Reviews in Fish Biology and Fisheries

, Volume 17, Issue 2–3, pp 207–221 | Cite as

Effects of commercial fishing on the population structure of spawning southern calamary (Sepioteuthis australis)

  • Ty Hibberd
  • Gretta T. Pecl
Original Paper


This study explored population dynamics of Sepioteuthis australis on a fine temporal scale before, during, and after a 3-month commercial fishing closure on the summer inshore spawning grounds of Great Oyster Bay, Tasmania, Australia. An abrupt change in male size (mantle length) and population sex ratio after the re-opening of the commercial fishery suggests that fishing alters the population structure on the spawning beds from a ‘natural’ structure which is highly biased towards males, to a more even ratio of males to females. Although jigs are taking a representative sample of the squid population using the spawning beds at any one time, the fishery is apparently still effectively selective for males, potentially as a function of differential spawning movements of the two sexes. Increased fishing pressure over the past 5 years had been correlated with a change towards a highly male-biased sex ratio on the spawning beds; however the current study suggests that increased fishing pressure in recent years may not have reduced the proportion of females. Instead, the inter-annual change in sex ratio may reflect changes in the degree of protection from fishing, with progressively longer closures allowing time for more males to accumulate on the beds and therefore, for the proportion of males to increase (as opposed to a decrease of females). As fishing is selective for males, fishing throughout the spawning season could potentially modify the process of sexual selection and the mating behaviors of the individuals within the spawning population, highlighting the need for closures over this crucial period. Additionally, examinations and comparisons of squid population structure need to be interpreted in light of fishing pressure and broader movement patterns.


Sex ratio Commercial closure Fishing pressure Population structure Squid Spawning aggregation 



Grateful acknowledgement is made to Dr George Jackson (IASOS, UTAS) whose valuable suggestions greatly improved the manuscript. The authors thank staff at Tasmanian Aquaculture and Fisheries Institute Marine Research Laboratories, particularly Sean Tracey for assistance with data collection and analysis; and Dr Natalie Moltschaniwskyj and Graeme Ewing for their enthusiasm and support with field operations. We are indebted to all the commercial fishers who volunteered their assistance in the collection of specimens, in particular to Ian and Barbara Barrett. This research was supported by ARC (grant number LP0347556), DPIWE, the Tasmanian Recreational Fishery Trust, and the Tasmanian Commercial Calamary Fishers.


