Distribution and ecology of bigeye thresher Alopias superciliosus in the Pacific Ocean

• Published in: Fisheries science Vol. 79; no. 5; pp. 737 - 748
• Main Authors: Matsunaga, Hiroaki, Yokawa, Kotaro
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01.09.2013; Springer Nature B.V
• Subjects: Alopias superciliosus; Archives & records; Autumn; Biomedical and Life Sciences; Ecology; Fish; Fish & Wildlife Biology & Management; Fisheries management; Fishery sciences; Food Science; Freshwater & Marine Ecology; Life Sciences; Marine; Neonates; Nursery grounds; Original Article; Sexes; Sharks; Studies; Summer; Thermal capacity; Thunnus; Tuna; Water temperature; Winter; Pacific Ocean; IN, North Pacific; Pacific Ocean; Bigeye thresher; Ecological characteristics; Distribution
• ISSN: 0919-9268; 1444-2906
• DOI: 10.1007/s12562-013-0660-3

We analyzed records of shark capture by tuna longline vessels during the period 1992–2006 to document the distribution and ecology of bigeye thresher in the Pacific Ocean. Catch per unit effort (CPUE) was highest in the area of 10–15°N in the north and 5–10°S in the south. Juveniles <150 cm were also distributed in this area. Seasonal changes in the distribution of abundance are thought to represent seasonal migrations in latitude. We observed an increase in the ratio of large individuals at high latitude, likely a result of their increased thermal capacity allowing them to migrate further. Males were captured more often than females, suggesting that there is segregation by sex. Pregnant females were observed from 0°N to 36°N in the north Pacific. Neonates were observed between 10–15°N/150–180°W, overlapping with the area in which large numbers of juveniles were captured. Thus, we hypothesize that this area represents the parturition and nursery grounds for bigeye thresher in this region.