 40:191-195. 

 Cousteau J.-Y.. and P. Diole. 



1973. Octopus and squid: the soft intelligence, 304 p. Cas- 

 sell, London. 