  1. Anderson MB (1994) Sexual selection. Princeton University Press, Princeton, NJGoogle Scholar
  2. Birkhead TR, Parker GA (1997) Sperm competition and mating systems. In: Krebs JR, Davies NB (eds) Behavioural ecology: an evolutionary approach. Blackwell, Oxford, pp 121–145Google Scholar
  3. Boyle PR, Boletzky SV (1996) Cephalopod populations: definition and dynamics. Phil Trans R Soc Lond B 351:985–1002CrossRefGoogle Scholar
  4. Caddy JF (1983) The cephalopods: factors relevant to their population dynamics and to the assessment and management of stocks. In: Caddy JF (ed) Advances in assessment of world cephalopod resources. FAO Fish Tech Pap 231. Rome, FAOGoogle Scholar
  5. Emlen ST, Oring LW (1977) Ecology, sexual selection, and the evolution of mating systems. Science 197:215–223PubMedCrossRefGoogle Scholar
  6. Hall KC, Hanlon RT (2002) Principal features of the mating system of a large spawning aggregation of the giant Australian cuttlefish Sepia apama (Mollusca: Cephalopoda). Mar Biol 140:533–545CrossRefGoogle Scholar
  7. Hanlon RT (1998) Mating systems and sexual selection in the squid Loligo: How might commercial fishing on spawning squids affect them? CalCOFI Rep 39:92–100Google Scholar
  8. Hewitt GM, Butlin RK (1997) Causes and consequences of population structure. In: Krebs JR, Davies NB (eds) Behavioural ecology: an evolutionary approach. Blackwell, Oxford, pp 350–372Google Scholar
  9. Ho J, Moltschaniwskyj NA, Carter CG (2004) The effect of variability in growth on somatic condition and reproductive status in the southern calamary Sepioteuthis australis. Marine and freshwater Research 55:423–428CrossRefGoogle Scholar
  10. Jackson GD, Pecl G (2003) The dynamics of the summer spawning populations of the loliginid squid Sepioteuthis australis in Tasmania, Australia - a conveyor belt of cohorts. ICES J Mar Sci 60:290–296CrossRefGoogle Scholar
  11. Jantzen TM, Havenhand JN (2003) Reproductive Behaviour in the Squid Sepioteuthis australis from South Australia: Interactions on the Spawning Grounds. Biol Bull 204:305–317PubMedCrossRefGoogle Scholar
  12. Law R (2000) Fishing, selection, and phenotypic evolution. ICES J Mar Sci 57:659–668CrossRefGoogle Scholar
  13. Lipiński MR (1979) ‘Universal maturity scale for the commercially important squids. The results of maturity classification of the Illex illecebrosus population for the years 1973–77. ICNAF Res Doc 79/2/38, Serial 5364, International Commission for the Northwest Atlantic Fisheries, Dartmouth, CanadaGoogle Scholar
  14. Lipiński MR (1994) Differences amoung basic biological parameters in a population of Chokka squid Loligo vulgaris reynaudii (Cephalopoda: Loliginidae) sampled by three methods. South African Journal of Marine Science 14:281–286Google Scholar
  15. Lyle JM (2003) Tasmanian Scalefish Fishery Assessment - 2002. Tasmania Aquaculture and Fisheries Institute, University of Tasmania, HobartGoogle Scholar
  16. Lyle JM and Haddon M (2003) Description and assessment of the Tasmanian southern calamary fishery – Chapter 7. In: Moltschaniwskyj NA, Pecl G, Lyle JM, Haddon M, Steer M (eds) Population dynamics and reproductive ecology of southern calamary (Sepioteuthis australis) in Tasmania. FRDC Final Report 2000/121. pp 117–143Google Scholar
  17. Mangold K, Young R, Nixon M (1993) Growth versus maturation in cephalopods. In: Okutani T, O’Dor R, T Kubodera T (eds) Recent Advances in Cephalopod Fisheries Biology. Tokai University Press, Tokyo, pp 697–703 Google Scholar
  18. Moltschaniwskyj NA, Pecl G (2003) Small-scale spatial and temporal patterns of egg production by the temperate loliginid squid Sepioteuthis australis. Mar Biol 142:509–516Google Scholar
  19. Moltschaniwskyj NA, Pecl G, Lyle J (2003) The effect of short temporal fishing closures to protect spawning southern calamary populations from fishing pressure in Tasmania, Australia. Bull Mar Sci 71:501–514Google Scholar
  20. Moltschaniwskyj NA, Semmens J (2000) Limited use of stored energy reserves for reproduction by the tropical loliginid squid Photololigo sp. J Zool Lond 251:307–313CrossRefGoogle Scholar
  21. Parker GA (1984) Sperm competition and the evolution of animal mating systems. In: Smith RL (ed) Sperm Competition and the Evolution of Animal Mating Systems. Academic Press, Orlando, FL, pp 1–60Google Scholar
  22. Pecl G (2001) Flexible reproductive strategies in tropical and temperate Sepioteuthis squids. Mar Biol 138:93–101CrossRefGoogle Scholar
  23. Pecl G, Moltschaniwskyj NA, Tracey S, Jordan A (2004a) Inter-annual plasticity of squid life history and population structure: ecological and management implications. Oecologia 139:515–524CrossRefGoogle Scholar
  24. Pecl GT, Steer MA, Hodgson KE (2004b) The role of hatchling size in generating the intrinsic size-at-age variability of cephalopods: extending the Forsythe hypothesis. Mar Freshwater Res 55:387–394CrossRefGoogle Scholar
  25. Piatkowski U, Pierce GJ, Morais da Cunha M (2001) Impact of cephalopods in the food chain and their interaction with the environment and fisheries: an overview. Fish Res 52:5–10CrossRefGoogle Scholar
  26. Rodhouse PG (2001) Managing and forecasting squid fisheries in variable environments. Fish Res 54:3–8CrossRefGoogle Scholar
  27. Rodhouse PG, Murphy EJ, Coelho ML (1998) Impact of fishing on life histories. FAO Fish Tech Pap 376:255–268Google Scholar
  28. Ryan MJ (1997) Sexual selection and mate choice. In: Krebs JR, Davies NB (eds) Behavioural ecology: and evolutionary approach. Blackwell, Oxford, pp 179–202Google Scholar
  29. Sauer WHH, Roberts MJ, Lipiński MR, Smale MJ, Hanlon RT, Webber DM, O’Dor RK (1997) Choreography of the squid’s “Nuptial Dance”. Biol Bull 192:203–207PubMedCrossRefGoogle Scholar
  30. Sims D, Genner M, Southward A, Hawkins S (2001) Timing of squid migration reflects North Atlantic climate variability. Proc R Soc Lond B 268:2607–2611CrossRefGoogle Scholar
  31. Steer MA, Pecl G, Moltschaniwskyj NA (2003) Are bigger calamary Sepioteuthis australis hatchlings more likely to survive? A study based on statolith dimensions. Mar Ecol Prog Ser 261:175–182Google Scholar
  32. van Camp LM, Donnellan SC, Dyer AR, Fairweather PG (2004) Multiple paternity in field- and captive-laid egg strands of Sepioteuthis australis (Cephalopoda: Loliginidae). Mar Freshwater Res 55(8):819–823CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  1. 1.Institute of Antarctic and Southern Ocean StudiesUniversity of TasmaniaTasmania, HobartAustralia
  2. 2.Tasmanian Aquaculture and Fisheries InstituteUniversity of TasmaniaTasmania, HobartAustralia

Personalised recommendations