VI. Cephalopod biology

ICES mar. Sei. Symp., 199: 411-413. 1995

Session report: The questions of squid recruitment

Ron O’Dor

The theme of the Symposium is shell fisheries, and, Ommastrephid squids, which account for the largest while cephalopods clearly belong here taxonomically, commercial biomass and value, are oceanic or nearly so the largest cephalopod fisheries are for squids, which and range over thousands of kilometers during individ­ seem functionally more like finfishes and long ago aban­ ual lifespans, typically of 6-18 months. All share charac­ doned their shells. Nonetheless, it was valuable and teristic rhynchoteuthion larvae, which are often difficult appropriate for the squid group to join in the Sym­ to distinguish. Most genera and some species or species posium, as the short life histories of squid mean that complexes are globally distributed, but the genus Illex is fisheries models designed for typical long-lived fishes are confined to the Atlantic. It may have arisen in the Medi­ often inappropriate. terranean during a period of isolation, with I. coindetii as In fact, our session produced more questions than its progenitor, and its spéciation may have been associ­ answers and did not reach the level of modelling because ated with Atlantic spreading (Lipinski, 1981). Figure 1 there are still such large gaps in our knowledge of popu­ indicates the distribution of the four currently accepted lation structure that it remains impossible in most cases species. Illex illecebrosus and argentinus are commer­ to contemplate population dynamics. A most reassuring cially important and are associated, respectively, with report from Sanchez showed clearly the power of the the Gulf Stream and the Brazil Current. It has been statolith aging technique to separate Illex coindetii into proposed that large biomass fisheries are often associ­ different cohorts with differing life histories, providing a ated with individually large squids that have a selective new confidence that we can, at least know when squid advantage for life cycles requiring migrations in such start their life cycles. Bizikov provided an exciting new powerful, productive eastern boundary currents advance on this theme with a procedure for reconstruct­ (Coelho, 1985; Hatanaka et al., 1985; O ’Dor, 1992). ing growth histories for individuals by combined reading Illex oxygonius is a sympatric species with a distribution of gladii and statoliths. This is a powerful new tool for that overlaps both I. illecebrosus and the Caribbean I. assessing the “quality of life” on a day-by-day basis for coindetii. squids over most of their lives, which really has no Figure 1 also includes an outline of major current counterpart in most other organisms. Nigmatullin put systems in the North and South Atlantic, as well as a bar this growth record into perspective with his discussion of indicating the length of the longest spawning migration the changing ecological niches of squids as their scale of an I. illecebrosus recorded from tag recapture. Given changes during ontogeny. this adult mobility and the evidence that Illex eggs Where and who questions remained as complex as (O’Dor and Balch, 1985) and larvae (Rowelle/a/., 1984) ever. While Rodhouse etal. clarified the life cycle of part can be transported thousands of kilometers in these of the Illex argentinus population, Haimovici et al. currents, one must wonder how reproductively isolated showed that the larvae are even more widely distributed any of these squids really are. Geography is not much of than had been thought. Borges used discriminate analy­ a barrier, and male I. illecebrosus will even mate with sis of morphological characters to demonstrate potential Loligo pealei in captivity. Reports in this Symposium overlaps in time and space of distinct populations or, at provide good evidence that, while there is more than one least cohorts, of Todarodes sagittatus, and Katugin simi­ peak of breeding activity in the year, these peaks are not larly showed allozymic differences in geographically so distinct as to isolate populations temporally. In fact, overlapping stocks of Berryteuthis magister. Lipinski they suggest that morphology may be as strongly and O’Dor reviewed the distribution and taxonomic influenced by when squid hatch as by who their parents problems in the genus Illex from the perspective of are. population dynamics, and, while it seemed inappro­ Clearly squid are tremendously adaptable to varying priate to publish a detailed taxonomic work in this thermal and dietary regimes. This plasticity, combined forum, the presentation is summarized here because it with a short generation time and a highly competitive, provides a useful context for the other works. highly selective life style, may allow squid to “evolve” 412 R. O ’D o r ICES mar. Sei. Symp., 199 (1995)

