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Growth and population structure of Dosidicus gigas in the Southeastern Pacific Ocean
Masuda, S.; Yokawa, K.; Yatsu, A.; Kawahara, S. (1998). Growth and population structure of Dosidicus gigas in the Southeastern Pacific Ocean, in: Okutani, T. Contributed papers to International Symposium on Large Pelagic Squids, July 18-19, 1996, for JAMARC's 25th anniversary of its foundation. pp. 107-118
In: Okutani, T. (1998). Contributed papers to International Symposium on Large Pelagic Squids, July 18-19, 1996, for JAMARC's 25th anniversary of its foundation. Japan Marine Fishery Resources Research Center: Tokyo. 269 pp., more

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    Marine

Authors  Top 
  • Masuda, S.
  • Yokawa, K.
  • Yatsu, A.
  • Kawahara, S.

Abstract
    In order to describe population structure of Dosidicus gigas, mantie lengths (ML) , total and gonadal weight were measured and maturity stages were determined on 9,284 individuals, 8-98 cm ML, collected off Peru and Ecuador during 1987-95. Age of 584 squid, 2-86 cm ML, were estimated from the statolith microstructure. In most of the areas and seasons, all males and females were mature or maturing at 20-30 cm and 30-40 cm ML, respectively. Between latitudes 3.5 and 13.5 during the austral spring and summer (October to January) , however, some males were still immature until 50-60 cm and same females did not sexually mature until 65- 75 cm ML, indicating that two groups are occurring in that area in terms of size at maturity. The estimated age in days ranged from 44 in an unsexed 2 cm ML juvenile to 352 in a 77 cm male and to 338 in a 86 cm female. ML-age relation was best approximated by a linear model when juveniles (2-9 cm ML) were excluded. The ML-age relationship varied with sex and hatch seasons, which were almost year round. The present results indicated that D. gigas consists of early- and late-maturing groups and is probably a multiple spawner without negative effect of maturation on their growth.

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