The diamond squid (Thysanoteuthis rhombus): A review of the fishery and recent research in Japan

Age, growth and hatching season of the diamond squid Thysanoteuthis rhombus estimated from statolith analysis and catch data in the western Sea of Japan

“…T. rhombus that migrate into the Sea of Japan are transported by the Tsushima Current from the southwestern Pacific through the East China Sea (Nishimura, 1966). Therefore, the wide range of the hatching season, the correspondence of hatching/spawning seasons between the up-and downstream areas of the Tsushima Current, and the possible time difference of the peaks all suggest that T. rhombus caught in the Sea of Japan hatch over a wide area extending from the southwestern Pacific (probably from southwest of Okinawa) to the East China Sea, which is where free-floating egg masses and paralarvae have been widely collected (see the review by Bower and Miyahara, 2005).…”

“…The biology and fishery of T. rhombus are summarized by Nigmatullin and Arkhipkin (1998) and Bower and Miyahara (2005), but the age, growth and hatching season for individuals that migrate into the Sea of Japan are poorly known. Miyahara and Gorie (2004) investigated length-weight relationships using 10,432 squids caught in the western Sea of Japan and estimated parameters for allometry formulae.…”

Approaches to resolving cephalopod movement and migration patterns

“…Similarly, distinct coastal and oceanic parasite communities have been identified for a number of Atlantic ommastrephid species (Gaevskaya 1977, in Gonzá lez et al 2003Gaevskaya and Nigmatullin 1978;Bargov 1982;Shukhgalter 1990, in Gonzá lez et al 2003). Geographic differences in parasite fauna made stock discrimination possible in the oceanic squid O. bartramii (Bower and Margolis 1991) and T. rhombus (Bower and Miyahara 2005), and indirectly provided information on movement. However, explicit movement and migration studies require more detailed information on parasitehost specificity and parasite geographic distribution (Nagasawa and Moravec 2002).…”

“…Sea surface temperature is the most easily obtained, and therefore the most common parameter used to assess links between cephalopod distribution and environment, providing an easily obtained proxy for oceanographic variability. Other factors such as rainfall, river discharge (Sobrino et al 2002), water turbidity (Roberts and Sauer 1994;Faure et al 2000;Schö n et al 2002), solar flux, sea level pressure, wind speed, wind direction (Denis et al 2002) sea level variability (Miyahara et al 2005) and salinity (Laughlin and Livingston 1982) may also be important in influencing the distribution and migration of various cephalopod populations.…”

“…Interest in the influence of environmental parameters on cephalopod movement/migration at the various life cycle stages is increasing. Much work has been done examining environmental influences on the abundance and distribution of cephalopods (particularly those which form significant fisheries), and the development of models utilising some of the observations described here to predict abundance and distributions are becoming more common (Roberts et al 1998;Waluda et al 1999;Agnew et al 2002;Denis et al 2002;Ichii et al 2002;Pierce and Boyle 2003;Reiss et al 2004;Zuur and Pierce 2004;Miyahara et al 2005;Sacau et al 2005), enabling a better understanding of the processes influencing cephalopod population variability. Understanding these patterns will become increasingly important, with increased ocean temperatures predicted as a consequence of global warming, which could disrupt or change migration patterns for some cephalopod species, as is predicted for migrating pacific salmon (Welch et al 1998).…”