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Ahe=k/nX ^ StribUt.i0n 0fSq?JJoîrT_'^e 8en“s 7//f according to Lu (1973), supplemented with data from Korzuna e, f n u lllecef)r™us Lesueur, 1821, - I. coindetii Verany, 1837; □ = /. oxygonius Roper, Lu & Mangold 1969- 0 = 1 7 : Z Z Cr f T ' r i ° r ? * “ cu";fntsfarc md,cated bV arrows< «* **U as the length of the longest recorded migration of a tagged I. illecebrosus by the bar between Newfoundland and France. ICES mar. Sei. Symp., 199 (1995) The questions of squid recruitment 413 rapidly into different “morphs” . Such “re-evolution” of Coelho, M. L. 1985. Review of the influence of oceanographic a high-altitude morph from a valley morph has been factors on cephalopod distribution and life cycles. NAFO Sei. Coun. Stud., 9: 47-57. associated with cyclic abundance of the larch bud moth Rodhouse, P., Dawe, E. G., and O’Dor, R. K. (editors) 1995. and defoliation in the European Alps (Baltensweller, Squid recruitment dynamics, ca. 350 pp., FAO, Rome. 1984). The possible analogy between the cycle of Hatanaka, H., Kawahara, S., Uoxumi, Y., and Kasahara, S. morphs in this short-lived, highly competitive species 1985. Comparison of life cycles of five ommasterphid squids fished by Japan: Todarodes pacificus, Illex illecebrosus, Illex and abundance cycles of “high latitude” squids in cur­ argentinus, Nototodarus sloani sloani and Nototodarus sloani rent systems is being explored (O’Dor, 1992; O’Dor and gouldi. NAFO Sei. Coun. Stud., 9: 59-68. Coelho, 1993). We can only be sure that a morph that Korzuna, J. V., Nesis, K. N., Nigmatullin, C. M., Ostajenko, spends its entire life in high temperature, oligotrophic A .A ., and Pinchukov, M. A. 1979. Novye drannye o raspre- water is genetically (or even taxonomically) different delenii Kalmanov Semejstva Ommasterphidae v Mirovom Okeane (New data about the distribution of squids from the from one exposed to a range of low temperatures in family Ommastrephidae in the World Ocean). Okeanologya, more productive waters, if we study their genetics. How 19: 701-711 (in Russian). many generations does it take to restock a long-mi- Lipinski, M. R. 1981. Systematyune i ewolucyjne znaueuie gration morph population from a localized tropical zmien nosci Kalwarow z retraju Illex (Systematic and evolu­ tionary significance of variability in the squid genus Illex). morph through reselection of specific genomic charac­ Ph.D. Thesis, University of Goterisk, Poland. 196 pp. (in ters? Polish). During the discussion period after the session, the Lu, C. C. 1973. Systematics and zoogeography of the squid group prepared an outline and organized authorship of a genus Illex (Oegopsida; Cephalopoda). Ph.D. Thesis, volume on squid recruitment processes which has been Department of Biology, Memorial University of Newfound­ land, Canada. 389 pp. accepted for publication by FAO (Rodhouse et al., O’Dor, R. K. 1992. Big squid in big currents. S. Afr. J. Mar. 1995). The focus of this volume will be the Illex complex Sei., 12:225-235. and the interpretation of squid population dynamics O’Dor, R. K., and Coelho, M. L. 1993. Big squid, big currents based on the techniques described here. We have the and big fisheries. In Recent advances in cephalopod fishery biology. Ed. byT. Okutani, R. K. O’Dor, andT. Kubodera. techniques to know when and where squid were spawned Tokai University Press, Tokyo. and why they survived, but we think that it will only be O’Dor, R. K., and Balch, N. 1985. Properties of Illex illecebro­ possible to predict what will happen to squid stocks, if we sus egg masses potentially influencing larval oceanographic also know who was responsible. distribution. NAFA Sei. Coun. Stud., 9: 69-76. Rowell, T. W., Trites, R. W., and Dawe, E. G. 1984. Distri­ bution of short-finned squid (Illex illecebrosus) larvae and References juveniles in relation to the Gulf Stream frontal zone between Florida and Cape Hatteras. NAFO Sei. Coun. Stud., 9: 77- Baltensweller, W. 1984. The role of environment and repro­ 92. duction in the population dynamics of the larch bud moth, Zeiraphera diniana Gn. (Lepidoptera, Tortricidae). In Ad­ vances in invertebrate reproduction 3. Ed. by W. Engels el Ron O'Dor, Biology Dept., Dalhousie University, Halifax, al., pp. 291-302. Elsevier, Amsterdam. Canada, B3H4JI.